Insulation resistance test (IR Test) standard operating procedure (SOP)

                                             

What is insulation resistance (IR) test

An insulation resistance (IR) test measures the total resistance between any two points separated by electrical insulation. The test, therefore, determines how effective the dielectric (insulation) is in resisting the flow of electrical current.

Procedure

1. Use a megger to measure insulation resistance.

2. Insulation resistance is measured routinely on all types of electrical cables.

3. Measure insulation resistance under direct voltage (DC) of 50, 100, 250, 500, 1000 V.

4. Insulation resistance is measured in mega ohms.

5. All electric appliances under IR Test (Insulation Resistance Test) should be disconnected from the supply.

6. Never use a megger in an explosive environment.

7. Make sure all connections in the test circuit are tight.

8. Make sure that all the equipment are disconnected from the supply and then the test voltage will be applied so that there is no danger to the person conducting the test.

9. Ensure that all switches in the test circuit are off and the cable end is properly marked.

10. Make sure that the other end of conductor does not touch the ground during the test. If this is the case, it may cause an error in the test.

11. The ends of the cables will be kept separate and will also be separated from the supply so that there will be no problem / accident.

12. The Electrical Officer shall instruct the concerned electrician / technician to take all PPEs (personal protective equipment) with him at the time of insulation resistance measurement test and to paste a sign or to have an official stand where to work.

13. Line (or L) terminal has positive or phase wire and is connected to conductor whose resistance we are checking.

14. Earth (or E) is the terminal which is connected to the conductor which is connected to the ground.

15. The GUARD (or G) terminal provides a return circuit that ignores the meter. For example, you are measuring a circuit in which there is a current but you do not want to add it. How to connect this terminal to the circuit is shown in the diagram.