CP CU1. Reference Manual

Transcription

1 CP CU1 Reference Manual

2 CP CU1 Reference Manual Article Number: VESD0671 Manual Version: CPCU1.AE.5 OMICRON electronics All rights reserved. This manual is a publication of OMICRON electronics GmbH. All rights including translation reserved. Reproduction of any kind, for example, photocopying, microfilming, optical character recognition and/or storage in electronic data processing systems, requires the explicit consent of OMICRON electronics. Reprinting, wholly or in part, is not permitted. The product information, specifications, and technical data embodied in this manual represent the technical status at the time of writing and are subject to change without prior notice. We have done our best to ensure that the information given in this manual is useful, accurate and entirely reliable. However, OMICRON electronics does not assume responsibility for any inaccuracies which may be present. The user is responsible for every application that makes use of an OMICRON product. OMICRON electronics translates this manual from the source language English into a number of other languages. Any translation of this manual is done for local requirements, and in the event of a dispute between the English and a non-english version, the English version of this manual shall govern. 2

3 Contents Contents 1 Hardware Information Overview Circuit Diagram of the CP CU Operating Controls of the CP CU CP CU1 Accessories Optional Accessories CP GB1 Grounding Box Description Shorting the Phases Changing the Surge Arrestors Clamp-on Ammeter CP AL Description Connectors Battery Replacement Operation Measurement Setup Operating Principle Configuring the CPC Setting the CP CU Safety Instructions for Connecting the CP CU1 to Power Lines Before Starting Recommended Current Range Settings Estimating the Open-Line Voltage Connecting the Measurement Setup to Power Lines Applications Template Usage Line Impedance Measurement and k Factor Determination Why k Factor Measurement? Mutual Coupling of Power Lines Performing Measurements Interpretation of Measurement Results CPC 100 Excel File Loader Ground Impedance Measurement

4 CP CU1 Reference Manual Introduction Performing Measurements Reduction Factor Performing Measurements Interpretation of Measurement Results Step and Touch Voltage Measurements Introduction to Measurement According to VDE 0101/CENELEC HD 637 S1: Introduction to Measurement According to IEEE , and Performing Measurements Measurement Principles Measurement Procedure Measurement According to VDE 0101/CENELEC HD 637 S1: Measurement According to IEEE , and Interpretation of Measurement Results Measurement of Coupling into Signal Cables Introduction Performing Measurements Technical Data CP CU1 Output Ranges CP CU1 Measuring Transformers CP CU1 Inputs CP GB1 Specifications Output Power Accuracy Environmental Conditions Mechanical Data Clamp-on Ammeter (Accessory) Specifications CP AL1 Specifications CE Declaration of Conformity Test & Calibration Certificates International Warranty Appendix CP AL

5 Contents Operation of the CP AL Menu Bar Measurement Functions FFT Analysis Setup Screen Battery State Indication Contact Information / Technical Support

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7 Using This Manual Using This Manual This Reference Manual provides detailed information on how to use the CP CU1 coupling unit safely, properly and efficiently. The CP CU1 Reference Manual contains important safety instructions for working with the CP CU1, gets you familiar with operating the CP CU1, and provides typical application examples. Following the instructions in this Reference Manual will help you to prevent danger, repair costs and possible down time due to incorrect operation. The CP CU1 Reference Manual always has to be available at the site where the CP CU1 is used. It must be read and observed by all users of the CP CU1. Reading the CP CU1 Reference Manual alone does not release you from the duty of complying with all national and international safety regulations relevant to working with the CPC 100 and CP CU1. The regulation EN "The Erection and Operation of Electrical Test Equipment" as well as all the applicable regulations for accident prevention in the country and at the site of operation has to be fulfilled. Operator Qualifications and Safety Standards Working on overhead lines is extremely dangerous. Testing and measuring with the CP CU1 must be carried out only by qualified, skilled and authorized personnel. Before starting to work, clearly establish the responsibilities. Personnel receiving training, instructions, directions, or education on the CP CU1 must be under constant supervision of an experienced operator while working with the equipment. Testing and measuring with the CP CU1 must comply with the relevant national and international safety standards listed below: EN (VDE 0104) "Erection and Operation of Electrical Equipment" EN (VDE 0105 Part 100) "Operation of Electrical Installations" IEEE 510 "IEEE Recommended Practices for Safety in High-Voltage and High-Power Testing" LAPG NASA "Electrical Safety" Moreover, additional relevant laws and internal safety standards have to be followed. 7

8 CP CU1 Reference Manual Conventions and Symbols Used In this manual, the following symbols indicate paragraphs with special safety relevant meaning: Symbol Description Equipment damage or loss of data possible. Personal injury or severe damage to objects possible. Related Documents The following documents complete the information covered in the CP CU1 Reference Manual: Title CPC 100 User Manual CPC 100 Reference Manual Description Contains information on how to use the CPC 100 test system and relevant safety instructions. Contains detailed hardware and software information on the CPC 100 including relevant safety instructions. 8

9 Safety Rules Safety Rules Before operating the CP CU1 coupling unit, read the following safety rules carefully. If you do not understand some safety rules, contact OMICRON electronics before proceeding. The CP CU1 is designated for use with the CPC 100 test system. Therefore, observe the safety rules both in this Reference Manual and in the CPC 100 User/Reference Manual when working with the CP CU1. Depending on the application and the device under test, specific safety instructions must be observed. Very often, the danger coming from the device under test is even higher than the danger from the CP CU1 itself. For application-specific safety instructions, see 3.2 "Line Impedance Measurement and k Factor Determination" on page 42. General Always observe the five safety rules: Disconnect completely Secure against re-connection Verify that the installation is dead Carry out grounding and short-circuiting Provide protection against adjacent live parts Do not touch any terminals without a visible connection to ground. Before handling the CP CU1 or CPC 100 in any way, connect them with a solid connection of at least 6 mm 2 cross-section to ground. Ground the CP CU1 as close as possible to the CPC 100. Use the CP GB1 grounding box to connect the CP CU1 to overhead lines and power cables. For detailed information, see the application-specific 3.2 "Line Impedance Measurement and k Factor Determination" on page 42. When using the CP GB1, ground it near the place where the connection to the test object is made. Make sure that the grounding stud is in good condition, clean and free of oxidation. Make sure that all studs and cables of the CP GB1 are screwed tight. Make sure that the test object s terminals to be connected to the CP CU1 do not carry any voltage potential. During a test, the only power source for a test object should be the CP CU1 (powered by the CPC 100). The only exception are measurements on overhead lines as described in 3 "Applications" on page 41. 9

10 CP CU1 Reference Manual Do not open the CP CU1 s or CP GB1 s housing. Do not repair, modify, extend, or adapt the CP CU1, CP GB1 or any accessories. Use only original accessories available from OMICRON electronics. Use the CP CU1, CP GB1 and their accessories only in a technically sound condition and when its use is in accordance with the regulations. In particular, avoid disruptions that could in turn affect safety. Do not use the CP CU1 if you have a cardiac pacemaker. Before operating the CP CU1 make sure that there is no person with a cardiac pacemaker in the immediate vicinity of the measurement setup. Operating the Measurement Setup Before operating the CP CU1, CPC 100, and CP GB1 ground them as described in "General" on page 9. When using the CP GB1, ground it near the place where the connection to the test object is made. Make sure that the grounding stud is in good condition, clean and free of oxidation. Life threatening voltages up to 600 V can appear on all CP GB1 s contacts and on all clamps and cables connected to the CP CU1 during the test. Keep safe distance from them. Before handling the CP CU1 or CP GB1 in any way (even before setting the current range switch), make sure that the device under test (for example, overhead lines or power cables) are well grounded (for example, by closing the grounding switch) near the measurement setup. Power the CP CU1 only from the CPC 100 s EXT. BOOSTER output. Use only booster cables supplied by OMICRON electronics. Ensure that the short-circuit bar is always plugged in the CP CU1 s IAC output whenever the output is not connected to the IAC input of CPC 100. Connect the CP CU1 s IAC output exclusively to the IAC input of the CPC 100. Before connecting the CP CU1 with the CPC 100, turn off the CPC 100 either by the POWER ON/OFF switch or the Emergency Stop button. Set the current range switch on the CP CU1 s front panel only when the CPC 100 is turned off and the test object is grounded. In addition to the above safety rules follow the application-specific 3.2 "Line Impedance Measurement and k Factor Determination" on page

11 Safety Rules Orderly Measures The CP CU1 Reference Manual or alternatively the e-book in PDF format has always to be available on site where the CP CU1 is being used. It must be read and observed by all users of the CP CU1. The CP CU1 may be used only as described in 3 "Applications" on page 41. Any other use is not in accordance with the regulations. The manufacturer and/or distributor is not liable for damage resulting from improper usage. The user alone assumes all responsibility and risk. Following the instructions provided in this Reference Manual is also considered part of being in accordance with the regulations. Disclaimer If the equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may be impaired. 11

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13 Hardware Information 1 Hardware Information 1.1 Overview The CP CU1 is a coupling unit designated for measurements with the CPC 100 test system mainly on overhead lines and power cables. Typical applications include line and cable impedance measurements, measurements of k factors, mutual coupling of power lines, step and touch voltage measurements, measurements of coupling between power lines and signal cables, and ground impedance measurements. The CP GB1 grounding box (see 1.5 "CP GB1 Grounding Box" on page 19) is a surge arrestor unit protecting the operating staff and equipment from high-voltage hazards during measurements on overhead lines and power cables in case of unexpected events on the power line. 1.2 Circuit Diagram of the CP CU1 Figure 1-1 "Circuit diagram of the CP CU1" below shows the principal circuit diagram of the coupling unit. Fuse 30 A Power transformer Current range switch IAC (0 2.5A) Surge arrestor BOOSTER CT I OUT (0 100 A) Voltmeter V1 AC (0 30 V) V SENSE (0 600 V) Surge arrestor VT Figure 1-1 Circuit diagram of the CP CU1 13

14 CP CU1 Reference Manual 1.3 Operating Controls of the CP CU1 The front panel of the CP CU1 provides the following functional elements: BOOSTER input for connecting with the CPC 100 s EXT. BOOSTER output Current range switch for setting the current range of the CP CU1 Voltmeter for measuring the voltage at the test object s terminals IOUT current output IAC output for measuring the output current using a CT (current transformer) with the 100 A : 2.5 A transformation ratio The output is to be connected with the IAC input of the CPC 100. V SENSE input for measuring the voltage at the test object s terminals V1 AC output for measuring the voltage at the test object s terminals using a VT (voltage transformer) with the 600 V : 30 V transformation ratio The output is to be connected with the V1 AC input of the CPC 100. Short-circuit bar for shorting the IAC output whenever the output is not connected to the IAC input of the CPC 100 Equipotential ground terminal for grounding the CP CU1 close to the position of the operating staff 14

15 Hardware Information Figure 1-2 "Front panel of the CP CU1" below shows the CP CU1 s functional elements. Equipotential ground terminal Location to I AC output V1 AC output V SENSE input store the shortcircuit bar Fuse 30 A BOOSTER input Current range switch Voltmeter I OUT output Figure 1-2 Front panel of the CP CU1 15

