ABB Transformer protection RET670 Pre-configure Application

Application

The differential function offers a high sensitivity for

low-level internal faults. The unique and innovative

sensitive differential protection feature of the

RET670 provides the best possible coverage for

winding internal turn-to-turn faults, based on well

known theory of symmetrical components .

Low impedance restricted earth-fault protection

functions are available as complimentary sensitive

and fast main protection against winding earth

faults. This function includes a directional zero

sequence current criterion for additional security.

Additionally a high impedance differential function

is available.

It can be used as restricted earth

fault or, as three functions are included, also as

differential protection on autotransformers, as

differential protection for a tertiary connected

reactor, as T-differential protection for the

transformer feeder in a mesh-corner or ring

arrangement, as tertiary bus protection and so on.

Tripping from Pressure relief/Buchholz and

temperature devices can be done through the

transformer IED where pulsing, lock-out contact

output and so on, is performed. The binary inputs

are heavily stabilized against disturbance to

prevent incorrect operations at for example, dc

system capacitive discharges or DC earth faults.

Distance protection functionality for phase-to

phase and/or phase-to-earth faults is available as

back-up protection for faults within the

transformer and in the connected power system.