Insulation Tester

Insulation Tester

Is your insulation dangerous? Insulation testers use a high voltage and low current to test the resistance of wires, motor windings, and insulation. They can determine if there is any arcing or faulty insulation that can lead to electrical shock or an electrical fire. RAAH International testers are perfect for monitoring machine health and improving preventative maintenance efforts.

What equipment requires testing?

It’s important to know what equipment will require insulation resistance testing and the best way to test for it. One piece of information that is key is the nominal voltage found on the nameplate of your equipment. So make a list, including the nominal voltage and the approximate number of insulation resistance tests you plan to conduct annually. Next, take into account the following factors when choosing a tester:

What Are the Electrical Requirements for Insulation Testers?

You need to make sure your test voltage is appropriate for the type of equipment you’re testing–depending on the manufacturer’s recommended dc resistance (or the appropriate fig. See table). If there is no specified test voltage, use the industry’s best standard; this should be used as a last resort and not as a replacement for specific input data. Industry-standard is different for testers depending on what voltage they provide. Some may only provide up to 1000 V dc, while others may supply 4000 V dc or more.


Our digital insulation resistance testers provide noise-free, reliable measurements of the insulation resistance. Our testers are designed to be easy to use, safe, and without gimmicks. Our testers are used for insulation troubleshooting, commissioning, and preventive maintenance applications in electrical motors, generators, cables, and switchgear.

Why Use an Insulation Tester?

Avoid downtimes

Equipment that becomes insulated means increased equipment downtime and repairs.

Insulation resistance testing with our Insulation Testers allows you to identify changes in equipment before they become big problems.

Better equipment management

Insulation testers have one of the most important job descriptions in the electrical wiring and plant equipment management industries.

Easy application

With years of experience as a field instrument handler, RAAH International offers the most expertly engineered models for insulation testers that are incredibly easy to use.


You’ll find fast response and excellent visibility on our digital models, and this line includes models that can measure the insulation resistance for photovoltaic cells, too.

Specialized use

The insulation tester can perform three different types of insulation resistance tests, short-time spot reading, time-resistance, and dielectric absorption ratio. Each test has its particular use, with results that vary.

Available Models Based on Function

Short-Time or Spot-Reading Test

Our Insulation Testers are used for short-time or spot reading. You can complete the test by simply connecting a tester across the insulation that you’re testing. It is then to be operated for 60 seconds while remembering the effects of temperature, humidity, and the condition of the insulation on the reading.

Time-Resistance Method

This time-resistance method can be used without considering the temperature. Instead, this method is based on the insulation’s absorption properties. During this test, the insulation resistance will change according to time, and repeated readings must show an increase in resistance for good insulation.

Dielectric Absorption Ratio

A dielectric absorption ratio is a type of test that measures the insulation of electrical connections in switches, control panels, and high-voltage equipment. Some people may find it difficult to take readings every 30 seconds; however, using a Megger tester will allow you to take readings at the 30-second interval and at the 60-second interval.

Safety & Insulation Testing

When testing and troubleshooting a safety-sensitive circuit, it’s important to be aware of a few things.

  • 1. First, the insulation resistance tester must never be connected to an energized circuit. The device will produce excessive dc voltages, which can destroy electronic circuits.
  • 2. Connecting the insulation resistance tester to power supplies, PLCs, VSDs, UPS systems, battery chargers, or other solid-state devices will result in voltage overloads.
  • 3. Some insulation resistance testers offer a built-in type of warning system that indicates when voltage is on the line.
  • 4. Before you can use a test tool like an insulation resistance tester, it should be rated for its application and compatible with the environment in which it will be used.
  • 5. The insulation resistance tester should also have been tested by one of our Nationally Recognized Testing Laboratories.
  • 6. If it is also a meter, it should have been appropriately categorized and its leads rated and tested.

Contact Us

For more information or to place an order, get in touch with us today.