16 CP CU1 Reference Manual 1.4 CP CU1 Accessories The following accessories are delivered with the CP CU1 coupling unit: Accessories Booster cable V1 AC coax. cable Description Power connection from the CPC 100 s EXT. BOOSTER output to the CP CU1 s BOOSTER input Connection from the CPC 100 s V1 AC input to the CP CU1 s V1 AC output 4 x Banana cable Connection from the CPC 100 s I AC input to the CP CU1 s I AC output and connection from the CP CU1 s V SENSE input to the Kelvin clamps voltage sense outputs 2 x Kelvin cable Connection from the CP CU1 s I OUT output to the current feed-in point (usually at the CP GB1) Grounding cable Connection from the CP CU1 s equipotential ground terminal to the substation ground Short-circuit bar A bar for shorting the CP CU1 s I AC output when the output is not connected to the I AC input of the CPC

17 Hardware Information Optional Accessories Accessories Clamp-on Ammeter Description Clamp-on ammeter for up to 400 A AC Step and Touch Voltage Accessory Set CP AL1 FFT Voltmeter including adapter for 1k resistors For step and touch voltage measurements Test peak For touch voltage measurements on metal surfaces 2 x Banana cable Connection to CP AL1 for step and touch voltage measurements Ground rod For step and touch voltage measurements to be driven into the soil Pair of foot electrode water cans For step voltage measurements according to HD637S1 and IEEE

18 CP CU1 Reference Manual Accessories Ground Impedance Set GPS Garmin etrex Description For distance measurements Rogowski coil For reduction factor measurements 6 x Cable reels For connection between the CPC 100 and the ground rods 3 x Ground electrode For ground impedance measurements to be driven into the soil MV-cable set 3 x Cable with clamps on both ends For connecting the CP GB1 to MV-cable installations 18

19 Hardware Information 1.5 CP GB1 Grounding Box Description The CP GB1 grounding box (see Figure 1-3 "CP GB1 grounding box" below) is a surge arrestor unit for connecting the CP CU1 to the test object. If high voltage appears for a short time on the test object s terminals, an arc discharges the voltage and exstinguishes without destroying the grounding box. If the arc persists for a longer time period, the surge arrestor insulator melts and the terminals are short-circuited to ground, thereby protecting the operating staff, CP CU1 and CPC 100. Other stud standards available optionally L1 line stud A/L1/red Equipotential ground stud L2 line stud B/L2/yellow L3 line stud C/L3/blue Figure 1-3 CP GB1 grounding box Caution: The CP GB1 grounding box must be used for measurements on overhead lines or power cables. 19

20 CP CU1 Reference Manual To test object To CP CU1 Surge arrestor Ground connection Figure 1-4 Connection of the CP GB1 The CP GB1 grounding box is available for three different ground connection types: cylindrical grounding studs of 16 mm diameter or ball studs of 20 mm and 25 mm (1 inch) diameter. The grounding socket clamp is needed for secure ground connection of the CP GB1 to the substation ground. The grounding socket clamps compatible with the grounding studs in the substation are given in the table below. For ordering information, contact OMICRON electronics sales office. When ordering the CP GB1, choose one connection set; additional connection sets are available optionally. 20

21 Hardware Information Grounding Stud in the Substation 16 mm cylindrical grounding stud Proper Grounding Socket Clamp mm grounding socket clamp (shipped with the 16 mm cylindrical and 20 mm ball CP GB1 s studs) 12 mm 20 mm ball grounding stud 25 mm ball grounding stud 25 mm grounding socket clamp (shipped with the 25 mm CP GB1 s studs) 16 mm 21

22 CP CU1 Reference Manual Warning: Depending on the type of grounding studs in the substation, the appropriate connection set and socket clamp have to be used. Connecting socket clamps of one type to a grounding point of another system is highly dangerous on both the connection of the grounding set to the CP GB1 and the connection of the CP GB1 to the grounding point in the substation. The 16 to 20 mm socket clamps are designed and tested for fault currents up to 26.5 ka, the 25 mm (1 inch) socket clamp for fault currents up to 30 ka, both for a maximum duration of 100 ms. On locations where higher fault currents are possible, the CP CU1 and CP GB1 must not be used. Figure 1-5 Screwing the CP GB1 s studs For transportation, the CP GB1 s studs are usually removed. If this is the case, mount them onto the CP GB1 using the delivered wrench and screw them tight (see Figure 1-5 "Screwing the CP GB1 s studs" on page 22). 22

23 Hardware Information Shorting the Phases A three-lead cable is delivered with the CP GB1 for shorting all phases for L1 L2 L3-E measurements (see Figure 3-2 "Line-to-line impedance measurements" on page 45, Figure 3-9 "Ground impedance and step voltage measurement" on page 56, Figure 3-21 "Measurement with the loop between parallel lines and ground" on page 77). Figure 1-6 Three-lead cable To short the phases, connect the line studs of the CP GB1 as shown in Figure 1-7 "Shorting the phases" below. Figure 1-7 Shorting the phases 23

24 CP CU1 Reference Manual Changing the Surge Arrestors The surge arrestors of the CP GB1 can permanently short-circuit the CP GB1 s terminals to ground if overvoltage appears on the terminals. Even short transients can cause a discharge and, if the energy is too high, possibly damage the surge arrestor. Defective surge arrestors can result in erroneous measurement results. If the measurement results obtained using the CP GB1 differ considerably from the expected values, check the surge arrestors using the CPC 100 as follows. Apply a voltage of 500 V for at least 10 seconds using the VWithstand test card from the resistance test cards. Set a test current of 0.01 A. If the current is exceeded, an error message is displayed. In this case, the surge arrestor under test is defective and you have to replace it. If no message is displayed, the surge arrestor is intact. For detailed information on this test, see the CPC 100 Reference Manual. Repeat the test for all three studs A/L1, B/L2 and C/L3. Replace defective surge arrestors only with spare parts from OMICRON electronics (see Figure 1-8 "Surge arrestors" below). For ordering information, contact OMICRON electronics sales office. Figure 1-8 Surge arrestors Note: Before changing the surge arrestors, check whether there is a fault that caused the problem and remove it. 24

25 Hardware Information To replace a surge arrestor: 1. Disconnect the CP GB1 completely and observe the five safety rules in "Safety Rules" on page Open the surge arrestor chamber using a 22 mm wrench by removing the contact screw (see Figure 1-9 "Opening the surge arrestor chamber" below). Contact screw Figure 1-9 Opening the surge arrestor chamber 3. Turn the CP GB1 upright and move the stud over the surge arrestor chamber until the surge arrestor falls out. 4. Replace the defective surge arrestor by the spare one. 5. Screw the contact screw very tight (torsional moment of Nm). 25

26 CP CU1 Reference Manual 1.6 Clamp-on Ammeter A clamp-on ammeter for AC 50/60 Hz (see Figure 1-10 "Clamp-on ammeter" below) is available from OMICRON electronics as an accessory. For ordering information, contact OMICRON electronics sales office. Figure 1-10 Clamp-on ammeter The clamp-on ammeter provides the following features: Hold function Battery check Auto power off Bar display Voltmeter Ohmmeter Contact check with beeper 26

27 Hardware Information 1.7 CP AL1 The CP AL1 (see Figure 1-11 "CP AL1") is available from OMICRON electronics as an accessory for step and touch voltage measurement. For ordering information, contact OMICRON electronics sales office. Figure 1-11 CP AL Description Connectors NTI's FFT (Fast Fourier Transform) voltmeter CP AL1 is a product which is primarily designed for professional acoustical test applications. For step and touch voltage measurements, the CP AL1 is delivered with an OMICRON electronics software which allows measuring the frequency-selective voltage level by using a real-time Zoom FFT. The CP AL1 makes understanding and handling the step and touch voltage measurements simple. However, fundamental working knowledge of the step and touch voltage measurement techniques is a prerequisite for using the CP AL1. The CP AL1 provides the following connectors on the rear: XLR input for feeding a signal to the CP AL1 RCA input for feeding a signal to the CP AL1 3.5 mm (1/18") jack designed for internal use only Never connect any electrical signal to this connector. 27

28 CP CU1 Reference Manual Note: Never connect electrical signals simultaneously to both the XLR and the RCA connector. XLR connector RCA connector For internal use only Figure 1-12 Connectors Figure 1-13 CP AL1 with CP AL1 Adapter 28

29 Hardware Information Battery Replacement To insert or replace batteries, remove the rear cover, and then insert three 1.5 V alkaline batteries, type AA/LR6 into the CP AL1 battery compartment as shown below. The typical life-time for a set of alkaline batteries is 16 hours. Figure 1-14 Inserting batteries When replacing the batteries: Do not use rechargeable NiCd or NiMH batteries. Do not use batteries of different types. Observe the correct battery polarity. Remove the batteries as soon as they are flat and replace all batteries at the same time. Note: For the operation of the CP AL1 refer to "Operation of the CP AL1" on page

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31 Operation 2 Operation 2.1 Measurement Setup The measurement setup consists of the CPC 100 test system, of the CP CU1 coupling unit and, in case of measurements on overhead lines and power cables, of the CP GB1 grounding box. Figure 2-1 "Measurement setup" below shows the functional block diagram. Warning: The CP CU1 must be connected to the test object through the CP GB1 grounding box for measurements on overhead lines or power cables. For these applications, connect the measurement setup by following 3.2 "Line Impedance Measurement and k Factor Determination" on page 44. Dangerous zone V1 AC IAC V SENSE IAC V1 AC CPC 100 CP CU1 Device under test CP GB1 EXT. BOOSTER BOOSTER IOUT (optional) Figure 2-1 Measurement setup 2.2 Operating Principle The CP CU1 is a coupling unit controlled by the CPC 100 test system via the BOOSTER interface. The CP CU1 provides selectable current signals at the IOUT output and facilitates measuring of the output current and the voltage at the test object s terminals. The current range of 10 A, 20 A, 50 A or 100 A is set by the CPC 100 software (see 2.3 "Configuring the CPC 100" on page 32) and the current range switch on the front panel of the CP CU1 is set manually by the user (see 2.4 "Setting the CP CU1" on page 33). The output current and the voltage at the test object s terminals connected to the CP CU1 s V SENSE input and IOUT output are processed by the coupling unit for measuring with the CPC

32 CP CU1 Reference Manual The output current is transformed by a current transformer with the transmission ratio 100 A : 2.5 A and the secondary transformer winding wired to the IAC output. The transformed current at the IAC output is measured via the IAC input of the CPC 100. The test object s voltage is transformed by a voltage transformer with the transmission ratio 600 V : 30 V and the secondary transformer winding wired to the V1 AC output. The transformed voltage at the V1 AC output is measured via the V1 AC input of the CPC 100. The measurements are performed frequency-selective, that is, only signal components at the generated frequency different from the mains frequency are analyzed. Due to the high-power disturbances at the mains frequency, the spectral components around the mains frequency and its harmonics are filtered out. For detailed information on the frequency-selective measurement, see "Getting Started with Quick: The frequency selective measurement" in the CPC 100 Reference Manual. 2.3 Configuring the CPC 100 Note: The minimum CPC 100 software version required is V 1.4. If you have an earlier version installed, upgrade the software from the Toolsets delivered with your CP CU1. The CPC 100 must be configured for the CP CU1. To configure the CPC 100: 1. Press the Options view selector button. The Options window with the Device Setup tab selected (see Figure 2-2 "Options window" below) opens. Figure 2-2 Options window 2. Select CU1 from the External booster combo box. The CT and VT settings are set according to the built-in current and voltage transformers automatically. 32

