Training, Class I, Testing, IIb, 1-10 [PDF]

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CUSTOMER'S GUIDE Large AC Motor Testing



At



Kings Mountain N.C. Plant



TABLE OF CONENTS Reference Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22



Test Ac Hi-pot Test Bearing Inspection Bearing Insulation Test Bearing Run For API Motors Bracket Natural Frequency Test Check Test With Customer Supplied Coupling Dc Hi-potential Test Dynamometer cold to hot uncoupled vibration test Heat Run Locked Rotor Saturation No Load Saturation Noise Overspeed Unbalanced Coastdown Performance (method B) Performance (method F) Polarization Index Routine Mechanical Run Test Routine Test - Standard Setup Guidelines For API Testing Speed Torque Stator Core Test Stator Winding Immersion



Completed



1. AC HI-POT TEST



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46101 Section 10 IEEE 112-9.2, NEMA MG-20.17 Hi-pot tester Verify the integrity of the insulation. 1) Apply a voltage of twice rated + 1000 to the stator windings. 2) Measure and record leakage amps. 3) If applicable, apply 1000 volts to accessories. 4) Measure and record leakage amps.



2. BEARING INSPECTION



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419530-138 Part I API-541 / 547 Assembly Verify bearing wear pattern 1) Perform bearing inspection on sleeve bearing motors. 2) Sketch bearing patterns and plastigage the bearing to shaft clearance and bearing to bracket crush. Use a six (6) mil shim between the bracket cap and bearing when plastigaging the OD of the bearing. Reassemble the motor and continue with specified testing on sales order.



3. BEARING INSULATION TEST Reliance Specification: 419530-138 Part J API-541 / 547 Industry Specification: Assembly Location: Verify integrity of bearing insulation system Purpose: Note: For TEFC or TEAAC motors, bearing insulation test will be performed prior to final assembly due to construction of fan housing components. Data and records will be provided to a Customer witness if necessary. This test will not be performed for a Customer witness, unless it is previously agreed to and scheduled. Witness will need to be present two days prior to start of other tests. 1) List all the test equipment used for motor testing. Include equipment Procedure: description and calibration date. 2) Reassemble brackets and measure bearing insulation with a multimeter set on maximum ohms. The readings must show an open circuit.



4. BEARING RUN FOR API-541 3rd Edition MOTORS Reliance Specification: 419530-138 Part B API-541 / 547 Industry Specification: Seismic Mass Location: Perform bearing run on sleeve bearing motors to determine bearing Purpose: Procedure:



performance through measurements of bearing temperatures, vibration and bearing contact pattern 1) Review all inspection records. When the motor has customer specified proximity probes, check for probe calibration plots. If there are no calibration records, generate calibration plots for proximity probes – 0 to 70 mil. 2) Set motor on mass per 419530-138 Part A. 3) Perform a bearing run with motor operating at rated voltage. Run the motor for 20 minutes and measure the following: 4) Record vibration levels every minute for the 20-minute bearing run test. 5) At the end of the 20-minute bearing run, record the ambient temperature and the bearing temperatures. 6) c. When the motor has proximity probes record the proximity probe run-out during the coast down at a speed between 300 and 200 rpm. Hold the shaft on magnetic center when recording slow roll runout. 7) Inspect the entire motor for signs of oil leakage, no leakage allowed. 8) Send motor back to assembly and perform bearing inspection.



5. BRACKET NATURAL FREQUENCY TEST Reliance Specification: 419530-138 Part H API-541 / 547 Industry Specification: Seismic Mass Location: Verify bracket natural frequency locations Purpose: 1) If motor set-up has changed since the last test, prepare motor for Procedure: testing per Section A. 2) Ring both brackets for a resonance response in the horizontal, vertical and axial directions. Start the motor so shaft rotation is between 200300 rpm when ringing brackets. Plot the frequency response from 0 200 Hz.



6. CHECK TEST WITH CUSTOMER SUPPLIED COUPLING Reliance Specification: 419530-138 Part C API-541 / 547 Industry Specification: Seismic Mass Location: Determine effect of customer mounted coupling on vibration performance Purpose: 1) Note: This test is required only when the coupling balance was not Procedure: checked at the finish line. 2) Perform motor setup per 419530-138 Part A, except mount the customer coupling on the shaft extension. 3) Start the motor and increase voltage to rated voltage. Run the motor at rated voltage until the bearing temperatures stabilize to a 1 °C change per 30 minutes. 4) Record vibration level in 30-minute increments throughout test beginning at motor startup. For the last set of vibration levels, record the vibration in one (1) minute increments for 15 minutes to generate time plots. When there are no proximity probes provided, record only the bracket vibration levels. 5) After the bearing temperatures stabilize reduce the voltage to ¼ voltage, hold the shaft on magnetic center and record a set of vibration readings. 7. DC HI-POTENTIAL TEST



