Directional Phase Overcurrent Protection, Four Steps Oc4Ptoc - ABB REC670 Applications Manual

Section 8
Current protection
8.2
8.2.1
8.2.2
146
Directional phase overcurrent protection, four steps
OC4PTOC
Identification
Function description
Directional phase overcurrent
protection, four steps
Application
Directional phase overcurrent protection, four steps OC4PTOC 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 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 DirModex (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 delay characteristics. The selectivity between different overcurrent protections
is normally enabled by co-ordination between the function time delays of the
different protections. To enable optimal co-ordination between all overcurrent
IEC 61850 IEC 60617
identification identification
OC4PTOC
TOC-REVA V2 EN-US
1MRK 511 401-UEN A
SEMOD129998-1 v8
M14885-1 v6
ANSI/IEEE C37.2
device number
51_67
M15335-3 v9
Bay control REC670 2.2 IEC
Application manual