© 2008 Siemens Energy & Automation, Inc. All Rights Reserved
PMCM-9340D-0208 ACCESS 9340 and 9360 Meters
2/2008 Appendix C—EN50160 Evaluation
EN–225
Evaluations During Abnormal Operation
Count of Magnitude of Rapid Voltage Changes
The standard does not specify the rate of change of the voltage for
this evaluation. For this evaluation, the ACCESS 9360 counts a
change of ≥ 5% nominal and ≤ 10% nominal from one one-second
meter cycle to the next one-second meter cycle. It counts rapid
voltage decreases and increases separately. The interval for
accumulation of these events is one week.
You can configure the number of allowable events per week in
register 3917. (Default = -32768 = Pass/Fail evaluation disabled.)
Detection and Classification of Supply Voltage Dips
According to EN50160, voltage dips are generally caused by faults in
installations or the electrical utility distribution system. The faults are
unpredictable and frequency varies depending on the type of power
system and where events are monitored.
Under normal operating conditions, the number of voltage dips
expected may be anywhere from less than a hundred to nearly a
thousand. The majority of voltage dips last less than one second with
a depth less than 60%. However, voltage dips of greater depth and
duration can occasionally occur. In some regions, voltage dips with
depths between 10% and 15% of the nominal voltage are common
because of the switching of loads at a customer’s installation.
Supply voltage dips are under-voltage events that last from 10 ms to
1 minute. Magnitudes are the minimum rms values during the event.
Disturbance alarms are used to detect these events in the ACCESS
9360. The standard does not specifically address how to classify
supply voltage dips or how many are allowable. The ACCESS 9360
detects and classifies the dips for each phase voltage as follows:
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