ABB RELION REX640 Technical Manual page 1032

Section 4
Protection functions
1026
Phase angle of the compensated
unbalance current (degrees)
-75...-105
-105...-135
-135...-165
-165...-180
+165...+180
+135...+165
+105...+135
+75...+105
+45...+75
+15...+45
After Alarm delay time has elapsed, the corresponding counter value is incremented
based on the magnitude of the unbalance current. If I_AMPL_COMP is less than 1.5
times the set Alarm value, the counter is incremented by one. Furthermore, if
I_AMPL_COMP is between 1.5 and 2.5 times the set Alarm value, the counter is
incremented by two and so on.
Normally, the setting Alarm value is about 0.1 percent lower than the
value of the unbalance current which is caused by one faulty element.
This setting value has to be chosen carefully because a slightly lower
value may lead to a situation where the counters show more failures
than the actual. Too high setting leads to a situation where a fault is not
detected.
The counter values COUNT_BR1_A, COUNT_BR2_A, COUNT_BR1_B,
COUNT_BR2_B, COUNT_BR1_C and COUNT_BR2_C are available in the
monitoring data view. The total number of element failures in double-Y-connected
capacitor banks, FAIL_COUNT, is available in the monitored data view.
The ALARM output is activated, when the value of FAIL_COUNT exceeds the setting
Element failure limit.
The counter values can be reset via CUBPTOC counters which is located under the
Clear menu.
Level detector 2
The calculated compensated unbalance current I_AMPL_COMP is compared to the
set Alarm start value. If the I_AMPL_COMP exceeds the set Alarm value the Level
detector 2 sends enabling signal to the Alarm control module.
Phase and branch of the element
failure
Phase-B branch 2
Phase-C branch 1
Phase-B branch 2
Phase-B branch 2
Phase-A branch 1
Phase-A branch 1
Phase-A branch 1
Phase-C branch 2
Phase-A branch 1
Phase-C branch 2
Phase-C branch 2
Phase-B branch 1
Phase-B branch 1
Phase-A branch 2
Phase-B branch 1
1MRS759142 C
Counters to be incremented
COUNT_BR2_B
COUNT_BR1_C
COUNT_BR2_B
COUNT_BR2_B
COUNT_BR1_A
COUNT_BR1_A
COUNT_BR1_A
COUNT_BR2_C
COUNT_BR1_A
COUNT_BR2_C
COUNT_BR2_C
COUNT_BR1_B
COUNT_BR1_B
COUNT_BR2_A
COUNT_BR1_B
REX640
Technical Manual