Current Protection - ABB REG650 Product Manual

Generator protection REG650
Product version: 1.3
power system, then the one which finds the center of oscillation
in its zone 1 should operate first.
Load encroachment LEPDIS
Heavy load transfer is common in many power networks and
may make fault resistance coverage difficult to achieve. In such
a case, Load encroachment LEPDIS function can be used to
enlarge the resistive setting of the underimpedance measuring
zones without interfering with the load.
Each of the three measuring phase-to-phase loops has its own
load encroachment characteristic.

6. Current protection

Four step phase overcurrent protection, 3-phase output
OC4PTOC
The four step phase overcurrent protection function OC4PTOC
has an inverse or definite time delay independent for step 1 and
4 separately. Step 2 and 3 are always definite time delayed.
All IEC and ANSI inverse time characteristics are available.
The directional function is voltage polarized with memory. The
function can be set to be directional or non-directional
independently for each of the steps.
Second harmonic blocking level can be set for the function and
can be used to block each step individually
Four step residual overcurrent protection, zero sequence and
negative sequence direction EF4PTOC
The four step residual overcurrent protection, zero or negative
sequence direction (EF4PTOC) has a settable inverse or definite
time delay independent for step 1 and 4 separately. Step 2 and
3 are always definite time delayed.
All IEC and ANSI inverse time characteristics are available.
EF4PTOC can be set directional or non-directional
independently for each of the steps.
The directional part of the function can be set to operate on
following combinations:
• Directional current (I3PDir) versus Polarizing voltage (U3PPol)
• Directional current (I3PDir) versus Polarizing current (I3PPol)
• Directional current (I3PDir) versus Dual polarizing (UPol+ZPol
x IPol) where ZPol = RPol + jXPol
IDir, UPol and IPol can be independently selected to be either
zero sequence or negative sequence.
Second harmonic blocking level can be set for the function and
can be used to block each step individually.
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
ABB
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, 3I ·cosj or 3I
0
·cos j, for operating quantity. There is also
component 3U ·3I
0 0
available one non-directional 3I
3U overvoltage tripping step.
0
Thermal overload protection, two time constant TRPTTR
If a power transformer or generator reaches very high
temperatures the equipment might be damaged. The insulation
within the transformer/generator will have forced ageing. As a
consequence of this the risk of internal phase-to-phase or
phase-to-earth faults will increase. High temperature will
degrade the quality of the transformer/generator insulation.
The thermal overload protection estimates the internal heat
content of the transformer/generator (temperature)
continuously. This estimation is made by using a thermal model
of the transformer/generator 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/generator.
Estimated time to trip before operation is presented.
Breaker failure protection CCRBRF, 3-phase activation and
output
CCRBRF can be current based, contact based, or an adaptive
combination of these two conditions.
Breaker failure protection, 3-phase activation and output
(CCRBRF) ensures fast back-up tripping of 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.
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.
Breaker failure protection, 3-phase activation and output
(CCRBRF) 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 function can be programmed to give a three-phase
re-trip of the own breaker to avoid inadvertent tripping of
surrounding breakers.
1MRK 502 050-BEN B
·j, or residual power
0
step and one non-directional
0
15