ABB Relion 670 series - Four step residual overcurrent protection, zero, negative sequence direction EF4 PTOC (51 N;67 N); Introduction

Function Range or value Accuracy
Critical impulse time 10 ms typically at 0 to 2 x I
set
-
Operate time 10 ms typically at 0 to 10 x I
set
-
Reset time 35 ms typically at 10 to 0 x I
set
-
Critical impulse time 2 ms typically at 0 to 10 x I
set
-
Dynamic overreach < 5% at t = 100 ms -
7.4 Four step residual overcurrent protection, zero,
negative sequence direction EF4PTOC (51N/67N)
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Four step residual overcurrent
protection
EF4PTOC
4
4
alt
IN
TEF-REVA V1 EN
51N/67N
7.4.1 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.
1MRK505222-UUS C Section 7
Current protection
399
Technical reference manual