Power Transformer Installation Procedure

Power Transformer Installation Procedure

1. Site and Equipment Preparation

Ensure that the transformer foundation is complete, level, and fully cured.
Confirm that the grounding system is installed and tested.
Verify that weather conditions are appropriate for installation.
Inspect the transformer and accessories for any transportation damage.
Check the availability and calibration of necessary tools and test equipment as per OEM guidelines.

2. Moving and Positioning

Determine the suitable method for moving the transformer, such as using a crane or the jacking and sliding technique.
Position the transformer on the foundation, aligning it with the GIB and cable bus.
Ensure the transformer is level and securely positioned on the foundation or stoppers.
Review impact recorder data with the OEM to confirm that no abnormal shocks occurred during transit and submit the report to the client.

3. Assembly of Main Components

Install radiators, conservator tank, fan panels, OLTC panel, and associated piping and valves.
Mount Buchholz relay, marshalling box, and other accessories.
Test tan delta and capacitance before installing HV and LV bushings.
Assemble HV cable boxes and secure all mechanical fasteners.
Connect internal wiring for panels, sensors, and control systems.

4. Oil Handling and Processing

Apply vacuum to the main tank and maintain it until the required level is reached.
Fill the main tank with filtered and degassed insulating oil.
Circulate the oil to eliminate residual moisture and air pockets.
Conduct a pressure test on the oil system and monitor for stability.

5. Electrical Testing (Pre-Commissioning)

Perform insulation resistance (IR) testing for windings to earth and between windings.
Conduct turns ratio test (TTR) to verify voltage ratios.
Measure winding resistance for all phases.
Perform tan delta (power factor) testing on windings and bushings.
Test the breakdown voltage (BDV) of the insulating oil.
Perform Sweep Frequency Response Analysis (SFRA) and bushing capacitance testing.

6. Cable Termination and Grounding

Connect HV and LV cables to the designated bushings or cable boxes.
Complete all grounding connections, including the main tank, surge arresters, and neutral point.
Connect control wiring for protection relays, sensors, temperature indicators, and alarms.

7. Stability and Functional Checks

Verify mechanical stability if anchor bolts are not used.
Test the protection system, including differential, REF, Buchholz, pressure relief, and oil level/temperature alarms.
Check cooling system operation—verify fan and pump control, thermostat settings, and automation.

8. Energization

Energize the transformer without load, monitoring for unusual noise, vibration, or temperature rise.
Confirm phase sequence and voltage levels.
Gradually apply load under controlled conditions, continuing to monitor for any abnormalities.