Section 20 Inverse time characteristics
20.1 Application
M16686-3 v5
In order to assure time selectivity between different overcurrent protections at
different points in the network different time delays for the different protections are
normally used. The simplest way to do this is to use definite time-lag. In more
sophisticated applications current dependent time characteristics are used. Both
alternatives are shown in a simple application with three overcurrent protections
operating in series.
IEC05000129 V1 EN-US
Figure 334: Three overcurrent protections operating in series
en05000130.vsd
Time
Fault point
position
Stage 1
Stage 2
Stage 3
Stage 1
Stage 2
Stage 1
IEC05000130 V1 EN-US
Figure 335: Definite time overcurrent characteristics
1MRK 505 384-UEN A Section 20
Inverse time characteristics
Breaker protection REQ650 2.2 IEC 733
Technical manual
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