Second harmonic blocking restraint level can be set
for the function and can be used to block each step
individually.
EF4PTOC (51N/67N) can be used as main
protection for phase-to-ground faults.
EF4PTOC (51N/67N) 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.
Current reversal and weak-end infeed functionality
are available as well.
Sensitive directional residual overcurrent and
power protection SDEPSDE (67N)
In isolated networks or in networks with high
impedance grounding, the ground fault current is
significantly smaller than the short circuit currents.
In addition to this, the magnitude of the fault current
is almost independent on the fault location in the
network. The protection can be selected to use
either the residual current or residual power
component 3V
0
·3I
0
·cos j, for operating quantity.
There is also available one non-directional 3I
0
step
and one non-directional 3V
0
overvoltage tripping
step.
Thermal overload protection, one time constant
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
an I
2
t characteristic with settable time constant and
a thermal memory. The temperature is displayed in
either in Celsius or in Fahrenheit depending on
whether the function used is Thermal overload
protection one time constant, Fahrenheit LFPTTR
(26) or Celsius LCPTTR.
An alarm pickup gives early warning to allow
operators to take action well before the line is
tripped.
Breaker failure protection, 3-phase activation and
output (50BF)
CCRBRF (50BF) can be current based, contact
based, or an adaptive combination of these two
conditions.
Breaker failure protection (CCRBRF, 50BF) ensures
fast back-up tripping of surrounding breakers in
case the protected breaker fails to open. CCRBRF
(50BF) can 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.
Breaker failure protection, 3-phase activation and
output (CCRBRF, 50BF) current criteria can be
fulfilled by one or two phase currents the residual
current, or one phase current plus residual current.
When those currents exceed the user defined
settings, the function is triggered. These conditions
increase the security of the back-up trip command.
CCRBRF (50BF) function can be programmed to
give a three-phase re-trip of the protected breaker
to avoid unnecessary tripping of surrounding
breakers.
Stub protection STBPTOC (50STB)
When a power line is taken out of service for
maintenance and the line disconnector is opened,
line side voltage transformers will be on the
disconnected part of the line. 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
Bay control REC650 ANSI
1MRK 511 265-BUS B
Product version: 1.2
22 ABB
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