DTR n n n n n. Notice de fonctionnement User s manual Bedienungsanleitung Libretto d istruzioni Manual de instrucciones 3

Transcription

1 n n n n n RATIOMÈTRE RATIOMETER RATIOMETER RAPPORTOMETRO RATIOMETER DTR 8500 FRANÇAIS ENGLISH DEUTSCH ITALIANO ESPANOL Notice de fonctionnement User s manual Bedienungsanleitung Libretto d istruzioni Manual de instrucciones 3

2 Meaning of the symbol : Warning! Please refer to the User s Manual before using the instrument. In this User s Manual, the instructions preceded by the above symbol, should they not be carried out as shown, can result in a physical accident or damage the instrument and the installations. Thank you for purchasing a Ratiometer DTR To get the best service from this instrument: - read this user s manual carefully, - respect the safety precautions detailed. SAFETY PRECAUTIONS n The Digital Transformer Ratiometer DTR 8500 is designed for use on de-energised («deactivated») transformers only. Make sure that the device tested has been completely disconnected from the mains power supply and that it is fully discharged, before connecting the test leads. n Only qualified staff should use the instrument. The user is entirely responsible for his own safety. n Proceed with due care when working near transformers: high voltage and current may be present and constitute a danger of electrocution. n In the event of an electric shock, the ratiometer (especially its leads) does not provide sufficient protection/insulation against high voltages. n Do not touch, adjust or reposition test cables when the DTR 8500 is conducting a test. n Never open the instrument when connected to the mains power supply or when test leads are connected to transformers, equipment, circuits, etc. n Always check the instrument and test cables before use. Faulty parts should be replaced immediately with genuine spare parts only (see 9. Maintenance). n Always use the correct fuse rating and type: failure to do so may result in damage to the instrument, causing the warranty to be null and vold (see 9. Maintenance). n This instrument has been designed for use indoors in an environment with the following characteristics: degree of pollution 2, altitude < 2000 m, temperature between 0 and 50 C and relative humidity of 0 to 90 %. n It can be used in category III installations, for voltages never exceeding 300 V with respect to the earth. Category III meets stringent reliability and availability crtiteria, corresponding to permanent use on industrial installations (see IEC 664-1). 21

3 CONTENTS 1. Presentation Description Technical specifications Measurements and operation Mode selection Voltage transformers (VT/PT) Current transformers (CT) Displayed messages Power supply (230V / 115V) Tips on obtaining accurate ratio measerements Appendix Warranty Maintenance Accessories and spare parts (to order)

4 1. PRESENTATION The DTR 8500 is a portable, sturdy and lightweight digital transformer ratiometer, designed for onsite testing of power, voltage and current transformers. Operation of the DTR 8500 is fully automatic. Calibration, range selection, hand-start or tedious adjustment is unnecessary. During each test cycle, the DTR automatically checks: n H/X lead reversal, n continuity of circuits/windings tested, n short-circuit conditions (high current). Upon completion of a test cycle, the DTR 8500 displays: n The transformation ratio the ratio of the primary to the secondary voltage at the transformer terminals resulting from the test. n Test current test current in RMS in the H winding resulting from the test during negligible loading of the associated X winding. n Polarity Indicates the polarity (phase) of X in relation to H. The transformation ratio, test current and polarity are useful parameters for diagnosing and predicting various faults that may occur in power, voltage and current transformers. The DTR 8500 displays the following messages: n Incorrect lead connections n H/X reversal (incorrect primary and secondary circuit connection, causing voltage set-up) n Short-circuit (excess test current) n Open circuits n Circuit continuity n Low battery The DTR 8500 uses an advanced, low-voltage step-down measurement technique in which the high voltage winding «H» is subjected to the test. Operator safety is thus improved and a larger range of types and sizes of transformer can be tested. 23

5 2. DESCRIPTION 2.1 Instrument 3 4 « V 50 Hz Top side cable connector «H» (primary) 2. Bottom side cable connector «X» (secondary) 3. Display 4. Battery charge indicator 5. Mains input 6. Fuse tray 7. Power supply adjustment (label) 8. Adjustment of display contrast 9.TEST button 10. Off/on switch 2.2 Cables 24

