Transformer protection relay
7SG15 Siemens Energy

The 7SG15 provides automatic control for a transformer on-load tap change mechanism.
The relay monitors system voltage and load current levels and ensures that the optimum tap position is selected to maintain system volts within limits and minimize circulating currents for all power system configurations.
One relay is used per transformer. 7SG15 relays within a substation can be connected together or installed as stand-alone units providing compatibility with network configurations where power transformers are connected in parallel within a substation or across the power system network.
Relays are housed in size E8 or E12 cases. Integrated logic is provided to allow the optimal configuration of relay functionality with the relays analogue inputs and binary input/output circuits.
Instrumentation and metering functionality is accessible via data comms channels. A 25 pin RS232 front port for local PC connection and two rear fibre optic ports for remote connection are provided.