If the measured insulation value is more than unity, what value should be taken as the maximum working value?

Question

Question

This question was previously asked in

RSMSSB JE Electrical (Diploma) 19 May 2022 Official Paper

Answer 1

Insulation Resistance

Insulation resistance is the resistance offered by an electrical insulation material to the flow of leakage current.
It is a critical parameter in electrical systems to ensure safety, prevent electric shocks, and avoid equipment failures due to insulation breakdown.
It is measured in megaohms (MΩ). A higher value indicates better insulation quality.

Minimum Insulation Resistance Guidelines (Based on Voltage Levels):

System Voltage	Minimum Insulation Resistance
< 1 kV	1 MΩ
1 - 35 kV	(Voltage in kV + 1) MΩ
> 35 kV	100 MΩ or higher

Explanation

If the measured insulation resistance is more than unity (i.e., greater than 1 ohm), the commonly accepted minimum insulation resistance for electrical equipment operating at low voltage (<1 kV) is 1 MΩ.
This is based on industry standards and insulation resistance testing guidelines.