V
ref
I
dir
RCA
ROA
Forward
Reverse
ROA
en05000745_ansi.vsd
ANSI05000745 V1 EN-US
Figure 248: Directional characteristic of the phase overcurrent protection
The default value of
AngleRCA
is –65°. The parameters
AngleROA
gives the angle sector from
AngleRCA
for directional borders.
A minimum current for directional phase pickup current signal can be set.
PUMinOpPhSel
is the
pickup level for directional evaluation of IA, IB and IC. The directional signals release the
overcurrent measurement in respective phases if their current amplitudes are higher than the
pickup level (
PUMinOpPhSel
) and the direction of the current is according to the set direction of
the step.
If no blockings are given, the pickup signals will start the timers of the step. The time
characteristic for each step can be chosen as definite time delay or inverse time characteristic. A
wide range of standardized inverse time characteristics is available.It is also possible to create a
tailor made time characteristic.
The possibilities for inverse time characteristics are described in section
"Inverse characteristics".
All four steps in OC4PTOC (51/67) can be blocked from the binary input BLOCK. The binary input
BLKx (x=1, 2, 3 or 4) blocks the operation of respective step.
Section 8 1MRK 502 066-UUS B
Current protection
464
Technical manual
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