Cewe Prometer 100, Руководство пользователя

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BGX501-943-R01 Prometer 100 User Manual Page 51 of 72
Power transformer compensations
Name
Value to be entered
Copper losses, Total values Active loss as percent of nominal power
Reactive loss as percent of nominal power
Iron losses, Total values Active loss as percent of nominal power
Reactive loss as percent of nominal power
7.15.2 Instrument transformer compensations
To compensate for errors in instrument transformers, their amplitude error in percent and phase angle error in
minutes are configured in the meter. One minute is equal to the angle 1˚/60. The errors can be specified
separately for all voltages and currents. When instrument transformer compensations are used, current and
voltage are affected, as well as all quantities that arise from these: power, energy, etc.
7.15.2.1 2-element meter
When voltage errors are compensated on a 2-element meter, this is done on phase to phase voltages L12, L23
and L31 instead of on phase voltages. Only L12 and L23 are included in the calculation of power and energy.
Compensation of L31 has no significance in this respect. In compensation of current errors for 2-element
meters, only L1 and L3 can be compensated for because they are the only currents measured.
7.15.3 Power transformer losses
Power transformer losses consist of copper and iron losses. They are expressed as percentages of nominal
power. One value is specified for active loss and one for reactive. When compensation of losses is configured,
power, energy, power factor, etc. are affected but not current and voltage.
When copper losses are added per phase, the resulting copper loss is the average of the value.
Calculating loss values
Based on the nominal total power and the measured loss value in watts, a loss value can be calculated as a
percentage of nominal power. It is the loss value that is configured in the meter. Nominal power is calculated
with configured nominal current and voltage.
Nominal power:
3
⋅ ⋅ =
nom nom nom
voltage Line Current Power
Loss value:
100 /
⋅ =
nom
Power Loss value Loss
7.16 Quality of Supply
Power quality encompasses voltage monitoring and harmonics measurement. Harmonics measurement is
described in the section Instant values (pg. 37).
7.16.1 Voltage monitoring
Voltage monitoring monitors the following states: swells (overvoltage), sags (under voltage), unbalance and
interrupts. Monitoring is enabled by checking the check box and configuring limit values for the events. The
occurrence and restoration limits are expressed as percentages of configured nominal voltage.
Example: For an occurrence limit of 110% and a restoration limit of 90%, and the configured nominal primary
voltage of 10 kV, the limits attained are 9 kV and 11 kV.
These events are monitored phase wise every second. For 3-element meters, the average value for phase
voltage is monitored, and for 2-element meters, the average value for phase to phase voltage is monitored.
The states shorter than three seconds are registered by accumulating registers. If the states last longer than
three seconds, they are instead registered in the event log with time stamp and duration. The accumulating
counters and the event log can be read in M-Cubed.