2, when the line varistor switch is not connected to the lightning arrester, line to cold standby state, the operation of the line varistor only need to be the varistor switch to pull open (no high-voltage switch to take the voltage side fuses) can be. (the voltage without high-voltage switch to remove the low-voltage voltage side fuse) can be.
3, line maintenance: refers to the line in the cold standby state on the basis of the line, the line of the grounding gate is closed or in the line side of the line gate knife line to install a grounding wire.
4. Switch overhaul: Both sides of the switch are opened, and the switch operating circuit fuse is removed. The CT of the switch is removed from the differential circuit (the differential is first deactivated, and the CT circuit is dismantled and short-circuited to the ground). Measure the differential unbalance current within the permissible range before applying the differential protection), and close the grounding gates or install grounding wires on both sides of the switch.
5. When the main transformer is in operation, but one side switch is under maintenance, the longitudinal differential CT of the switch should be disconnected from the longitudinal differential circuit of the main transformer. In the process of AC circuit switching, the mother differential or longitudinal differential protection should be deactivated for a short time. If there is a voltage transformer between the switch and the line (or transformer) gate for maintenance, the gate of the voltage transformer should be pulled away (or the high and low voltage fuses should be removed).