Commissioning of an induction motor is a process that ensures the motor operates efficiently and reliably within its required application. This process involves a series of steps to verify the motor’s performance, identify any issues, and optimize its operation.
Functional Testing of Motor Control.
At substation Side (Control Room Side)
Day before of the Solo Run Test or megger test.
- Disconnect the power cable of motor in contactor.
- Switch on the breaker, measure the voltage output and test the contactor for functional.
- Push start button and check contactor if close and red lights on.
- Push stop button and check contactor if open and green lights on.
2. At field side (for LCS with selector switch type).
Note:
- Remote : On – Not Activate: Off – Off
- Remote : On – On: Off – Off
See Attachment of Local Control Station (LCS) sequence function checklist for LV & MV Motors.
- Check the power supply to the LCS.
- Rotate the selector switch to start and release, check contactor if close in substation and green lights on in LCS.
- Rotate the selector switch to stop and check contactor if open in substation and red lights in contactor.
- Switch the breaker on, bump motor and check for proper rotation.
At field side (for built-in LCS with push button type for Motor skid)
- Check the power supply to the LCS.
- Rotate selector switch to local position.
- Push start button and check contactor if close.
- Push stop button and check contactor if open.
- After function test of LCS are completed, switch off the breaker and connect power supply cable in contactor.
Switch the breaker on, bump motor and check for Proper rotation.
4 Hour Motor Solo Run Test.
Preparation:
- Secure approved work permit prior to start of work.
- Ensure that the approved lock-out/tag-out permit is applied.
- Conduct tool box meeting to discuss possible hazard for the activities.
- Barricade the working area (testing).
- Make sure that the personnel in substation and field side have a clear communication (i.e. Two way radio).
Ensure that the motor to be tested is uncoupled.
Note:
- Check if power cable is meggered (megger test) prior to start of the motor.
- Continuity check on cables.
- Check the rotation by instant energize – Bump Start.
Start The Motor.
Measure and record the temperature, vibration, voltage, current and winding resistance using the following document.
- Low Voltage Squirrel Cage Induction Motors (SCIM).
- Medium Voltage Induction and Synchronous Motors (Up to Nameplate Voltage).
- (LV Motor 4 Hour Run Test) Variable Frequency Drives for NEMA Frame Motors (Pre-commissioning form).
- (MV Motor 4 Hour Run Test) NEMA Frame, Form Wound Induction and Synchronous Motors (Pre-commissioning form).
After the completion of solo run motor testing, re-install LOTO, ensure that the lock-out/tag-out permit was signed off.
Ensure that the lock-out/tag-out isolator will put back the padlock @ MCC and LCS.
Polarization Index Test: 1 minute & 10 minutes readings.
The polarization index test (PI test) is performed to quantitatively measure the ability of the ground wall insulation to polarize. The PI test is the most confusing HVDC test in use due to the subtleties in the interpretation of the results. When an insulator polarizes, the electric dipoles distributed in the insulator align themselves with an applied electric filed.
As the molecules polarize, a “polarization current”, also called an absorption current, is developed that adds to the insulation leakage current. The test results become confusing when attempting to attribute variations in the PI value to the polarizability of the insulator or other affects such as humidity, moisture and instrument error.
The PI test is typically performed at the same voltage as the megaohm test and takes 10 minutes to complete. The PI value is calculated by dividing the insulation resistance at 10 minutes by the resistance at 1 minute as shown below:
Polarization Index (PI) = IR (10 min)/ IR (1 min)
In general, the insulators that are in good condition will show a “high” polarization index while insulators that are damaged will not. IEEE 43 recommends minimum acceptable values for the various thermal classes of motor insulation.
| NEMA Class A | 1.5 |
| NEMA Class B | 2.0 |
| NEMA Class F | 2.0 |
| NEMA Class H | 2.0 |
- Ground the motor leads after the test and discharge motor windings.
- Check the motor is correctly connected to the available power supply voltage.
- Measure and record initial bearing temperatures and the ambient temperature and record temperatures during testing.
- Prior to execute, earthing shall be checked to ensure it is as per the detail drawing and installed in accordance with SAES-P-111. Testing for motor grounding is necessary by using earth resistance teat or equivalent as in SAES-P-111 para 6.1.18.
- Prior to test, the winding shall be grounded in order to drain off any static.
Industry Codes For Megger Test.
- NFPA 70 – National Electrical Code.
- IEC 60840 – International Standard.
Tools and Equipment Used.
