Insulation Testers

Insulation testers are electrical measurement test tools used for preventative or predictive maintenance programmes. Also known as megohmmeters (mega insulation 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 digital or analog IR resistance testers from leading brands including Megger, Fluke, Chauvin Arnoux, and of course RS PRO.

We also offer an in-house calibration service. See here for more details on calibration services.

Insulation Tester Types

Insulation testers come in a variety of configurations to suit different needs, here are the key types:

Portable Insulation Testers with Handle

Portable insulation testers are the most common type, offering a compact and handheld design for easy manoeuvrability around a worksite. They are ideal for routine maintenance and troubleshooting tasks.

Bench-Mounted Insulation Testers

These larger insulation test meters are designed for stationary use on a workbench or in a lab environment. They often offer more advanced features and higher test voltages compared to portable models.

Digital Insulation Testers

Modern insulation testers primarily use digital displays for clear and accurate readings of insulation resistance. They often offer additional features like data logging and test result storage. Nowadays, testers usually have an LCD or digital display, but some have the more traditional analogue needle such as the Megger IR tester MIT310A.

Analog Insulation Testers

While less common today, some older models or budget-friendly options may still utilise analog needle displays. These analog insulation testers require some interpretation from the user but can still be effective for basic testing.

High Voltage Insulation Testers

Unlike low voltage insulation testers, these specialised testers are designed for applications requiring higher test voltages, often exceeding 5000V. These are used for testing high-voltage equipment like transformers and transmission lines.

Multi-Function Insulation Testers

These versatile IR testers can perform additional functions beyond insulation resistance measurement, such as continuity testing, ground resistance testing, and even basic voltage and current measurement. They offer a more comprehensive solution for electrical maintenance tasks.

How Do Insulation Resistance Testers Work?

You can test the integrity of insulation by measuring its resistance to current flow across it. Here’s a simplified work process:

Testers will use high voltage low current DC (Direct Current) charge to measure the resistance, typically ranging from 250V to 10,000V depending on the tester and application. Importantly, the current used is very low, designed for measurement purposes without causing damage to the insulation itself.
The tester applies this high voltage across the insulation being tested, creating a small current flow. It then measures the resistance of the insulation to this current flow, typically displayed in Megaohms (MΩ).
A high insulation resistance reading (in the thousands of MΩ or more) indicates good insulation health, meaning very little current is escaping through the insulation. Conversely, a low reading (potentially in the tens or hundreds of MΩ or lower) suggests potential deterioration or damage in the insulation, as a significant amount of current may be leaking through and along the insulation.

What is the Purpose of Insulation Testing?

Testing with an insulation resistance test meter can help you determine whether the insulation is performing at an effective and safe level. 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.

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.

Advantages of Insulation Testers

Insulation testers provide noise-free, reliable results.
They are safe and easy to use.
They are ideal for troubleshooting, commissioning, and preventative maintenance applications.
They save time and money on repairs and replacements down the line.
You can prevent electrical leakage and potential shock hazards.
Modern IR tester models have more than basic functions, include perform continuity testing, ground resistance testing, and even basic voltage and current measurements.
Help you achieve code and safety regulations compliance with periodic insulation resistance testing.

How to Order a Digital Insulation Tester from RS?

Ready to order? No matter if you’re looking for Megger insulation resistance testers or other brands like Fluke, Chauvin Arnoux, Kyoritsu, RS PRO and more, you can order from RS New Zealand, a trusted supplier and distributor of insulation testers in NZ.

Explore the range of digital and analog insulation testers available at RS NZ, and find the ideal product for your requirements. Each of our listings provides comprehensive descriptions and datasheets to guide your decision-making. You can easily filter products by model number, minimum/maximum test voltage, display type, and other specifications to pinpoint exactly what you need.