Supervision Functions
PRS-7367 237
SIGCT_InsALM
=1
=0
Op_Val=CTS_Cur_Str
+0.1*I3P_max
CTS_3Io_Calc_EnaSET
I_Dif=|I_A+I_B+I_C|
Op_Val=CTS_Cur_Str
+0.2*I3P_max
I_Dif=|I_A+I_B+I_C|-|I0|
U0<10VANA
I_Dif>Op_ValANA
&
&
SIGCT_ALM
&
SIG BLOCK
SIG CTS_Ena=1
I_Dif<0.9*Op_ValANA
I3P_max<2*InANA
I3P_max>0.05*InANA
&
3ms
3s
3ms
10s
Figure 4.3-2 Functional module diagram
Differential current calculation
Differential current calculation and operate value depend on whether there is an external CT to
measure the residual current.
If the external CT is unavailable, that is to say CTS_3Io_Calc_Ena=1, differential current is the
summed phase currents I_A, I_B and I_C. The formula is shown as below.
_ _ _ _I Dif I A I B I C
Then the operate value is according to the following formula:
Op_Val =Set_value+0.1*I3P_max
If the external CT is available, that is to say CTS_3Io_Calc_Ena=0, differential current is the
difference between the summed phase currents I_A, I_B, I_C and the measured residual current.
The formula is shown as below.
0
_ _ _ _I Dif I A I B I C I
The operate value is according to the following formula:
Op_Val =Set_value+0.2*I3P_max
“CTS_3Io_Calc_Ena” is the signal to judge whether there is an external CT to measure the
residual current;
“CTS_Cur_Str” is the operation start current value;
“I3P_max” is the max phase current of three phases;
Current circuit failure criteria
To Next Page
Loading...