Pre-Commissioning Inspection in Transformer Installation

Transformers are essential components of power distribution systems, serving the vital function of stepping up or stepping down voltage levels to enable efficient electricity transmission.

the key steps involved in the pre-commissioning inspection of transformers:

1. Electric Tests on Oil Sample: An oil sample is taken and tested to determine its dielectric strength. This test helps assess the condition of the transformer's insulation system and its ability to withstand voltage stresses.
2. Air Release: Trapped air inside the transformer is released through air-release plugs and valves. Eliminating air pockets is crucial to ensure proper oil circulation and cooling.
3. Magnetic Oil Level Indicator: The magnetic oil level indicator is checked to ensure it functions correctly. It provides a visual indication of the oil level inside the transformer, aiding in monitoring oil levels.
4. Buchholz Relay Check: The operation of the alarm and trip contacts in the Buchholz relay is verified. The Buchholz relay detects internal faults and triggers alarms or trips to protect the transformer.
5. Valve Inspection: All valves, except drain, filter, and sampling valves, are checked to ensure they are open and functioning correctly. Proper valve operation is essential for controlling oil flow and pressure.
6. Silica Gel Condition: The condition of the silica gel in the breather is inspected to ensure it is active. Silica gel helps prevent moisture from entering the transformer, protecting it from potential damage.
7. Bushings Inspection: Bushings, that provide electrical connections to the transformer, are physically inspected for cracks or defects. Bushing failures can lead to electrical faults and pose safety hazards.
8. Earthing Verification: If specified, the neutral earthing system is checked to ensure it is correctly configured. Proper earthing is essential for electrical safety.
9. Transformer Tank Earthed: The transformer tank is checked to ensure it is effectively earthed. This is crucial to prevent electrical shocks and ensure the safety of personnel working on or near the transformer.
10. Thermometer Pockets: The thermometer pockets on the transformer tank cover are checked for proper oil filling. Accurate temperature measurement is essential for monitoring transformer performance.
11. Component Functionality: Various components, such as CT secondary terminals and relief vent diaphragms, are checked to ensure they operate correctly. Malfunctioning components can compromise transformer safety and efficiency.

Conclusion

The pre-commissioning inspection of transformers is a comprehensive process that involves multiple tests and checks to ensure the transformer's readiness for safe and efficient operation.

References:

1-IEEE Std C57 series for transformer-specific standards.

2-Transformer Manufacturer Manuals.