Difference Between Moving Iron & Moving Coil Instrument

One of the significant difference between the moving iron and moving coil instrument is that in moving iron instrument, the soft iron system is used for measuring mechanism. Whereas in moving coil instrument the conductor coil is used for DC measurement. The other differences between the moving iron and moving coil instrument are shown below in the comparison chart.

Content: Moving Iron Vs Moving Coil

  1. Comparison Chart
  2. Definition
  3. Key Differences
  4. Conclusion

Comparison Chart

Basis for Comparison Moving Iron Instrument Moving Coil Instrument
DefinitionIn moving iron instrument the soft iron is used for moving mechanism.In moving coil instrument the conductor coil is used for measuring the current and voltage.
Working Principle MagnetismSimilar to working principle of DC Motor
Symbolic Representation moving-ironmoving-coil
Uses Both for AC and DC measurementDC Measurement
AccuracyLessMore
Scale Non-uniform Uniform
Damping Air Friction DampingEddy Current Damping
Power ConsumptionHighLow
Controlling Torque Gravity or spring Spring
Deflection Proportional to Current Square of current
Hysteresis Loss Not occurs Occurs
Can be used as Ammeter, Voltmeter and WattmeterVoltmeter, ammeter, galvanometer, ohmmeter

Definition of Moving Iron Instrument

The instrument which uses the soft iron core for measuring the current or voltage is known as the moving iron instrument. It works on the principle that the iron attracts towards the magnet. The magnetic field induces because of the electromagnet and the iron piece is placed between this field. The force of attraction acting on the soft iron core and the magnitude of the force depends on the strength of the magnetic field.

Definition of Moving Coil Instrument

The instrument in which the coil rotates between the magnetic field of the permanent magnet for measuring the DC such type of instrument is known as the moving coil instrument. It works on the principle that the force acting on the coil places between the magnetic field of the permanent magnet. And because of this magnetic field, the coil rotates.

Key Differences Between Moving coil and Moving Iron Instrument

The following are the key differences between the moving coil and the moving iron instrument.

  1. The moving iron instrument uses the soft iron piece as a rotating element. Whereas the moving coil instrument uses the coil as a rotating element.
  2. The working principle of the moving iron instrument depends on magnetism. Whereas, the working principle of moving coil instrument is similar to the working principle of dc motor.
  3. The MI iron instrument has the non-uniform scale. Whereas the moving coil instrument has the uniform sale.
  4. The moving iron instrument is less accurate as compared to the moving coil instrument.
  5. The moving iron instrument uses the air friction damping while the moving coil instrument uses the eddy current damping system. The damping is the phenomenon through which the amplitude of the oscillations decreases.
  6. The moving iron instrument consumes more power as compared to the moving coil instrument.
  7. The moving iron instrument is used for measuring both the direct and alternating current whereas the moving coil is used for the DC measurement.
  8. In moving iron instruments, the gravity or spring provides the controlling torque to the instrument. Whereas in moving coil instrument the spring provides the controlling torque to the moving coil instrument.
  9. The deflection of the moving iron instrument is proportional to the current. Whereas in moving coil instrument the deflection is proportional to the square of the current.
  10. The moving iron instrument is free from the hysteresis loss. Whereas the hysteresis loss occurs in the moving coil instrument.
  11. The instrument which uses the soft iron piece as a moving element such type of instrument is known as the MI instrument.
  12. The moving iron instrument can be used as an ammeter, voltmeter and wattmeter. Whereas the moving coil instrument is used as a voltmeter, ammeter, galvanometer and ammeter.

Conclusion

The moving iron instrument consists the soft iron core and is used for both the AC and DC measurement. In moving iron instrument, the coil made of the conductor is placed between the magnetic field of the permanent magnet and the movement of coil gives the DC measurement.

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