33 Operation 3. Press the Test Card View view selector button and insert the Quick (default), Sequencer or Ramping test card. Figure 2-3 "Quick test card window" below shows the setting using the Quick test card as example. Output Range combo box Measured Quantities combo box Figure 2-3 Quick test card window 4. Open the item list from the Output Range combo box. The item list displays the CU1:10A, CU1:20A, CU1:50A and CU1:100A CP CU1 relevant current ranges. 5. Select the current range you want to use. 6. Select VT sel and/or CT sel from the Measured Quantities combo boxes when measuring with the CP CU1 s built-in voltage and current transformers to account for their transformation ratio. 2.4 Setting the CP CU1 Set the current range of CP CU1 using the current range switch (see 1.3 "Operating Controls of the CP CU1" on page 14) to the value configured by the CPC 100 software. Warning: Set the current range switch on the CP CU1 s front panel only when the CPC 100 is turned off and the test object is connected to ground with closed grounding switch near the measurement setup. Caution: Current range settings on the test card and on the CP CU1 s front panel must be the same. 33

34 CP CU1 Reference Manual 2.5 Safety Instructions for Connecting the CP CU1 to Power Lines Before Starting Warning: A lightning discharge to the line under test can cause injury or possibly death of the operating staff. Do not connect the measurement setup to overhead lines if there is a possibility of a thunderstorm over any part of the lines to be measured. Warning: Connecting the measurement setup to overhead lines with a life parallel system brings about high-voltage hazards. It is strongly recommended to take all parallel lines out of service before proceeding. Before connecting the CP CU1 to overhead lines or power cables (further on referred to as power lines), you must estimate the open-line voltage as follows. Follow the instructions below exactly and sequentially to protect yourself from high-voltage hazards. In addition to the following safety instructions, observe "Safety Rules" on page Recommended Current Range Settings The highest current range allowed by the open-line voltage (see "Connecting the Measurement Setup to Power Lines" on page 38) provides the best measurement accuracy. However, depending on the length of the power line under test, this setting may result in CPC 100 overload due to low driving voltage. As a rule of thumb, the current range required for the power line length is given in Table 2-1 "Recommended current range settings" below. Set the current range switch of CP CU1 to the value according to the table. Line Length Current Compliance Voltage Range 0 2 km/0 1.5 miles 100 A 50 V 1 10 km/0.5 5 miles 50 A 100 V 5 50km/3 30miles 20A 250V >20km/15miles 10A 500V Table 2-1 Recommended current range settings Note: Steps as shown in the following comprehensive diagram will be explained in more detail in sections and

35 Operation Reduce the current for the higher frequencies as needed to avoid overloads. Try to keep identical settings for all test cards in one procedure. Yes Are 60 A possible? Start the measurement according to the application description in one of the following chapters. Try to find out the maximum possible current at 20 Hz above and below the mains frequency to avoid overload display. No Is the value greater than 50 V? No Is Line Length /km (0.64 /mi) I GS greater than 50 V? Yes Set 50 A No Set 50 A Yes Set 50 A Yes Stop! The measurement cannot be performed on this line. Try to take parallel lines out of service or to reduce the current flow on the parallel systems. Connect a grounding set in parallel to the closed grounding disconnector to each phase. Connect it first to the ground and then to the line. Open the grounding disconnector and measure the currents in all three grounding sets. Use the highest measured value of I GS in the following formula. Close the grounding disconnector after the measurement is done. Start with the 100 A current range. Is the line longer than 2km/1.5 No Yes Set 50 A Is the line longer than 10 km/6 mi No Yes Set 20 A Is the line longer than 50 km/30 No Yes Set 10 A Use the 10 A current range. Are 30 A possible? No Is the value greater than 100 V? Close the grounding disconnector, disconnect the grounding sets first from the line and then from the ground. Connect the grounding sets to the CP GB1 and then to the line. Make the connections to the CP CU1 and CPC 100 according to the figures on the following pages. Open the grounding disconnector and read the display value of the CP CU1. Close the grounding disconnector afterwards. No Is Line Length /km (0.64 /mi) I GS greater than 100 V? Yes Set 20 A No Set 20 A Yes Set 20 A Yes Are 12 A possible? No Is the value greater than 250 V? No Is Line Length /km (0.64 /mi) I GS greater than 250 V? Set 10 A Yes Set 10 A No Set 10 A Yes Yes Is 1 A possible? No Is the value greater than 500 V? No Is Line Length /km (0.64 /mi) I GS greater than 500 V? No Yes Yes 35

36 CP CU1 Reference Manual Estimating the Open-Line Voltage Before connecting the CP CU1 to overhead lines or power cables (further on referred to as power lines), estimate the open-line voltage as follows. Follow the instructions below exactly and sequentially to protect yourself from high-voltage hazards. In addition to the following safety instructions, observe "Safety Rules" on page 9 of this manual and the safety rules in the CPC 100 User/Reference Manual. To estimate the open-line voltage: Warning: Before grounding a power line, make sure that the line is not powered with the life-dead-life test as follows: Using a certified voltage tester approved for the voltage tests, verify on a life system that the tester is operational, on the line to be unpowered that it is dead and on a life system again that the tester is still working. When grounding a power line, observe the five safety rules as described in "General" on page Switch off, short-circuit and ground the power line on both sides using an installed grounding switch or, if no grounding switch is available on site, using grounding cables (further on, the grounding switch or these extra grounding cables are referred to as grounding switch). 2. Make sure that the connection to ground at the far end of the power line is not removed during the complete test procedure. 3. In addition to the grounding switch, ground the line at the near end using a grounding set consisting of three cables rated for the maximum short-circuit current possible on the line. This connection is called working ground further on. 4. Open the grounding switch at the near end of the power line and measure the current through the working ground using a clamp-on ammeter on all three phases. 5. Close the grounding switch. 6. Calculate the estimated open-line voltage after removal of the grounding cables as follows: V est [V] = meas [A] 0.4 [ /km] 2 l line [km] (Eg. 2-1) or V est [V] = meas [A] 0.64 [ /mile] 2 l line [miles] (Eg. 2-2) 36

37 Operation where V est [V] is the estimated open-loop voltage in volts, meas is the highest measured current in ampers, 0.4 [ /km] = 0.64 [ /mile] is the constant of a typical overhead line per wire and l line [km] and l line [miles] is the length of the line in km and miles respectively. Warning: If the estimated open-line voltage is > 500 V, stop. The measurement is not possible due to high-voltage hazard. Try to take parallel lines out of service V, the measurement is possible only in the 10 A range V, the measurement is possible in the 10 A or 20 A range V, the measurement is possible in the 10 A, 20 A or 50 A range. < 50 V, the measurement is possible in all current ranges. 7. If the current range allowed by the estimated open-line-voltage is lower than the current range set according to Table 2-1 "Recommended current range settings" on page 34, set the current range switch of the CP CU1 to the value allowed by the open-line voltage. Warning: While the grounding switch at the near end of the power line is open, the area around CP GB1 in the range of 5 m/15 ft and around CP CU1 in the range of 2 m/5 ft is a dangerous zone due to high-voltage and mechanical hazards. Do not enter the dangerous zone. Keep the grounding switch open for a time as short as possible. Caution: If you see or hear anything uncommon in the test equipment, for example, noise of electrical discharge or lightening of surge arrestors, close the grounding switch before touching the measurement setup. 37

38 CP CU1 Reference Manual Connecting the Measurement Setup to Power Lines After determination of the current range with estimated open-line voltage (see "Estimating the Open-Line Voltage" on page 36), connect the measurement setup to the power line as follows: 1. Make sure that the grounding switch is closed. 2. Connect CP GB1 to ground using the delivered cable near the place where the connection to the line is made. Make sure that the grounding stud is in good condition, clean and free of oxidation. Warning: Depending on the type of grounding points in the substation, the appropriate connection set and socket clamp have to be used. Connecting socket clamps of one type to a grounding point of another system is highly dangerous on both the connection of the grounding set to the CP GB1 and the connection of the CP GB1 to the grounding point in the substation. The 16 to 20 mm socket clamps are designed and tested for fault currents up to 26.5 ka, the 25 mm (1 inch) socket clamp for fault currents up to 30 ka, both for a maximum duration of 100 ms. On locations where higher fault currents are possible, the CP CU1 and CP GB1 must not be used. 3. Disconnect the grounding cables from the ground (the grounding switch is closed!) and connect them to the CP GB1 s line studs. 4. Position the CP CU1 at a minimum distance of 5 m/15 ft from the CP GB1. 5. Position the CPC 100 at a minimum distance of 5 m/15 ft from the CP CU1 and 10 m/30 ft from the CP GB1. 6. Ground the CP CU1 using a cable of at least 6 mm 2 cross-section close to the CPC 100 and the position of the operator. 38

39 Operation 7. Connect the CP CU1 with the CP GB1 as shown in Figure 2-4 "Wiring the measurement setup" on page 39. ***) Use the short-circuit bar when the output is not connected to the I AC input of the CPC 100. Connection using grounding sets on site L3/C L2/B L1/A *** Figure 2-4 Wiring the measurement setup 8. Ground the CPC 100 using a cable of at least 6 mm 2 cross-section close to the position of the operator. 9. Connect the CP CU1 with the CPC 100 as shown in Figure 2-4 "Wiring the measurement setup" above. 10.Mark the area around the CP GB1 in the range of at least 5 m/15 ft and around the CP CU1 in the range of at least 2 m/5 ft as dangerous zone. 11.Set the current range switch to 10 A (500 V range). 12.Open the grounding switch and read the voltmeter on the CP CU1 s front panel from outside of the dangerous zone. 39

40 CP CU1 Reference Manual Figure 2-5 "Connecting the measurement setup" below shows the measurement setup connected to an overhead line. CPC 100 CP CU1 CP GB1 Figure 2-5 Connecting the measurement setup Warning: If the voltmeter s reading is > 500 V, stop. The measurement is not possible due to high-voltage hazard V, the measurement is possible only in the 10 A range V, the measurement is possible in the 10 A or 20 A range V, the measurement is possible in the 10 A, 20 A or 50 A range. < 50 V, the measurement is possible in all current ranges. 13.If the open-line voltage allows measurement in a higher current range as already set on the CP CU1, set the current switch of the CP CU1 to the minimum of the current range set according to Table 2-1 "Recommended current range settings" on page 34 and the current range allowed by the open-line voltage. If the open-line voltage allows measurement, proceed with the requested application. Caution: Make sure that the grounding switch is always closed when no measurement is performed and especially when the wiring is modified or the current range switch of the CP CU1 is set. 40

