This commissioning procedure and technical specification outline the essential practices for the proper commissioning and maintenance of low voltage distribution systems, motor control centers (MCC), load centers, and automatic transfer switches (ATS).
Electrical Commissioning / Start-up Checklist
Low-Voltage Distribution Systems, Motor Control Centers, Load Centers, Auto transfer Switches Nameplate Data
Date:__________
Facility:_______________ Equipment Location___________________ Project #: ___________
Equipment Designation:____________________________ Unit # _______ of ______ Units
Manufacturer:_____________________ Serial number:__________________________
Model number:____________ Type:__________ Shop Order number: ________________
Equipment Rating:__________ Volts:_________ Amps:_________ Amps S/C: ______________
Technician:__________________________________ Sheet # ____ of ____
Visual and Mechanical Inspection Checklist for Electrical Equipment:
- Shipping Inspection:
Upon receipt of the equipment, carefully inspect for any physical damage resulting from shipping. Follow the shipper’s instructions for reporting any incidents.
- Nameplate Comparison:
- Compare the equipment’s nameplate information with the latest single line diagram and equipment specifications.
- Ensure that cubicle markings correspond accurately with the single line diagram and designated equipment.
- Safety Grounding Cables:
- Verify that safety grounding cables are correctly connected to the main incoming power supply terminal point of the facility or equipment under construction.
- Confirm that these cables are sized appropriately to handle the available fault current as specified by Electrical Engineering. The minimum cable size should be 2/0 AWG.
- Note that safety grounding cables should remain connected until the commissioning of the electrical equipment is completed and the facility or equipment is ready for energizing.
- Fuse Rating Verification:
- Check that the fuse rating matches the information provided in the single line diagram. Record this information on the cubicle door for reference.
- Overload Heater Rating Verification:
- Verify that the overload heater rating matches the motor’s nameplate rating. Record this information on the cubicle door for reference.
- Group Loop Terminations:
- Physically inspect all group loop terminations and connections to ensure they are properly crimped.
- Current Transformers (C.T.s) and Potential Transformers (P.T.s):
- Visually inspect all C.T.s and P.T.s to verify their proper ratio and polarity.
- Ensure that ring-type terminals are used for all C.T. wiring connections.
- Wiring Terminations:
- Tighten all line, load, and control wiring terminations to ensure secure connections.
- Cubicle Inspection:
- Inspect the cubicle to ensure that bushings and grommets are in place to prevent damage to wiring insulation due to sharp edges.
- Check for any signs of insulation damage caused by overbending.
- Cleaning and Preparation:
- Ensure that all cubicles are cleaned and checked thoroughly before energizing to remove any debris or contaminants.
- Cable Terminations:
- Confirm that all cable terminations have been installed correctly with crimp-type terminals.
- Wiring Splices:
- Verify that there are no splices in power, instrument, or thermocouple wiring, especially in below-grade situations such as manholes, switchgear pits, and MCC pits.
- Autotransfer Switches:
- If applicable, ensure that autotransfer switches have emergency and normal feeders installed correctly.
- Low-Voltage Draw-Out Switchgear:
- Check low-voltage draw-out switchgear connections by racking in and verifying the alignment of breaker primary and secondary stab connections.
- Interlocks:
- Verify the proper and complete operation of all mechanical and electrical interlocks, including any key-type systems.
This comprehensive inspection checklist helps ensure that electrical equipment is in optimal condition and ready for safe and reliable operation.
Low-Voltage Circuit Breaker Checks Procedure:
- Mechanical Operator Checks:
- Follow the manufacturer’s instruction literature to perform all mechanical operator checks on the breaker.
- Ensure that the breaker’s mechanical components are functioning correctly.
- Preventive Maintenance (P.M.):
- Perform normal preventive maintenance (P.M.) procedures, referring to the manufacturer’s instruction literature.
- During preventive maintenance, verify the proper mechanical operation of the breaker.
- Lubrication:
- After completing cleaning and preventive maintenance, lubricate both primary and secondary contacts with an approved lubricant.
- Proper lubrication helps ensure smooth breaker operation.
- Insulation-Resistance Test (Megger Test):
- Conduct an insulation-resistance test (Megger test) on the breaker.
- This test assesses the insulation integrity of the breaker to identify any potential issues.
- Function Test:
- Perform a function test on the breaker to confirm its proper operation.
- During the function test, evaluate the breaker’s response to various operating conditions and ensure it functions as expected.
By following these steps and referring to the manufacturer’s instruction literature, you can conduct thorough checks and maintenance on low-voltage circuit breakers, helping to maintain their reliability and safety.
