Phase angle of the
compensated unbalance
current (degrees)
Phase and branch of the
element failure
Counters to be incremented
+75...+105
Phase-C branch1
Phase-B branch2
COUNT_BR1_C
COUNT_BR2_B
+45...+75
Phase-B branch2
COUNT_BR2_B
+15...+45
Phase-A branch1
Phase-B branch2
COUNT_BR1_A
COUNT_BR2_B
If the capacitor bank is fuseless, then the setting
Fuse location should
be set to “External” and
can be used to determine the element
failure location.
If the compensated unbalance current I_AMPL_COMP is greater than three times
the set
Alarm value, it is considered to be a case of blown external fuse. For the
internal fuse and blown fuse cases, the element failure location and corresponding
counters to be incremented are determined based on the phase angle of the
compensated unbalance current.
Table 750: Element failure location and counters to be incremented for internal
fuse and blown fuse case
Phase angle of the
compensated unbalance
current (degrees)
Phase and branch of the
element failure
Counters to be incremented
-15...+15
Phase-A branch 2
COUNT_BR2_A
-15... -45
Phase-A branch 2
Phase-C branch 1
COUNT_BR2_A
COUNT_BR1_C
-45...-75
Phase-C branch 1
COUNT_BR1_C
-75...-105
Phase-B branch 2
Phase-C branch 1
COUNT_BR2_B
COUNT_BR1_C
-105...-135
Phase-B branch 2
COUNT_BR2_B
-135...-165
Phase-B branch 2
Phase-A branch 1
COUNT_BR2_B
COUNT_BR1_A
-165...-180
Phase-A branch 1
COUNT_BR1_A
+165...+180
Phase-A branch 1
COUNT_BR1_A
+135...+165
Phase-C branch 2
Phase-A branch 1
COUNT_BR2_C
COUNT_BR1_A
+105...+135
Phase-C branch 2
COUNT_BR2_C
+75...+105
Phase-C branch 2
Phase-B branch 1
COUNT_BR2_C
COUNT_BR1_B
Table continues on the next page
1MRS757644 H
Protection functions
620 series
Technical Manual
787