Electrical Switchgear Testing and Procedure

Electrical switchgear testing is a important of ensuring the reliability, safety, and performance of electrical power systems. Switchgear is considered as the backbone of power distribution networks, facilitating the control, protection, and isolation of electrical circuits.

To maintain the integrity and functionality of switchgear, testing procedures are essential. In this article, we explain into the importance of switchgear testing, key testing procedures, and best practices for ensuring optimal switchgear performance.

Read Also: Switchgear What It Is? Functions | Components | Working Principle

To check switchgear completely, we need to visually, mechanically and finally electrical testing of switchgear.

Electrical Switchgear Testing Procedure.

Mfg.
Location.
Voltage Class.
Main Bus Current Rating.
Total Breakers and Types.
Total Relays and Types.

Switchgear Visual Inspection.

1. General inspection of exterior of equipment.
2. Check panel lights for operation, burned out or missing bulbs LED’s and covers.
3. Inspect for damaged, bent, or twisted doors and verify ground bonding.
4. Inspect for broken instrument, relay cover glass and damaged phase indicator lights.
5. Inspect bus for physical damage, missing insulation, connections at joints, confirm plating is acceptable.
6. Check cleanliness of interior of cubicle.
7. Inspect insulation, stand-off insulators, and bus separators for damage or clearance problems.
8. Inspect for proper compartmentalization as required.

Mechanical Switchgear Inspection.

1. Check control knobs and switches for freedom of movement and contact condition.
2. Inspect door handles, locking bars, and mechanism.
3. Check door interlocks for positive operation.
4. Torque test bolted bus. (Exposed Connections only.)
5. Check bus for support & spacing. Remove all shipping bracing.
6. Remove draw out breakers. Check draw out mechanism for freedom of movement.
7. Check rails, guides, rollers, and shutter mechanism.
8. Lubricate draw out assembly parts as required.
9. Inspect breaker and cell primary and secondary contacts and alignment.
10. Close and trip breakers manually in the connected, test and disconnected positions.
11. When applicable, check metering transformers compartments for proper operation of racking in/out, isolation features.  Check for proper grounding of fuses in the withdrawn position.
12. Verify that all breakers of the same rating are inter-changeable by racking each breaker into each cell of the proper rating.

Electrical Switchgear Testing.

1. Inspect for proper grounding of equipment and neutral bus.
2. Measure insulation resistance to ground.
3. Inspect and megger power cable or bus to switchgear.
4. Clean bus insulators, Megger test for grounds.
5. Dielectric test cables/terminations and bus work as specified.
6. Inspect and test control and metering transformers and fuses as required.
7. Verify operation of resistors, grid assemblies (if applicable) and space heaters.
8. Verify the condition of wiring & terminal connections (point to point wire check).
9. Note and report any unmarked circuits.
10. Verify proper operation of cell interlocks and auxiliary contact assemblies.
11. Perform breaker inspection and tests as specified.
12. Inspect and test meters, transducers, and relays as specified.
13. Perform relay calibration and settings.
14. Check relays and protective devices for positive tripping of circuit breaker.
15. Test annunciator, alarm and/or target operation.
16. Verify proper phasing of bus.
17. Verify all control fuse types and ratings.
18. Verify control circuits operate according to engineering specifications.

What are Testing Procedures for Electrical Switchgear?

1. Visual Inspection: A visual inspection involves examining switchgear components for physical damage, signs of overheating, loose connections, and corrosion. This initial assessment helps identify visible defects and potential safety hazards.
2. Functional Testing: Functional tests verify the proper operation of switchgear components under simulated operating conditions. This includes testing circuit breakers, relays, contactors, and other control devices to ensure they operate as intended.
3. Electrical Testing: Electrical tests assess the insulation integrity, conductor continuity, and electrical connections within the switchgear. Common electrical tests include insulation resistance tests, dielectric strength tests, and continuity tests.
4. Protection Relay Testing: Protection relays play a critical role in detecting and isolating electrical faults. Testing ensures that relays operate correctly in response to overcurrent, overvoltage, and other fault conditions, providing effective protection to electrical systems.
5. Performance Monitoring: Continuous monitoring of switchgear performance allows for the detection of gradual degradation or changes in operating conditions. Regular performance assessments help identify potential issues before they escalate into serious problems.

Electrical switchgear testing is essential for ensuring the reliability, safety, and performance of electrical power systems. By conducting thorough testing procedures, organizations can identify potential issues, maintain compliance with regulations, and optimize switchgear performance for efficient and reliable operation.

Investing in switchgear testing and maintenance is a proactive approach to mitigating risks, minimizing downtime, and ensuring the continued functionality of critical electrical infrastructure.