Section 19 Time inverse characteristics
19.1 Application
In order to assure time selectivity between different overcurrent protections in different
points in the network different time delays for the different relays are normally used. The
simplest way to do this is to use definite time delay. In more sophisticated applications
current dependent time characteristics are used. Both alternatives are shown in a simple
application with three overcurrent protections connected in series.
xx05000129_ansi.vsd
IPickup IPickup IPickup
ANSI05000129 V1 EN
Figure 281: Three overcurrent protections connected in series
en05000130.vsd
Time
Fault point
position
Stage 1
Stage 2
Stage 3
Stage 1
Stage 2
Stage 1
IEC05000130 V1 EN
Figure 282: Definite time overcurrent characteristics
1MRK 511 287-UUS A Section 19
Time inverse characteristics
655
Technical manual
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