Figure 127: Two-phase short circuit, short circuit is between phases B and C
The equations are valid when network rotating direction is counter-
clockwise, that is, ABC. If the network rotating direction is reversed,
180 degrees is added to the calculated angle difference. This is done
automatically with a system parameter
Phase rotation
.
Negative sequence voltage as polarizing quantity
When the negative voltage is used as the polarizing quantity, the angle difference
between the operating and polarizing quantity is calculated with the same formula
for all fault types:
ANGLE X U I
RCA
_ ( ) ( )= − − −
ϕ ϕ ϕ
2
2
(Equation 5)
This means that the actuating polarizing quantity is - U
2
.
1MRS758755 C
Protection functions
REC615 & RER615
Technical Manual
247
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