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Lightning Arresters

The need for lightning arrestors varies on industry. They are normally outfitted for higher voltage areas and are categorized by maximum fault current. Depending on the available fault current your power system holds, this will determine whether you have a distribution class, intermediate class, or a station class. Station class lightning arresters are the most expensive, and have the highest ratings due to the heavy duty application.

Device or Equipment Procedure for Maintenance Interval Electrician/Shift
Lightning Arrester Visual Test Each Month Electrician Name
Lightning Arrester Infrared Thermography, connection integrity, and most important ~ Hi-Test Insulation Tester Bi-Annually or after power outage Electrician Name
Lightning Arrester Direct Current Insulation Test, Dielectric Loss, and Power Factor. 5 years
Electrician Names

Troubleshooting Arresters

The visual check is good for checking chipped porcelin or a blown disconnect, but having physical damage sometimes does not prove a damaged arrester. You can have a nuisance tripping but a large portion (over 85%) of insulation failures are caused by moisture invasion.

A reading from a Hi-Test insulation tester will let you know if there is a non-visual insulator failure. This can be done safely under load conditions. It has it's own DC power source that allows a megger of the insulators, independant of the alternating current flowing through the insulators.

Here is an example of the The Hi-Test® IT-4 Insulator Tester. It measures under load, and connects to a hotstick, so you are within a safe range when testing.

There are several ways, and several pieces of equipment that can make your job safer. We understand that downtime is critical for some industries, like Power Utility companies; but remember...ask yourself if what you are doing is out of range of a fault. Always.