What is tan delta test of transformer and what is difference between GST and GSTg mode?

Question

Accepted Answer

Tan delta test is used to measure insulation quality of transformer. GST and GSTg modes differ in the type of voltage applied.

Tan delta test measures the power loss in transformer insulation.
It helps to identify the presence of moisture, oil, or other contaminants in the insulation.
GST mode applies AC voltage to the transformer while GSTg mode applies DC voltage.
GSTg mode is more sensitive to insulation defects than GST mode.
The test is important for ensuring the reliability and safety of the transformer.
Results of the test can be used to determine if maintenance or repairs are needed.

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