ML0035 September 27, 2017 - 82 - Copyright 2017 Bitronics, LLC
6.7 Compensated Watts and VARs (Line and Transformer Loss Compensation)
The total Watt and Var losses can be calculated using five user entered parameters
and measured current and voltage values. These losses are added or subtracted
to/from the measured Total Watts and Total Vars when accumulating Energy.
Loss compensation on the M650 takes the following general form:
P
COM
= P
UNC
+ A·I
2
+ B·V
2
+ E·P
UNC
Q
COM
= Q
UNC
+ C·I
2
+ D·V
4
+ E·Q
UNC
Where:
P
COM
Compensated three-phase total watts. Note the accumulators for +kWh and –
kWh in the M650 are calculated by integrating the P
COM
measurement over time.
P
UNC
Uncompensated three-phase total watts measured at the point where the meter
is connected.
Q
COM
Compensated three-phase total VARs. Note the accumulators for +kVARh and –
kVARh in the M650 are calculated by integrating the Q
COM
measurement over
time.
Q
UNC
Uncompensated three-phase total VARs measured at the point where the meter
is connected.
I RMS line current measured at the point where the meter is connected.
V RMS line-line voltage measured at the point where the meter is connected.
A Meter setting that accounts for the sum of the full-load-watt-losses from all
sources.
B Meter setting that accounts for the transformer’s no-load-watt-losses.
C Meter setting that accounts for the sum of the full-load-VAR-losses from all
sources.
D Meter setting that accounts for the transformer’s no-load-VAR-losses.
E Meter setting that accounts for any “system” losses, proportional to the
uncompensated power.
Configuring the meter to perform loss compensation simply requires the user to
calculate the coefficients A, B, C, D, and E defined above, and enter them in the
appropriate fields in the M650’s webserver interface on the Settings/Input page as
shown in the screen shot below
The sign of the settings A, B, C, D, and E determines whether losses will be added to
or subtracted from the uncompensated measurements in order to determine the
compensated power and energy. To add losses, be sure the settings are all positive.
To subtract losses, be sure the settings are all negative. Settings should always have
the same sign.
Making all of the settings equal to zero turns off loss compensation.
System losses (E) are a fixed percentage, mutually agreed upon between two electric
utilities, about an interchange point that lies on a branched line. As such, E is not a
physical property of any particular line, transformer or the meter, so no further
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