What should be checked if a transformer shows signs of physical or coil damage after shipping or installation?
Transformers can become physically damaged during installation or shipping.
| Check: | Solution: |
|---|---|
| Enclosure is damaged but the core and coil is intact. | Minor damage can be repaired in the field with spray paint (scratches) or individual enclosure pieces. Enclosure components located in the base or replacing the entire enclosure will require facilities capable of lifting the entire core and coil Units can also be returned to the plant for enclosure repair and full testing. Encapsulated (potted) units that have enclosure damage may not be repairable. |
| Jumpers are damaged. | Replace jumpers. |
| The coil has been damaged with arcing between the coil taps. | Voltage spikes such as lightning or utility transients caused voltages to exceed the transformers BIL rating and caused arcing. If a conductive dust or liquid (water) is present, this may also cause arcing. The transformer will need to be repaired or replaced. Voltage spikes can be mitigated with lightning arrestors or transformers with higher BIL rates. |
| The coil has been damaged with arcing and physical damage between the coils (turn to turn). | The insulation between the coils has failed. This may be due to age, overheating, overvoltage or damaged insulation. Each of these failure modes will have to be checked and if found to be a problem fixed. The transformer will need to be repaired or replaced. |
| The coil has been damaged with arcing and physical damage between the coil layers or between the coil and shield. | The insulation between the coils has failed. This may be due to age, overheating, overvoltage or damaged insulation. Each of these failure modes will have to be checked and if found to be a problem fixed. The transformer will need to be repaired or replaced. |
| Connections points show signs of heat including damaged insulation or excessive corrosion. | Replace jumpers or lugs if they are damaged. Verify the mounting surfaces are clean of insulation and smooth. Verify any mechanical components are tight. In some cases a braise joint at a lug or pad point may be damaged and cause excessive heat. |
| Coil is damaged. Coil damage can include insulation that has been ripped, worn or is burnt or discolored from heat. | Some units can be returned to HPS for repair or coil replacement. In some cases it may be more economical to replace the unit than to repair it. |