Tools and equipment needed should be in good condition and must be checked by Supervisor / Safety Engineer prior to use in the construction area. These includes but not limited to:
- Welding Machine.
- Electric Power Tools (i.e. drill etc.)
- Boom Truck.
- Insulation Tester.
- Multi-meter (VOM) – Rated up to 1kV.
- Vibration Meter.
- Temperature Detector Meter.
- Hi-pot Tester.
- Termination Tools.
- Common Hand Tools.
- Ladder.
- Protective Relay Calibration Test Set – (Substation).
- Current Injector.
- Earth Resistance Test.
- Low Resistance Tester / Ductor Resistance Ohmmeter.
- Phase Sequence.
- LCR Meter.
- Torque Wrench.
- Power Supply.
All tools utilized in megger test a classified area should be intrinsically safe and suitable for hazardous areas.
All test equipment to be used for megger test shall be calibrated in accordance with schedule Q requirements shall not exceed six (6) months. Contractor shall provide backup equipment when the primary equipment is being calibrated or tested.
Safety Precautions for Induction Motor Commissioning.
- Secure the approved work permit from the concerned Representative before starting any work.
- Conduct proper preparation to include required safety equipment and tools for the commencement of the work.
- Activities shall be executed in accordance with this procedure and related standards and specifications
- Provide warning sign and sufficient barricade on working area. Only assigned personnel will be allowed in the area to maintain a safe work environment.
- Conduct safety briefing to all working crew to remind them of all the basic safety requirements on the job to ensure safe work flow.
- Continuous monitoring and inspection shall be implemented by the site supervisor/foreman together with the assigned safety supervisor in the area. Any unsafe practices while performing the work activities shall be corrected immediately to avoid stoppage of the work.
- Good housekeeping shall be maintained throughout the work activity. The work site shall be kept clean and safe before start up of solo runs.
- Safety Supervisor shall monitor the work activities to help and protect all assigned workers against exposure to safety hazards. He shall ensure that Personal Protective Equipment (PPE’s) are supplied and worn at all times.
- MV (PPE’s) to be available at substations.
- MV Rated Protective Cover.
- Face shield.
- Job Hazard and Risk Assessment of this procedure shall be disseminated and explained to workers for safety awareness.
Physical Inspection:
Before commissioning, visually inspect the motor for any signs of damage, such as dents, scratches, or loose connections. Ensure that all electrical connections are tight and secure.
Alignment:
Align the motor shaft with the driven equipment to minimize mechanical stress and vibration. Proper alignment ensures smooth operation and prolongs the life of both the motor and the driven equipment.
Electrical Connections:
Verify that the motor is correctly connected to the power supply according to the manufacturer’s specifications. Check the voltage, frequency, and phase rotation to ensure compatibility with the motor’s rating.
Lubrication:
If applicable, ensure that the motor bearings are properly lubricated according to the manufacturer’s recommendations. Insufficient lubrication can lead to premature bearing failure and motor downtime.
Motor Start-Up:
Gradually start the motor and monitor its performance, including voltage, current, and speed. Observe any abnormal noises or vibrations that may indicate mechanical or electrical issues.
Load Testing:
Apply a gradual load to the motor and observe its response. Ensure that the motor operates within its rated load capacity and does not overheat or exhibit excessive vibration.
Performance Testing:
Conduct performance tests to verify the motor’s efficiency, power factor, and torque characteristics. Compare the test results with the manufacturer’s specifications to ensure compliance.
Protective Devices:
Verify that all protective devices, such as overload relays and thermal protectors, are properly calibrated and functioning correctly. These devices are essential for protecting the motor from overload and overheating.
Efficiency Optimization:
Adjust motor parameters, such as voltage and frequency, to optimize efficiency and performance. Fine-tune control settings as necessary to achieve the desired operating conditions.
10. Documentation:
Maintain comprehensive records of the commissioning process, including test results, adjustments made, and any issues encountered. This documentation serves as a reference for future maintenance and troubleshooting.
11. Training:
Provide training to operators and maintenance personnel on the proper operation, maintenance, and troubleshooting of the motor. Ensure that personnel are familiar with safety procedures and protocols.
12. Final Checks:
Perform a final inspection of the motor and surrounding equipment to ensure everything is in order. Address any remaining issues or concerns before putting the motor into full operation.
The commissioning process of an induction motor can be completed effectively, ensuring optimal performance, reliability, and safety in its operation. Proper commissioning not only maximizes the motor’s efficiency but also minimizes the risk of unexpected failures and downtime, contributing to overall system reliability and productivity.