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AST8800 Partial Discharge Detection Option

 Conduct pass/fail partial discharge testing quickly and easily in a manufacturing environment
 Provide customers with high quality wound products
Ensure insulation longevity in variable speed drive applications
 Upgrade existing Windows based AST8800s in the field and maintain Master file compatibility

What is the Partial Discharge Test?Partial Discharge (PD) also known as Corona is a very small electrical discharge caused by the ionization of oxygen in the presence of a high voltage electrical field. The ionized oxygen or ozonechemically reacts with many insulation materials and over a long period of time is corrosive to the insulation causing premature failure in the winding insulation system.

Partial discharge has longbeen a known failure mode in high voltage motors and generators. Motors and generators which pass a high voltage breakdown insulation test will usually fail prematurely if they can not pass a partialdischarge test. In contrast, low voltage motors traditionally do not encounter voltages which generate ozone except in the case of relatively rare line transients. The primary concern with linetransients is breakdown. Line transients are not frequent enough to cause a serious PD failure concern. So testing for the presence of PD in lower voltage motors is usually considered unnecessary.

But,partial discharge has become a major concern in motors operating at nominally low voltages (i.e. under 600 volts) due to the effects of variable speed inverter drive systems. Variable speed drives arenotorious for causing frequent over voltage transients which far exceed the nominal operating voltage. These frequent transients can exceed the Corona Inception Voltage (CIV) and therefore generateozone damaging the insulation of low voltage motors slowly over time. Eventually the insulation will degrade to the point where a hard arc occurs causing a catastrophic insulation failure.

The PD...