PD Detector Monitoring helps prevent Medium Voltage equipment outages.

You’ve heard us say it before, we truly believe that EVERY outage is preventable. All it takes is a little bit of time, money and effort. One of the number one preventable outages or failures of Medium Voltage equipment is the failure of the insulation system. Insulation failures typically show up months or even years in advance as partial discharge – a minor break down in the insulation system that emits various forms of energy shown in either light, sound and/or TEV or transient earth voltage. Future failures show in milliseconds worth of energy that can be detected with the PD Detector test.

The Partial Discharge or PD monitor provides ultrasonic, UHF radio frequencies and TEV. These 3 pieces of information allow us to determine problems related to partial discharge.

Bus Work Damage due to PD


Customers often tell us they don’t have time to take equipment down for routine maintenance. However, the PD Detector is portable and can survey even large facilities in a day. During the partial discharge detection test, the Power & Generation Testing, Inc. (PGTI) team will “listen” for acoustic and UHF evidence of PD as well as use the capacitive coupled portion of the test equipment to detect TEV. This provides us a representative sample of what is going on inside that gray box (because we understand, you just can’t open these everyday!)

Recently, the PGTI team went through an entire facility, surveying over 100 pieces of equipment. When we found a problem with one piece of failing equipment, we were able to focus on maintenance of that one piece of out of hundreds. Our team cleans, inspects, repairs and will continue to monitor the Medium Voltage equipment overtime.

Since PD is not always present and can vary based on atmospheric conditions, a program of routine inspections will yield the best results. The PD Detector test is most valuable when done quarterly or even on a monthly basis. Routine inspections detect problems before they become nightmares.

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