Demand Values; Frequency Measurements; Other Measurements; Measurement Setup - GE MiCOM P747 Agile Technical Manual

MiCOM P747
Measurement Mode
3
The device also calculates the per-phase and three-phase power factors.
These power values are also used to increment the total real and reactive energy measurements. Separate
energy measurements are maintained for the total exported and imported energy. The energy
measurements are incremented up to maximum values of 1000 GWhr or 1000 GVARhr at which point they
will reset to zero, it is also possible to reset these values using the menu or remote interfaces using the
Reset demand cell.
These measurements are contained in the MEASUREMENTS 2 column.
4.1.4

DEMAND VALUES

The device produces fixed, rolling and peak demand values. It is possible to reset these quantities using the
Reset demand cell.
The fixed demand value is the average value of a quantity over the specified interval. Values are produced
for three phase real and reactive power. The fixed demand values displayed are those for the previous
interval. The values are updated at the end of the fixed demand period according to the Fix Dem Period
setting in the MEASURE'T SETUP column.
The rolling demand values are similar to the fixed demand values, the difference being that a sliding window
is used. The rolling demand window consists of a number of smaller sub-periods. The resolution of the
sliding window is the sub-period length, with the displayed values being updated at the end of each of the
sub-periods according to the Roll Sub Period setting in the MEASURE'T SETUP column.
Peak demand values are produced for each phase current and the real and reactive power quantities. These
display the maximum value of the measured quantity since the last reset of the demand values.
These measurements are contained in the MEASUREMENTS 2 column.
4.1.5

FREQUENCY MEASUREMENTS

The device produces a range of frequency statistics and measurements relating to the Frequency Protection
function. These include Check synchronisation and Slip frequency measurements found in the
MEASUREMENTS 1 column, Rate of Change of Frequency measurements found in the MEASUREMENTS
3 column, and Frequency Protection statistics found in the FREQ STAT column.
The device produces the slip frequency measurement by measuring the rate of change of phase angle
between the bus and line voltages, over a one-cycle period. The slip frequency measurement assumes the
bus voltage to be the reference phasor.
4.1.6

OTHER MEASUREMENTS

Depending on the model, the device produces a range of other measurements such as thermal
measurements.
These measurements are contained in the MEASUREMENTS 3 column.
4.2

MEASUREMENT SETUP

You can define the way measurements are set up and displayed using the MEASURE'T SETUP column, as
shown below:
P747-TM-EN-1
P747-TM-EN-1.1
Parameter
Export Power
Import Power
Lagging Vars
Leading VArs
Chapter 6 - Monitoring and Control
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