EF4PTOC can be set directional or non-directional
independently for each of the steps.
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.
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
GUID-485E9D36-0032-4559-9204-101539A32F47 v5
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.
Thermal overload protection, two time constant TRPTTR
M13243-3 v10
If a power transformer reaches very high temperatures the
equipment might be damaged. The insulation within the
transformer will experience forced ageing. As a consequence
of this the risk of internal phase-to-phase or phase-to-earth
faults will increase.
The thermal overload protection estimates the internal heat
content of the transformer (temperature) continuously. This
estimation is made by using a thermal model of the
transformer with two time constants, which is based on
current measurement.
Two warning levels are available. This enables actions in the
power system to be done before dangerous temperatures are
reached. If the temperature continues to increase to the trip
value, the protection initiates a trip of the protected
transformer.
The estimated time to trip before operation is presented.
Breaker failure protection CCRBRF
M11550-6 v16
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.
Pole discordance protection CCPDSC
M13269-3 v14
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 persists the surrounding breakers
should be tripped to clear the unsymmetrical load situation.
The Pole discordance protection function CCPDSC operates
based on information from auxiliary contacts of the circuit
breaker for the three phases with additional criteria from
unsymmetrical phase currents when required.
5. Voltage protection
Two step undervoltage protection UV2PTUV
M13789-3 v11
Undervoltages can occur in the power system during faults or
abnormal conditions. Two step undervoltage protection
(UV2PTUV) function can be used to open circuit breakers to
prepare for system restoration at power outages or as long-
time delayed back-up to primary protection.
UV2PTUV has two voltage steps, each with inverse or definite
time delay.
UV2PTUV has a high reset ratio to allow settings close to
system service voltage.
1MRK 505 362-BEN B
Busbar protection REB650 2.1 IEC
Product version: 2.1
ABB
13
