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Power Quality

The European standard EN 50160 describes the main characteristics of the supply voltage at the customer's point of connection in public power supply networks. It specifies the limits that must be respected by the various parameters of the mains voltage under normal operating conditions.
Essentially, the following parameters must be permanently monitored:

  1. Voltage amplitude
  2. Frequency
  3. Symmetry
  4. Flicker
  5. Harmonics

For example, EN50160 allows a tolerance of +-10% of the nominal voltage for voltage deviations, which must be met by 99% of all measured values within a weekly interval. For the remaining 1% within a week, a deviation of +10 and -15% is allowed.
10-minute average values are used to determine the voltage deviation. The specified deviations therefore apply to slow voltage changes.
For the other parameters such as frequency, total harmonic content, individual harmonics, ripple, flicker, etc., the same procedure is followed. However, with different limit values, percentiles, averaging and sometimes other observation intervals.

Power System Disturbances
As a result of mains disturbances, rapid voltage changes usually occur, the measured values of which are determined 2 times per mains period (rms1/2). If the measured value falls within a range of 1% to less than 90% of the nominal voltage, this is called voltage dip. If the measured value of all phases falls below the 1% threshold, there is a supply interruption. Measured values greater than 110% of the nominal voltage are referred to as an overvoltage.
Power disturbances are classified according to their duration and the amplitude reached.

Power Quality Report
Since these power quality thresholds are valid only for the undisturbed operating case, measured values accumulated during a power disturbance must be marked and excluded from the statistical power quality assessment.
The Expert operating software for the EPPE and SHERLOG devices can perform this work automatically on request. It generates fully automated, standard-compliant power quality reports from all measuring points over definable observation periods.
The content of the reports can be customized and, in addition to the standard-compliant power quality verification, also includes information on the number and duration of supply interruptions, voltage dips and swells, including classification according to UNIPEDE, CBEMA, ITIC and SEMI F47.
Also signal fluctuations and statistics on current, active, image and apparent powers, as well as power factor can be included in the report.
The reports can be automatically saved as PDF or DOCX files for later use and sent to network printers and e-mail addresses.

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