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Power quality
thd and TDD
Your meter can be configured to provide thd (total harmonic distortion using the
total RMS value for the content rather than the fundamental content) and TDD
(total demand distortion, the harmonic current distortion against the maximum
demand of the electrical system).
thd = H
C
/ RMS *100%
TDD = H
C
/ Demand
Max
*100%
See the ION Reference , available from www.usa.siemens.com/pds, for details
about the Harmonics Measurement module.
Phasors
Phasors are used to represent the voltage and current magnitude and angles.
The length of the lines in the phasor diagram represent the relative magnitude of
the voltages with respect to the other phase voltages, and the currents with
respect to the other phase currents. All angles are measured with respect to the
Va/V1 phase. The Va/V1 phasor is fixed to the right-hand horizontal axis (positive
x-axis). Positive angles are measured counterclockwise.
Measured values are provided for the magnitude and relative angle for each
voltage and current phase.
Delta vector diagrams can be configured to display two different ways:
• Instrument (voltage vectors appear 60 degrees apart - showing the actual
voltage and current values that the meter is measuring).
• System (voltage vectors appear 120 degrees apart - showing true system
operation including any calculated values).
Phasor information can be used to troubleshoot incorrect connections on the
meter’s voltage and current inputs (for example, switched phase wiring or polarity
errors), if you know how the phasors should be oriented for your power system.
Phasor information can be viewed using ION Setup, the webpages or display.
Power quality standards compliance
Your meter has additional frameworks and settings related to the following power
quality standards.
EN 50160
The EN 50160 framework is composed of numerous ION modules including:
Mains Signaling Evaluation, Harmonics Evaluation, Voltage Harmonics, Flicker,
and more.
Your meter’s framework is pre-configured for a low voltage system.
NOTE: Connect your meter to a UPS to avoid losing EN 50160 data in the
event of a power outage.
See the Power quality: ION meters and EN 50160:2010 technical note for details.
IEC 61000-4-30
IEC 61000-4-30 power quality standard compliance is provided by a variety of ION
modules including: Power Quality Aggregator, Harmonics Measurement,
Disturbance Analyzer, Symmetrical Components, Mains Signaling Evaluation,
Sag/Swell and more.
See the IEC 61000-4-30 compliance and ION meters technical note for details.
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