ABB RELION Series, Technical Manual

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GUID-134928BF-ACE3-42C9-A70F-985A1913FB75 V3 EN
Figure 251: Description of the equivalent load distance
The exact value for Equivalent load Dis can be calculated based on the load flow and
voltage drop calculations using data from DMS-system and the following equation.
Equivalent load Dis
U
U
d real
d tap d
=
=
( )
( , ) 1
GUID-E447E8AC-65F7-4586-B853-C297347303FF V2 EN
(Equation 50)
U
d(real)
The actual maximum voltage drop of the feeder
U
d(tap,d=1)
The fictional voltage drop, if the entire load would be tapped at the end (d=1) of the
feeder (not drawn in Figure 251 ). The calculation of this value requires data from
the DMS system.
Alternatively, the setting Equivalent load Dis can be determined by conducting a
single-phase earth-fault test (R
fault
= 0 Ω) at that point of the feeder where the
maximum actual voltage drop takes place. This point is typically located at the end of
the main line. As a result, the calculated value is stored in the recorded data Equivalent
load Dis.
In addition, when the setting EF algorithm Sel is equal to “Load modelling”, the EF
algorithm Cur Sel setting determines whether zero-sequence “Io based” or negative-
sequence “I2 based” current based algorithm is used. The difference between “Io
1MRS758755 A
Section 5
Protection related functions
REC615 and RER615 487
Technical Manual