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
📅 May 2023
Reference Answer
### (a) Explanation of the Working of a Megger with Aid of its Internal Circuit (12 Marks)
A Megger, short for Megaohm-meter, is a specialized portable electrical instrument used for measuring high electrical insulation resistance. Its primary purpose is to test the integrity of electrical insulation in cables, motors, generators, and other electrical equipment, providing an indication of their operational safety and reliability. A healthy insulation system will exhibit very high resistance (typically in Megaohms or Gigaohms), whereas a degraded or damaged insulation will show significantly lower resistance.
#### 1. Principle of Operation
The fundamental principle behind the Megger's operation is Ohm's Law, $$ R = \frac{V}{I} $$. It works by applying a high DC voltage (typically 500V, 1000V, 2500V, or 5000V) across the insulation to be tested and then measuring the resulting leakage current. The instrument then calculates and displays the insulation resistance directly in Megaohms (MΩ).
A Megger, short for Megaohm-meter, is a specialized portable electrical instrument used for measuring high electrical insulation resistance. Its primary purpose is to test the integrity of electrical insulation in cables, motors, generators, and other electrical equipment, providing an indication of their operational safety and reliability. A healthy insulation system will exhibit very high resistance (typically in Megaohms or Gigaohms), whereas a degraded or damaged insulation will show significantly lower resistance.
#### 1. Principle of Operation
The fundamental principle behind the Megger's operation is Ohm's Law, $$ R = \frac{V}{I} $$. It works by applying a high DC voltage (typically 500V, 1000V, 2500V, or 5000V) across the insulation to be tested and then measuring the resulting leakage current. The instrument then calculates and displays the insulation resistance directly in Megaohms (MΩ).
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