Every electric wire in your plant—whether it’s in a motor, generator, cable, switch, transformer, etc.—is carefully covered with some
form of electrical insulation. Insulation is there to protect your electrical assets—resisting current and keeping the current in its path along
the conductor.
The purpose of insulation around a conductor is much like that of a pipe carrying water. Pressure on water from a pump causes flow along the pipe.
If the pipe were to spring a leak, you’d waste water and lose water pressure. With electricity, voltage is like the pump pressure—causing
electricity to flow along the wire. Like a water pipe, there is some resistance to flow along the wire, but it’s much less than it is
through the insulation. The more voltage we have, the more current there will be, and the lower the resistance of the wire, the more
current at the same voltage.
“Good” insulation has a relatively high resistance to current. When your plant electrical system and equipment are new, electrical
insulation should be in great shape. But with normal wear and tear—combined with electrical stresses like mechanical damage and vibration,
plus environmental factors including heat, cold, dirt, oil, vapors, moisture, or humidity—insulation can degrade. As pin holes or cracks
develop, moisture and foreign matter penetrate the insulation’s surface, providing the perfect low resistance path for leakage current.
With regular scheduled maintenance and routine insulation resistance measurements, you can easily check trends towards insulation deterioration. When
checked periodically, electrical equipment typically gives plenty of warning, so you can plan reconditioning before service failure. To learn more
about insulation resistance testing, click here to download our complete guide to insulation testing—A Stitch in Time.
Since its development in 1889, the insulation tester has been synonymous with the Megger name. A hundred years later, and the insulation—
or “Megger test”—is still as relevant as ever. Our top-of-the-line 1, 5, 10, and 15 kV DC insulation resistance testers offer unparalleled
testing capabilities—built-in a tough, yet portable case for on-the-go testing.
See our full line of insulation testers