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Procedure:



419530-144 API-541 / 547, IEEE-95 DC Hi-Pot Tester May aid in predicting the condition of the stator winding. May also allow approximate prediction of the insulation breakdown voltage. Note - IEEE points out that there is some controversy in the interpretation of test results. 1) Bleed any residual charges on the stator windings by grounding. 2) Preferably this test should be conducted when the stator winding is at or near ambient temperature. 3) Connect the stator lead to the DC power supply. Apply voltage in not less than four approximate equal steps, pausing one minute at each step and five minutes at the final voltage. Maximum recommended DC test voltage is given by the following equation: Vdc max = (2*VLL + 1) * (1.75) * (0.75) 4) Record applied voltage, leakage current and insulation resistance.



8. DYNAMOMETER COLD TO HOT UNCOUPLED VIBRATION TEST Reliance Specification: 419530-138 Part G API-541 / 547 Industry Specification: Load Stand Location: The Cold to Hot Uncoupled Test verifies rotor vibration stability between Purpose: cold operating conditions and when the rotor reaches operating temperature. The cold to hot vibration levels takes out any vibration associated with misalignment or vibration transmitted from the gearbox and provides vibration data only on the motor characteristics. 1) Align the motor to the dynamometer with a spacer in the coupling. Procedure: 2) Prepare motor for test per 419530-138 Part A. 3) Uncouple the motor. Run the motor uncoupled at rated voltage and at rated speed for 1 hour after the bearing temperatures stabilize to 1°C change per 15 minutes. 4) Record the bearing and stator winding temperatures in 15-minute increment. 5) Record vibration level in 30-minute increments throughout test, beginning at motor startup. When there are no proximity probes provided record only the bracket vibration. 6) Record volts, amps and watts per phase in 30-minute increments. 7) Couple the motor. Perform a heat run per 46101-F electrical test procedure. Load test must be a minimum of 4 hours. 8) Record vibration level in 30-minute increments throughout test beginning at motor startup. When there are no proximity probes provided record only the bracket vibration levels. For the last set of vibration levels, record the vibration in 30-second increments for 10 minutes to record the frequency of the vibration modulation. Use the recorded vibration data to review frequency sweeps from 0 - 250 Hz for all points. 9) Record electrical data per 46101-F. 10) Perform a heat run test for a minimum of 4 hours. The loaded heat run is level and ready for shutdown when there is no more than a 1°C change in temperatures between two successive readings taken 30 minutes apart. Take a complete set of readings before shutdown. 11) Take hot resistance shutdown. 12) Note: Perform steps’ five (5) and six (6) only when the motor does not meet the specified vibration levels at any specific location and frequency under load and/or during the Cold Uncoupled. 13) Quickly uncouple the motor and cover 80% of the air inlet. The motor must be running again within 20 minutes. 14) Run the motor uncoupled at rated voltage and speed. Record vibration bearing temperatures immediately upon restarting the motor. 15) Note: If the loaded, hot or cold uncoupled vibration readings do not meet the limits shown in Table 1 of the Appendix contact Mechanical Engineering and perform the following calculations for each point that fails. 16) Divide each hot uncoupled vibration point that exceeds the limits, by the corresponding cold uncoupled vibration point to obtain the hot to cold ratio. 17) Multiply this ratio, by the corresponding vibration point, with the highest amplitude, recorded during the no-load mechanical run in Section D of this procedure on the rigid mass. 18) Couple the motor back to the dynamometer. Perform speed-torqueamp test per tests 46101-D and load performance at six (6) loads per 46101-E, when specified on the sales order. Hold for electrical engineering to work up performance data. 19) On sleeve bearing motors perform a bearing inspection. 9. HEAT RUN



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46101-F IEEE 112-8 Dynamometer Verify temperature rating 1) Load the motor by dynamometer to rated load torque/horsepower at nameplate voltage and frequency. 2) Measure and record input volts, amps, watts, and temperatures of RTDs and thermocouples every 30 minutes. 3) Repeat step 2 until the temperature has stabilized. 4) Once stabilization has been reached, power is removed from the motor and consecutive stator winding resistance values are recorded.



