Question

Megger is used to measure ________.

• A. Low resistance
• B. Earth resistance
• C. Breakdown voltage
• D. High currents

Hint:

In practice, a standard Megger tests electrical insulation (winding to winding or winding to ground), whereas an Earth Megger (Earth Tester) measures the electrical resistance of the grounding electrodes inserted into the earth.

Answer 1

The Correct Option is B

Step 1: Understanding Megger Functionality:
A standard Megger (megohmmeter) is a high-voltage testing device designed specifically to measure high electrical insulation resistance (values in megaohms, $10^6\,\Omega$, or gigaohms).

Step 2: Evaluating the Given Options:
Let's analyze the options based on standard electrical measurements:

• Low resistance: Typically measured using Kelvin's Double Bridge, potentiometer methods, or micro-ohmmeters.
• Earth resistance: Measured using an Earth Tester, which is frequently referred to as an Earth Megger or ground resistance tester in practical field engineering.
• Breakdown voltage: Measured using high-potential (Hi-Pot) insulation testers or dielectric strength test kits.
• High currents: Measured using clamp-on ammeters or current transformers.

Step 3: Conclusion:
Because “high insulation resistance” is not explicitly listed, option (B) Earth resistance is the correct and intended answer since Earth Meggers are standard instruments used in maintenance to measure the grounding system resistance of electrical structures.