ACCELERATION TRANSDUCER INSTRUCTION MANUAL

Transcription

1 MANUAL NO E2.0 Published in Dec.2003 Revised in Jun.2011 MODEL CA-302 ACCELERATION TRANSDUCER INSTRUCTION MANUAL

2 TABLE OF CONTENTS CA Series For Use in Safety... Thank you for your using our CA Series Acceleration Transducer. SHINKAWA Sensor Technology applies strict quality control and inspections to ensure the high reliability of its products. This instruction manual contains descriptive information, specifications, principle of operation, installation procedures and field wiring with monitor. Please study contents of this manual and related manuals thoroughly before installing or operating the equipment, and keep it handy for future reference.! CAUTION 1. Do not measure insulation resistance and dielectric strength other than those at places specified. If measured, transducer damage may result. 2. Do not remodel this unit without permission. Otherwise the guarantee can not be made. 3. This unit is designed for use by specialists or persons thoroughly familiar with the field. 4. Make sure that the end user receives the Instruction Manual delivered with this unit. Before Use... When the unit is received, inspect it for damage suffered in transport and check whether it is the item you ordered. In the unlikely event that it was damaged in transport or does not function according to specifications, please contact the SHINKAWA Office or dealer nearest you. Store the unit under the ambient conditions given in the specification. Avoid places where it is exposed to high humidity or corrosive gases.

3 TABLE OF CONTENTS CA Series 1. INSTALLATION 1-1 INSTALLATION OF ACCELERATION TRANSDUCER INTRODUCTION CABLING REQUIREMENTS MOUNTING OPERATION VERIFICATION SPECIFICATIONS INTRINSIC SAFETY 3-1 TIIS NEPSI KTL

4 1. INSTALLATION CA Series 1-1 INSTALLATION OF ACCELERATION TRANSDUCER The proper performance of vibration sensors depends greatly on the installation techniques employed. Proper sensor installation requires careful attention to powering, cabling, and mounting consideration. Installation techniques may vary between differing applications. Therefore, the monitoring requirements and the capabilities of the sensor must be well understood. 1-2 INTRODUCTION This note describes basic installation techniques for acceleration transducers. It will allow qualified field technicians to install transducers in a variety of applications and environments. Some techniques will be general to all installations, whereas others may be specific to a particular application. If additional information is required, please consult the sensor manufacturer. The process of installation begins with verifying that the proper sensor was selected for the measurement point. Consult us on additional information. The plant engineer must evaluate and determine the mounting location of the individual sensor based on the specific machine and vibration source to be monitored. With a firm understanding of the sensors requirements, capabilities, and limitations the installation can now be accomplished. After installation, verification of operation must be made to complete the process ELECTRICAL POWERING REQUIREMENTS Most internally amplified transducers require a constant current DC power source. Generally, the power supply contains an 20 to 30volt source with a 2 to 10mA constant current diode (CCD) (See figure 1-2-1). When other powering schemes are used, consultation with the sensor manufacturer is recommended. A more thorough discussion of powering requirements follows. 20 to 30VDC mA CCD 22µF (35 VDC) + 500kΩ Connector Amplifier Shield To instrumentation Crystal Isolation layer Figure Powering schematic -1-

5 1. INSTALLATION CA Series AC COUPLING AND THE DC BIAS VOLTAGE The sensor output is an AC signal proportional to the vibration applied. This AC signal is superimposed on a DC bias voltage (also referred to as Bias Output Voltage or Rest Voltage). The DC component of the signal is blocked by a capacitor thereby leaving the AC output signal. Most monitors and sensor power units contain an internal blocking capacitor for AC coupling. If not included, a blocking capacitor must be field installed AMPLITUDE RANGE AND THE SUPPLY VOLTAGE The sensor manufacturer usually sets the bias voltage halfway between the lower and upper cutoff voltages ( 2V above ground and 2V below the minimum supply voltage). The difference between the bias and cutoff voltages determines the voltage swing available at the output of the sensor. The output voltage swing determines the peak vibration amplitude range (See figure 1-2-2). Thus an accelerometer with a sensitivity of 100mV/g, and a peak output swing of 5 volts, will have an amplitude range of 50g peak. Peak amplitude range Supply voltage 2V below supply voltage Bias output voltage 2V above ground Ground Figure Area of linear operation If a voltage source lower than 18 volts is used, the amplitude range will be lowered accordingly. Custom bias voltages are available for lower or higher voltage supply applications CONSTANT CURRENT DIODES Constant current diodes are required for two wire internally amplified sensors. In most cases, they are included in the companion power unit or monitor supplied. Generally, battery powered supplies contain a 2mA CCD to ensure long battery life. Line powered supplies (where power consumption is not a concern) should contain 6 to 10mA CCDs to drive long cables. For operation above 100 C, where amplifier heat dissipation is a factor, limit the current to less than 6mA. If the power supply is not current limited, a CCD should be placed in series with the voltage output of the supply. Ensure that proper diode polarity is observed! CCDs are available from Motorola and Siliconix (4mA-part #1N5312 and J510 respectively). -2-