6 3. TECHNICAL SPECIFICATIONS 3.1. Electrical Characteristics n Ratio range: Autoranging: to :1 n Accuracy: Ratio 1000:1 : ± 0.1 % of reading Ratio > 1000:1 : ± 0.2 % of reading NB : 23 C ± 5 C, 50 to 70% HR, full battery charge, no external fields. n Test signal : Mode PT/VT : 44 Vrms maximum Mode CT : 0-1A automatic level, Vrms n Test current display: Range: ma Accuracy: 2 % reading ± 2 ma n Test frequency: 70 Hz n Display: LCD, 20 x 2, adjustable backlighting, visible day/night n Measurement method: In accordance with ANSI/IEEE C n Power supply: NiCd rechargeable battery and 230/115 V (50/60 Hz) mains supply. Unit can be changed from 230 V to 115 V by an internal switch. Units supplied pre-set to 230 V are available. n Battery: NiCd 12.5 V x 2, 1300 ma/h, Panasonic P-130SCR or equivalent n Battery life: Up to 10 hrs continuous operation. The DTR can be used while recharging. Low battery is indicated on the LCD. n Charging time: Approximately 14 hrs n Fuses: 1.0 A V (5x 20 mm), slow-acting 0.5 A V (5 x 20 mm), slow-acting 4 A V (5 x 20 mm), slow-acting 3.2. General characteristics n Safety: IEC , Cat III, 300 V, degree of pollution 2 n EMC: EN /EN n Connections: Cannon XLR connectors and large industrial colour-coded clips n Leads: 5 m, H and Y colour-coded, in a shoulder bag n Display: 99 x 24 mm alphanumeric, adjustable contrast and backlighting n Operation temperature: 0 to 50 C, 0 to 90% RH (without condensation) n Storage temperature: - 20 C to 70 C n Unit: High-resistance yellow polypropylene (yellow) n Dimensions: 330 x 305 x 152 mm n Weight: 6.4 kg 25

7 4. MEASUREMENT AND OPERATION The Digital Transformer Ratiometer DTR 8500 is designed for use on non-energised transformers only. Make sure that the device tested has been disconnected from the mains power supply and that it is fully discharged. To conduct a test: 1. Connect the DTR test cables correctly to a non-energised transformer. See examples of connection et Switch the DTR on and select the appropriate test mode. (See below for mode selection 4.1). 3. When the Ready message appears, press the test button to start. After a short test cycle, the ratio, polarity and test current will be displayed. NB : Please refer to the VT/PT and CT Test of this manual for complete operating information Mode selection The operating mode of the DTR is configured when the instrument is powered up. The default test mode is VT/PT. To enter the CT test mode, press on the TEST button while switching the machine on and hold down until «CT Test Mode Selected» is displayed. n Use VT/PT test mode for testing voltage transformers (maximum test voltage of 44 V). n Use CT test mode for testing current transformers (maximum test current of 5 V). n The DTR automatically reverts to the VT/PT test mode when the power is switched off. 26

8 4.2. Voltage transformers (VT/PT) Examples of VT/PT connections Here is an example of connections to an ordinary 7200: 120/240 distribution transformer with a centre-tapped secondary winding. NB : n Unlike other instruments, the DTR 8500 does not impose polarity restrictions or forced autoconnections; thus there are several valid connections and virtually all transformer configurations can be tested. n In all tests, a minus sign before the ratio displayed indicates phase reversal (inverted polarity) of the X signal detected in relation to the test signal at H. When using the DTR, always make a note of the colour code of the test cable clamps. 27

9 VT/PT Tests 1. When the instrument is set up for a VT/PT test, the DTR displays the message «VT/PT Test Mode Ready» after the initial power-up sequence. This message indicates that the DTR is now ready to execute a test. 2. Press the TEST button once. The test must not be performed when staff are handling transformer connections. 3. «Press TEST to Check Continuity» is now displayed for three (3) seconds. If you wish to do a continuity test, press the TEST button once. The results of the continuity test are displayed as CONT or OPEN for the X and H connections. Refer to the VT/ PT continuity test ( 4.25) for more information. 4. The next message to be displayed is *Ratio Testing TEST to Cancel». The asterisk (*) will flash while testing lasts. You can cancel the test at this stage by pressing the TEST button once. If the test continues, the ratio and test current will be displayed. 5. Once the results of the test are recorded, press the TEST button to reset for the following test. NB: This sequence can be repeated as often as required without disconnecting the unit. 28

