11 April 2020

Difference between moving iron and moving coil instruments

One of the major difference between the moving iron and moving coil instrument is that in moving iron is a soft iron system is used for measuring mechanism. While in moving coil instrument the conductor coil is used for DC measurement. Now let us discuss the difference between moving the iron and moving coil instruments to better understand this topic.

Definition of moving iron instrument:

Moving iron is an instrument that 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 toward the magnet. The magnetic field induces because of the electromagnetic 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 magnetic 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.

The main key difference between moving the iron and moving coil instruments are listed below:

  • The MI iron instrument has a non-uniform scale whereas the moving coil instrument has a uniform sale.
  • Moving ironwork on the principle of magnetism, Moving coil work on the principle of DC motor.
  • The moving iron instruments use the soft iron piece as a rotating element. While the moving coil instrument uses the coil as a rotating element.
  • In moving iron, the defection of torque proportional to the square of the current while moving coil defection torque is proportional to the current.
  • The moving iron instrument is less accurate as compared to the moving coil instrument.
  • In moving iron the damping is provided by air damping while in moving coil instrument damping is provided by eddy current.
  • The working iron instrument is used for measuring both the direct and alternating current whereas the moving coil is used for the DC measurement.
  • The moving iron instrument consumes more power than the moving coil instrument.
  • Moving iron is gravity controlled instrument while in moving coil is a spring control instrument.
  • The moving iron instrument is free from totally from the hysteresis loss but in the hysteresis loss occurs in the moving coil instrument.
  • The instrument which uses the soft iron piece as a moving element such type of instrument is known as the MI instrument.
  • In moving iron instruments the gravity or spring provides the controlling torque to the instrument while in moving coil instrument the spring provides the controlling torque to the moving coil instrument.
  • The moving iron instrument can be used as an ammeter, voltmeter and wattmeter whereas the moving coil instrument is used as a voltmeter, ammeter, ammeter, and galvanometer.
  • The moving iron instrument uses the air friction damping while the moving coil instrument use for the eddy current damping for the system. The damping is the phenomenon through which the amplitude of the oscillations decreases.
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