SATEC EM920 Operation Manual - Manual (Page 219)

Appendix F EN50160 Evaluation and Recording
EM920 Power Quality and Revenue Meter 219
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 EM920 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.
Method of Evaluation
A temporary overvoltage is classified as one polyphase event
regardless of the shape and of the number of phases affected
(as per 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 rises above
the start threshold on one of the phases to that at which it
becomes lower than the end threshold on all affected phases
including a threshold hysteresis.