10 4.2.3 VT/PT test mode flow chart Display indication for VT/PT mode Version XXX 1997 Chauvin Arnoux Operator action Switch unit on Comments Indicates version of internal firmware AEMC Instruments DTR* Model 8500 N/A Identification of the model AEMC Instruments Low Battery N/A Replaces above indication when battery needs recharging VT/PT Test Mode N/A Indication of selected mode Calibrating Please Wait VT/PT Test Mode Ready N/A Now press on TEST to initiate test Internal calibration in process System ready to begin test Press TEST to Check Continuity Ratio Testing Test to Cancel Now press TEST to verify continuity or do nothing to skip Now press TEST to cancel test in process Continuity test Option selected Ratio test in process with test cancel option Ratio: : 1 Current: 11 ma Now press TEST to reset for the next test 29

11 4.2.4 VT/PT test current Test current, displayed in milliamperes is the RMS current in the H winding due to the test, during negligible loading of the associated X winding. The DTR uses a maximum test signal of 44 V for testing; the test current value displayed will almost always be a small fraction of the no-load excitation of the transformer tested at full rate voltage. The majority of transformers require 100 ma or less; some require less than 1 ma. Note: If you are currently using a ratiometer with X side step-up excitation (for example, a manually-operated instrument), the test current displayed by the DTR will be significantly lower in the majority of cases. This is normal and is due to the fact that in most step-down type transformers, the H winding shows a much higher impedance than the associated X winding VT/PT continuity test The DTR 8500 continuity test function is used to identify open primary and secondary windings, open circuit-breakers and blown fuses. When the function is selected, the DTR alternately verifies continuity between the X and H cables. The continuity test is selected when the user presses TEST at the Press TEST to Check Continuity prompt. The DTR displays the results of the continuity test then enters a brief demagnetising period. In the meantime, the Pre-Test Checks message is displayed. n The DTR indicates OPEN for tested circuits greater than 2 kw and CONT for those less than 2 kw. A small percentage of transformers (for example, those with high inductance or winding resistance) can be considered as open circuits by the DTR. n If OPEN is indicated, this does not cancel out the test cycle in process and the results of the ratio test will continue to be displayed. n Transformers with winding arrangements involving several parallel paths (for example, delta connected types) may display CONT, when, in fact, one or several windings are open. 30

12 4.3 Current transformers (CT) Examples of CT connections Current transformer ratio testing (CT) is performed by connecting the H cable set to the X winding and by short-circuiting the X cable set through the CT aperture as described below. This creates a step-down type set up in which the X winding serves as the primary circuit and the X set of cables as a one-turn secondary winding CT tests 1. When the instrument is set for a CT test; the DTR displays the message «CT Test Mode Selected» after the initial power-up sequence. This message indicates that the DTR is now ready to execute a test. 2. Press the TEST button once to begin the test cycle. 3. The next message displayed is «*Ratio Testing TEST to Cancel». The asterisk (*) flashes while testing lasts. You can cancel the test at this stage by pressing the TEST button once. If the test continues, the ratio and test current will be displayed. 4. Once the results of the test are recorded, press the TEST button to reset for the following test. NB: Comes pre-set to 230 V the DTR may not be able to provide the correct ratio for some low mass, low ratio current transformers. The message «High Excitation Current» is displayed. As in VT/PT test mode, the sequence can be repeated as often as required without disconnecting the unit. CT test mode remains active until the power supply is switched off. 31

