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PA-9 Series
Application Guide
NEUTRAL OVERHEATING
Neutral Wires will over heat in 3 phase systems generally when
the 3 phase system is unbalanced or there is an excess of
Harmonic Triplens. (Harmonics divisible by 3 / Zero Sequence
Harmonics) Zero sequence harmonics do not cancel out, instead
they add together on the neutral. This can cause neutral currents
that exceed the line current. This is commonly seen in single phase
systems that are dedicated to electronic loads.
Common Causes of Overheated Neutrals include the following.
 Shared Neutrals
 Improper or Inadequate Wiring
 High Source Impedance
 SCR / Rectifier & Notching
 Harmonics.
Harmonic Waveform Example:
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
Swell Limit See Below
Sub-cycle Disabled
Sub-Cycle Limit NA
This configuration is designed
to focus on Harmonic
detection. Note that the
waveform capture is set to
THD. The time interval
between waveform captures
should be set to the same time
interval of the storage
interval. The length of this
interval should be determined
by how long the unit is
intended to record.
The unit will now capture
waveforms every storage
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_15_AG_En_V02
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Feature Status Notes
THD Limit Enable Voltage Only
THD Limit See Below
Enable Waveform Capture Enabled
Waveform Trigger THD
Pre-Triggers NA
Post Triggers 5
Waveform Limit Disabled
Expected Number of Events NA
Memory Mode Stop When Full
Default Frequency 50 or 60Hz as Required
Enable Frequency Recording Enabled
MIN, AVG, MAX AVG
interval which will allow the
software to perform THD
and Harmonic trending. This
is the data required to find
steady state harmonic
problems.
IEEE Recommendations: For a 120V / 60Hz Load
per IEEE1159.
Sag Limit = 108V (10% of Nominal)
Swell Limit = 126V (5% of Nominal)
Voltage THD Limit = 5%
European Recommendations: For a 230V / 50Hz Load
per EN50160.
Sag Limit = 207V (10% of Nominal)
Swell Limit = 253V (10% of Nominal)
Voltage THD Limit = 8%
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