SATEC PM175 Manual - Manual (Page 97)

‎Chapter 4 PAS Application Software EN50160 Evaluation and Recording
Series PM175 Powermeters 97
The PQ recorder is programmable to trigger the waveform
recorder to record the fault waveforms before, during and after
the PQ event for detailed event analysis.
Methods of Evaluation
This section describes methods used by the PM175 for
evaluating supply voltage characteristics to ensure compliance
with the standard.
Frequency Variations
Method of Evaluation
The basic frequency measurement is the mean value of the
frequency over fixed time intervals of 10 seconds under
normal operating conditions.
A frequency variation is not evaluated if the supply voltage
crosses a voltage tolerance limit (
 15% Un).
Target Values
The ranges of frequency variations given in the EN50160 are:
50Hz  1% for 95% of a week
50Hz  1% for 99.5% of a year
50Hz+4/-6% for 100% of the time
The same limits are used for 60Hz systems. The frequency
compliance limit can be programmed in the meter in percent of
the nominal power frequency via the EN50160 PQ Recorder
setup.
Supply Voltage Variations
This characteristic defines slow variations of steady state
supply voltage magnitude.
Method of Evaluation
The basic supply voltage magnitude measurement is the RMS
value of the steady state voltage over a period of 10 minutes
under normal operating conditions.
A voltage variation is not evaluated if the supply voltage
crosses a voltage tolerance limit (
 15% Un).
Target Values
The range of voltage variations given in the EN50160 is:
 10% Un for 95% of a week
The supply voltage compliance limit can be changed in the
meter via the EN50160 PQ Recorder setup.
Rapid Voltage Changes
Rapid voltage changes are sudden but relatively weak voltage
variations between two steady state voltage levels.
Method of Evaluation
Evaluation of rapid voltage changes is made on an hourly
basis. The RMS voltage is evaluated over 3-second time
integration intervals. The meter establishes the maximum
difference of the RMS voltage between two intervals selected
from three 3-second consecutive intervals and compares it
with the target compliance limit.