ABB REL 551 2.3 Series - Page 109

103
Line differential protection (DIFL) &KDSWHU
9HULI\LQJVHWWLQJVE\VHFRQGDU\
LQMHFWLRQ
 ,QFUHDVHWKHWKUHHSKDVHYROWDJHWRLWVUDWHGYDOXH
Read the values of the differential and bias currents under the
menu:
6HUYLFH5HSRUW'LII9DOXHV
They must correspond to the value:
(Equation 8)
The bias currents are available under the same menu. They must
be equal to the measured differential current in each phase.
 'LVFRQQHFWWKHYROWDJHVIURPWKHWHUPLQDODQGFRQQHFWRQO\
RQHSKDVHWRDOOWKUHHYROWDJHLQSXWVRIWKHWHUPLQDO
 ,QFUHDVHWKHPHDVXUHGYROWDJHWRWKHUDWHGSKDVHYDOXHDQG
REVHUYHWKHYDOXHVRIWKHGLIIHUHQWLDODQGELDVFXUUHQWVSUH
VHQWHGRQWKHWHUPLQDO
They must correspond to the following values:
(Equation 9)
(Equation 10)
I
Diff
= I
Bias
for each phase.
U Represents measured phase voltage.
IDiffL1 IDiffL2 IDiffL3
U
XC1 CTFacto
r
⋅
----------------------------------------
----
===
IDiffL1 IDiffL2 IDiffL3
2
U
⋅
XC0 CTFacto
r
⋅
----------------------------------------
----
===
IBiasL1 IBiasL2 IBiasL3
U
XC0 CTFacto
r
⋅
----------------------------------------
----
===