Insulation resistance test is used to measure the whole resistance between any two points which are separated through electrical insulation. This test is also known as the megger test.
Once an electric current is supplied throughout a conducting wire to reach the destination but due to some reasons, there is a loss in electric current along the way. Thus we need to perform the insulation testing to verify if there is any current leakage because this leakage could be very harmful.
The insulation resistance test principle is to apply the voltage to measure the steady-state leakage current and after that divide the voltage by the current (R = V/I). If the IR meets otherwise beats the necessary value, then the IR test is successful.
To perform an insulation resistance test, you have to verify the cable is detached from any devices and ensure that no eddy current within the device through earthing it. The instrument must be in normal working temperature as resistance is related to temperature.
Make sure that both ends of the cable are separated from each other. Now connect the two terminals of megger to conductors which have to be tested. If the reading displays infinity then the insulation of the conductor is good
Different ranges of Insulation Tester are available in the Market. Rishabh and Sonel are some of the popular brands in Nepal. E.store Pvt. Ltd. is selling Rish Insu-10 model of Rishabh's Insulation Tester and MIC-5001 model of Sonel's Insulation Resistance Meter through estore.com.np. You can go through the link
https://www.estore.com.np/category/11/insulation-resistance-tester