Negative-Sequence Overcurrent Protection; Functionality; Principle Of Operation; Phase Discontinuity Protection - ABB REF601 Applications Manual

1MDU07212-YN Rev. C
4.4
4.4.1
4.4.2
4.5
4.5.1
REF601 / REJ601
Application Manual

Negative-sequence overcurrent protection

Functionality

The negative-sequence overcurrent protection is used for increasing sensitivity to
detect unbalance load or unsymmetrical feeder voltages.
The operate time characteristics is based on definite time (DT) i.e. function
operates after a predefined operate time and resets when the fault current
disappears.

Principle of Operation

The function is based on the measurement of negative sequence current. In a fault
situation, the function starts when the negative sequence current (I2) exceeds the
set value. When the set definite time operation timer has reached the value set by
the operate delay time, the OPERATE output is activated.
On occurrence of fault, fulfilling the trip condition of respective stage, the LED
"Trip" and programmable LED if configured will be activated. Additionally the
output relays (Trip and signalization) will be activated according the binary output
configuration.
The protection could be blocked by settings or via binary input of the relay.
Table 10: Setting ranges Negative sequence overcurrent protection
Parameter
Start value, 'I2>"
Operate delay time, 'tI2>'
Block the negative phase sequence
protection
Operation accuracy
Operation time accuracy
Reset ratio

Phase discontinuity protection

Functionality
The phase discontinuity protection is used for detecting unbalance situations
caused by broken conductors.
The operate time characteristics is based on definite time (DT) i.e. function
operates after a predefined operate time and resets when the fault current
disappears.
Protection and Control Function
Value (Range)
0.1...1.5 x In, in steps of 0.01
0.1 ... 300 sec, in steps of 0.1
0 = No, 1 = Yes
± 5.0% of set value
3% of set value or ± 30ms
0.98
Section 4
19