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© 2011 Schneider Electric. All Rights Reserved.
63230-500-225A2 PowerLogic
TM
Series 800 Power Meter
3/2011 Chapter 4—Metering Capabilities
37
Power Analysis Values
The power meter provides a number of power analysis values that can be used to detect
power quality problems, diagnose wiring problems, and more. Table 4–6 on page 38
summarizes the power analysis values.
• THD. Total Harmonic Distortion (THD) is a quick measure of the total distortion present
in a waveform and is the ratio of harmonic content to the fundamental. It provides a
general indication of the “quality” of a waveform. THD is calculated for both voltage and
current. The power meter uses the following equation to calculate THD, where H is the
harmonic distortion:
• thd. An alternate method for calculating Total Harmonic Distortion, used widely in
Europe. It considers the total harmonic current and the total rms content rather than
fundamental content in the calculation. The power meter calculates thd for both voltage
and current. The power meter uses the following equation to calculate THD, where H is
the harmonic distortion:
• Displacement Power Factor. Power factor (PF) represents the degree to which
voltage and current coming into a load are out of phase. Displacement power factor is
based on the angle between the fundamental components of current and voltage.
• Harmonic Values. Harmonics can reduce the capacity of the power system. The power
meter determines the individual per-phase harmonic magnitudes and angles for all
currents and voltages through the:
— 31st harmonic (PM810 with PM810Log, and PM820) or
— 63rd harmonic (PM850, PM870)
The harmonic magnitudes can be formatted as either a percentage of the fundamental
(default), a percentage of the rms value, or the actual rms value. Refer to “Operation
with PQ Advanced Enabled” on page 99 for information on how to configure harmonic
calculations.
Table 4–5: Energy-per-shift recorded values
Quantity Register Number(s) Description
Shift Start Time
• 1st shift: 16171
• 2nd shift: 16172
• 3rd shift: 16173
For each shift, enter the minutes from
midnight at which the shift starts.
Defaults:
1st shift = 420 minutes (7:00 am)
2nd shift = 900 minutes (3:00 pm)
3rd shift = 1380 minutes (11:00 pm)
Cost per kWHr
• 1st shift: 16174
• 2nd shift: 16175
• 3rd shift: 16176
Enter the cost per kWHr for each shift.
Monetary Scale Factor 16177
The scale factor multiplied by the
monetary units to determine the
energy cost.
Values: -3 to 3
Default: 0
++
H
2
2
H
3
2
H
4
2
+
x
100%
THD =
H
1
++
H
2
2
H
3
2
H
4
2
Total rms
+
x
100%
thd =