Trip and alarm signals from the pressure relief, Buchholz and temperature devices can be

sent directly to the RET670 via the binary input channels for alarm and standby.

The binary inputs are highly stable against interference and prevent incorrect operation due to,

for example, capacitive discharges in the DC system or DC ground faults.

The distance protection function serves as backup protection against faults within the transformer and in the connected power system.

Positive-, negative- and zero-sequence overcurrent functions (selectable direction and/or voltage control) provide further back-up protection.

Thermal overload, overexcitation, overvoltage/undervoltage and overfrequency/underfrequency protection functions are also provided.

A circuit breaker fault protection function for each transformer circuit breaker allows high-speed backup tripping of surrounding circuit breakers.

A built-in disturbance and event recorder provides the user with valuable data on status and operation for post-fault disturbance analysis.

The RET670 can also be optionally equipped with a full range of control and interlocking features,

including a synchronization check function for integration of primary or local standby control functions.