• the zero-sequence voltage 3U
0
• the zero-sequence current 3I
0
• the negative sequence current 3I
2
• the negative sequence voltage 3U
2
The measured signals are compared with their respective set values 3U0< and 3I0>,
3U2< and 3I2>.
The function enable the internal signal FuseFailDetZeroSeq if the measured zero-
sequence voltage is higher than the set value 3U0> and the measured zero-sequence
current is below the set value 3I0<.
The function enable the internal signal FuseFailDetNegSeq if the measured negative
sequence voltage is higher than the set value 3U2> and the measured negative
sequence current is below the set value 3I2<.
A drop off delay of 100 ms for the measured zero-sequence and negative sequence
current will prevent a false fuse failure detection at un-equal breaker opening at the
two line ends.
IL1
IL2
IL3
Zero
sequence
filter
Negative
sequence
filter
UL1
UL2
UL3
Zero
sequence
filter
Negative
sequence
filter
CurrZeroSeq
CurrNegSeq
a
b
a>b
a
b
a>b
a
b
a>b
a
b
a>b
3I2<
t
100 ms
t
100 ms
VoltZeroSeq
VoltNegSeq
AND
AND
FuseFailDetZeroSeq
FuseFailDetNegSeq
Sequence Detection
3U0>
3U2>
3I0
3I2
3U0
3U2
IEC10000036-2-en.vsd
3I0<
IEC10000036 V2 EN
Figure 90: Simplified logic diagram for sequence detection part
The calculated values 3U
0
, 3I
0
, 3I
2
and 3U
2
are available as service values on local
HMI and monitoring tool in PCM600.
Section 9 1MRK 511 287-UEN A
Secondary system supervision
198
Technical manual
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