Monitored Data; Operation Principle; Zero And Negative Sequence Detection - ABB RET650 Technical Manual

Section 11
Secondary system supervision
11.1.6
11.1.7
11.1.7.1
246

Monitored data

Table 172: SDDRFUF Monitored data
Name Type
3I0 REAL
3I2 REAL
3U0 REAL
3U2 REAL

Operation principle

Zero and negative sequence detection

The zero and negative sequence function continuously measures the currents and
voltages in all three phases and calculates: (see figure 111)
• the zero-sequence voltage 3U
• the zero-sequence current 3I
• the negative sequence current 3I
• the negative sequence voltage 3U
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.
Values (Range) Unit
- A
- A
- kV
- kV
0
0
2
2
1MRK 504 135-UEN A
Description
Magnitude of zero
sequence current
Magnitude of negative
sequence current
Magnitude of zero
sequence voltage
Magnitude of negative
sequence voltage
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