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PA-9 Series
Application Guide
COMPONENT FAILURES
Component Failures: When referring to component failures we
are referring to fuses blowing, surge protectors failing, automatic
transfer switch failures, cables switch gear, CT’s or PT’s etc. The
failure of these components can be due to transients. Transient
voltages caused by lightning or switching operations can result in
degradation or immediate dielectric failure in all classes of
equipment. High magnitude and fast rise time contribute to
insulation breakdown in electrical equipment like rotating
machinery, transformers, capacitors, cables, CT’s, PT’s and
switchgear. Repeated lower magnitude application of transients can
cause slow degradation and eventual insulation failure, decreasing
equipment mean time between failures.
Another cause of these failures can be voltage swells. An
increase in voltage applied to equipment above its nominal rating
may cause failure of the components depending upon the
frequency of occurrence. Electronic devices, including adjustable
speed drives, computers and electronic controllers may show
immediate failure modes during these conditions. However,
transformers, cable, bus, switchgear, CTs, PTs and rotating
machinery may suffer reduced equipment life over time. A
temporary increase in voltage on some protective relays may result
in unwanted operations while others will not be affected. Frequent
voltage swells on a capacitor bank can cause the individual cans to
bulge while output is increased from the bank. The visible light
output from some lighting devices may be increased during a
temporary swell. Clamping type surge protective devices (varistors
or silicon avalanche diodes) may be destroyed by swells exceeding
their MCOV rating.
Common Causes: Some common causes of transients include
lightning, load Switching, capacitor switching or loose
wiring/arcing. Some common sources of Swells include source
voltage variations and loads dropping out.
Picture Below shows an example of an RMS voltage swell.
Swell
Time
06/19/2000 - 07:42:32 06/19/2000 - 07:42:36 06/19/2000 - 07:42:41 06/19/2000 - 07:42:45 06/19/2000 - 07:42:50
60.00
97.50
135.00
172.50
210.00
VPHA MAX (Volts)
PA-9 Configuration
Feature Status Notes
Enable Power Calculations Enable (Select correct configuration)
Enable RMS Recording Enable
MIN, RMS and MAX MIN, RMS and MAX
Clock Hour Orientation Enabled
Enable Flicker Recording Disabled
Hysteresis 2%
Sags Enabled
Sag Limit See Below
This configuration is designed to
capture out of limit events. It
focuses on sub-cycle, sag and swell
events.
In this configuration the waveform
capture is set to Exceedance. This
will allow the unit to capture a
waveform every time there is an
out of limit event. By analyzing the
PA-9
Application Guide
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ISO STATEMENT
Registered to ISO 9001:1994 Reg no. Q 09250
Registered to ISO 14001 Reg no. EMS 61597
PA9_14_AG_En_V02
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Feature Status Notes
Swells Enabled
Swell Limit See Below
Sub-cycle Enabled
Sub-Cycle Limit See Below
THD Limit Disabled
THD Limit NA
Enable Waveform Capture Enabled
Waveform Trigger Event Trigger
Pre-Triggers 2
Post Triggers 5 - 10
Waveform Limit Enabled
Expected Number of Events 300
Memory Mode Stop When Full
Default Frequency 50 or 60Hz as Required
Enable Frequency Recording Enabled
MIN, AVG, MAX AVG
waveforms associated with
transients one can determine
whether the transient is due to
lightning or capacitor switching.
Also note that waveform limit is
enabled and set to 200. This will
limit the number of waveforms
captured to 200. This is done so
that the unit’s memory does not fill
prematurely in the case of a large
amount of events in a small period
of time.
IEEE Recommendations: For a 120V / 60Hz Load
per IEEE1159.
Sag Limit = 108V (10% of Nominal)
Swell Limit = 126V (5% of Nominal)
Sub-cycle = 200V (Approx 2 times Phase to Neutral)
European Recommendations: For a 230V / 50Hz Load
per EN50160.
Sag Limit = 207V (10% of Nominal)
Swell Limit = 253V (10% of Nominal)
Sub-cycle = None Provided
NOTE: If equipment is tripping out due to over voltages it may
be advantageous to set the sub-cycle limit to approximately 25% of
nominal. (Often sensitive electronic equipment will trip out at
transient over-voltages of no more than 115-120% of nominal.)
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