How to deal with insulation damage in transformers?

What is the regular repair cycle for transformers?

According to the nature of maintenance work, transformer maintenance is divided into major and minor repairs. Traditionally, oil immersed transformers that require oil suspension (or lifting the bell cover) for maintenance are called major repairs; If there is no need to drain oil, do not lift the core (lift off the bell cover), and only perform external maintenance, oil replenishment, and oil treatment, it is called minor maintenance.

1. Overhaul cycle of transformer during operation

The overhaul cycle of transformers in operation is as follows in accordance with DL/T573-2010 "Guidelines for Power Transformer Maintenance":

(1) The overhaul cycle of transformers should generally be more than 10 years. If a transformer malfunctions during operation or is found to be abnormal during preventive testing, core suspension maintenance should be carried out in advance as needed.

(2) Based on the structural characteristics and manufacturing situation of the transformer, as well as the impact of transient short-circuit fault current during operation, as well as daily load conditions and previous electrical tests and oil analysis data, it is possible to arrange for early or extended overhaul intervals as appropriate. For example, fully sealed transformers are generally only overhauled when the main body experiences severe oil leakage or internal faults are identified.

(3) After the on load tap changer of the transformer reaches the operating frequency specified by the manufacturer, or when defects are found, the on load tap changer should be overhauled.

2. Transformer minor repair cycle

Transformer minor maintenance should be carried out once every 1-3 years. For transformers installed in particularly polluted environments, the number of minor repairs can be increased.

How to deal with insulation damage in transformers?

1. During operation, transformers should be checked for oil leakage in their parts. The transformer body should be free of accumulated water to prevent moisture and air from entering the transformer and causing insulation damage.

2. The oil seal of the respirator of the transformer should be kept at a certain oil level and unobstructed, and the desiccant should be kept dry to ensure good moisture absorption effect.

3. Regularly inspect and ensure that the explosion-proof film and safety relief valve of the transformer are intact, to prevent direct connection with air, which may increase the water content in the transformer oil and deteriorate the insulation performance of the oil.

4. When refueling transformers, attention should be paid to the qualified oil quality in the oil storage tank to prevent oil deterioration caused by refueling. It is also prohibited to refuel the oil tank from the bottom of the transformer to prevent air and impurities from entering the transformer body, especially metal impurities from entering the interior of the transformer.