13 4.3.3 CT test flow chart Display indication for CT mode Operator action Comments Version XXX 1997 Chauvin Arnoux Switch unit on holding down TEST button Indicates version of internal firmware AEMC Instruments DTR* Model 8500 Hold TEST button down Identification of the model AEMC Instruments Low Battery Hold TEST button down Replaces above indication when battery needs recharging CT Test Mode Release TEST button Indication of selected mode Calibrating Please Wait CT Test Mode Ready N/A Now press on TEST to initiate test Internal calibration in process System ready to begin test Ratio Testing Test to Cancel Ratio: : 1 Current: 35 ma Now press on TEST to cancel test in process Now press on TEST to reset for the next test Ratio test in process with test cancel option 32

14 4.4 Displayed messages Check for H <> X Cable Reversal The DTR may have detected a potentially dangerous voltage step-up while trying to test the transformer as connected. Verify the connections: HRED and HBLACK should be attached to the high voltage winding. XRED & XBLACK should be attached to the low voltage winding. High Excitation Current Verify test cable connections to check for inadvertent short-circuits. Check there are no shortcircuited transformer windings. Check Cables & Connectors Verify that all test cable connections have been made correctly and are firmly attached to transformer terminals. Verify the transformer terminal for dielectric coating, fungus and corrosion. Low Battery Indicates the battery is low. Recharge the battery immediately. Note: The DTR can operate while battery is being recharged. Calibrating Please Wait The DTR always self-calibrates when powered up. The DTR will also automatically selfcalibrate:. at periodic intervals,. after 32 test cycles in a row,. after detection of an error causing the DTR to automatically cancel the test in progress. VT/PT Test Mode Operating mode used for a VT/PT test, default mode when powered up. VT/PT Test Mode Ready Indicates the system is ready for the VT/PT test. CT Test Mode Selected Indicates selection by the user of the CT test mode. This mode is selected by pressing down the TEST button and holding it down during the power-up sequence. CT Test Mode Ready Indicates the system is ready for the CT test. X Circuit: OPEN (or CONT) See the VT/PT continuity test section H Circuit: OPEN (or CONT) See the VT/PT continuity test section Low X Signal Check X cables for inadvertent short-circuits. The X winding may be short-circuited or the transformer circuit-breaker may be open. Low H Signal Check H cables for inadvertent short-circuits. Check H cable connector on the DTR front panel. 33

15 5. POWER SUPPLY The DTR 8500 can be used for a maximum of 10 hours with fully-charged NiCd batteries. The DTR can also be powered from the mains supply during measurement. In this mode, the DTR also recharges the NiCd batteries. LOW BATTERY is displayed when the internal batteries are low. When this signal is displayed, a limited number of measurements can still be executed, although we recommend recharging the DTR as soon as possible. If battery voltage drops too low, the DTR will block further operations. In blocked mode, the DTR interrupts all functions until the mains supply is restored and the battery recharged. We recommend recharging the DTR at night. Each time the DTR is connected to the mains, a 14-hour recharge cycle begins. Repeated charging of partially discharged batteries will not damage the battery. During the 14-hour cycle, the CHARGING indicator will remain lit; after this period, a pulse maintenance charge mode is instituted and the indicator flashes. NB: The ratiometer comes pre-set to 230 V. 34

16 Changing power setting between 230 V and 115 V The power supply setting of the instrument can be switched between 230 and 115 volts by following the procedure below: 1. Switch the power off. Disconnect the instrument from all inputs and power. 2. Unscrew the four bottom screws. 3. Remove the instrument from the unit. 4. Locate the switch next to the transformer (see drawing). 5. Set the red switch to 115 V or 230 V. The switch setting indicates the selected voltage. 6. Replace the fuse (see power input) with the appropriate current rating. 115 V = 1 A, 230 V = 0.5 A 7. Carefully replace the instrument in the unit and fasten the bottom screws. 8. Remove the old voltage label. Place the input voltage label (115 V or 230 V) beneath the mains power supply input. 35

