Electrical Measurements Questions and Answers – Megger

This set of Electrical Measurements & Measuring Instruments Multiple Choice Questions & Answers (MCQs) focuses on “Megger”.

1. High resistances are of the order of __________
a) 0.1 Mῼ
b) 10 mῼ
c) 1 kῼ
d) 10 Gῼ
View Answer

Answer: a
Explanation: Resistances of the order of 0.1 Mῼ and above are known as high resistances. Resistance values upto 1 ῼ are known as low resistances. Resistances upto a few kῼ are known as medium resistances.

2. Megger is a ________
a) source of e.m.f
b) source to measure high resistance
c) type of a null detector
d) current carrier
View Answer

Answer: b
Explanation: Megger is a portable instrument to measure high resistances.

3. Megger is also used for ________
a) providing additional e.m.f
b) bridge balance
c) testing insulation resistance
d) controlling the temperature
View Answer

Answer: c
Explanation: A null detector is used to balance the bridge. Additional e.m.f can be provided to a circuit by increasing the magnitude of the voltage source. Megger is used for testing the insulation resistance of cables.


4. Megger works on the principle of ________
a) kirchhoff’s current laws
b) ohm’s law
c) gauss’s law
d) electromagnetic induction
View Answer

Answer: d
Explanation: Ohm’s law is applicable to only purely resistive circuits which are based on the linearity principle. Megger basically works on the principle of electromagnetic induction.

5. The role of the permanent magnet in a megger is to ________
a) provide field
b) provide voltage
c) generate power
d) balance the circuit
View Answer

Answer: a
Explanation: Voltage can be provided by means of an e.m.f source. Power generation occurs when current flows through a circuit. Permanent magnet in a megger is used to provide a field for the generator as well as the ohmmeter.

6. A guard ring is provided in a megger to ________
a) protect the circuit
b) eliminate error
c) reduce current flow
d) limit the temperature rise
View Answer

Answer: b
Explanation: Temperature rise can be prevented by reducing the flow of excessive current through the circuit. The role of a guard ring in a megger is to reduce the errors due to leakage current.

7. The supply to the megger is given by ________
a) ac motor
b) ac generator
c) permanent magnet dc motor
d) dc generator
View Answer

Answer: c
Explanation: Megger works on the principle of electromagnetic induction. Supply can be given through a dc motor. A permanent magnet dc motor driven by hand is used as a source of supply to the megger.

8. The moving element of the ohmmeter in a megger consists of ________
a) 1 coil
b) 4 coils
c) 3 coils
d) 10 coils
View Answer

Answer: c
Explanation: The moving element of an ohmmeter in a megger consists of three coils, namely current or deflection coil, pressure or control coil and compensating coil.

9. The role of the compensating coil in a megger is ________
a) reduce current
b) increase voltage
c) control temperature
d) scaling
View Answer

Answer: d
Explanation: Temperature is controlled by minimising the flow of current through the circuit. Better scaling proportions can be achieved in a megger by making use of a compensating coil.

Sanfoundry Global Education & Learning Series – Electrical Measurements.

To practice all areas of Electrical Measurements, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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