Name
Unit
Range
Step
Description
Maximum
harmonics value
("UxMaxH")
V
0.00…100000.00 0.01
Displays the maximum harmonics value of the selected voltage
input Ux.
Fundamental
frequency
("Ux Fund")
V
0.00…100000.00 0.01
Displays the voltage value of the fundamental frequency value
(RMS) of the selected voltage input Ux.
Ux harmonics
(2
nd
...31
st
harmonic)
V
0.00...100000.00 0.01
Displays the selected harmonic from the voltage input Ux.
Ux Amplitude THD
%
0.000...100.000
0.001 Amplitude ratio THD voltage. Recognized by IEC.
Ux Power THD
%
0.000...100.000
0.001 Power ratio THD voltage. Recognized by the IEEE.
5.2.3 Power and energy calculation
The relays that are equipped with both a voltage and a current measurement card can calculate power,
and can therefore have power-based protection and monitoring functions (the number of available
functions depends of the relay type). In addition to power calculations, energy magnitudes are also
calculated.
Power is divided into three magnitudes: apparent power (S), active power (P) and reactive power (Q).
Energy measurement calculates magnitudes for active and reactive energy. Energy can flow to the
forward direction (exported) or to the reverse direction (imported).
If a unit has more than one CT measurement module, the user can choose which module's current
measurement is used by the power calculation.
Line
Line-t
-to-ne
o-neutral v
utral volta
oltages a
ges avvailable
ailable
Power is calculated from line-to-neutral voltages and phase currents. If line-to-line voltages are
connected, the relay can calculate line-to-neutral voltages based on the measured zero sequence
voltage. The following equations apply for power calculations with the line-to-neutral mode and the line-
to-line voltage mode (with U0 connected and measured):
Figure. 5.2.3 - 17. Three-phase power (S) calculation.
Figure. 5.2.3 - 18. Three-phase active power (P) calculation.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
42
© Arcteq Relays Ltd
IM00021
Summary of Contents for AQ-M257
Page 1: ...AQ M257 Motor protection IED Instruction manual...
Page 2: ......
