ABB RELION Series, Technical Manual

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U
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U
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U
C
I
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I
B I
C
U
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U
B
U
C
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I
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-I
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c
-90°
U
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U
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GUID-1937EA60-4285-44A7-8A7D-52D7B66FC5A6 V3 EN
Figure 130: Phasors in a single-phase earth fault, phase A to ground, and a two-
phase short circuit, phases B-C, are short-circuited when the
polarizing quantity is the positive-sequence voltage U
1
Network rotation direction
Typically, the network rotating direction is counter-clockwise and defined as "ABC".
If the network rotating direction is reversed, meaning clockwise, that is, "ACB", the
equations for calculating the angle difference needs to be changed. The network
rotating direction is defined with a system parameter
Phase rotation . The change in
the network rotating direction affects the phase-to-phase voltages polarization
method where the calculated angle difference needs to be rotated 180 degrees. Also,
when the sequence components are used, which are, the positive sequence voltage or
negative sequence voltage components, the calculation of the components are
affected but the angle difference calculation remains the same. When the phase-to-
ground voltages are used as the polarizing method, the network rotating direction
change has no effect on the direction calculation.
The network rotating direction is set in the protection relay using the
parameter in the HMI menu
Configuration/System/Phase rotation .
The default parameter value is "ABC".
1MRS758755 A
Section 4
Protection functions
REC615 and RER615 237
Technical Manual