ABB RELION REX640 Technical Manual page 1199

1MRS759142 F
of radial feeders, this algorithm can be applied with low-impedance/effectively
earthed systems where the fault current is fed from one side only. The "Load
modelling" algorithm has been especially designed for unearthed systems.
The "Load modelling" algorithm requires the
equivalent load distance, as an additional parameter. The derivation and meaning of
this parameter is illustrated in
distributed along the feeder, resulting in the actual voltage drop curve as seen in the
middle part of
In case of evenly distributed load,
tapped at the end of the feeder,
is unknown, a default value of 0.5 can be used for
The maximum value of the voltage drop, denoted as U
of the feeder. The
tap corresponding to the total load of the feeder results in a voltage drop equal to
U
drop
Figure 684: Description of the equivalent load distance
The exact value for
voltage drop calculations using data from DMS-system and the following equation.
REX640
Technical Manual
Figure 684
.
Equivalent load Dis setting is the distance at which a single load
(real). The dashed curve shows the voltage drop profile in this case.
Equivalent load Dis can be calculated based on the load flow and
Equivalent load Dis setting, that is, an
Figure 684 , where the load is assumed to be evenly
Equivalent load Dis ~ 0.5. When the load is
Equivalent load Dis = 1.0. If the load distribution
Equivalent load Dis .
Protection related functions
(real), appears at the end
drop
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