Toshiba GR200 Series Instruction Manual page 51

will operate unnecessarily for a fault between the breaker and the CT. To avoid this, Zero
ampere control is effective. As the coupler/section CB is open, DIFZA will not operate due to
Zero ampere control, which sets current to 0A.
I1
I2
Figure 2.1-15 Operation with bus-coupler CB open
Differential current(Id) of DIFZA:
Differential current(Id) of DIFZB:
Bus-A
Coupler
CB open
Ic1
Ic2
DIFZA
DIFZB
-ZA = | I1+I2+Ic1(*) | ≠ 0
I
d
-ZB = | I3+I4+Ic2(*) | ≈ 0
I
d
(*)Ie1 and Ie2 controlled to 0A by CB open
- 37 -
6F2S1931 (0.20)
Bus-B
I3
I4

DIFZA does not operate

DIFZB operates
Centralized GRB200
(Soft: 030, 031, 032, 033, 034)
(2.1-13)
(2.1-14)