Section 24 Inverse Time Characteristics - ABB Relion 670 Series RES670 Technical Manual

1MRK 511 365-UUS A
Section 24
24.1
Phasor measurement unit RES670 2.1 ANSI
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.
IPickup
ANSI05000129 V1 EN
Figure 325: Three overcurrent protections operating in series
Time
Stage 1
IEC05000130 V1 EN
Figure 326: Definite time overcurrent characteristics
Inverse time characteristics
IPickup
Stage 2
Stage 1
Section 24
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Stage 3
Stage 2
Stage 1
Fault point
position
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