The additional backup protection (DRZ) of the power transformer 110/x has the task of acting (according to the established algorithm) on the disconnection of the circuit breaker in the 110kV substation in the event of a loss or an unauthorized drop of the DC command voltage 110Vdc.

For disconnection, a special coil is used in the 110kV switch drive, and for power supply, energy from the group of capacitor disconnecting devices (KIU) is used.

Practically, the DRZ is a backup protection of the transformer in case of loss of the basic command voltage.