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PA-9 Series
Application Guide
EQUIPMENT TRIPPING OUT
Equipment Tripping Out problems are most associated with
sags and swells. In many industries with critical process loads, even
instantaneous short duration phenomena can cause process
shutdowns requiring hours to re-start. In these facilities, the effect
on the process is the same for a short duration variation as for
long duration phenomena. Transient voltages caused by lightning
or switching operations can result in degradation or immediate
dielectric failure in all classes of equipment.
Common Causes of voltage sags include source voltage changes,
inrush currents as well as inadequate wiring.
Common Causes of voltage swells can include load switching or
utility faults.
Common Causes of transients include lightning, load switching,
capacitor switching as well as loose wiring.
Another Common Cause includes the wrong voltage for
equipment in use coming into the building. These wrong voltages
can include 230volt equipment being fed from 208 volts or vice
versa, 460 volt equipment being fed from 480 volts.
Note: Some 460 volt equipment have over-voltage, under-voltage
and phase lost relays, when 460 volt equipment gets to 10% or
about 506volts it causes an over-voltage trip or alarm. A Utility
voltage can be at the upper limit of 504 volts and when a utility cap
comes on the voltage may go to 508 for less than a cycle and
causing an over-voltage trip.
Note: Open Delta and Closed Delta transformer banks are very
inefficient with no load, so is they are under-sized they become
even more of a problem.
Example of a Sag
Sag
Time
12/22/2004 - 13:00:00 12/22/2004 - 13:19:00 12/22/2004 - 13:38:00 12/22/2004 - 13:57:00 12/22/2004 - 14:16:00
47.00
72.28
97.56
122.84
148.12
Va MIN (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
Swells Enabled
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
waveforms associated with
transients one can determine
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_05_AG_En_V02
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Feature Status Notes
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 - 20
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
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: For Semi conductor manufacturing equipment the
recorded event data can be compared against a SEMI F47 curve
using the MetReport software.
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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