41 Applications 3 Applications 3.1 Template Usage This chapter contains information on template usage, power line impedance, mutual coupling of power lines, ground impedance and step and touch voltage measurements, as well as measurement of coupling into signal cables. The test procedures running on the measurement setup are controlled by templates available on the Toolsets shipped with your CP CU1 or on the CPC 100 Start Page. The templates are pairs of XML documents and Microsoft Excel templates designed by OMICRON electronics for designated applications. The XML templates are predefined test procedures, often with comments, that run on the CPC 100 and guide the user through the test. Once completed, the XML file is saved, downloaded to the PC using the CPC Explorer and then loaded into the corresponding Microsoft Excel template. There the results are post-processed and a final test report is generated. The template pairs facilitate and speed testing with the CP CU1 and the evaluation of results. Note: Some template pairs allow version control. If an error message appears after loading the XML template, use a template pair of the same version. To run a test procedure according to a template: 1. Upload the XML template for the intended application from the PC to the CPC Open the template on the CPC Run the test procedure according to the template. 4. After completing the test procedure, save the test in a new file. 5. Download the test results from the CPC 100 to your preferred working directory on the PC. 6. Open the corresponding Microsoft Excel template by double-clicking the *.xlt file in the folder labeled with the test procedure name. A Microsoft Excel workbook appears. 7. Click the Load XML-File button and open the *.xml file saved in your preferred working directory before you load the test results. 8. After all worksheets are filled with data, the test results are calculated. 41

42 CP CU1 Reference Manual 3.2 Line Impedance Measurement and k Factor Determination Why k Factor Measurement? On most modern secondary distance protection relays, the value of the positivesequence (line) and zero-sequence (line-to-ground) impedance or the ground impedance matching factor (k factor) is required to make the relay settings and sometimes also the mutual coupling factor. The line impedance can be readily calculated but the chosen values for the ground impedance often do not match the actual conditions. This is because nearby parallel systems have an influence on the measurement and thus discrepancies between the calculated and actual values are generated. Therefore, the mutual coupling factor between two systems has to be determined to consider these influences for the evaluation of the measurement results. The accuracy of these settings is crucial to the operation of the relay because they directly affect the reach of the different protection zones, for example, in case of a line-to-ground fault. Measurements show that in a significant number of cases the k factor of the measured lines is set more than 20% from its actual value. This can result in zone under- or overreach and consequently, the selectivity is lost. This situation is particularly relevant to underground power cables. The k factor is an important setting of distance protection relays. The precision of this setting affects the accuracy of distance protection relays dramatically. The k factor can be calculated, but the calculation results give only a rough estimate of the actual value. As a wrong k factor setting can cause worse power quality, higher risk to lose the system stability and loss of power supply, k factor measurements are essential for fast, selective and reliable distance protection. Because there are usually strong disturbances by other lines in service, measurement at the mains frequency is not feasible. All measurements running according to the templates are done below and above the mains frequency and the results are interpolated. From these results the positive- and zero-sequence impedances as well as the k factor in various formats are calculated. The k factors are line parameters independent of the fault location describing the ratio of the line and ground impedances. The following k factor definitions are commonly used: 42

43 Applications 1. The complex ratio of the ground impedance and the line impedance Z E Z L k L = Z E = Z L Z Z , (Eg. 3-1) 3 Note: Z 1 = Z L Z0 2. the complex ratio of the zero-sequence impedance and the positivesequence impedance Z 1 (see Figure 3-1 "Zero-sequence impedance definition" below) Z 0 k 0 = Z 1 (Eg. 3-2) 3. and a couple of real values R E R L (Eg. 3-3) X E X L (Eg. 3-4) where R E and X E are the real and imaginary parts respectively of the ground impedance and R L and X L are the real and imaginary parts respectively of the line impedance. Figure 3-1 Zero-sequence impedance definition The single-phase zero-sequence impedance corresponds to a serial connection from the line impedance and the triple ground impedance. Z 1 Z E 43

44 CP CU1 Reference Manual Mutual Coupling of Power Lines Basically, mutual coupling is nothing but a voltage induced in the parallel system II, which is caused by a current in system I. Due to the voltage induced in system II, a current also flows in the parallel system, which in turn induces a voltage in system I. For measuring the coupling impedance Z M, the template requires two measurements. The advantage of this measurement is that no measurement is required on system II. Rather, all measurements are conducted on system I. In the first measurement, system II is separated from the ground on at least one end. Consequently, no current can flow through system II. The result is the zerosequence impedance Z 01 for the case that no current can flow in system II. For the second measurement, both ends of the line have to be grounded to ensure a flow of current. However, the voltage in system II becomes zero. The result of this measurement is the zero-sequence impedance Z 02. The coupling impedance Z M is now calculated from Z 01 and Z 02 : 1 Z M = -- Z (Eg. 3-5) 3 01 Z 02 Z 01 The coupling factor can be presented in two versions. The following equation shows the complex coupling factor k M. k M = Z M Z 1 (Eg. 3-6) In the two equations below, the real and imaginary components are split. R M R L X M and (Eg. 3-7) X L Performing Measurements Connect the measurement setup to the overhead lines or power cables under test following 3.2 "Line Impedance Measurement and k Factor Determination" on page 42. Note: For line length below 5 km/3 miles it is recommended to connect the V SENSE input of the CP CU1 as close as possible to the VT of the line to reduce the additional impedance of the current feed in the path. For longer lines, you can connect the V SENSE input with the Kelvin clamps directly on the CP GB1. 44

45 Applications In the course of the k factor test procedure, the following measurements are performed: Line-to-line impedance measurements: L1-L2, L1-L3, L2-L3 (Figure 3-2 "Line-to-line impedance measurements" below shows the L1-L2 measurement as example.) Far end Overhead line Near end V1 AC IAC CPC 100 EXT. BOOSTER IAC V1 AC V SENSE CP CU1 BOOSTER IOUT CP GB1 Figure 3-2 Line-to-line impedance measurements 45

46 CP CU1 Reference Manual Line-to-ground impedance measurements: L1-E, L2-E, L3-E (Figure 3-3 "Line-to-ground impedance measurements" below shows the L1- E measurement as example.) Far end Overhead line Near end V1 AC IAC CPC 100 EXT. BOOSTER IAC V1 AC VSENSE CP CU1 BOOSTER IOUT CP GB1 Figure 3-3 Line-to-ground impedance measurements Zero-sequence impedance measurements: L1 L2 L3-E (see Figure 3-4 "Zero-sequence impedance measurement - System II is in operation", Figure 3-5 "Zero-sequence impedance measurement - System II is off and disconnected from the ground on at least one end", and Figure 3-6 "Zero-sequence impedance measurement - System II is off and connected to the ground on both ends" below). 46

47 Applications Short the three phases with the delivered three-lead cable as shown in "Shorting the Phases" on page 23. Far end Overhead line Near end V1 AC IAC CPC 100 EXT. BOOSTER IAC V1 AC V SENSE CP CU1 BOOSTER IOUT CP GB1 Note: Use the three-lead cable (see "Shorting the Phases" on page 23) to short-circuit the phases. Figure 3-4 operation Zero-sequence impedance measurement - System II is in 47

48 CP CU1 Reference Manual Far end Overhead line Near end V1 AC IAC CPC 100 EXT. BOOSTER IAC V1 AC V SENSE CP CU1 BOOSTER IOUT CP GB1 Note: Changes to the previous figures are marked with a blue ellipsis. Figure 3-5 Zero-sequence impedance measurement - System II is off and disconnected from the ground on at least one end 48

49 Applications Far end Overhead line Near end V1 AC IAC CPC 100 EXT. BOOSTER IAC V1 AC V SENSE CP CU1 BOOSTER IOUT CP GB1 Note: Changes to the previous figure are marked with a blue ellipsis. Figure 3-6 Zero-sequence impedance measurement - System II is off and connected to the ground on both ends The test procedure is controlled by templates available on the Toolsets shipped with your CP CU1 or on the CPC 100 Start Page. It is recommended to use the same test current for all measurements. To find out the highest test current possible, start the test procedure with the measurement featuring the highest impedance, that is the phase-to-phase measurement in general (depending on the arrangement of wires and cables) and the phase-to-ground measurement on overhead lines. 49

50 CP CU1 Reference Manual After wiring the measurement setup to the line under test proceed as follows: 1. Configure the CPC 100 as described in 2.3 "Configuring the CPC 100" on page 32 for the CP CU1 s current range set by the current range switch. Caution: The configured current range must not exceed the limit by the openline voltage. 2. Choose the XML template (XMT) for the mains frequency (e.g. "Line Imp CU1 60Hz.xmt" for the 60 Hz mains frequency) and open the template. Warning: Open the grounding switch at the near end before making the test and keep it open only during the measurement. Close the grounding switch after the test and before reconnecting the measurement setup. 3. Run the test procedure. The following measurements are performed: Line-to-line measurements: L1-L2, L1-L3, L2-L3 For each measurement, connect the IOUT and V SENSE inputs of the CP CU1 to the corresponding CP GB1 s line studs. Line-to-ground measurements: L1-E, L2-E, L3-E For each measurement, connect the IOUT and V SENSE inputs of the CP CU1 to the corresponding CP GB1 s line studs. Zero-sequence impedance measurements: L1 L2 L3-E 4. Close the grounding switch after the test and before reconnecting the measurement setup. 5. If an overload of the CPC 100 occurs, reduce the test current or set a lower current range and run the test procedure once again. Lower test currents at the two highest frequencies are recommended. 6. Save the test procedure as a file on the CPC Download the test file from the CPC 100 to the PC using the CPC Explorer. Load the test file into the Microsoft Excel template. The measurement results are displayed Interpretation of Measurement Results To interpret the results of line impedance measurements correctly, you have to know details about the overhead line or power cable under test. You will find below some useful notes about how to interpret the measurement results. 50

51 Applications Usually, the resistive part of the line impedance is relatively constant over the L1-L2, L1-L3 and L2-L3 as well as L1-E, L2-E and L3-E measurements. If the measurement results differ considerably, typically contact problems are the reason. In some cases, the grounding switches at the far end of the line are not as good as necessary for the measurement. Additional grounding cables could help to avoid the contact problems. For the lines under test shorter than 5 km/3 miles, it is not recommended to connect the V SENSE input of the CP CU1 with the Kelvin clamps, but rather to use additional clamps directly on the wires of the power line, if a safe connection can be provided. The inductive part of the line impedance increases with the distance between the lines. This is documented by the measurement results stored in an example file delivered with the line impedance templates (see the marked results in Figure 3-7 "Measurement results" on page 52). The measured overhead line with the shortest distance between the lines L1 and L3 is shown in Figure 3-8 "Measured overhead line" on page 53. Note: For each line of measurement results there is a separate overload indication top right on the CPC 100 s screen (or in the report) explained below. No overload indication means no overload during that step of the measurement sequence. Dotted overload indication means that there was an overload during that step of the measurement sequence but not all the time. Solid overload indication means a permanent overload during that step of the measurement sequence CPC 100 Excel File Loader The CPC 100 Excel File Loader allows loading XML test files generated with the CPC 100 into Microsoft Excel templates for post-processing. The CPC 100 Excel File Loader is installed with the CPC 100 Toolset. After the installation, a shortcut to the CPC 100 Start Page appears on your desktop where you can start the CPC 100 Excel File Loader. Templates are pairs of XMT documents and Microsoft Excel templates designed by OMICRON electronics for designated applications. The XMT templates are predefined test procedures that run on the CPC 100 and guide the user through the test. Once completed, the XMT file is saved as an XML test file, and then loaded with the CPC

