ABB 1MRK504053-BEN Application RET670 Transformer protection IED

Application

RET 670 provides fast and selective protection, monitoring and control for two- and three-winding

transformers, autotransformers, generator-transformer units, phase shifting transformers,

special railway transformers 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.

RET 670 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,

and 5th harmonic restraint to avoid tripping for overexcitation.

The differential function offers a high sensitivity for low-level internal faults.

RET 670's unique and innovative sensitive differential protection feature, based on well-known theory of symmetrical components provide best possible coverage for

winding internal turn-to-turn faults.

A low impedance restricted earth-fault protection function is available as complimentary sensitive and fast main protection against winding earth

faults. This function includes a directional zero-sequence current criterion for additional security.

Alternatively 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 etc.

Tripping from Buchholz and temperature devices can be done through the IED where pulsing, lock-out etc. is performed.

The binary inputs are heavily stabilized against disturbance to prevent incorrect operations at e.g. dc system capacitive discharges.

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.

Versatile phase, earth, positive, negative and zero sequence overcurrent functions,

which can optionally be made directional and/or voltage controlled,

provide further alternative backup protection.

Thermal overload, volts per hertz, over/under voltage and over/under frequency protection functions are also available.

Built-in disturbance and event recorder provides valuable data to the user about status and operation for post-fault disturbance analysis.

Breaker failure protection for each transformer breaker allow high speed back-up tripping of surrounding breakers.

The IED can also be provided with a full control and interlocking functionality including Synchrocheck function to allow integration of the main or

a local back-up control.

The advanced logic capability, where user logic is prepared with a graphical tool, allows special applications such as

automatic opening of disconnectors in multi-breaker arrangements, closing of breaker rings, load transfer logic etc.

The graphical configuration tool ensures simple and fast testing and commissioning.

Serial data communication is via optical connections to ensure immunity against disturbances.

The wide application flexibility makes this product an excellent choice for both new installations and the refurbishment of existing installations.