Four Step Negative Sequence Overcurrent Protection Ns4Ptoc; Thermal Overload Protection, One Time Constant Lcpttr/Lfpttr; Breaker Failure Protection Ccrbrf; Stub Protection Stbptoc - ABB RED670 Product Manual

Line differential protection RED670 2.1 IEC
Product version: 2.1
IDir, UPol and IPol can be independently selected to be either
zero sequence or negative sequence.
Second harmonic blocking can be set individually for each step.
EF4PTOC can be used as main protection for phase-to-earth
faults.
EF4PTOC 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.
Residual current can be calculated by summing the three phase
currents or taking the input from neutral CT
Four step negative sequence overcurrent protection
NS4PTOC
Four step negative sequence overcurrent protection
(NS4PTOC) has an inverse or definite time delay independent
for each step separately.
All IEC and ANSI time delayed characteristics are available
together with an optional user defined characteristic.
The directional function is voltage polarized.
NS4PTOC can be set directional or non-directional
independently for each of the steps.
NS4PTOC can be used as main protection for unsymmetrical
fault; phase-phase short circuits, phase-phase-earth short
circuits and single phase earth faults.
NS4PTOC can also be used to provide a system backup 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.
Sensitive directional residual overcurrent and power
protection SDEPSDE
In isolated networks or in networks with high impedance
earthing, the earth 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 3U0·3I0·cos j,
for operating quantity with maintained short circuit capacity.
30
There is also available one nondirectional 3I0 step and one 3U0
overvoltage tripping step.
No specific sensitive current input is needed. SDEPSDE can be
set as low 0.25% of IBase.
Thermal overload protection, one time constant LCPTTR/
LFPTTR
The increasing utilization of the power system closer to the
thermal limits has generated a need of a thermal overload
protection 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
characteristic with settable time constant and a thermal
memory. The temperature is displayed in either Celsius or
Fahrenheit, depending on whether the function used is LCPTTR
(Celsius) or LFPTTR (Fahrenheit).
An alarm level gives early warning to allow operators to take
action well before the line is tripped.
Estimated time to trip before operation, and estimated time to
reclose after operation are presented.

Breaker failure protection CCRBRF

Breaker failure protection (CCRBRF) ensures a fast backup
tripping of the surrounding breakers in case the own breaker
fails to open. CCRBRF can be current-based, contact-based or
an adaptive combination of these two conditions.
A current check with extremely short reset time is used as
check criterion to achieve high security against inadvertent
operation.
Contact check criteria can be used where the fault current
through the breaker is small.
CCRBRF can be single- or three-phase initiated to allow use
with single phase tripping applications. For the three-phase
version of CCRBRF 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 start. This gives a higher security to the
back-up trip command.
CCRBRF function can be programmed to give a single- or
three-phase re-trip of its own breaker to avoid unnecessary
tripping of surrounding breakers at an incorrect initiation due to
mistakes during testing.

Stub protection STBPTOC

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.
1MRK 505 346-BEN -
2
t
ABB