Dry-type Transformer Commissioning

After careful inspection before putting into operation, Dry Type Transformer can be powered on for trial operation. During the trial operation, special attention must be paid to the following points. Are there any abnormal sounds, noises and vibrations? Are there any abnormal smells such as burnt odors? Are there any discolorations caused by local overheating? Is the ventilation good? In addition, the following points should be noted.

First, although dry-type transformers are highly resistant to moisture, they are generally open structures and are still susceptible to moisture, especially the dry-type transformers produced in my country have a low insulation level (lower insulation level). Therefore, dry-type transformers can only achieve higher reliability when they are operated at a relative humidity below 70%. Dry-type transformers should also avoid long-term shutdown to avoid serious moisture. When the insulation resistance value is lower than 1000/V (operating voltage), it means that the dry-type transformer is seriously damp and the trial operation should be stopped.

Second, the dry-type transformers used for step-up in power stations are different from oil-immersed transformers. It is forbidden to operate on the low-voltage side in an open circuit to avoid overvoltage on the grid side or lightning strikes on the line, which may cause overvoltage to be transmitted and break down the insulation of the dry-type transformer. In order to prevent the transmission of overvoltage hazards, a set of overvoltage protection arresters (such as Y5CS zinc oxide arresters) should be installed on the voltage bus side of the dry-type transformer.