6 1. INSTALLATION CA Series 1-3 CABLING REQUIREMENTS Cabling is one of the most important aspects of transducer installation. Careful attention must be given to four major considerations: cable length, routing, grounding, and anchoring CABLE LENGTH AND CAPACITANCE All cables have capacitance across their leads, therefore the capacitance load on the output of the sensor increases with cable length. Generally this capacitance is 30 to 45 picofarads per foot, depending on the cable construction. After the cable length has been determined, is effect on the sensor operation should be evaluated. Capacitive loading attenuates the high frequency output of transducers. However, cable lengths for velocity transducers are less important since velocity transducers are used at low frequency and contain filtering of acceleration components AMPLITUDE RANGE VERSUS CABLE CAPACITANCE When the amplifier drives a long cable, its performance is limited by the current available from the CCD to charge the cable capacitance at high frequencies. This limits the amount of voltage swing from the amplitude range. A reduction of the amplitude range increases the sensor s susceptibility to high frequency amplifier overload. This will cause signal distortion and produce erroneous signals at low frequencies. Sources of high frequency overload could be gear impacts or the broadband hiss of a steam release valve. Most SHINKAWA acceleration transducers are protected from distortions from moderate overloads POWERING VERSUS CABLE LENGTH Proper powering will reduce signal distortion in long cable applications. It is recommended that for cable length cable applications. It is recommended that for cable lengths over 100 feet, the constant current source should be 6 to 10mA. In addition the voltage source should be no less than 24V for maximum amplitude range. Even when using very short cables, the current source should be increased if amplifier overload signals are present or suspected. Note: For most industrial applications, cable lengths of several hundred feet are normally acceptable with todays monitoring equipment as long as the sensor is not mounted on a structure with high level vibrations CABLE ROUTING AND ELECTROMAGNETIC INFERFERENCE Walky-talkies, power lines, or even electrical sparks may cause signal interference. The following guidelines will eliminate many measurement errors due to electromagnetic radiation and electrostatic discharge (ESD). Assure that high quality, well shielded cable are used. maintained. If cable splices are made, complete shielding must be Proper cable routing is also required. Never run sensor cable alongside AC power lines; cables must cross AC power lines at right angles. Where possible, provide a separate grounded conduit to enclose the sensor cable. In addition, route the cable away from radio transmission equipment, motors/generators, and transformers. Finally, avoid routing the cable through areas prone to ESD. Even though the sensor is protected against ESD failure, temporary distortion products may appear at the output. -3-

7 1. INSTALLATION CA Series CABLE GROUNDING AND GROUND LOOPS In order to provide proper shielding and prevent ground loops, cable grounding should be carefully considered. Ground loops are developed when a common line (i.e. signal return/shield) is grounded at two points of differing electrical potential (See figure 1-3-1). Non-isolated accelerometer Readout equipment Ground loop Figure Ground loop from improper grounding For sensors with coaxial cable, the center conductor carries the signal and power, while the outer braid provides shielding and signal return. Normally, the cable shield is electrically isolated from the sensor housing. This isolates the shield from the mounting point of the machine and prevents ground loops. If a non-isolated sensor is used, it is recommended that an isolated mounting pad be used to break possible ground loops. For sensors using two conductor/shielded cable, the signal and power are carried on one lead and signal return on the other. The cable shield serves to protect the signal from ESD and electromagnetic interference (EMI). The shield is normally grounded to the sensor housing and at the far end of the cable it is not directly connected to the grounded terminal box. If EMI signals are found to affect the vibration signal, a filtering capacitor (0.01µF, 200V low loss) should be placed between the shield and the grounded terminal box. This capacitor prevents the passage of low frequency ground currents, yet shunts high frequency EMI signals to ground. (See figure ) 0.01µF HF Capacitor (optional) Readout equipment Internal shield isolated from housing Figure Multiconductor/shield configuration -4-

