MTR-3
Installation Instructions
DEIF A/S
Page 28 of 51
Power factor and power angle
Power factor is calculated as quotient of active and apparent power for each phase separately
(cos
ϕ
1
, cos
ϕ
2
, cos
ϕ
3
) and total power angle (cos
ϕ
t
). For correct display of PF via analogue output
and application of the alarm, ePF (extended power factor) is applied. It illustrates power factor
with one value as described in the table below. For a display on the remote display, both of them
have an
equal display function: between −1 and −1 with the icon for inductive or capacitive load.
Load
C
→
←
L
Angle [°]
−
180
−
90
0
+90
+180 (179.99)
PF
−
1
0
1
0
−
1
ePF
−
1
0
1
2
3
Example of analogue output for PF and ePF:
The power angle represents the angle between the first voltage harmonic and the first current
harmonic for each individual phase. The total power angle is calculated from the total active and
reactive power (see equations for total power angle, in chapter 8, “Appendix B: Calculations and
equations on page 36). A positive sign shows inductive load, and a negative sign shows capacitive
load.
Frequency
Network frequency is calculated from time periods of measured voltage. Frequency is an average
of number of periods set in general settings/average interval.
Energy
The energy of each of four energy counters is available.
MD values
Measurements of MD values.
THD − Total Harmonic Distortion
THD is calculated for phase currents, phase and phase-to-phase voltages and is expressed as
percent of high harmonic components regarding RMS value or relative to first harmonic.
The instrument uses a measuring technique of true RMS values that assures exact
measurements with the presence of high harmonics up to 31st harmonic.