1. Application
A very fast differential protection function with settable 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.
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 the
theory of symmetrical components .
A low impedance restricted earth-fault protection function is
available as a complimentary sensitive and fast main
protection against winding earth faults. This function includes
a directional zero-sequence current criterion for additional
security.
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.
The binary inputs are heavily stabilized against disturbances
to prevent incorrect operations during for example during 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.
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 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 allows high speed back-up tripping
of surrounding breakers.
The transformer IED provided with Synchrocheck function to
allow integration of the main and/or a local back-up control.
RET670 can be used in applications with the IEC
61850-9-2LE process bus with up to two Merging Units (MU).
Each MU has eight analogue channels, normally four current
and four voltages. Conventional and Merging Unit channels
can be mixed freely in your application.
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.
Transformer protection RET670 9-2 LE
1MRK504119-BEN B
Customized
Product version: 1.2 Issued: February 2015
Revision: B
ABB 3