8 1. INSTALLATION CA Series Environments containing high levels of electromagnetic noise from sources such as radio transmitters, static discharge, and motor bush arcing, may require a cable with dual isolated shields. In this configuration the outer shield is grounded to the sensor housing and the inner shield, which is electrically isolated from the outer, is grounded to the terminal box. The double shielding allows electrical charges impressed on the cable to be attenuated twice to minimize influence on the vibration signal. Similar to the previous configuration, it is recommended that a capacitor (0.01µF, 200V low loss) be placed in the terminal box between the inner and outer shields to maximize this protection (See figure 1-3-3). Readout equipment Figure Dual isolated shield configuration Note: In all cases it is very important that the cable shield terminations be properly grounded. so can result in damage to the sensor electronics in high EM/ESD environments. Failure to do CABLE ANCHORING After mounting the sensor, the cable should be anchored to reduce stress at the cable terminations. When securing the cable, leave enough slack to allow free movement of the transducer (See figure 1-3-4). 3 inches minimum clearance 1.9 inches minimum clearance Cable Clamp Machine surface Figure

9 1. INSTALLATION CA Series 1-4 MOUNTING The mounting configuration depends primarily upon dynamic measurement requirements such as frequency and amplitude range. Other factors to be considered are mounting location, prohibitions, accessibility, and temperature. In general, there are four configurations for mounting vibration sensors: threaded studs, adhesives, magnets, and probe tips (See figure 1-4-1) Probe tip 2-pole Magnet Flat Magnet Adhesive Mounting pad Adhesive Stud Relative sensitivity (db) ,000 10, ,000 Frequency (Hz) Figure Mounting techniques -6-

10 1. INSTALLATION CA Series STUD MOUNTING threaded stud mounting results in the widest dynamic measurement range. It is recommended for permanent monitoring systems, high frequency testing, and harsh environments. The surface should be faced 1.1 times greater than the diameter of the mounting surface of the sensor. For measurements involving frequencies above 1kHz, the surface should be flat within 1mil and have surface texture no greater than 32 microinches. The tapped hole must be perpendicular to within 1 of the mounting point and at least two threads deeper than the stud. This will prevent a gap between the sensor and the mounting surface. Proper screw torque on the mounting stud is also required. Under-torquing the sensor reduces the stiffness of the coupling. Over-torquing can cause permanent thread damage to the sensor. It is recommended that studs be torqued to a nominal value of 20 inch-ponds, M6 studs to a nominal value of 26 inch-pounds, and M6 captive screws to 30 inch-pounds. 32 >1.1 sensor dia A A Figure Before stud mounting the accelerometer, a coupling fluid should be applied to the mating surfaces. The coupling fluid protects the mounting surface and optimizes the frequency response by increasing the coupling stiffness. Suggested coupling fluids are machine oil or vacuum grease. It is recommended that a thread adhesive such as Loctite 222 be used. -7-

11 1. INSTALLATION CA Series ADHESIVE MOUNTING If a hole cannot be tapped into the machine, an adhesive mount is recommended. When using an adhesive, the sensor may be directly attached to the machine. An adhesive mounting pad may be used if repeated removal of the sensor is required. If the circuit grounding scheme requires the sensor case to be grounded to the machine, then the installer must ensure that the adhesive mounting pad is electrically grounded to the machine. The adhesive mounting pad is flat on one side with a threaded stud on the other. After the pad is adhered to the machine, the sensor is torqued onto the stud. A coupling fluid should be applied to the stud side. In order to optimize the frequency response, machine the bonding surface flat within.001 inches. Following standard adhesive bonding practice is critical to durability. The surfaces should be abraded and carefully cleaned with a solvent. Mixing and application of the adhesive must be done in compliance with the adhesive manufacturer. Suggested adhesives are shown in the chart below. Loctite 380 (Black Max.) Adhesives Comments Cyanoacrylate adhesive. Single component, sets up quickly, use at temperatures below 200 F, remove by twisting the sensor. Surface must be clean and very smooth MAGNETI MOUNTING AND PROBE TIPS In walk around monitoring programs magnetic mounts and probe tips may be used. The frequency range of both mounting methods is dramatically reduced when compared to stud or adhesive mounts. Magnetic mounts are available with flat surfaces for flat locations or two pole configurations for curved surfaces. Probe tips should be made of steel and be no longer than six inches. 1-5 OPERATION VERIFICATION Once installation is complete, it is recommended that the vibration sensor be tested for proper operation. Measure the DC bias output voltage (BOV) by powering the sensor and connecting a voltmeter in parallel with the signal and common leads. sheet (usually 8 to 12V). The BOV should rest within ±2V of the value note on the specification DIAGNOSTIC HINTS If the BOV is correct, the sensor and cabling are in proper working order. If the BOV equals 0V the circuit is shorted; test the cable connections and power supply. If the BOV equals the supply voltage, the circuit is open; test the cable connections. To verify sensor amplifier operation, temporarily replace the suspect sensor with a new unit. To test for vibration sensitivity, tap the machine surface near the sensor. Observe the signal on an oscilloscope to ensure that the sensor is picking up vibrations. Monitor the measurements of a newly installed sensor to determine if its output is reasonable. -8-

