Exam Question
(a) Explain the working of a Megger with the aid of its internal circuit. (12)
(b) What safety measures are taken while using a Megger? (4)
Class 4 (4th Engineer)
MET
📅 Mar 2025
Reference Answer
### (a) Explanation of the Working of a Megger with its Internal Circuit
A Megger, or insulation resistance tester, is a crucial diagnostic tool for marine engineers to assess the integrity of electrical insulation in equipment such as motors, generators, cables, and switchgear. Its primary function is to apply a high DC voltage to an insulation system and measure the resulting leakage current, thereby calculating the insulation resistance. A high insulation resistance indicates good health, while a low resistance suggests deterioration, moisture ingress, or contamination, which could lead to electrical faults, equipment damage, or safety hazards.
#### Internal Circuit (Traditional Hand-Cranked Megger):
Adhering to the principle of describing legacy systems, the traditional Megger utilizes a hand-cranked DC generator and a direct-reading ohmmeter based on the moving coil principle. Its internal circuit comprises two main sections:
A Megger, or insulation resistance tester, is a crucial diagnostic tool for marine engineers to assess the integrity of electrical insulation in equipment such as motors, generators, cables, and switchgear. Its primary function is to apply a high DC voltage to an insulation system and measure the resulting leakage current, thereby calculating the insulation resistance. A high insulation resistance indicates good health, while a low resistance suggests deterioration, moisture ingress, or contamination, which could lead to electrical faults, equipment damage, or safety hazards.
#### Internal Circuit (Traditional Hand-Cranked Megger):
Adhering to the principle of describing legacy systems, the traditional Megger utilizes a hand-cranked DC generator and a direct-reading ohmmeter based on the moving coil principle. Its internal circuit comprises two main sections:
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