52 CP CU1 Reference Manual Excel File Loader into the corresponding Microsoft Excel template. There the results are post-processed and a final test report is generated. The template pairs facilitate and speed testing with the CPC 100 and the evaluation of results. Figure 3-7 Measurement results 52

53 Applications Click the button Load XML-File to open the browse menu to load the desired data to the template. Click Print Report to print the calculated data. Under "Measurements", the results of the impedances of the nine conducted measurements are shown in Cartesian and Eulerian form. The relevant calculated impedances are listed under "Impedance Results". Z 1 is the arithmetic mean value of the first three measurements. Z 0 is the triple value of the measured three-phase zero-sequence impedance and thus refers to one phase (see Figure 3-1 "Zero-sequence impedance definition"). The coupling impedance Z M is calculated according to (Eg. 3-5) on page 44. The coupling zero-sequence impedance Z M0 corresponds to the triple value of the coupling impedance Z M. The "Residual Compensation Factor" is the k factor calculated from the determined data for setting the relays. Under "Residual Compensation Factor Format", one of the three manufacturer-dependent formats can be selected. Under "Mutual Coupling Factor", the mutual coupling factor is indicated. As for the k factor, three different display formats are available. L2 L1 L3 Figure 3-8 Measured overhead line 53

54 CP CU1 Reference Manual The L2-E measurement features the lowest X component because the line is very close to the ground wire. The X component of the L3-E measurement is decreased by a parallel system taking course close to L3 on the other side of the tower. Short-circuiting of the parallel system during the measurement would have increased the effect and would have lead to erroneous results because this is not the normal operating condition. Another interesting effect can be observed when measuring power cables. If the screen or shield is very close to the conductors but the conductors are relatively wide from each other, the inductive part of the line-to-line measurements is higher than the inductive part of the line-to-ground measurements, resulting in a negative X component of the calculated impedance Z E. This seemingly strange result is explained as follows. Recalling (see "Why k Factor Measurement?" on page 42) that the zero-sequence impedance is given by Z 0 = Z 1 + 3Z E (Eg. 3-8) and hence Z 0 Z 1 Z E = (Eg. 3-9) where Z 1 is the positive-sequence impedance and Z E is defined as a difference between the line-to-ground loop measurement and a half of the line-to-line loop measurement, the X component of can become negative. 3.3 Ground Impedance Measurement Introduction Z E A good substation grounding system is crucial to protect people from injury and prevent damage of equipment. International standards such as DIN VDE 0101/CENELEC HD637S1, IEEE Std or IEEE Std give guidelines on how to measure such impedances. This application describes the measurement of large substations. Smaller grounding systems could be tested without connection to an existing overhead line or power cable and therefore the use of the CP CU1 and CP GB1 would not be necessary. However, the procedure is the same when injecting the current into a long wire directly from the 6 A AC output. Anyway, when injecting the current into a test probe, special safety measures are required to avoid hazards when people approach the test probe. The current-voltage method as called in CENELEC HD637S1 or fall of potential method as called in IEEE standards is a good solution to measure the ground impedance of a substation. Before starting the test procedure, take one 54

55 Applications overhead line or power cable leaving the substation under test out of service and ground it at the far end. Feed a current via this power line into a remote ground. For larger substations, a distance of the remote ground of at least 5 km/3 miles is recommended, the minimum distance is 10 times the size of the grounding system. Then measure the voltages with a test probe at various distances around the substation. If possible, choose the measurement points in a 90º angle (bird s-eye view) relative to the current path. In any case, avoid measuring close (<60º) to the current path. For an accurate estimate of the step voltage, set the measurement points as close as 1 m/3 ft to the substation and to each other. The step voltage is calculated for a certain fault current. Enter the highest possible fault current for the substation under test in the relevant field of the Microsoft Excel template. Measurement data at a large distance (typically three times the length of the substation) from the substation allow the calculation of the overall substation ground impedance Z ground as defined in VDE Performing Measurements To measure ground impedance and step voltage: 1. Connect the measurement setup to an overhead line or a power cable leading from the substation under test following 3.2 "Line Impedance Measurement and k Factor Determination" on page Short the three phases with the delivered three-lead cable as shown in Figure 1-7 "Shorting the phases" on page Connect one pin of the CPC 100 s V1 AC input to the ground substation ground, the other pin to a test probe as shown in Figure 3-9 "Ground impedance and step voltage measurement" on page 56. The V SENSE input and the V1 AC output of the CP CU1 are not used in this application. The voltage is measured directly using the V1 AC input of the CPC

56 CP CU1 Reference Manual Figure 3-9 Ground impedance and step voltage measurement The test procedure is controlled by templates available on the Toolsets shipped with your CP CU1 or on the CPC 100 Start Page. For detailed information on the templates and instructions how to use them, see 3.1 "Template Usage" on page 41. Using the CPC 100 s Sequencer test card, the test procedure runs without user interaction, performing the recommended six measurements per test probe position. Warning: Do not touch the test probe without insulating gloves outside of the substation area. In case of a high-current ground fault within the substation during the test, considerably high voltages could arise in any wire connected to the substation and leading away from it. 56

57 Applications After wiring the measurement setup to the line proceed as follows: 1. Configure the CPC 100 as described in 2.3 "Configuring the CPC 100" on page 32 for the CP CU1 s current range set by the current range switch. Warning: The configured current range must not exceed the limit by the openline voltage. 2. Choose the XML (XMT) template for the mains frequency (e.g. "Ground Imp CU1 60Hz.xmt" for the 60 Hz mains frequency) and open the template. 3. Select the Enter Distance Here card from the template. 4. Select Save as Default to reuse this card later on. 5. Stick the test probe into the ground at the specified distance from the substation and proceed from short to long distances. Recommended distances for the ground impedance measurement are 1, 2, 5, 10, 20, 50, 100, 150, 200 m and continuing in 100 m steps (5, 10, 20, 50, 100, 200, 500, 750, 1000 ft and continuing in 250 ft steps). You can measure the distance for this application conveniently with a commercial GPS device. Note: Make sure that the measurement points take course in a 90º angle (bird s-eye view) relative to the current path and, if possible, avoid additional overhead lines or power cables as well as current paths. 6. Start the test card for the current test point. 7. Label the test card with the distance in units m or ft without blanks, e.g. "10m" or "30ft". 8. Add one Sequencer test card for every test point you want to measure. 9. Proceed with step 6 as long as you want to measure at another distance. 10.Save the test procedure as a file on the CPC 100. Note: It is recommended to save at most 15 test cards in one file, but having more files is possible. 11.Download the test file(s) from the CPC 100 to the PC using the CPC Explorer. 12.Load the test file(s) into the Microsoft Excel template. The ground impedance and the step voltage are displayed as a function of the distance from the substation. A reduction factor can be determined. For details refer to "Reduction Factor" on page 58. Note: If there are more files, load one after another. 57

58 CP CU1 Reference Manual Reduction Factor Due to the inductance of the feed-in line, a considerable part of the current I out injected into the ground does not flow back through the ground but through the ground wire, the line shield or other pathes (railway tracks, pipes), not causing a voltage drop across the ground. This current I shield has to be subtracted from I out and, consequently, the ground impedance is given by Z ground = V meas /(I out I shield ) (Eg. 3-10) This effect is compensated by the current reduction factor r as defined in the CENELEC HD637 S :1999. A field in the XML template allows setting the current reduction factor between 0.01 and 1.00 (1.00 means no current compensation). For 110 kv overhead lines, the standard gives typical values of r = 0.98 for steel ground wires and down to 0.60 for steel/aluminum ground wires. For current feeding via power cables, the r factor can be as low as The effect of the current I shield can be eliminated by disconnecting the line shield or the ground wire of the feed-in line. If the disconnection is not possible, it is recommended to measure the current I shield with a Rogowski coil and to calculate the current reduction factor as r = 1 I shield /I out (Eg. 3-11) Performing Measurements The following section describes how the user can perform a test to measure the reduction factor. The proposed measurement methodology consists of four parts: Basic measurement setup (steps 1-2) CPC 100 configuration and accuracy check (steps 3-10) Measurement of the relevant currents (steps 11-12) Calculation of the reduction factor (steps 13-14) 1. Connect the measurement setup to an overhead line or a power cable leading from the substation under test following "Connecting the Measurement Setup to Power Lines" on page 38. Follow the safety rules before starting with the setup. 2. Short the three phases with the delivered three-lead cable as shown in Figure 1-7 "Shorting the phases" on page Connect the CPC 100 s V1 AC input to the Rogowski coil as shown in Figure 3-10 "Accuracy check for reduction factor measurement" on page 59. The V SENSE input and V1 AC output of the CP CU1 are not used in this 58

59 Applications application. Set the output range of the Rogowski coil to 100 mv/a (for current measurement 0 20 A). 4. Connect the Rogowski coil around one of the IOUT connection cables to the CP GB1. The Rogowski coil measures the magnitude and the phase angle of the current. Make sure that the current direction of the coil, which is indicated by an arrow on the connection joint, coincides with the test current. Using a shielded cable with twisted wires is recommended (the V2 AC input of the CPC 100 can also be used and configured for this measurement). Overhead line / cable Figure 3-10 Accuracy check for reduction factor measurement After wiring the measurement setup to the line proceed as follows: 5. Configure the CPC 100 as described in 2.3 "Configuring the CPC 100" on page 32, and set the ratio for I Clamp according to the adjusted output ratio of the Rogowski coil (100 mv/a or 10 mv/a). Warning: The configured current range must not exceed the limit by the openline voltage. 6. Open a Quick test card. 7. Choose the CP CU1 as output. Select the same test current mode as set for the CP CU1 (for example, CU1 10A) and configure the measurement inputs as shown in Figure 3-11 "Quick test card for reduction factor measurement" on page 60. Set the output frequency to 30 Hz and the output current according to the selected current mode (here A). 59

60 CP CU1 Reference Manual 8. Select Save as Default to reuse this card later on. Figure 3-11 Quick test card for reduction factor measurement Warning: Open the grounding switch at the near end before conducting the test and keep it open only during the measurement. Close the grounding switch after the test and before reconnecting the measurement setup. 9. Start the test. Press Keep Result for the measurement at 30 Hz. Change the output frequency to 70 Hz. Start the test and keep the result again. For the measurement of the reduction factor at a mains frequency of 60 Hz change the output frequencies to 40 and 80 Hz. 10.Check if the measured ratio is approximately 1. If the ratio differs from 1 considerably, verify that the setting for the external current clamp in the device setup matches the adjusted output range of the Rogowski coil and repeat the test. 11.Insert a new Quick test card. Connect the Rogowski coil to the measurement point (for example, cable shield, ground wire or foot of a tower) considering the correct current direction (current into ground). Continue with step Add a new Quick test card for every test point and repeat the measurement with steps 9 and For determining the reduction factor the measured currents at 30 and 70 Hz have to be interpolated to the mains frequency. Therefore, calculate the average current of the two measurments for each test point. If the test current at the two frequencies or the different test points should differ noticeably, also calculate the average of all output currents. 14.The reduction factor can now be calculated with the formula: r = 1 I shield /I out (Eg. 3-12) I shield is the sum of all currents interpolated to the mains frequency. 60

