Insulation testers are electrical measurement test tools used for preventative or predictive maintenance programs. Also known as megohmmeters or Megger testers, they are designed to identify potential equipment failures before they occur. Insulation resistance testers are perfect for testing a wide range of high voltage equipment including switchgear, motors, generators and cables.

RS offer a range of high-quality electrical test tools from leading brands including Megger, Fluke, Chauvin Arnoux, Keysight Technologies, Metrohm, FLIR and of course RS PRO.

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Insulation tester types

Insulation testers are handheld devices but can be portable with a handle or bench mounted. Testers usually have an LCD or digital display, but some have the more traditional analogue needle such as the Megger MIT310A.

How do insulation resistance testers work?

Testing the integrity of insulation requires measuring its resistance to current flow across it. Testers use high voltage low current DC charge to measure the resistance. A high level of resistance means that very little current is escaping through the insulation. Conversely, a low level of resistance indicates a significant amount of current may be leaking through and along the insulation.

What is the purpose of insulation testing?

Ideally, all the electrical current sent along a conductive wire should reach its intended destination. However, you do find that some of it is lost along the way due to various reasons. Wires are insulated with a resistant sheathing to contain the conductivity of the copper or aluminium core, but even with this insulation in place, some of the current still manages to escape. The electricity that leaks out can be detrimental to electrical circuits and machinery.

Testing can help you determine whether the insulation is performing at an effective and safe level. Excessive heat or cold, moisture, vibration, dirt, oil and corrosive vapours can all contribute to deterioration therefore routine testing can identify problems before they result in injury or equipment failure.

Insulation testers provide noise-free, reliable results. They are safe and easy to use and the ideal solution for troubleshooting, commissioning and preventative maintenance applications.