1MDU07212-YN Rev. D Section 4
Protection and Control Function
REF601 / REJ601 / REM601 19
Application Manual
4.3.2 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 9: Setting ranges Negative sequence overcurrent protection
0.1…1.5 x In, in steps of 0.01
Operate delay time, ‘tI2>’
0.1 … 300 sec, in steps of 0.1
Block the negative phase sequence
protection
3% of set value or ± 30ms
4.4 Phase discontinuity protection
4.4.1 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.
4.4.2 Principle of Operation
The unbalance of network is detected by monitoring the ratio of negative sequence
current to positive sequence current I
2
/I
1
. The function operates when the ratio of
unbalance current I
2
/I
1
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.
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