I_COM_ANGL_B ~+60° Phase B - Branch 1 or Phase B
- Branch 4
I_COM_ANGL_B ~–120° Phase B - Branch 2 or Phase B
- Branch 3
I_COM_ANGL_C ~–60° Phase C - Branch 1 or Phase C
- Branch 4
I_COM_ANGL_C ~+120° Phase C - Branch 2 or Phase C
- Branch 3
If external fuses are used, the direction of an unbalance current is opposite to that
of the bank where internal fuses are in use.
Table 1078: Detection of element failure location for external fuse capacitor bank
Name of the phase angle Phase angle of unbalance cur-
rent
Element failure branch loca-
tion
Figure 634
I_COM_ANGL_A ~0° Phase A - Branch 1 or Phase A
- Branch 4
I_COM_ANGL_A ~+180° Phase A - Branch 2 or Phase A
- Branch 3
I_COM_ANGL_B ~–120° Phase B - Branch 1 or Phase B
- Branch 4
I_COM_ANGL_B ~+60° Phase B - Branch 2 or Phase B
- Branch 3
I_COM_ANGL_C ~+120° Phase C - Branch 1 or Phase C
- Branch 4
I_COM_ANGL_C ~–60° Phase C - Branch 2 or Phase C
- Branch 3
Level detector 1
The phasewise-compensated unbalance currents I_COM_AMPL_A, I_COM_AMPL_B
and I_COM_AMPL_C are compared to the set
Start value
. If the compensated
unbalance current in one or more phases exceeds the set
Start value
, the Level
detector 1 module sends the enabling signal to the Timer 1 module.
Timer 1
Once activated, the Timer 1 module activates the START output. Depending on the
value of the
Operating curve type
setting, the time characteristics are according
to DT or IDMT. When the operation timer has reached the value of
Operate delay
time
in the DT mode or the maximum value defined by the inverse time curve, the
OPERATE output is activated.
When the user-programmable IDMT curve is selected, the operation time
characteristics are defined by the parameters
Curve parameter A
,
Curve parameter
B
,
Curve parameter C
and
Curve parameter E
.
In a drop-off situation, that is, when a fault suddenly disappears before the
operation delay is exceeded, the Timer 1 reset state is activated. The functionality
of Timer 1 in the reset state depends on the combination of the
Operating curve
type
and
Reset delay time
settings. When the DT characteristic is selected, the reset
timer runs until the set
Reset delay time
value is exceeded. When the IDMT curves
1MRS759142 F
Protection functions
REX640
Technical Manual
1135
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