Why Pmmc Is Used for Dc Only?
The Moving Coil Instrument Can Only Be Used on D. C Supply as the Reversal of Current Produces a Reversal of Torque on the Coil. It's Very Delicate and...
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Keeping this in view, why Pmmc instruments are most widely used?
PMMC instruments (i.e. D'Arsonval meters) are only used for measuring the Direct Current (DC) current. If we were to use Alternating Current (AC) current, the direction of current will be reversed during the negative half cycle, and hence the direction of torque will also be reversed.
Furthermore, why do we use AC for moving iron? The angular deflection of needle of moving iron instruments is related to the current flowing through the field coil. There fore the needle will always move in the same direction into or towards the coil be it energised by AC or DC.
Likewise, people ask, what is a Pmmc?
Definition: The instruments which use the permanent magnet for creating the stationary magnetic field between which the coil moves is known as the permanent magnet moving coil or PMMC instrument. It operates on the principle that the torque is exerted on the moving coil placed in the field of the permanent magnet.
What are the advantages and disadvantages of Pmmc instruments?
The PMMC has consumes low power. The PMMC has a very high accuracy. The PMMC is free from hysteresis error. The PMMC has efficient damping characteristics and is not affected by stray magnetic field.
