ABB Relion 650 Series Product Manual page 21

Transformer protection RET650
Version 2.2
time to allow use as a high set short-circuit protection
function.
Directional phase overcurrent protection, four steps
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.
Directional phase overcurrent protection, four steps
(OC4PTOC) has an inverse or definite time delay for each
step.
All IEC and ANSI inverse time characteristics are available
together with an optional user defined time characteristic.
The directional function needs voltage as it is voltage
polarized with memory. The function can be set to be
directional or non-directional independently for each of the
steps.
A second harmonic blocking level can be set for the function
and can be used to block each step individually.
Instantaneous residual overcurrent protection
EFPIOC
The Instantaneous residual overcurrent protection
(EFPIOC) has a low transient overreach and short tripping
times to allow use for instantaneous earth-fault protection,
with the reach limited to less than typical eighty percent of
the transformer impedance at minimum source impedance.
EFPIOC can be configured to measure the residual current
from the three-phase current inputs or the current from a
separate current input.
Directional residual overcurrent protection, four
steps EF4PTOC
EF4PTOC has an inverse or definite time delay independent
for each step.
All IEC and ANSI time-delayed characteristics are available
together with an optional user-defined characteristic.
EF4PTOC can be set to be directional or non-directional
independently for each step.
IDir, UPol and IPol can be independently selected to be
either zero sequence or negative sequence.
A second harmonic blocking can be set individually for each
step.
The residual current can be calculated by summing the
three-phase currents or taking the input from the neutral CT.
EF4PTOC also provides very fast and reliable faulty phase
identification for phase selective tripping and subsequent
reclosing during earth fault.
Hitachi Power Grids
Four step directional negative phase sequence
overcurrent protection NS4PTOC
Four step directional negative phase sequence overcurrent
protection (NS4PTOC) has an inverse or definite time delay
M12846-3 v18
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.
Thermal overload protection, two time constants
TRPTTR
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 (TRPTTR) 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
M12701-3 v16
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, 3-phase
activation and output
M13667-3 v20
Breaker failure protection, 3-phase activation and output
(CCRBRF) ensures fast backup 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.
A current based check with extremely short reset time is
used as check criterion to achieve high security against
inadvertent operation.
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 backup trip command.
CCRBRF function can be programmed to give a three-
phase retrip of the own breaker to avoid inadvertent tripping
of surrounding breakers.
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1MRK 504 172-BEN G
GUID-485E9D36-0032-4559-9204-101539A32F47 v6
M13243-3 v12
M11550-6 v19
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