61 Applications I out is the average value of the test currents. Figure 3-12 line Connection for reduction factor measurement on an overhead The CPC 100 allows for measuring the magnitude and phase angle of currents. If multiple measurements are necessary for the calculation of the recution factor, the phase angle should also be taken into account. The calculated reduction factor can now be set in the ground impedance template. The results for the ground impedance and step and touch voltages are calculated by the template, taking the reduction factor into account Interpretation of Measurement Results The example file delivered with the templates includes measurement results for a terrain approaching the optimum. Figure 3-13 "Ground impedance vs. distance for a terrain approaching optimum" on page 62 shows a graph displayed after loading the example file into the Microsoft Excel template. The voltage between the grounding system under test and the test probe (and hence the ground impedance) increases slowly until it reaches an approximately constant value. This limit value corresponds to the ground impedance Z ground, the impedance of the substation against the "rest of the world". In the example considered, Z ground is approximately 60 m. 61

62 CP CU1 Reference Manual Figure 3-13 optimum Ground impedance vs. distance for a terrain approaching In some cases, measurement results show peaks and drops until an area free of buildings and buried conductors or pipes is reached. Until then, erroneous results can be obtained. Figure 3-14 "Ground impedance vs. distance for a difficult terrain" below shows typical measurement results obtained under such conditions. The graph shows a peak due to a street lamp close to the test probe. The street lamp was connected to a protective ground wire approaching the location of the remote grounding system. Voltage drops can be observed when the measurement points are set close to objects (i.e. towers of power lines leaving the substation under test) connected to the grounding system under test. Figure 3-14 Ground impedance vs. distance for a difficult terrain 62

63 Applications In a difficult terrain, the measurement results may show no noticeable trend until values converging to a constant are obtained. Consequently, the terrain analysis on site is of highest importance. Setting the measurement points close to the line injecting the current results in erroneously high measured values. An area within the angle of at least 60º relative to the line should be avoided. 3.4 Step and Touch Voltage Measurements In different countries, states and utilities, different rules and regulations apply to step and touch voltage measurements. For information on whether or not and how the measurement is to be performed, refer to the relevant standards. The following figure shows the possible scenarios of the touch voltage hazard. < 2m 1m 1m 1m V Tp V Tp V step V Tp Figure 3-15 Touch voltage hazard scenarios This Reference Manual describes the step and touch voltage measurements according to the VDE 0101/CENELEC HD 637 S1:1999 and IEEE , and standards. 63

64 CP CU1 Reference Manual Introduction to Measurement According to VDE 0101/CENELEC HD 637 S1:1999 Note: This excerpt from the above standard is for reference only. Reading this Reference Manual does not release you from the duty of reading and observing the standard. For the decision whether step and touch voltage measurements have to be performed, the grounding current I E is of major importance. The grounding current is the maximum fault current through the earth for the maximum fault duration t F assuming the protection works properly. The grounding current depends on the neutral-point connection and is to be calculated from the grid s impedance. The VDE 0101/CENELEC HD 637 S1:1999 standards specify when the touch voltage measurement is not required. According to the standards, the touch voltage needs not be measured if: The substation is a part of a global grounding system (as defined in the standard). A set of measures described in Appendix D of the standard is applied, for example, insulation of metal parts or their protection against touch. The whole system s grounding voltage (Z ground I E ) is less than two times the allowed touch voltage for the maximum possible fault current into ground. The system s grounding voltage limit depends on the fault duration as shown in Table 3-1 "System s grounding voltage vs. fault duration" on page 64. In all other cases, the touch voltage measurement is recommended. Table 3-1 System s grounding voltage vs. fault duration Fault duration t F in seconds System s grounding voltage limit in Volts

65 Applications Table 3-1 Fault duration t F in seconds The touch voltage measurement is usually performed on the periphery of a grounding system, that is on the fence of a substation and additional peripheral grounding points, such as the first tower of a power line or other grounding system s singularities Introduction to Measurement According to IEEE , and Note: This excerpt from the above standard is for reference only. Reading this Reference Manual does not release you from the duty of reading and observing the standard. According to the IEEE standard, more extensive measurements including the touch voltage measurement should be performed if the calculated ground potential rise (GPR) exceeds a value of 2 5 kv. Because this limit seems quite high compared with the specifications in the CENELEC HD 637 S1:1999 standard, OMICRON electronics recommends to evaluate the object under test carefully. Particularly, if areas are involved where people are likely to be, it is a good idea to measure the touch voltage if the criterion of the CENELEC HD 637 S1:1999 is met. According to the IEEE standard, the expected touch voltages can alternatively be read from a contour map generated from extensive step voltage measurements in all directions. Note: If the reduction factor is considered, refer to "Reduction Factor" on page Performing Measurements System s grounding voltage vs. fault duration System s grounding voltage limit in Volts To measure step and touch voltages, a current is forced to flow into the ground, usually by connecting one pin of the CP CU1 current output to the ground system and the other pin to a remote grounding system far away from the system under test typically by using a shut-down overhead line or power cable. After then, the voltages arising in and around the test object are measured. 65

66 CP CU1 Reference Manual Measurement Principles If an object to be touched is in the range of 2 m around the test object, measure the touch voltage between two hand electrodes. If no object to be touched is in this range, measure the touch voltage between a hand and a foot electrode placed in a distance of 1 m from the test object (see Figure 3-16 "Touch voltage measurement" on page 66). There are two ways to perform this measurement. In one approach, the voltage measurement is done with the CPC 100 using the V1 AC input and the "Step & Touch Voltage" template. According to the other method, the CPC 100 and the CP CU1 are used just for current injection and the voltage in and around the substation is measured with the CP AL1 FFT voltmeter. In this case, the CPC 100 and the CP CU1 generate currents with a frequency 20 Hz below and 20 Hz above mains frequency in an endless loop, requiring no communication between the generating and measuring units. This method uses the "Step & Touch Voltage with CP AL1" template but you must enter the results into the Microsoft Excel worksheet manually. The big advantage of the latter method is that no wired connection between the generating and the measuring unit is needed, which is a crucial issue, especially in large substations. Note: When using the CP AL1 for voltage measurement, it is a good idea to start generating current with the CPC 100 and the CP CU1 exactly at an even minute because of the following time scheme. During the first 20 seconds current is generated followed by a 100 seconds break to let the transformers and mains fuse cool down. Consequently, the generating sequence is restarted exactly at every even minute, which is helpful information on the measurement side. Note: Connect the electrodes to the CPC 100 s V1 AC input using a twisted cable. to the CPC 100 V1 AC input (use twisted cable) or to the CP AL1 FFT voltmeter Figure 3-16 Touch voltage measurement 66

67 Applications Note: The touch electrode shall have a pointed end to safely break through the coat of paint. According to the CENELEC HD 637 S1:199 standard, the foot electrode shall have a size of 400 cm 2. The electrode has to be pressed against ground with a force of at least 500 N (approx. 50 kg). The foot electrode shall have good contact with ground. On dry soil or concrete, place the foot electrode onto a wet fabric or the like. The OMICRON foot electrodes are water cans equipped with a standard conform electrode. Their empty weight for transportation is only about 6 kg, while filled with water their weight is about 25 kg each. According to the test probe method defined in the IEEE standard, the voltage drop is measured close to objects in a distance of 1 m from the object using a m (1 2 ft) long test probe (wholly driven into the soil - see "Optional Accessories" on page 17) of mm (0.5 inch) diameter. If this voltage divided by a hypothetical human body resistance of 1 k stays under the critical body current limit described in "Measurement According to IEEE , and " on page 71, no further measurements are required. If the above criterion is not met, a higher resistance could be taken into account; it could be measured using the so-called footprint method. However, it seems to be possible to combine the two measurements and to directly measure the current over a 1 k resistance simulating the human body and two footprint electrodes according to the standard. The two electrodes (see "Optional Accessories" on page 17) shall have a surface area of 200 cm 2 each and a weight of at least 20 kg. They shall be placed 0.5 m from each other and 1 m in front of the test object. The soil under the electrodes shall be soaked with salty water to obtain worst-case conditions. Therefore, the CENELEC methods can be applied accordingly. For the measurements with a foot electrode, the CENELEC standard recommends to take into account additional resistances as shown in Figure 3-17 "Measurement with foot electrode" on page 68. The human body is to be represented by a resistance of 1 k switched in parallel to the voltage input during the measurement. In areas where people usually wear shoes, the shoe 67

68 CP CU1 Reference Manual resistance can be simulated by an additional resistance of 1 k switched in series to the ground electrode. In areas such as public baths where no shoe wearing is expected, this additional resistance must not be used. R body 1k R shoe 1k 1m Foot electrode Figure 3-17 Measurement with foot electrode The adapter for the CP AL1 allows switching in these resistors, if applicable. Three-position switch Sensitivity (range) switch Position 1: direct (high impedance) Position 2: 1 k - "human body" (resistance switched in parallel) Position 3: 1 k - "human body" (resistance switched in parallel with additional 1k "shoe resistance" switched in series) Note: If the voltage exceeds 3.5 V, set the range of the sensitivity switch to 1:10 to avoid damage to the CP AL1. Figure 3-18 CP AL1 Adapter 68

69 Applications Alternatively, use a ground rod driven at least 10 cm into the soil connected without additional resistances to get an overview of the touch potential. If the allowed touch voltage is not exceeded using this method, it can be expected that the footprint method will not yield results above the limits. For the step voltage measurement, use the foot electrodes of 200 cm 2 each in a distance of 1 m from each other and measure the voltage between them Measurement Procedure The measurement procedure is controlled by templates available on the Toolsets shipped with the CP CU1 or on the CPC 100 Start Page. For detailed information on the templates and instructions how to use them, refer to 3.1 "Template Usage" on page 41. Using the CPC 100 Sequencer test card, the test procedure runs without user interaction. After wiring the measurement setup to the power line, configure the CPC 100 as described in 2.3 "Configuring the CPC 100" on page 32 for the CP CU1 s current range set by the current range switch. Warning: The configured current range must not exceed the limit by the openline voltage. The further procedure depends on the measurement method (see "Measurement Principles" on page 66). If you measure the voltage with the CP AL1 FFT voltmeter (recommended), use the "Step & Touch Voltage with CP AL1" templates and proceed as follows: 1. Choose the template for the mains frequency and the optimum current range (for example, "Step & Touch Voltage with CP AL1 and CU1 20A 50Hz.xmt") and open the template. 2. Start the test exactly at an even minute and check whether the current really flows without causing an overload. Lock the keyboard using the key on the front panel if you leave the device uncontrolled and make sure the dangerous zone around the CP CU1 and the CP GB1 is protected against passersby. 3. Measure the step and touch voltages in around the station using the CP AL1 and write down (or type directly into the Microsoft Excel worksheet) the results for the frequencies 20 Hz below and 20 Hz above the mains frequency. To read out the amplitude, set the cursor of the CP AL1 to these frequencies manually. It is helpful to know that the generation starts always exactly at an even minute. 4. Enter the results into the Microsoft Excel template. When entering the possible ground fault current of the station under test, the possible touch voltages are calculated. 69

