Directional Phase Overcurrent Protection, Four Steps Oc4Ptoc(51_67) - ABB RELION RET670 Applications Manual

1MRK 504 163-UUS A
9.2
9.2.1
9.2.2
Transformer protection RET670 2.2 ANSI
Application manual
Directional phase overcurrent protection, four steps
OC4PTOC(51_67)
Identification
Function description
Directional phase overcurrent
protection, four steps
Application
Directional phase overcurrent protection, four steps OC4PTOC (51_67) is used in
several applications in the power system. Some applications are:
• Short circuit protection of feeders in distribution and subtransmission systems.
Normally these feeders have a radial structure.
• Back-up short circuit protection of transmission lines.
• Back-up short circuit protection of power transformers.
• Short circuit protection of different kinds of equipment connected to the power
system such as; shunt capacitor banks, shunt reactors, motors and others.
• Back-up short circuit protection of power generators.
In many applications several steps with different current pickup levels and time delays
are needed. OC4PTOC (51_67) can have up to four different, individually settable
steps. The following options are possible:
Non-directional / Directional function: In most applications the non-directional
functionality is used. This is mostly the case when no fault current can be fed from the
protected object itself. In order to achieve both selectivity and fast fault clearance, the
directional function can be necessary.
If VT inputs are not available or not connected, the setting parameter
DirModeSelx (x = step 1, 2, 3 or 4) shall be left to the default value
Non-directional.
Choice of time delay characteristics: There are several types of time delay
characteristics available such as definite time delay and different types of inverse time
IEC 61850 IEC 60617
identification identification
OC4PTOC
TOC-REVA V2 EN-US
Section 9
Current protection
SEMOD129998-1 v8
M14885-1 v6
ANSI/IEEE C37.2
device number
51_67
M15335-3 v9
519