Calculating General Settings - ABB REL650 Applications Manual

1MRK 506 334-UUS A
3.1.9.1
Application manual
The reach of phase overcurrent line protection is dependent of the operation state and the
fault type. Therefore the setting must be based on fault calculations made for different
faults, fault points and switching states in the network. Although it is possible to make
hand calculations of the different faults it is recommended to use computer based fault
calculations. Different time delay principles can be used. This is due to different praxis.
The following principle for the phase overcurrent protection is proposed:
• Step 1 (I>>>) with high current setting and zero delay. This step gives fast trip for the
line short circuits close to the nearest line end.
• Step 2 (I>>) with a current setting that enables detection of all short circuits on the
protected line and on the local and remote busbars. The function has a short delay to
enable selectivity.
• Step 3 (I>) with a current setting that enables detection of all short circuits on the
adjacent lines connected to the local and remote busbars. The function has a longer
delay to enable selectivity.
6
10
5
9
2
Y
ANSI11000114 V1 EN
Figure 21: Fault points for phase overcurrent setting calculations
The phase overcurrent protection in line end A is considered in this example. The same
principle can be used for line end B.

Calculating general settings

1. Set GlobalBaseSel to 1
The settings are made in primary values. These values are given in the base settings
in Global base 1.
2. Set DirModeSel1(2,3) to Non-directional
It is assumed that the phase overcurrent protection shall operate also when the
distance protection is deactivated due to fuse failure. Therefore the function shall be
non-directional as the directional function must use voltage measurement.
REL650 setting examples
A
REL 650 REL 650
Section 3
80 %
B
4
3
1
Y
ANSI11000114_1_en.vsd
8
7
67