Application - ABB RET670 Product Manual

Transformer protection RET670 2.0
Product version: 2.0

1. Application

RET670 provides fast and selective protection, monitoring and
control for two- and three-winding transformers,
autotransformers, step-up transformers and generator-
transformer block units, phase shifting transformers, special
railway transformers and shunt reactors. The 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.
RET670 has a fast, low-impedance differential protection
function with very low requirements on the CTs.It is suitable for
differential applications with multi-breaker arrangements with
up to six restraint CT inputs. The differential protection function
is provided with a 2nd harmonic and waveform-block restraint
feature to avoid tripping for CT saturation and transformer
inrush current, and 5th harmonic restraint to avoid tripping for
transformer overexcitation.
The differential function offers a high sensitivity for low-level
internal faults by using a sensitive differential protection feature
based on an amplitude measurement and directional
comparison of the negative sequence components.
Multiple low impedance restricted earth-fault protection
functions are available as a sensitive and fast main protection
against winding earth faults. This function includes a internal/
external fault discriminator for additional security.
Additionally, a high impedance differential protection function is
available. It can be used for different applications including
restricted earth fault protection as winding protection,
autotransformer differential protection, shunt reactor
protection, T-feeder protection, busbar protection and
generator differential protection.
Tripping and alarm signals from pressure relief, Buchholz and
temperature devices can be sent directly to RET670 via binary
input channels for alarm and back-up purposes. The binary
inputs are highly stabilized against disturbances to prevent
incorrect operation due to, for example, DC system capacitive
discharges or DC earth faults.
Distance protection functionality is available as back-up
protection for faults within the transformer and in the connected
power system.
Positive, negative and zero sequence overcurrent functions,
which can optionally be made directional and/or voltage
controlled, provide further alternative backup protection.
Thermal overload, overexcitation, over/under voltage and over/
under frequency protection functions are also available.
Breaker failure protection for each transformer breaker allows
high speed back-up tripping of surrounding breakers.
ABB
A built-in disturbance and event recorder provides valuable
data to the user about status and operation for post-fault
disturbance analysis.
RET670 can optionally be provided with full control and
interlocking functionality including a synchrocheck function to
allow integration of the main or local back-up control
functionality.
A pole slip protection function is also available in RET670 to
detect, evaluate, and take the required action for pole slipping
occurrences in the power system. The electrical system parts
swinging to each other can be separated with the line(s) closest
to the centre of the power swing, allowing the two systems to
be stable when separated.
RET670 can be used in applications with the IEC 61850-9-2LE
process bus with up to six merging units (MU).
The advanced logic capability, where user logic is prepared
with a graphical tool, allows for special applications such as
automatic opening of disconnectors in multi-breaker
arrangements, closing of breaker rings and load transfer logic.
Logic can be monitored and debugged online in real time for
testing and commissioning.
Communication via optical connections ensures immunity
against disturbances.
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.
For details on included basic functions, refer to chapter
IED functions"
1MRK 504 141-BEN C
Issued: July 2016
Revision: C
"Basic
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