ABB Relion 670 series Product Manual page 14

Line distance protection REL670 ANSI
Pre-configured
Product version: 1.2
All IEC and ANSI time delayed characteristics are
available together with an optional user defined
characteristic.
The directional function is voltage polarized or dual
polarized.
NS4PTOC (4612) can be set directional or non-
directional independently for each of the steps.
NS4PTOC (4612) can be used as main protection
for unsymmetrical fault; phase-phase short circuits,
phase-phase-ground short circuits and single phase
ground faults.
NS4PTOC (4612) can also be used to provide a
system back-up for example, in the case of the
primary protection being out of service due to
communication or voltage transformer circuit failure.
Directional operation can be combined together
with corresponding communication logic in
permissive or blocking teleprotection scheme. The
same logic as for directional zero sequence current
can be used. Current reversal and weak-end infeed
functionality are available.
Thermal overload protection, one time constant
LPTTR (26)
The increasing utilizing of the power system closer
to the thermal limits has generated a need of a
thermal overload protection also for power lines.
A thermal overload will often not be detected by
other protection functions and the introduction of
the thermal overload protection can allow the
protected circuit to operate closer to the thermal
limits.
The three-phase current measuring protection has
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an I t characteristic with settable time constant and
a thermal memory.
An alarm pickup gives early warning to allow
operators to take action well before the line is
tripped.
Breaker failure protection CCRBRF (50BF)
Breaker failure protection (CCRBRF) ensures fast
back-up tripping of surrounding breakers in case
the own breaker fails to open. CCRBRF (50BF) can
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be current based, contact based, or an adaptive
combination of these two conditions.
Current check with extremely short reset time is
used as check criterion to achieve high security
against unnecessary operation.
Contact check criteria can be used where the fault
current through the breaker is small.
CCRBRF (50BF) can be single- or three-phase
initiated to allow use with single pole tripping
applications. For the three-phase version of
CCRBRF (50BF) the current criteria can be set to
operate only if two out of four for example, two
phases or one phase plus the residual current
pickups. This gives a higher security to the back-up
trip command.
CCRBRF (50BF) function can be programmed to
give a single- or three-phase re-trip of the own
breaker to avoid unnecessary tripping of
surrounding breakers at an incorrect initiation due
to mistakes during testing.
Stub protection STBPTOC (50STB)
When a power line is taken out of service for
maintenance and the line disconnector is opened in
multi-breaker arrangements the voltage
transformers will mostly be outside on the
disconnected part. The primary line distance
protection will thus not be able to operate and must
be blocked.
The stub protection STBPTOC (50STB) covers the
zone between the current transformers and the
open disconnector. The three-phase instantaneous
overcurrent function is released from a normally
open, 89b auxiliary contact on the line disconnector.
Pole discordance protection CCRPLD (52PD)
An open phase can cause negative and zero
sequence currents which cause thermal stress on
rotating machines and can cause unwanted
operation of zero sequence or negative sequence
current functions.
Normally the own breaker is tripped to correct such
a situation. If the situation warrants the surrounding
1MRK 506 317-BUS A
ABB