State working principle of PMMC instrument.

1 Answer

Answer :

Working Principle of PMMC Instrument: When current carrying conductor is placed in a constant magnetic field, it experiences a force proportional to the current and produces proportional deflection torque. 

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Last Answer : The direction of force exerted on moving coil depends on the direction of current flowing through moving coil. If the direction of magnetic field is kept constant, it produces unidirectional torque if the current is ... on the coil in one cycle to zero. Hence the meter cannot read A.C. quantities.

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Last Answer : (i) Material used for Moving coil: Copper, Aluminum( some times)  (ii) Permanent magnets are made of special alloys such as :  Aluminum-Nickel-Cobalt (Alnicos)  Strontium-Iron  Neodymium-Iron-Boron  Samarium-Cobalt.

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Last Answer : 1. It has uniform scale. 2. Power consumption is low 3. It can be obtained in wide ranges. 4. High sensitivity & accuracy 5. It is unaffected by external magnetic field. 6. Additional damping device not required. 7. Hysteresis problem is not there.

Description : feature of PMMC instrument. 

Last Answer : Consumes less power Great accuracy. High torque to weight ratio

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