Application

RET670 provides fast and selective protection,

monitoring and control for two- and three-winding

transformers, autotransformers, generator

transformer units and shunt reactors. The

transformer IED is designed to operate correctly

over a wide frequency range in order to

accommodate power system frequency variations

during disturbances and generator start-up and shut-down.

A very fast differential protection function, with

automatic CT ratio matching and vector group

compensation, makes this IED the ideal solution

even for the most demanding applications. Since

RET670 has very low requirements on the main

CTs, no interposing CTs are required.

It is suitable for differential applications with multi-breaker

arrangements with up to six restraint CT inputs.

The differential protection function is provided

with 2nd harmonic and wave-block restraint

features to avoid tripping for magnetizing inrush

current, and 5th harmonic restraint to avoid tripping for overexcitation.