Current Protection - ABB RELION 650 Series Product Manual

Transformer protection RET650 2.1 IEC
three-winding
power transformer
with two circuit
breakers and two
CT-sets on one side
xx05000053.vsd
IEC05000053 V1 EN-US
Autotransformer
with two circuit
breakers and two
CT-sets on two out
of three sides
xx05000057.vsd
IEC05000057 V1 EN-US
Figure 2. CT group arrangement for
differential protection
The setting facilities cover the application of the
differential protection to all types of power
transformers and auto-transformers without load tap
changer as well as shunt reactors and local feeders
within the station. An adaptive stabilizing feature is
included for heavy through-fault currents.
Stabilization is included for inrush and overexcitation
currents respectively, cross-blocking is also available.
Adaptive stabilization is also included for system
recovery inrush and CT saturation during external faults.
A high set unrestrained differential current protection
element is included for a very high speed tripping at
high internal fault currents.
Included is an sensitive differential protection element
based on the theory of negative sequence current
component. This element offers the best possible
coverage of power transformer windings turn to turn
faults.
Restricted earth-fault protection, low impedance
REFPDIF
Restricted earth-fault protection, low-impedance
function REFPDIF can be used on all directly or low-
impedance earthed windings. The REFPDIF function
provides high sensitivity and high speed tripping as it
protects each winding separately and thus does not
need inrush stabilization.
The REFPDIF function is a percentage biased function
with an additional zero sequence current directional
comparison criterion. This gives excellent sensitivity and
stability during through faults.
ABB

4. Current protection

Instantaneous phase overcurrent protection PHPIOC
The instantaneous three phase overcurrent function has
a low transient overreach and short tripping time to
allow use as a high set short-circuit protection function.
Four-step phase overcurrent protection OC4PTOC
The four step three-phase overcurrent protection
function OC4PTOC has an inverse or definite time delay
independent for step 1 to 4 separately.
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.
Four step residual overcurrent protection, zero
sequence and negative sequence direction EF4PTOC
The four step residual overcurrent protection EF4PTOC
has an inverse or definite time delay independent for
M13047-3 v18
each step.
All IEC and ANSI time-delayed characteristics are
available together with an optional user defined
characteristic.
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.
Residual current can be calculated by summing the three
phase currents or taking the input from neutral CT
1MRK 504 161-BEN C
M12910-3 v12
M12846-3 v16
M12701-3 v15
M13667-3 v18
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