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Device description
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– E650 Series 4 – ZMD400AT/CT, ZFD400AT/CT – User Manual
Depending on the metering point in the network, the meter does not only
measure the net energy that is transferred from the power station to the
user but also the line losses (caused by the copper resistance R
Cu
) and the
transformer losses (caused by the iron resistance R
Fe
).
Generator
Meter A
Production
Load
Meter B
Customer
Metering point A
Metering point B
Metering point C
R
Cu
R
Fe
Transmission
Figure 17. Calculation of losses
Line losses are caused by the copper resistance R
Cu
of the transmitting
line. The copper resistance is only effective if there is a load and therefore
current is actually flowing.
On Load Active OLA for line losses of active energy
The transformer losses represent all losses of the transformer. They are
mainly caused by the iron core of the transformer. Transformer losses
(equivalent resistance R
Fe
) are present whenever the transformer is
connected to the network.
No Load Active NLA for transformer losses of active energy
Based on the I
RMS
and U
RMS
values, the microprocessor generates the
following measured quantities:
OLA
On load active. Line (copper) losses of active energy.
OLA = I
2
h x R
Cu
. The value of R
Cu
can be set by parameterisation.
NLA
No load active. Transformer (iron) losses of active energy.
NLA = U
2
h / R
Fe
. The value of R
Fe
can be set by parameterisation.
I
2
h (Cu)
Ampere square hours (with R
Cu
= 1
)
U
2
h (Fe)
Voltage square hours (with R
Fe
1 M
)
It is also possible to track signed losses (±NLA/OLA). If this option is
chosen, NLA and OLA losses are not available any more as these registers
are used for signed losses.
Losses
