Multipurpose Protection - ABB RET670 Applications Manual

1MRK504116-UUS C
3.10
3.10.1
3.10.1.1
Application manual

Multipurpose protection

General current and voltage protection CVGAPC
Function description
General current and voltage protection
Application
A breakdown of the insulation between phase conductors or a phase conductor and
ground results in a short circuit or a ground fault. Such faults can result in large fault
currents and may cause severe damage to the power system primary equipment.
Depending on the magnitude and type of the fault different overcurrent protections,
based on measurement of phase, ground or sequence current components can be used
to clear these faults. Additionally it is sometimes required that these overcurrent
protections shall be directional and/or voltage controlled/restrained.
The over/under voltage protection is applied on power system elements, such as
generators, transformers, motors and power lines in order to detect abnormal voltage
conditions. Depending on the type of voltage deviation and type of power system
abnormal condition different over/under voltage protections based on measurement of
phase-to-ground, phase-to-phase, residual- or sequence- voltage components can be
used to detect and operate for such incident.
The IED can be provided with multiple General current and voltage protection
(CVGAPC) protection modules. The function is always connected to three-phase
current and three-phase voltage input in the configuration tool, but it will always
measure only one current and one voltage quantity selected by the end user in the
setting tool.
Each CVGAPC function module has got four independent protection elements built
into it.
1. Two overcurrent steps with the following built-in features:
• Definite time delay or Inverse Time Overcurrent TOC/IDMT delay for both
steps
• Second harmonic supervision is available in order to only allow operation of
the overcurrent stage(s) if the content of the second harmonic in the
measured current is lower than pre-set level
• Directional supervision is available in order to only allow operation of the
overcurrent stage(s) if the fault location is in the pre-set direction (Forward
IEC 61850 IEC 60617
identification identification
CVGAPC -
Section 3
IED application
ANSI/IEEE C37.2
device number
-
549