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Power frequency test <120 kV

(Dielectric withstand voltage test)

Power frequency test (Dielectric withstand voltage test)  

Dielectric withstand voltage tests should be performed by users of switchgear devices to prove the ability of insulating materials and spacings to withstand specified over-voltages for specified times without dielectric breakdown or puncture.


The test voltage levels in field tests are typically 75 or 80 % of the levels used on new equipment by the suppliers. Such tests should be conducted as:

- Commissioning tests before new equipment is placed into service

- Test before recently maintained equipment is returned to service

- In general, as part of a comprehensive preventive maintenance program.

Checking integrity of:

-Vacuum interrupters

- Busbar

- Switchgear

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