SATEC PM180 Operation Manual User Manual
Page 98
Chapter 8 Configuring Recorders
Configuring the EN50160 Power Quality Recorder
96
PM180 Substation Automation Unit
Target Values
The maximum rate of rapid voltage changes in normally once per hour or less. For
voltage variations repeating more than once an hour, amplitude is limited by the
flicker index. The maximum rate of rapid voltage changes in variations per hour can
be changed in the device via the EN50160 Advanced Setup. The target magnitude
limit of rapid voltage changes can be programmed in the device via the EN50160 PQ
Recorder setup.
Under usual operating conditions the magnitude of rapid voltage changes (once per
hour or less) should generally not exceed 5% of nominal voltage in LV networks, and
4% in MV networks. In some circumstances, like in systems where equipment
switching must be carried out to meet supply system or load requirements, it can
reach 10%Un in LV networks, and 6%Un in MV networks.
Flicker
Flicker expresses the visual discomfort caused by repetitive changes of brightness in
lightning subjected to fluctuations of the supply voltage. Flicker is indicated by the
long-term flicker severity parameter Plt, which is evaluated every 2 hours.
Method of Evaluation
The basic flicker measurement is the short-term flicker severity indicator Pst,
evaluated each 10 minutes by instrumentation complying with IEC 61000-4-15. The
indicative long-term flicker severity Plt is evaluated from 12 consecutive Pst values.
For testing purposes, the Pst period can be temporarily changed in the device in the
range of 1 to 10 minutes via the EN50160 Advanced Setup.
Pst values are not classified during intervals when the supply voltage magnitude
exceeds a voltage tolerance limit (
15% Un) or is affected by voltage dips with depth
more than 15% Un.
Target Values
The flicker compliance limit given in the EN50160 is:
Plt
1 for 95% of a week
The Plt compliance limit can be changed in the device via the EN50160 PQ Recorder
setup.
Voltage Dips
A voltage dip is a sudden reduction of the RMS voltage below 90% of the nominal
value, followed by a return to a value higher than 90% of the nominal in a time
varying from 10 ms to 60 s.
Method of Evaluation
A voltage dip is classified as one polyphase event regardless of the shape and of the
number of phases affected (as per Eurelectric’s Application guide to the European
Standard EN 50160, and IEC 61000-4-30). An event can begin on one phase and
end on another phase. The fault magnitude is recorded separately for each phase
involved. The event duration is measured from the instant at which the voltage falls
below the start threshold on one of the phases to that at which it becomes greater
than the end threshold on all affected phases including a threshold hysteresis.
The basic voltage dip measurement is one-cycle RMS voltage updated each half-
cycle.
The voltage dip threshold can be changed in the device via the EN50160 PQ
Recorder setup.
Statistical Results
The PM180 provides the statistical evaluation of voltage dips using the classification
established by UNIPEDE. Dips are classified by residual voltage magnitude and
duration as shown in Appendix D.
Indicative Values
Under normal operating conditions the expected number of voltage dips in a year
may be from up to a few tens to up to one thousand. The majority of voltage dips
have duration less than 1 s and a depth less than 60%.