17 6. TIPS ON OBTAINING ACCURATE RATIO MEASUREMENTS n Always verify the integrity of test cable connections and reposition test clips if necessary. Check the transformer terminals for dielectric coatings, fungus and corrosion. n During VT/PT mode operation, select «Continuity Test» whenever possible. Apart from being a useful way of checking windings and connections, this test has the advantage of reducing the magnetic afterglow in the transformer being tested. This is particularly important in transformers with series resistance or low kva transformers with extremely high primary side inductance. This is not necessary for most tap-change and regulator transformers. n When testing polyphase transformers, bear in mind that, in some cases, the ratios measured should be multiplied or divided by Ö3. Refer to Attachment 7. for polyphase connection diagrams and associated ratio equations. 1/1 Ratio test A simple test can be conducted to test the functionality of the DTR. By connecting HRED to XRED and (separately) HBLACK to XBLACK, you simulate a 1/1 transformer. Operation of the DTR in this configuration should give a ratio very nearly equal to If this is not the case, the DTR should be repaired or calibrated. 36

18 7. APPENDIX Polyphased connections Ref. N TRANSFORMER - XFMR TYPE PHASE HIGH HIGH VOLTAGE WINDING LOW VOLTAGE WINDING 1Ø STD D - D STD D - D REV D - Y STD D - Y REV Y- Y STD Y- Y REV Y - D STD Y - D REV 1 Ø H 1 - H 2 X 1 - X 2 V H V X A B C A B C A B C A B C A B C A B C A B C A B C VOLTAGE WINDING H 1 - H 3 (A) H 2 - H 1 (B) H 3 - H 2 (C) H 1 - H 3 (A) H 2 - H 1 (B) H 3 - H 2 (C) H 1 - H 3 (A) H 2 - H 1 (B) H 3 - H 2 (C) H 1 - H 3 (A) H 2 - H 1 (B) H 3 - H 2 (C) H 1 (A) H 2 (B) H 3 (C) H 1 (A) H 2 (B) H 3 (C) H 1 (A) H 2 (B) H 3 (C) H 1 (A) H 2 (B) H 3 (C) LOW VOLTAGE WINDING X 1 - X 3 (a) X 2 - X 1 (b) X 3 - X 2 (c) X 1 - X 3 (a) X 2 - X 1 (b) X 3 - X 2 (c) X 1 (a) X 2 (b) X 3 (c) X 1 (a) X 2 (b) X 3 (c) X 1 (a) X 2 (b) X 3 (c) X 1 (a) X 2 (b) X 3 (c) X 1 - X 2 (a) X 2 - X 3 (b) X 3 - X 1 (c) X 1 - X 2 (a) X 2 - X 3 (b) X 3 - X 1 (c) TRANSFOR- MATION RATIO V H V X V H V X V H x Ö3 V X V H x Ö3 V X V H V X V H V X V H V X x Ö3 V H V X x Ö3 37

19 8. WARRANTY Our guarantee is applicable for twelve months after the date on which the equipment is made available (extract from our General Conditions of Sale, available on request). 9. MAINTENANCE For maintenance, use only specified spare parts. The manufacturer will not be held responsible for any accident occurring following a repair done other than by its After Sales Service or approved repairers Replacing the fuses For your safety the leads mus be deconnected from the DTR before the cover is opened. n Open the cover. n Replace the faulty fuses respecting their value and their type : See To order. n Refit the cover before using the ratiometer Cleaning n Keep the jaw faces perfectly clean. Remove dust with a soft dry cloth. Now and then, clean the jaw faces with a lightly oiled solft cloth. n Clean the case with a cloth slightly moistened with soapy water. Rinse with a dry cloth. Then dry quickly with a cloth or in a hot air stream (80 C max.) Calibration As any other measuring or test instrument, your instrument must be regularly checked. For checking and calibration of your instrument, please contact our accredited laboratories (list on request) or the Chauvin Arnoux subsidiary or Agent in your country. Repairs under or out of guarantee: please return the product to your distributor. 38

20 10. TO ORDER DTR 8500 Ratiometer.... P Comes pre-set to 230 V, with a type power lead and two test leads (5 m marked «H» and «X») in a shoulder bag and operating instructions. Accessory n Set of 2 test leads (10 m - «H» and «X»)... P Spares n Set of 2 test leads (5 m - «H» and «X»)... P n NiCd 12 V 1.3 A/h battery... P n Set of 5 x 4 A V (5 x 20 mm) slow-acting fuses... P n Set of 5 x 0.5 A V (5 x 20 mm) slow acting fuses... P n Set of 10 x 1A V (5 x 20 mm) slow-acting fuses.... P