10. LOCKED ROTOR SATURATION Reliance Specification: 46101-C2 IEEE 112-7.2 Industry Specification: Seismic Mass Location: Verify locked rotor torque and current Purpose: 1) Connect the torque arm to the motor shaft. Procedure: 2) Set the voltage to 25% of rated voltage and apply rated frequency. If the impressed torque and amp values are very high, the motor may be tested with single-phase voltage. 3) Measure and record input volts, amps, watts, and torque. 4) Repeat steps 1 and 2 for higher voltages. Voltages will be limited such that the impressed amps and torque do not exceed safe limits of the test equipment and motor. 11. NO LOAD SATURATION



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46101-C1 IEEE 112-5.3 Seismic Mass/Dynamometer (Uncoupled) Determine the stator core loss and inherent running friction due to bearings and fans. 1) Set the voltage to 125% of rated voltage and apply rated frequency. 2) Measure and record input volts, amps, and watts. 3) Repeat steps 1 and 2 for 6 other voltages ranging from 125% to 25% rated voltage.



12. NOISE



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419530-14 IEEE 85 Aisle Verify sound level 1) Place assembled motor on rubber. 2) Record ambient noise at 4 positions around the motor. Each position is located at a specified distance from the motor (typically 3 feet). The average of all positions is recorded. 3) Energize motor at rated voltage. 4) Record sound level at 11 positions at a specified distance (typically 3 feet). Eight positions are around the motor and three positions are above the motor. The average of all positions is recorded.



13. OVERSPEED UNBALANCED COASTDOWN Reliance Specification: 419530-138 Part E API-541 / 547 Industry Specification:



Location: Purpose: Procedure:



Seismic Mass Verify rotor dynamic performance with an unbalanced mass added. On flexible rotors the location of the first lateral critical speed is confirmed 1) If the motor set-up has changed since the last test, prepare the motor for testing per 419530-138 Part A. 2) The unbalanced weight per plane used for this test equals (4*(4W/N)), where: 3) W = half the rotor weight in lbs. 4) N = the operating speed in rpm 5) Place the unbalance weight to each end of the rotor in phase. Perform overspeed unbalanced coastdown test from 115% of operating speed. Hold shaft on magnetic center and record the coast down to rest. 6) Place the unbalance weights 180° out of phase on the rotor. Perform overspeed unbalanced coast down test from 115% of operating speed. Hold shaft on magnetic center and record the coast down to rest.



14. PERFORMANCE (METHOD B) Reliance Specification: 46101-E NEMA MG1-20.21, IEEE 112-3.4, 6.4 Industry Specification: Dynamometer Location: Verify power factor and efficiency at different loads. Purpose: 1) Load the motor by dynamometer to near rated temperature at Procedure: nameplate voltage and frequency. 2) Measure and record input volts, amps, watts, speed and hottest RTD temperature reading at six approximate load levels from 150% rated load down to 25% rated load. Being sure to include rated load (100%), 75% and 50%. 3) This data is used to determine power factor and efficiency at different loads. Stray load loss is determined by linear regression. 15. PERFORMANCE (METHOD F) Reliance Specification: 46101-AR IEEE 112-6.7 Industry Specification: Seismic Mass Location: Verify performance of the motor. Purpose: 1) Connect torque arm to motor shaft. Procedure: 2) Set supply frequency to 60 hz and voltage such that current is approximately 50% of full load amps. 3) Record volts, amps, kilowatts, winding temperature, and line frequency. 4) Repeat steps 2 and 3 for 75%, 100%, and 115% of full load amps. 5) Repeat steps 2, 3, and 4 for 30 hz and 15 hz.



16. POLARIZATION INDEX



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412254-4 IEEE 43 Seismic mass Determine the condition and insulation resistance of the stator winding. 1) Bleed any residual charges on the windings by grounding. 2) Measure and record ambient temperature, winding temperature, and humidity. 3) Apply specified test voltage between the winding and ground. 4) Record resistance every 15 seconds for the first minute and every 30 seconds for the second minute and every minute thereafter for 10 minutes.



17. ROUTINE MECHANICAL RUN TEST Reliance Specification: 419530-138 Part D API-541 / 547 Industry Specification: Seismic Mass Location: Verify vibration performance under no load conditions Purpose: 1) Run the motor at rated voltage for 1 hour after the bearing Procedure: temperatures stabilize to a 1°C change per 30 minutes. 2) Record vibration level in 30-minute increments throughout test beginning at motor startup. For the last set of vibration levels, record the vibration in one (1) minute increments for 15 minutes to generate time plots. When there are no proximity probes provided record only the bracket vibration levels. 3) Review frequency sweep plots for all positions from 0 to 200 Hz. 4) Record bearing temperatures every 15 minutes throughout the test, beginning at startup. 5) Record the following data every 30 minutes throughout the test beginning at startup, stator temperatures, voltage, current and power per phase. 6) Reduce voltage from rated voltage to ¼ voltage, hold shaft on magnetic center and record vibration readings for all measurement location. 7) Record the slow roll run-out during the coastdown at a speed between 300 and 200 rpm for each proximity probe position. Hold the shaft on magnetic center.



