Tan Delta

It is used for measuring the insulation level of the transformer Bushing .

High value means the Dissipation is more and hence the Losses are more .

We are discussing about the different tests done on Transformers and its other parts for healthy life. Tan Delta is another essential test carries out for measuring the insulating capacity of transformer oil. It has been done to determine the break down strength, flash point, its fire point, and also to identify the moisture content of the oil.

Tan Delta is also known as the 'loss angle' or 'dissipation factor'. Regular measurement of electrical properties on periodical basis could help to know the operational unexpected breakdown. Tan Delta is one of the powerful tools to monitor the condition of solid insulation of various high voltage equipments. Tan Delta also applies on Transformer Bushing, Winding, CT, PT, CVT.

Importance of Tan Delta

• It helps to predict the upcoming faults.
• It helps to reduce the heavy cost on replacement of material.
• Quality of insulation can be check out.
• Its helps to plan the maintenance schedule.

Tan Delta & Capacitance should be done on regular basis. Testing period is depends upon the past history of failure, environmental condition. It is recommended once for every new transformer and then every 5 yrs.

High value of tan delta indiactes pure insulation.

It is indicating the detoriation of oil and/or ageing of paper insulation.

We can't tell which insulation is bad (Oil or paper). We will get the combined result only. Incase of paper insulation it may happen because of ageing, presence of moisture and so many other reasons. I don't have any idea about LFA, but filtration will increase the insulation property.