ABB Relion 670 Series Applications Manual page 123

1MRK 511 407-UUS Rev. J
Section 8
8.1 Directional phase overcurrent protection, four steps
OC4PTOC(51_67)
8.1.1 Identification
Function description
Directional phase overcurrent
protection, four steps
8.1.2 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.
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 standardized inverse time characteristics are available for IEC and ANSI. It is also possible
to tailor make the inverse time characteristic.
Phasor measurement unit RES670
Application manual
Current protection
IEC 61850
identification
OC4PTOC
If VT inputs are not available or not connected, the setting parameter
( x = step 1, 2, 3 or 4) shall be left to the default value Non-directional .
© Copyright 2017 Hitachi Power Grids. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
51_67
TOC-REVA V2 EN-US
Section 8
Current protection
SEMOD129998-1 v8
M14885-1 v6
M15335-3 v9
DirModeSelx
117