INTRODUCTION
5
bear in mind it is possible for some sections of the skin to have poor electrical connection
and that they thereby, can become a potential safety hazard in the event of a fault. This is
why isolation of the vehicle during the test is recommended.
Once these safety precautions have been taken and it has been established that the frame
and skin are properly grounded, the operator can proceed with the dielectric test.
Good safety practice dictates labeling of hazards properly. Since high voltage testing can
be hazardous, the work station should be labeled. Naturally, the location of the label
should be carefully selected so that it can be placed in a location that will do the most
good.
In some cases, this may be on the test instrument itself, and in others, it may be in a
location directly in front of the operator, somewhat removed from the instrument.
In addition to instrument labeling, we are supplying labels that you should apply in
accordance with the above suggestions. If you need a couple more, please let us know...
we will gladly supply them. If you need a large quantity, these are available at a nominal
price.
A final word about high voltage testers: Generally, commercial high voltage test
equipment is not in itself hazardous. The hazards come about when the equipment is
improperly used. These testers, when used properly and in a safe manner, can be a check
on the quality and reliability of your product. If used incorrectly and without proper
consideration for safety, they represent a hazard for both operating personnel and casual
bystanders. We strongly recommend proper training for all personnel involved in testing.
High Voltage Testing
High Voltage Testing has historically been the most misunderstood, misapplied,
misinterpreted inspection function in the average factory. Some manufacturers have
looked upon the High Voltage Dielectric Withstand test or Hipot test as it is more
commonly known, as an extra operation that must be performed to satisfy some agency
requirement. Though many times the high voltage test is simply a safety measure, its value
in quality control should not be overlooked.
First and foremost, the hipot test is done to ensure the safety of customers by detecting
"grounded" or "shorted" products. By applying a high voltage between "live" current
carrying parts of the product and the framework which is normally supposed to be "dead,"
or well insulated from the "live" parts, the product is "proof tested" against grounds or
shorts which at the least might cause inconvenience and at the most can cause fire or
injury. During the hipot test, all insulation is abnormally stressed for the duration of the
test. Additionally, it is possible to detect "potential" shorts. Consider there is a bare
conductor about .015" from the frame. In the factory, the product is clean and new, but
after a year or two of service, contaminants, dust, and moisture may cause this gap to
bridge at line voltage resulting in a shock hazard to the consumer.
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