Compliance West MegaPulse 2x10s-2.5, Instruction Manual

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Section 1
An Introduction to Impulse Testing with the MegaPulse series tester
The impulse test is designed to simulate impulse surges which occur in everyday life due to
nearby lightning strikes, switching transients, and other high-frequency faults on the power distribution
network. Impulse testing is the fundamental method for empirical verification of the adequacy of
insulation. Other methods of ensuring adequate insulation (AC or DC Dielectric Withstand testing,
measurement of over-surface creepage, through-air clearance, or distance-through-insulation) are all
extrapolated from the results of impulse testing. The impulse test is performed to ensure that the insulation
in question will be able to function properly when subjected to similar impulse surges in the field.
Safety Precautions
The impulse withstand test can generate voltages in excess of 7000 V peak at potentially lethal
current levels. Currents of as little as 5 mA at 120 volts can cause death; the MegaPulse can deliver
currents of more than 100 Amps peak for a very short time duration. The potential for serious injury or
death exists and personnel should be aware when they conduct this test.
Test Personnel
Personnel require special training to conduct the impulse test. They should understand electrical
fundamentals clearly, and be aware that high voltage is adept and creative at completing a path to ground.
Instructions should include a warning against any metal jewelry. Operators should not allow others in the
testing area, especially when tests are being conducted. Organization is to be stressed. The operator
should keep the area free of unused leads and equipment.
Testing Area
The area used for conducting the dielectric withstand test should be as remote as possible from
normal production line activities. Only personnel actually conducting the test should be allowed in the
area, and it should be taped or roped off to preclude casual entry by other employees. In addition, the area
should be marked "WARNING - HIGH VOLTAGE TESTING" or the equivalent to warn others of the
nature of the testing taking place.
The bench being used should be non-conductive, and any exposed metal parts should be tied
together and grounded. If a conductive surface must be used, it should be grounded.
Because of sparking during an impulse test failure, it is not safe to conduct impulse testing in
combustible atmospheres.
It is imperative that a good ground be provided to the MegaPulse tester. Before connecting the
equipment, ensure that the building wiring provides a low-resistance ground. If the MegaPulse tester is
used on a high-resistance grounding circuit, dangerous high voltages may be present to the operator. In
addition, the power to the Testing Area should be provided with an easily reached shutoff switch which
can be actuated by personnel outside the Area if needed.