Question

One of the following instruments is used to measure AC current only. Identify that instrument.
1. Megger
2. Multiplexer
3. Permanent Magnet Type ammeter
4. Induction type ammeter

Answer 1

Correct Answer - Option 4 : Induction type ammeter

• The operation of induction type instruments depends on the production of torque due to reaction between two magnetic fluxes having some phase difference or reaction between the flux of an AC magnet and the eddy current induced by this flux.
• Hence, These types of instruments are used only for AC measurements.

 

Type of Measuring Instrument:

Type	Effect	Suitable for	Work as
Moving Iron	Magnetic Effect	DC, AC	Ammeter, Voltmeter
PMMC (Permanent Magnet Moving Coil)	Electro-dynamic Effect	DC	Ammeter, Voltmeter
EMMC (Dynamometer)	Electro-dynamic Effect	DC, AC	Ammeter, Voltmeter, Wattmeter
Induction Type	Electro-Magnetic Induction	AC	Ammeter, Voltmeter, Wattmeter, Energy Meter
Hot Wire	Thermal Effect	DC, AC	Ammeter, Voltmeter
Electrolyte Meter	Chemical Effect	DC	Amp-Hr Meter
Electrostatics Meter	Electrostatics Effect	DC, AC	Voltmeter