Understanding Insulation Resistance: Properties, Testing & Degradation

Insulation resistance refers to the electrical resistance of a material that's made for insulation. The level of resistance depends on the material that will be affecting the insulation.

Temperature

• Insulation will degrade quickly when exposed to humidity. Additionally, when the temperature is increased, the resistance decreases.

Testing

• A majority of electrical maintenance depends on insulation resistance testing. To test insulation resistance, a voltage is applied to the material and measured.

Purpose

• It's important to perform insulation resistance testing in order to determine the quality of electrical equipment.

Terminology

• When talking about insulation resistance, the term "current" refers to the leakage current. The leakage current is the amount of electricity that escapes from the insulation. This will warm up the insulation and result in slight power loss. The resistant measurement is expressed in megohms.