Which statement best describes a megger's use?

Which statement best describes a megger's use?

• A. Measures air temperature.
• B. Tests insulation resistance to assess insulation quality.
• C. Measures engine RPM.
• D. Generates radio frequencies.

Answer: (B)

A megger is used to measure insulation resistance to assess insulation quality. It applies a high DC voltage to the insulation between conductors or between a conductor and ground and measures leakage current to determine resistance, usually reported in megohms. The idea is that strong, healthy insulation lets very little leakage current flow, yielding a high resistance, while degraded or damp insulation shows up as a lower resistance value. This test helps ensure electrical equipment like cables, motors, and transformers are safe to operate and less prone to faults caused by insulation failure. The other options don’t involve testing insulation—measuring air temperature, engine RPM, or generating radio frequencies are unrelated to assessing insulation condition.

A megger is used to measure insulation resistance to assess insulation quality. It applies a high DC voltage to the insulation between conductors or between a conductor and ground and measures leakage current to determine resistance, usually reported in megohms. The idea is that strong, healthy insulation lets very little leakage current flow, yielding a high resistance, while degraded or damp insulation shows up as a lower resistance value. This test helps ensure electrical equipment like cables, motors, and transformers are safe to operate and less prone to faults caused by insulation failure. The other options don’t involve testing insulation—measuring air temperature, engine RPM, or generating radio frequencies are unrelated to assessing insulation condition.