ABB Relion 670 Series Technical Reference Manual page 405

1MRK505222-UUS C
7.4
7.4.1
Technical reference manual
Function
Critical impulse time
Operate time
Reset time
Critical impulse time
Dynamic overreach
Four step residual overcurrent protection, zero,
negative sequence direction EF4PTOC (51N/67N)
Function description
Four step residual overcurrent
protection
Introduction
The four step residual overcurrent protection EF4PTOC (51N/67N) 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.
EF4PTOC (51N/67N) can be set directional or non-directional independently for each
of the steps.
IDir, VPol 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 (51N/67N) can be used as main protection for phase-to-ground faults.
EF4PTOC (51N/67N) 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.
Range or value
10 ms typically at 0 to 2 x I
set
10 ms typically at 0 to 10 x I
set
35 ms typically at 10 to 0 x I
set
2 ms typically at 0 to 10 x I
set
< 5% at t = 100 ms
IEC 61850 IEC 60617
identification identification
EF4PTOC
4
4
TEF-REVA V1 EN
Section 7
Current protection
Accuracy
-
-
-
-
-
ANSI/IEEE C37.2
device number
51N/67N
IN
alt
399