The Motwane IT-51 is a microprocessor based digital insulation tester designed for testing various types of electrical apparatus like transformers, switchgear, motors, generators, cables, and substation products. IT-51 has a digital display and an analog for arc display. It automatically performs IR Test and Polarization Index by selecting modes. IT-51 has a large LCD white backlight display that shows leakage current in scrolling form along with its IR value and PI value.

Insulation Resistance Test: The IR test is an acceptance test which is important for future comparative purposes. It helps to determine the suitability of the electrical apparatus for energizing or for the application of the high-potential (hi-pot) test. The IR test must attain successful completion to validate the factory warranty. It must be conducted immediately before energizing the electrical apparatus or  before commencing the high potential test.

Polarization Index Test: This is an extension of the IR test. In this test, two IR measurements are considered where the first reading is taken at 1 min and the second reading is taken at 10 mins. Then the ratio of the 10 min reading is compared to a 1 min reading which is then calculated to give the PI dielectric absorption value. The PI of winding-to-winding and winding-to-ground is determined. A PI value of below 2 is indicative of insulation deterioration and should be investigated further.

IT-51 is a lightweight instrument that can be easily moved around for electrical testing. It has rechargeable battery operation along with an AC mains provision for battery charging. It also has an ingress protection of IP54. The device has automatic capacitive loads discharged at the end of the test.