Compliance West MegaPulse D5-PF, Instruction Manual

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3
Using the MegaPulse PF Impulse Tester
The impulse test involves high voltage and caution should be exercised when using the tester. The
RETURN
lead is referenced to building ground when properly connected. However, both the OUTPUT and RETURN leads
must always be treated as Hazardous whenever the power switch of the MegaPulse is in the ON position.
The MegaPulse impulse tester generates the impulse waveform only; it does not determine Passing or Failing
results. It is the operator’s responsibility to monitor the output waveform and determine Passing or Failing results. In
monitoring the impulse waveform, consider the following points: The Impulse waveform is high voltage and high
frequency (short duration). Always ensure that the measuring instrument (usually an oscilloscope with a high-voltage
probe) is rated for the voltage involved, and that the frequency response of the instrument and probe can measure the
output waveform of the MegaPulse Impulse Tester. A measuring instrument or probe with a low frequency response
will result in erroneous readings that could be misread.
CAUTION
High voltage generated by the MegaPulse tester is exposed during this test. A risk of shock exists.
Exercise care when using the MegaPulse unit.
Pressing the POLARITY switch on the front panel can change the polarity of the output waveform. The
polarity is Normal when the NOR indicator is lit. In this case, the high voltage will appear on the OUTPUT as a
positive pulse relative to the RETURN jack. When the polarity switch is in the Reverse position ( REV indicator is
lit), the high voltage will appear on the OUTPUT as a negative pulse relative to the RETURN jack. The polarity
switch only operates when the CHARGE LED is lit, i.e. the output is not charged.
Note that the voltage meter may indicate that some residual voltage is present on the main storage capacitor, even
when the tester is first turned ON. This is due to inherent charging of the internal capacitors. Pressing the TRIGGER
switch will discharge the capacitors (Be sure not to touch the output and return leads when pressing the trigger switch).
Note that the peak amplitude of the measured output waveform is proportional to the voltage that is read on the
front panel of the MegaPulse, but it will always be somewhat lower. This is because the meter on the MegaPulse is
measuring the voltage on the main impulse storage capacitor. This voltage will intentionally dissipate to some extent
before reaching the output leads. Therefore, it is important to measure the peak amplitude of the output waveform,
and adjust the output of the MegaPulse accordingly.