18. ROUTINE TEST - STANDARD Reliance Specification: 46101-B1 & 419530-19A NEMA MG1-20.16.2 & Part 7 Industry Specification: Seismic Mass Location: Ensure that the unit is manufactured with the correct elements and meets Purpose: all the quality standards. In addition, sleeve bearing motors run twice, first to assure proper bearing alignment and afterward to assure all other aspects. 1) On sleeve bearing motors, measure and record air gaps at four Procedure: positions at both ends of the motor. 2) Measure and record winding resistance. 3) Measure resistance of electrical accessories. 4) Measure and record no load inputs (volts, amps, watts and speed). 5) Measure and record locked-rotor inputs (volts, amps and watts). Due to equipment capacity limitations, locked rotor points may be taken at a reduced voltage and/or single-phased. 6) Motor is rigidly bolted to the seismic mass for testing. 7) Motor is tested at rated voltage and speed at no load conditions for thirty minutes. 8) After the motor has run for thirty minutes, vibration levels are recorded for each bracket position on sleeve bearing motors the shaft vibration levels are also measured. Bearing temperatures are recorded at this time as well.



19. SETUP GUIDELINES FOR API-541 3RD EDITION TESTING Reliance Specification: 419530-138 Part A API-541 / 547 Industry Specification: Seismic Mass and Load Stand Location: Preparations for Testing Motor per API-541 3RD EDITION Requirements Purpose: 1) When applicable, install bearing RTD's and when supplied, proximity Procedure: probes. Set the gap voltage on the proximity probes at 9 to 10 volts. 2) Connect stator RTD’s or thermocouples when performing routine mechanical run and dynamometer tests. 3) Install a crowned half key and retaining collar on the shaft extension. 4) Mount the motor on the seismic mass for all no load testing and for loaded testing mount the motor on the dynamometer. No testing on isolation pads permitted. 5) Bolt the motor directly through the motor feet bolt holes - Do not clamp the motor down to the mass. Have each motor foot torqued to 80 ft-lb. Check foot deflection by loosening and then retightening each foot. Torque the hold-down bolts one at a time to 80 ft-lb. each with a torque-wrench to ensure repeatability. Foot deflection limited to no more than 1.00 mil. Shim the motor feet to limit foot deflection to 1.00 mil or less, if necessary. 6) When a motor has provisions for flood lubrication, connect flood lube system to the motor and operate the lubrication system as described on the Dimension Sheet (D/S). Do not connect the flood lube system for the bearing run. 7) When specified to record vibration levels, record (F/O, 1/2x, 1x, 1x phase angles, 2x and for non- two poles record 60 Hz line frequency and 120 Hz line frequency) vibration levels. Record shaft vibration levels in mils and bracket vibration levels in in/sec. On sleeve bearing motors, record the shaft vibration levels using proximity probes. Use shaft sticks to measure shaft vibration levels when there are no provisions for proximity probes. 8) List all the test equipment used for motor testing. Include equipment description and the calibration date. Use the form on the 419530-143 for documentation. 20. SPEED TORQUE



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46101-D IEEE 112-7.3 Dynamometer Verify the starting characteristics (torque and amps versus speed) 1) The power supply voltage will typically be set to a value lower than rated (usually 50%). 2) Drive the motor to the desired speed. 3) Record volts, amps, speed, torque, and winding temperature. 4) Let the motor return to full speed to cool. 5) Repeat steps 2, 3, and 4 for a minimum of eight times.



21. STATOR CORE TEST



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419530-160 API-541 / 547 Rock Hill Service Center Verify the stator core interlaminar insulation integrity 1) Test shall be performed on the stator core prior to the insertion of the stator coils. 2) Rated flux shall be maintained on the stator core for a minimum of 1/2 hour while continuously monitoring stator temperatures. 3) Deficiencies are defined as any core location which is 5°C above the adjacent core temperature.



22. STATOR WINDING IMMERSION Reliance Specification: 412254-1,3 NEMA MG1-20.18.1 Industry Specification: Water Tank Location: Verify the insulation system is sealed against moisture. Purpose: 1) Megger the dry stator and record insulation resistance. Procedure: 2) Immerse the core in a water solution containing a wetting agent. 3) Megger the wet stator for 10 minutes. Record initial insulation resistance and at a period 1 minute and 10 minutes. 4) Hi-pot the immersed windings at 1.15 times rated voltage for 1 minute. Record initial insulation resistance and at a period of 1 minute. 5) Remove stator from water. 6) Dry in oven.