70 CP CU1 Reference Manual If you perform the measurement without the CP AL1 FFT voltmeter, use the "Step & Touch Voltage" templates and proceed as follows: 1. Choose the XML template for the mains frequency (for example, "Touch Voltage CU1 60Hz.xmt" for the 60 Hz mains frequency) and open the template. 2. Select the Enter Location Here card from the template. 3. Select Save as Default to reuse this card later on. 4. Place the test probes as described above. 5. Start the test card for the current test point. 6. Rename the test card with the name of the location. 7. Add one Sequencer test card for every test point you want to measure. 8. Proceed with step 6 as long as you want to measure more points. 9. Save the test procedure as a file on the CPC 100. Note: It is recommended to save at most 15 test cards in one file. 10.Download the test file(s) from the CPC 100 to the PC using the CPC Explorer. 11.Load the test file(s) into the Microsoft Excel "Touch Voltage" template. The touch voltage values for the entered fault current are calculated. Note: If there are more files, load one after the other Measurement According to VDE 0101/CENELEC HD 637 S1:1999 The touch voltage automatically calculated in the template is given by V Tp = V 1AC I E /((I out r) (Eg. 3-13) where V Tp is the touch voltage in volts V 1AC is the measured voltage in volts I E is the grounding current of a worst case fault in the substation in ampers I out is the output current of the CP CU1 in ampers r is the reduction factor The touch voltage (depending on the expected fault duration) is assessed as tolerable if the calculated value V Tp is below the limit given in Table 3-2 "Allowed touch voltage vs. fault duration" on page 71. The value of the maximum fault 70

71 Applications duration can be entered under the assumption that the protection is working properly. If the resulting touch voltage is below the limit given in the table, the standard is met. Table 3-2 Fault duration t F in seconds Allowed touch voltage vs. fault duration Allowed touch voltage V Tp in volts Measurement According to IEEE , and The touch voltage automatically calculated in the template is given by V Tp = V 1AC I E /((I out r) (Eg. 3-14) where V Tp is the touch voltage in volts V 1AC is the measured voltage in volts I E is the grounding current of a worst case fault in the substation in ampers I out is the output current of the CP CU1 in ampers r is the reduction factor The assessement whether a touch voltage is permissible or not is a fairly complicated process. For relatively low touch voltages, simple formulas can be used to do the assessement. The equations below use the Dalziel s formulas for the body current. The Biegelmeier's curve is more complex and therfore not used here. However, when the results approach the limits, it is a good idea to refer to the IEEE standard for details. 71

72 CP CU1 Reference Manual Two formulas for the touch voltage limit depending on the body weight are given below. If the following criteria are met, no further calculations are required. V Tp50 = /t s ½ (Eg. 3-15) for body weight of 50 kg V Tp70 = /t s ½ (Eg. 3-16) for body weight of 70 kg where V Tp50 and V Tp70 is the touch voltage limit in volts for body weight of 50 kg and 70 kg respectively t s is the maximum fault duration in seconds assuming the protection is operational If one of the above limits is exceeded, the additional resistances of the soil can be taken into account in two ways. The first method calculates the touch voltage limits using the specific ground resistance and the factor of the protective surface layer, if applicable. The second method is based on the footprint resistance measurement. To calculate the touch voltage limit, the specific ground resistance has either to be measured as described in the CPC 100 Reference Manual or found in the relevant literature. The touch voltage limit is given by V Tp50 = ( C s s ) 0.116/t s ½ for body weight of 50 kg (Eg. 3-17) V Tp70 = ( C s s ) 0.157/t s ½ (Eg. 3-18) for body weight of 70 kg where V Tp50 and V Tp70 is the touch voltage limit in volts for body weight of 50 kg and 70 kg respectively C s is the coating factor s is the resistivity of the surface material in m t s is the duration of shock current in seconds For the coating factor C s, refer to the IEEE standard; s is affected by the coating, too. If no protective surface layer is involved, C s = 1. Alternatively, the footprint resistance can be measured as follows. Two electrodes with a diameter of 16 cm each weighted with at least 20 kg each shall be used. They shall be placed 0.5 m from each other and 1 m in front of the test object. The soil under the electrodes shall be soaked with water and the 72

73 Applications electrodes shall have a conducting medium between each electrode and ground, such as conductive rubber pad, a sponge fastened to the foot electrode and wetted in a salt solution, or steel wool soldered to the metal disk to obtain worst-case conditions. Then a current is fed into ground (6A AC output using the Quick test card) and voltage, current and impedance Z are measured. The absolute value Z in can be used as R fp in the formulas below. V Tp50 = ( R fp ) 0.116/t s ½ (Eg. 3-19) for body weight of 50 kg V Tp70 = ( R fp ) 0.157/t s ½ (Eg. 3-20) for body weight of 70 kg where V Tp50 and V Tp70 is the touch voltage limit in volts for body weight of 50 kg and 70 kg respectively R fp is the footprint resistance as measured above t s is the duration of shock current in seconds Interpretation of Measurement Results In opposition to the ground impedance measurement, the measurement of the step voltage is to be performed in the close vicinity of the grounding system under test in steps of at most 1 m/3 ft. The highest voltage gradients or step voltages occur typically at the corners of the grounding system or peripherals connected to the grounding system, such as the first towers of overhead lines or similar objects. The step voltage is given for the fault current set in the Microsoft Excel template. In some countries it is usual to give the step voltage in V/m per ka of the fault current. To obtain the step voltage in these units, enter 1 ka in the fault current field in the Microsoft Excel template and label the graph accordingly. 3.5 Measurement of Coupling into Signal Cables Introduction The measurement of the coupling impedance Z k between power and signal lines is performed for two current loops of the power lines under test. One loop is shaped by two lines featuring the largest area, the other loop is shaped by three lines in parallel and the ground. For each loop, the measurement setup is calibrated by measuring the voltage with the measurement cable short-circuited. 73

74 CP CU1 Reference Manual Performing Measurements Connect the measurement setup to the overhead lines or power cables under test following 3.2 "Line Impedance Measurement and k Factor Determination" on page 42. The V SENSE input and the V1 AC output of CP CU1 are not used in this application. Position the measurement cable near the connection terminal of the signal cable. Note: The voltage is measured directly using the V2 AC input of the CPC 100. In the course of the test procedure, the following tests are performed: 74

75 Applications Calibration with the loop shaped by two lines with the largest area (Figure 3-19 "Calibration with the line-to-line loop" below shows the L1-L3 calibration as example) Short-circuit the measurement cable and connect it to the cable under test. Signal cable Short circuit V2 AC IAC CPC 100 EXT. BOOSTER IAC CP CU1 BOOSTER IOUT CP GB1 Figure 3-19 Calibration with the line-to-line loop 75

76 CP CU1 Reference Manual Measurement with the loop shaped by two lines with the largest area (Figure 3-20 "Measurement with the line-to-line loop" below shows the L1-L3 measurement as example) Signal cable V2 AC IAC CPC 100 EXT. BOOSTER IAC CP CU1 BOOSTER IOUT CP GB1 Figure 3-20 Measurement with the line-to-line loop 76

77 Applications Measurement with the loop shaped by three lines in parallel and the ground (see Figure 3-21 "Measurement with the loop between parallel lines and ground" below) Short the three phases with the delivered three-lead cable as shown in Figure 1-7 "Shorting the phases" on page 23. Signal cable V2 AC IAC CPC 100 EXT. BOOSTER IAC CP CU1 BOOSTER IOUT CP GB1 Figure 3-21 Measurement with the loop between parallel lines and ground 77

78 CP CU1 Reference Manual Calibration with the loop shaped by three lines in parallel and the ground (see Figure 3-22 "Calibration with the loop between parallel lines and ground" below) Short the three phases with the delivered three-lead cable as shown in Figure 1-7 "Shorting the phases" on page 23. Short-circuit the measurement cable and connect it to the cable under test. Signal cable Short circuit V2 AC IAC CPC 100 EXT. BOOSTER IAC CP CU1 BOOSTER IOUT CP GB1 Figure 3-22 Calibration with the loop between parallel lines and ground The test procedure is controlled by templates available on the Toolsets shipped with your CP CU1 or on the CPC 100 Start Page. For detailed information on the templates and instructions how to use them, see 3.1 "Template Usage" on page

79 Applications After wiring the measurement setup to the line proceed as follows: 1. Configure the CPC 100 as described in 2.3 "Configuring the CPC 100" on page 32 for the CP CU1 s current range set by the current range switch. Warning: The configured current range must not exceed the limit by the openline voltage. 2. Choose the XML (XMT) template for the mains frequency (e.g. "Coupling CU1 60Hz.xmt" for the 60 Hz mains frequency) and open the template. 3. Connect the IOUT output of CP CU1 to the CP GB1 s line studs corresponding to the line-to-line loop with the largest area (see Figure 3-19 "Calibration with the line-to-line loop" on page 75). 4. Connect a twisted shielded measurement cable to the V2 AC input of CPC 100 and short-circuit it. Note: The measurement cable is not part of the scope of supply. 5. Start the L-L cal test card. 6. Measure the voltage between the shield of the measurement cable and the signal cable with a hand-held voltmeter. Caution: If the measured voltage is > 40 V, take safety precautions to avoid electrical hazard. > 300 V, stop. The measurement is not possible, because the V2 AC input limits are exceeded. 7. If the voltage allows measurement, connect the measurement cable to the signal cable (see Figure 3-20 "Measurement with the line-to-line loop" on page 76). 8. Start the L-L meas test card. 9. Connect the IOUT output of the CP CU1 to the CP GB1 s line studs corresponding the loop shaped by three lines in parallel and the ground (see Figure 3-22 "Calibration with the loop between parallel lines and ground" on page 78). 10.Start the L-E meas test card. 11.Disconnect the measurement cable from the signal cable and short-circuit it. 12.Start the L-E cal test card. 13.Save the test procedure as a file on the CPC Download the test file from the CPC 100 to the PC using the CPC Explorer. 79

80 CP CU1 Reference Manual 15.Load the test file into the Microsoft Excel template. The measurement results are displayed. 80

81 Technical Data 4 Technical Data 4.1 CP CU1 Output Ranges Table 4-1 Output ranges of the CP CU1 Range Current Compliance Voltage at > 45 Hz 10 A 0 10 Arms 500 Vrms 20 A 0 20 Arms 250 Vrms 50 A 0 50 Arms 100 Vrms 100 A Arms 50 Vrms 4.2 CP CU1 Measuring Transformers Table 4-2 Measuring transformers of the CP CU1 Transformer Ratio Accuracy at 50/60 Hz VT 600 V : 30 V Class 0.1 CT 100 A : 2.5 A Class CP CU1 Inputs Table 4-3 V SENSE Inputs of the CP CU1 Characteristic Rating Overvoltage category CAT III (IEC ) Voltage range Vrms 81

