E-Mon E-PS-A-RTU-N - Manual (Page 90)

Chapter 4 Power
S O F T W A R E E N 5 0 1 6 0 E V A L U A T I O N A N D
R E C O R D I N G
90 PowerSmart+ Advanced Power Quality Meter
The Plt compliance limit can be changed in the meter 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 meter via the EN50160 PQ Recorder
setup.
Statistical Results
The PowerSmart+ Advanced PQM 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 E.
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 a duration
less than 1 s and a depth less than 60%.
Voltage Interruptions
Voltage interruptions correspond to temporary loss of supply voltage on all phases lasting
less than or equal to 3 minutes in the event of short interruptions, and more than 3 minutes
for long interruptions.
Method of Evaluation
The voltage interruption is detected when the voltages on all phases fall below the
interruption threshold (as per IEC 61000-4-30) specified by the EN50160 at a level of
1%Un. The interruption threshold can be changed in the meter via the EN50160 PQ
Recorder setup.
The basic voltage measurement is one-cycle RMS voltage updated each half-cycle.
Statistical Survey
The PowerSmart+ Advanced PQM provides the statistical evaluation of voltage
interruptions using the classification recommended by Eurelectric’s Measurement guide for
voltage characteristics.
Interruptions are classified by duration as shown in Appendix E.
Indicative Values
Under normal operating conditions the expected number of short voltage interruptions in a
year may be from up to a few tens to up to several hundreds. Short interruptions generally
last less than a few seconds.
The annual frequency of long interruptions may be less than 10 or up to 50 depending on
the area.
Temporary Overvoltages
Temporary overvoltages are sudden rises of the voltage RMS value of more than 110% of
nominal voltage. Temporary overvoltages may last between 10 milliseconds and one
minute.