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The RET670 also features pole slip protection, which detects and evaluates pole slips occurring in the power system and takes the necessary action.

Sections of the power system that are swinging away from each other can be separated by

the line closest to the center of the power swing, allowing the two systems to remain stable when separated.

The RET670 can be used with the IEC 61850-9-2LE process bus with up to six Merge Units (MUs).

Advanced logic functions allow user logic to be programmed with graphical tools to enable special

applications such as automatic opening of disconnect switches in multi-breaker arrangements, closing of breaker loops and load transfer logic.

Logic can be monitored and debugged online in real time for testing and commissioning.

Communication via fiber optic connections ensures immunity to interference.

Six software packages are defined for the following applications:

– Transformer backup protection (A10)

– Voltage control (A25)

– Single-breaker, two-winding transformers (A30)

– Double-winding transformers with multiple circuit-breaker arrangement (B30)

– Three-winding transformers in single-breaker arrangement (A40)

– Triple-winding transformer in multi-breaker arrangement (B40)

The optional functions are not configured, but a maximum configuration with all optional

functions is available as a template in the graphical configuration tool.

Templates for alternative configurations for auto-transformers are also available.

The analog and trip I/O are pre-defined for basic use and come standard with one binary input module and one binary output module.

The binary I/O can be added at the time of ordering, depending on the needs of the application.

the other signals need to be set up according to the needs of the different applications.

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.

The wide application flexibility makes this product

an excellent choice for both new installations and

the refurbishment of existing installations.

Six packages have been defined for the following

applications:

• Transformer back-up protection (A10)

• Voltage control (A25)

• Two-winding transformer in single breaker

arrangements (A30)

•Two-winding transformer in multi breaker

arrangements (B30)

•Three-winding transformer in single breaker

arrangements (A40)

•Three-winding transformer in multi breaker

arrangements (B40)

Optional functions are not configured but a

maximum configuration with all optional functions

are available as template in the graphical

configuration tool. An alternative for

Autotransformers is also available as a

configuration template. Analog and tripping IO

has been pre-defined for basic use on the, as

standard supplied one binary input module and

one binary output module. Add binary I/O as

required for your application at ordering. Other

signals need to be applied as required for each application.

Application

Versatile phase, earth, positive and zero

sequence overcurrent functions, which can

optionally be made directional and/or voltage

controlled, provide further alternative backup

protection. Thermal overload with two time

constants, volts per hertz, over/under voltage and

over/under frequency protection functions are

also available.

A 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 allows high speed back-up tripping of

surrounding breakers.

The transformer IED can also be provided with a

full control and interlocking functionality including

Synchrocheck function to allow integration of the

main and/or a local back-up control.

Out of Step function is available to separate

power system sections close to electrical centre

at occurring out of step.

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 and so

on. The graphical configuration tool ensures

simple and fast testing and commissioning.

Serial data communication is via optical

connections to ensure immunity against disturbances.

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.