Field Skid Mounted Equipment
Field/Skid-Mounted Equipment Inspection and Maintenance Procedure:
- Physical Damage Inspection:
- Inspect all field/skid-mounted equipment for any physical damage resulting from transportation or handling.
- Ensure that the equipment’s enclosures conform to the required NEMA or IEC standards, including size and weatherproofing, as applicable.
- Wiring Practices and Methods:
- Verify that the wiring practices and methods used in the installation meet the requirements specified in 4AEL-620300 or any relevant industry standards.
- Ensure that wiring is properly routed, secured, and labeled for clarity and safety.
- Cleaning and Tightening:
- Clean the equipment as necessary to remove any dirt, debris, or contaminants that may affect its operation.
- Check and tighten all electrical connections to ensure they are secure and free from loose or corroded terminals.
- Insulation Resistance (Megger) Test:
- Conduct an insulation resistance (Megger) test on the equipment’s electrical insulation.
- This test helps identify any insulation breakdown or issues that could lead to electrical faults.
- Ensure the equipment passes the insulation resistance test before energizing.
By following these steps and adhering to the specified standards, you can ensure that field/skid-mounted equipment is in good condition, properly wired, and safe for operation. Regular inspections and maintenance contribute to the reliability and longevity of the equipment.
Electrical Testing Procedure for All Equipment:
- Bus Connection Inspection:
- Inspect all bus connections for high resistance using a digital, low-resistance ohmmeter (Ductor).
- Test values should be 30 micro-ohms per joint or less.
- Record the test results.
- Insulation-Resistance (Megger) Test:
- Conduct an insulation-resistance (Megger) test on all feeders, connected equipment, and control wiring.
- Disconnect all solid-state devices before testing.
- Record the test results.
- Primary Injection Test on Ground C.T.s:
- Perform a primary injection test on ground current transformers (50 GS type) to functionally test circuit wiring and relays.
- Secondary-Injection Test on Phase Current Transformers:
- Perform a secondary-injection test on all phase current transformers by injecting current at the C.T. secondary terminals without disconnecting the C.T.s.
- Inject sufficient current to functionally operate and/or trip all devices such as ammeters, relays, and computer transducers.
- Verify multifunction meter or ammeter and selector switch wiring and operation.
- Timer Relay Checks:
- Set and check for proper operation of all timer relays.
- Control Circuit Function Check:
- Function check each device in the control circuit.
- Verify that each device performs its intended function, such as dropping out starters or relays, or energizing solenoids, before energizing the load.
- Equipment Identification Verification:
- Verify that the starter/breaker identification matches the field equipment and control station identification.
- Solid-State Equipment Setup:
- Set up all solid-state equipment in accordance with the manufacturer’s instructions.
- Observe connected motors for proper acceleration.
- Electronic Overload Relay Calibration:
- Set all electronic overload relays to match motor nameplate ratings following the manufacturer’s instructions.
- Protective Relay and Trip Device Calibration:
- Calibrate all protective relays and trip devices according to the GSS Electrical Engineering department’s job-specific data.
- Record the calibration results.
- Testing Fail-Safe Mechanisms:
- Verify that each fail-safe, mechanical or electrical interlock, protective relay, or trip device is capable of tripping the breaker or starter when required.
By performing these operational and electrical tests, you ensure that all equipment is functioning correctly, calibrated to the specified settings, and capable of providing the intended protection and control functions. Recording the test results is essential for documentation and future reference.
Automatic Transfer Switch (ATS) Testing Procedure:
- Manual Transfer Operation:
- Perform a manual transfer operation to ensure that the ATS can be switched between power sources manually.
- Calibration of Voltage Sensing Relays:
- Calibrate the voltage sensing relays to ensure accurate voltage monitoring.
- Record the calibration results.
- Calibration of Transfer Time-Delay Relay:
- Calibrate the transfer time-delay relay to set the desired delay time for transferring between power sources.
- Record the calibration results.
- Function Test – Simulate Loss of Power:
- Simulate a loss of power on one of the power sources to trigger the ATS to transfer to the alternative source.
- Verify that the transfer occurs within the set time delay.
- Record the results of the function test.
- Return to Normal Power:
- After completing the function test, return the ATS to normal power source operation.
Performing these tests ensures that the ATS is functioning correctly, accurately sensing voltage levels, and transferring power sources as required. Recording the test results is essential for documentation and future reference.
Finally, Here we wrote down some electrical equipment commissioning procedure for low voltage only. Explore more commissioning article in our website.
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