a
b
a>b
OR
|I
OP
|
STx
TRx
AND
Ix>
BLKSTx
BLOCK
Characteristx=DefTime
DirModex=Off
DirModex=Non-directional
DirModex=Forward
DirModex=Reverse
AND
AND
FORWARD_Int
REVERSE_Int
OR
OR
STAGEx_DIR_Int
IEC12000008.vsd
AND
AND
Characteristx=Inverse
Inverse
tx
min
tx
IEC12000008.vsd
IEC12000008 V2 EN
Figure 160:
Simplified logic diagram for OC4PTOC
Different types of reset time can be selected as described in section
.
There is also a possibility to activate a preset change (
IxMult
x= 1, 2, 3 or 4) of the set
operation current via a binary input (enable multiplier). In some applications the
operation value needs to be changed, for example due to changed network switching
state. The function can be blocked from the binary input BLOCK. The start signals
from the function can be blocked from the binary input BLKST. The trip signals from
the function can be blocked from the binary input BLKTR.
8.2.8
Second harmonic blocking element
A harmonic restrain of the Four step overcurrent protection function OC4PTOC can
be chosen. If the ratio of the 2nd harmonic component in relation to the fundamental
frequency component in the residual current exceeds the preset level defined by
parameter
2ndHarmStab
setting, any of the four overcurrent stages can be selectively
blocked by parameter
HarmRestrainx
setting. When 2nd harmonic restraint feature is
active, the OC4PTOC function output signal 2NDHARMD will be set to logical value
one.
1MRK502052-UEN B
Section 8
Current protection
349
Technical manual
Summary of Contents for Relion REG670
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