Periodical Check and maintenance of the bushing of transformer:
As bushing is a self contained unit, as such there is no specific maintenance to be carried out. However , a periodical check of the oil level and cleaning of the porcelain will normally be sufficient.
In order to determine the healthiness of the bushing , measurement of capacitance and tan delta may be carried out during annual maintenance. These values are to be compared with the pre-commissioning test results. Tan delta value more than 0.007 and increase in capacitance by more than 10% or more .