ABB ret650, Technical Manual

Page: 252 / 670

11.1.6 Monitored data
Table 172: SDDRFUF Monitored data
Name Type Values (Range) Unit Description
3I0 REAL - A Magnitude of zero
sequence current
3I2 REAL - A Magnitude of negative
sequence current
3U0 REAL - kV Magnitude of zero
sequence voltage
3U2 REAL - kV Magnitude of negative
sequence voltage
11.1.7 Operation principle
11.1.7.1 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
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.
Section 11
1MRK 504 135-UEN A
Secondary system supervision
246
Technical manual