12 2. SPECIFICATIONS CA Series Model Code / Additional Spec. Code CA /EX Armor Intrinsically safe 0 Without 0 TIIS Ex ia IIB T3 X 1 With 1 TIIS Ex ia IIB T4 X 2 TIIS Ex ia IIC T3 X 7 NEPSI EX ia IIC T4 8 KTL EX ia IIC T3 SPECIFICATIONS Sensitivity 100mV/9.8m/s 2 (100mV/g REF.)pk±10% at 100Hz, and 25 C Acceleration Range Vibration Limit Shock Limit Max. Shock Energy Linearity Natural Frequency Frequency Response 490m/s 2 (50g REF.)pk 4,900m/s 2 (500g REF.)pk 9,800m/s 2 (1,000g REF.)pk 4J (intrinsically safe) ±1% of F.S. 30kHz 2 to 5,000Hz±10%, 1 to 10,000Hz±3dB Transvers Sensitivity Max. 10% Output Impedance Power Supply Grounding Temperature Response Operating Temperature range Relative Humidity Protection Rating Weight Case Material Cable Accessory 100Ω 20 to 30VDC, 2 to 10mA (non-intrinsically safe) 20 to 25.5VDC, 2 to 10mA (intrinsically safe) Case isolated, internally shielded Within ±10% (Around the operating temperature range) -20 to +120 C (non-intrinsically safe) -20 to +60 C (Intrinsically safe : EX0,EX2,EX7,EX8) -20 to +40 C (Intrinsically safe : EX1) 100%RH IP67 Approx.90g Stainless steel 2-conductor shielded, Cable length : Approx.5m M6 Mounting stud (1 piece) E1.7

13 3. INTRINSIC SAFETY CA Series 3-1 TIIS (Japanese Only) -10-

14 3. INTRINSIC SAFETY CA Series -11-

15 3. INTRINSIC SAFETY CA Series -12-

16 3. INTRINSIC SAFETY CA Series 3-2 NEPSI (Chinese Only) -13-

17 3. INTRINSIC SAFETY CA Series -14-

18 3. INTRINSIC SAFETY CA Series 3-3 KTL (Korean Only) -15-

19 Warranty The warranty period for the delivered product shall be 3 years from the date of delivery from our factory. But the warranty period for the special order product and software shall be 1 year, and for the repairing parts shall be 6 months. In the event that the delivered product develops any defects within the warranty period for which Shinkawa Electric is liable, the defective part will be replaced or repaired in our factory at our own expense. In the event that a Shinkawa engineer needs to be dispatched for repair purposes during the warranty period, the cost of the repairs will be borne by Shinkawa Electric ; however, the travel expenses shall be charged in accordance with our policies. However, the following are excluded from our warranty: (1) Any defects due to improper handling or operation by the user. (2) Any defects, the case of which is not attributable to Shinkawa Electric. (3) Any modifications or repairs made by others than Shinkawa Electric or persons commissioned by Shinkawa Electric. (4) Any handling, storage and operation under severe environmental conditions that exceed the design specifications. (5) Any defects due to fire, flood, earthquake, lightning and other Acts of God. (6) The consumables (7) Other defects considered not to be attributable to Shinkawa Electric. This warranty applies exclusively to the delivered product units. Shinkawa Electric will not be held liable for consequential damage caused either directly or indirectly through a defect of the delivered product. The warranty period and scope of machinery and equipment made by manufacturers other than Shinkawa Electric shall be in accordance with the conditions of the respective manufacturer, regardless of the provisions made above.

20 Hiroshima Factory 4-22 Yoshikawa-kogyodanchi, Higashi-hiroshima , Japan Tel Fax [Field support & Repair Dept] service@sst.shinkawa.co.jp