Section 19 Inverse Time Characteristics - ABB Relion 650 Series Technical Manual

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Section 19
19.1
Bay control REC650 2.2 IEC
Technical manual
Inverse time characteristics
Application
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.
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Figure 320: Three overcurrent protections operating in series
Time
Stage 1
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Figure 321: Definite time overcurrent characteristics
Inverse time characteristics
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Stage 2
Stage 1
Section 19
M16686-3 v5
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Stage 2
Stage 1
Fault point
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