ABB Remote I/O RIO600 Installation And Commissioning Manual page 159

1MRS757488 H
RIO600
Installation and Commissioning Manual
I_A
General
I_B
criterion
I_C
GUID-8F92E063-8E83-48B1-B2DD-DCF6A21E6395 V1 EN
Figure 83: Functional module diagram
General fault criterion (GFC)
The General fault criterion (GFC) module monitors the presence of earth fault in the
network. There are two fault detection methods evaluated in parallel based on residual
current (I ) and earth-fault current (I
o
Residual current amplitude I
I = 3·abs(I ) = 3·abs(I
o 0 A
where
I = Zero-sequence current phasor
0
In order to estimate single-phase earth-fault current, threefold negative-sequence
current component due to earth fault is used (phase A as reference, a=cos(120
o
j·sin(120 ), phase rotation: A-B-C). Estimated fundamental frequency earth-fault
current amplitude can be derived from phase currents as:
2
I = 3·I = I + a · I + a· I
EF 2 A B
I = abs(I )
EF EF
where
I = Negative-sequence current phasor
2
Earth-fault detection is based on monitoring the amplitude of residual current (I
earth fault current (I ) and by comparing them to setting values, Residual Start Cur
EF
and EF Start Cur, respectively.
I >Residual Start Cur
o
GUID-1C757E20-2395-4D0C-AAB1-01002674E9D4 V1 EN
I >EF Start Cur
EF
GUID-A18015C7-36AD-4450-9B8D-7699A3DBCB12 V1 EN
Setting Residual Start Cur must be set above the highest residual
current value measured during the healthy state.
Faulted
fault phase
selection
).
EF
can be derived from phase currents as:
o
+ I + I )/3
B C
C
Section 6
Commissioning
FPIPTOC_Oper
Fault
passage
indicator
FPIPTOC_Start
o
) +
) and
o
(Equation 18)
(Equation 19)
151