Testing of Insulation Resistance of Cable using Megger
Trade: Electrician | Semester: II
Question: Test the insulation resistance of the given electric cable using a Megger.
Introduction
Insulation resistance testing is an important method to check the condition of electrical cables. A Megger is used to measure high resistance and ensure proper insulation between conductors and earth.
Objective
To measure the insulation resistance of a cable using a Megger and determine its condition.
Apparatus Required
- Megger (Insulation Tester)
- Electric cable
- Connecting leads
Working Principle
The Megger generates a high DC voltage and measures the resistance offered by the insulation. Good insulation gives high resistance, while poor insulation gives low resistance.
Procedure
- Disconnect the cable from supply.
- Connect Megger terminals to conductor and earth.
- Rotate the handle (or switch ON digital Megger).
- Note the reading on the scale.
- Repeat for other conductors.
Observation
If the insulation resistance is high (in mega ohms), the cable is in good condition. If low, insulation is faulty.
Precautions
- Ensure cable is not live
- Do not touch terminals during test
- Discharge cable after testing
Result
The insulation resistance of the cable was measured successfully using Megger.