Permanent magnet moving coil( P.M.M.C.)Instrument

Permanent magnet moving coil( P.M.M.C.)Instrument

permanent magnet moving coil, construction and working of permanent magnet moving coil, use of permanent magnet moving coil instrument, PMMC instrument1. Working principle of permanent magnet moving coil

These instrument work on principle of D.C motor . According to this law when current carrying conductor lies in magnetic field then a force work current carrying conductor.
This force is directly proportional to conductor current
F,, is directly proportional to ,,I
where,, F, is force
,I, is current of conductor

2. Construction of permanent magnet moving coil 

Main parts

1. Permanent magnet 

It is made in U shape which made of  alnico or alcomax material. it provide uniform magnetic field .

2. Soft iron core 

It uses between permanent magnet  and it provide support to coil . it is also provide low reluctance path for magnetic field.

3. Pole shoe or Pole pieces

It only use for provide constant magnetic field to  coil.

4. Magnetic coil 

This coil connect with spindle and being movable . when coil  connect from supply then magnetic field developed in coil and it become movable.


5. Control spring 

Its work is dove-lope controlling torque in instrument. it connect with spindle.

6. Damper 

Air friction damping used in permanent magnet  moving coil


7. Spindle 

It is made from steel Rode. which connect various equipment  like as coil ,control spring , damper etc. it connect between two ball bearing .


8. Pointer and Scale 

It is made from Aluminum and its weight is low . In this type instrument scale being uniform.

3. Working principle of permanent magnet moving coil

permanent magnet moving coil, construction and working of permanent magnet moving coil, use of permanent magnet moving coil instrument, PMMC instrumentWhen we provide supply of instrument  then current will flow  in coil . which cause a magnetic field dove lope in coil and deflection torque work on coil . which deflect of moving system . By use control spring and damper generate controlling torque and damping torque when controlling torque is equal to deflecting torque then original reading show on scale.











4.Exasperation for various torque  

1. Defection torque is directly proportional to coil current




5. Use of permanent magnet moving coil 

1. Use as an ammeter 

This type instrument used as Ammeter by use resistance. A resistance connect in parallel with PMMC instrument. which called shunt resistance.

2. Use as a Voltmeter 

It is used as voltmeter by use of resistance . A resistance connect in  series. which called series resistance.

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