Current Protection - ABB Relion 650 series RET650 Product Manual

Transformer protection RET650
Product version: 1.1
voltage dependent resistor externally to the
IED.
HZPDIF can be used as high impedance REF
protection.

5. 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 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 time delayed 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.
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.
EFPIOC can be blocked by activating the
input BLOCK.
18
1MRK 504 127-BEN -
Issued: February 2011
Four step residual overcurrent
protection EF4PTOC
The four step residual overcurrent protection
(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 time delayed characteristics
are available.
The directional function is voltage polarized,
current polarized or dual polarized.
EF4PTOC can be set directional or non-
directional independently for each of the steps.
A second harmonic blocking can be set
individually for each step.
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.
Breaker failure protection CCRBRF
Breaker failure protection (CCRBRF) ensures
fast back-up tripping of surrounding breakers
in case the own breaker failure to open.
ABB