82 CP CU1 Reference Manual Table 4-3 BOOSTER 1 Inputs of the CP CU1 Characteristic Overvoltage category Voltage range Current range Frequency range Fuse Rating CAT I Vrms 0 30 Arms Hz 30 A fast acting, automatic circuit-breaker 1. The BOOSTER input supplies power to the CP CU1. It must be connected only to the CPC CP GB1 Specifications Table 4-4 CP GB1 Specifications Characteristic Rating Nominal AC spark-over voltage < 1000 Vrms Impulse spark-over voltage < 2000 Vpeak Short-circuit proof with: 16 mm cylindrical or 20 mm ball 26.5kA (<100ms)/67kApeak studs 25 mm or 1 inch ball studs 30 ka (<100 ms)/75 kapeak Torsional moment for changing > 15 Nm arrestors 82

83 Technical Data 4.5 Output Power Table 4-5 Characteristic Rating 1 Maximum power Continuous power Frequency Output power of the CPC 100 and CP CU1 1. Ambient temperature 23 ºC ± 5 ºC/73 ºF ± 10 ºF 5000 VA (45 70 Hz), cos < 1.0 for 8 s at 230 V AC mains voltage 5000 VA (45 70 Hz), cos < 0.4 for 8 s at 115 V AC mains voltage VA Hz (15 45 Hz with reduced voltage) 4.6 Accuracy Table 4-6 Impedance Range Accuracy of the CPC 100 and CP CU1 Typ. Accuracy 1 of abs(z) Value Typ. Accuracy 1 of Phase Angle 1. Ambient temperature 23 ºC ± 5 ºC/73 ºF ± 10 ºF V SENSE Voltage IOUT Current Current Range % º 5 20 V 100 A 100 A % º V A 100 A % 0.5º 100 V A 50 A % 0.5º V A 20 A % º V A 10 A 83

84 CP CU1 Reference Manual 4.7 Environmental Conditions Table 4-7 Environmental conditions for the CP CU1 and CP GB1 Characteristic Rating Operating temperature ºC/ ºF Transport & storage temperature ºC/ ºF Relative humidity 5 95%, non-condensing Safety EN Prepared for IEEE 510, EN (VDE 0104), EN (VDE 0105 Part 100), LAPG NASA "Electrical Safety" Protection IP Mechanical Data Table 4-8 CP CU1 CP GB1 Mechanical data of the CP CU1 and CP GB1 Characteristic Dimensions (w h d) Weight Dimensions ( h) Weight Rating mm/ inch 28.5 kg/62.78 lb mm/ inch 4.2 kg/8.81 lb (without grounding cable) approx. 6.8 kg/13.22 lb (with grounding cable) 84

85 Technical Data 4.9 Clamp-on Ammeter (Accessory) Specifications Table 4-9 Current AC Voltage AC General Clamp-on ammeter specifications Characteristic Rating Ranges 40 A/400 A with autoranging Accuracy ±2% at 50/60 Hz Resolution 3½ digits Range 600 V Accuracy 1.5% at 50/500 Hz Resolution 3½ digits Clamp size 30 mm/1.2 inch Insulation CAT III/600 V Battery 2 LR03 For detailed information on the clamp-on ammeter, see the Digital Clamp Meter User s Manual shipped with the clamp-on ammeter CP AL1 Specifications Delivery The CP AL1 delivery includes: FFT voltmeter CP AL1 Adapter ML 1 20 db (1:10) Adapter XLR to BNC with 1 k V LR6/AA battery CP AL1 User Manual 85

86 CP CU1 Reference Manual Warnings For a proper operation of the CP AL1, observe the following rules: Read this manual thoroughly before putting the CP AL1 into operation. Use the CP AL1 for the intended purpose only. Never connect the CP AL1 to a high-voltage output such as a power amplifier, mains power plug, etc. Do not disassemble the CP AL1. Never use the CP AL1 in a damp environment. Remove the batteries as soon as they are flat or if the CP AL1 is not intended to be used for a longer period of time. Table 4-10 Measurement Functions Zoom FFT Level RMS Distortion THD+N Frequency Measurement functions Specifications Real-time Zoom FFT with 50% overlapping, 93 bins Frequency range: 10 Hz 20 khz Resolution: 0.73 Hz Hz Units: Vrms (dbµ, dbv) Resolution: 4 digits (V scale), 3 digits (db scale) Accuracy: ±1% Bandwidth: 20 Hz 20 khz Bandwidth: 10 Hz 20 khz Resolution: 4 digits (% scale), 3 digits (db scale) Residual THD+N Balanced: < 85 db at 10 dbµ +20 dbµ Unbalanced: < 74 db at 0 dbµ +14 dbµ Range: 10 Hz 20 khz Resolution: 4 digits Accuracy: ±1% 86

87 Technical Data Table 4-11 Input filters Filter Characteristic Application FLAT Flat frequency response Default measurement setting (no filtering) A-WTD A-weighting filter Measuring residual noise of the unit under test according to IEC C-WTD C-weighting filter Special applications according to IEC HP400 High-pass filter 400 Hz according to DIN 45045, 120dB/dec Removes mains frequency (50/60 Hz) components of the measurement signal. HP19k High-pass filter 19 khz Removes low-frequency components of the measurement signal, e.g. for measuring the 20 khz pilot tone level of critical public announcements systems. Table 4-12 Characteristic Input level RMS (upper measurement limit) Max. DC input Input impedance Input connectors Display Batteries Technical specifications Specifications 3.8 Vrms (unbalanced) for input levels > 3.8 Vrms (unbalanced) the adapter ML 1 20 db has to be used ±50 V DC Balanced: 40 k Unbalanced: 20 k Balanced: XLR Unbalanced: RCA Graphical LCD pixel with backlight V alkaline battery type LR6/AA typical battery lifetime > 16 hrs Table 4-13 Environmental requirements Characteristic Rating Temperature ºC/ ºF Relative humidity < 90%, non-condensing 87

88 CP CU1 Reference Manual Table CE Declaration of Conformity We, the manufacturer NTI AG Im alten Riet Schaan Liechtenstein, Europe hereby declare that the product Acoustilyzer CP AL1, released in 2004, conforms to the following standards or other normative documents: EMC-Directives:89/336, 92/31, 93/68 Harmonized Standards:EN This declaration becomes void in case of any changes on the product without written authorization by NTI. Date:1. September 2004 Signature: Position of signatory:technical Director Test & Calibration Certificates This is to certify the Acoustilyzer CP AL1 is fully tested to the manufacturer s specifications. NTI recommends to calibrate this test instrument one (1) year after purchase. Thereafter the calibration and adjustment interval is subsequently one (1) year International Warranty Mechanical data Characteristic Rating Dimensions (l w h) mm/6.4" 3.38" 1.63" Weight 300 g/10.6 oz. incl.batteries NTI guarantees the functionality of the Acoustilyzer CP AL1 against defects in material or workmanship for a period of one year from the date of original purchase, and agrees to repair or to replace at its discretion any defective unit at no cost for either parts or labor during this period. 88

89 Technical Data Restrictions This warranty does not cover damages caused through accidents, misuse, lack of care, the attachment or installation of any components that were not provided with the product, loss of parts, connecting the instrument to a power supply, input signal voltage or connector type other than specified or wrongly polarized batteries. In particular, no responsibility is granted for special, incidental or consequential damages. This warranty becomes void if servicing or repairs of the product are performed by any party other than an authorized NTI service center or if the instrument has been opened in a manner other than specified in this manual. No other warranty, written or verbal, is authorized by NTI. Except as otherwise stated in this warranty, NTI makes no representation or warranty of any kind, expressed or implied in law or in fact, including, without limitation, merchandising or fitting for any particular purpose and assumes no liability, either in tort, strict liability, contract or warranty for products. 89

90 90 CP CU1 Reference Manual

91 Appendix 5 Appendix 5.1 CP AL Operation of the CP AL1 In spite of the wide range of available measurement functions and optional setups, the operation of the CP AL1 is almost self-explanatory. Menu bar Measurement result ESC button Power on/off button ENTER/cursor keys Figure 5-1 Operating controls To switch the CP AL1 on/off, press the power on/off button for at least 2 sec. The LCD displays the menu bar on the top and the measurement results beneath. The cursor keys and the ESC button allow straightforward navigation through the current screen displaying: Measurement settings (measurement function, filters) Measurement results (numerical or graphical display) The base element is the cursor (inverted area) which can be navigated through the various functions by using the cursor keys. All selectable settings can be simply set by pressing the Enter key. Alternatively, at longer selection lists the selected field is flashing. In this case, select the value you want to enter using the cursor keys, and then confirm the setting by pressing the Enter key again. 91

92 CP CU1 Reference Manual Menu Bar The menu bar allows configuring the CP AL1 for the measurement. Input filter Measurement function Setup screen Memory menu & battery state indication Figure 5-2 Menu bar Measurement Functions Figure 5-3 Meausurement function menu 92

93 Appendix FFT Analysis The CP AL1 features two major measurement functions accessible via the menu bar: FFT: real-time Zoom FFT RMS/THD: level and distortion measurements To set the measurement function, select FFT or RMS/THD on the measurement function menu. The CP AL1 implements an extremely fast, real-time Zoom FFT analysis with resolutions up to 0.7 Hz over the entire frequency range. The FFT analysis results are displayed by 93 bins. Pause Cursor readout Set menu FFT spectrum Y-axis X-axis Displayed start frequency Displayed end frequency Displayed frequency range Figure 5-4 FFT analysis display The screen elements in the FFT measurement mode are described below. 93

94 CP CU1 Reference Manual Pause Figure 5-5 Pause The command stops measurements temporarily. To pause a measurement: 1. Select the symbol, and then press the ENTER key. The symbol is flashing. 2. Select the symbol, and then press the ENTER key to continue the measurement. Cursor Readout Figure 5-6 Cursor readout 94

95 Appendix The cursor readout displays the frequency and level of the bin marked by the cursor. Initially, the cursor automatically marks the bin with the highest level. To control the cursor readout: 1. Select the cursor readout field, and then press the Enter key. A frame around the field is flashing. 2. Move the cursor using the left/right arrow keys. The cursor readout field displays the measurement values corresponding to the bin marked by the cursor. X-Axis Figure 5-7 X-axis The X-axis displays from left to right the start frequency, the frequency range and the stop frequency. To set the displayed frequency range: 1. Select the frequency range field, and then press the Enter key. 2. Set the displayed frequency range using the up/down arrow keys. 3. Move the displayed frequency range using the left/right arrow keys. 95

96 CP CU1 Reference Manual Y-Axis Figure 5-8 Y-axis The Y-axis displays the signal level in db. The signal level in volts is given by U = 10 x (Eg. 5-1) where U signal level in volts x signal level in db By the default setting, the Y-axis range is db. This corresponds to the following range in volts: x = 80dB : U = = 0.002V (Eg. 5-2) x = 150dB : U = 10 = = 6.3V (Eg. 5-3) Note: The signal level is displayed in logarithmic scale. To scale the Y-axis: 1. Select the Y-axis maximum value field, and then press the ENTER key. 2. Move the displayed Y-axis range using the up/down arrow keys. 3. Set the Y-axis resolution using the left/right arrow keys. 96

97 Appendix Setup Screen Figure 5-9 Setup screen The setup screen allows customizing the CP AL1 basic settings. To customize the settings: 1. Select the setup screen menu (SET) on the menu bar. The setup screen opens. 2. Move the cursor to the entry field corresponding to the setting you want to change, and then press the Enter key. 3. Select the required value by using the arrow keys. 4. Press the Enter key. 97