Directional Phase Overcurrent Protection, Four Steps Oc4Ptoc - ABB REG670 Applications Manual

Section 9
Current protection
9.2
9.2.1
9.2.2
324
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 protections,
they should have the same time delay characteristic. Therefore, a wide range of
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
IEC 61850 IEC 60617
identification identification
OC4PTOC
TOC-REVA V2 EN
1MRK 502 071-UEN -
ANSI/IEEE C37.2
device number
51_67
Application manual