Moving iron instruments can be used for measuring (1) Direct currents and voltages (2) Radio frequency currents (3) A.C currents and voltages (4) Both (a) and (c)
19 Answers
Answer :
The instrument in which the moving iron is used for measuring the flow of current or voltage is known as the moving iron instrument. It works on the principle that the iron place near the magnet attracts towards it. The force of attraction depends on the strength of the magnet field. The magnetic field induces by the electromagnet whose strength depends on the magnitude of the current passes through it
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Answer :
Moving Coil Instruments are used for measuring DC quantities. They can be used on AC systems when fed through bridge rectifiers. Center magnet system is incorporated in our moving coil instruments which completely shields the movement from the effect of external magnetic fields. The movement is pivoted between synthetic sapphire jewel bearings for frictionless operation.The permanent magnet moving coil instrument is the most accurate type DC measurements.
Answer :
AC Aas well as DC current.
If radio frequency is applied then due to high frequency, these induce large amount of flux , thus more induced emf, thus more Eddy current, thus more heating of the iron disc , and it may happen that, there is wear and tear in the disc,or the disc mat burn also ,when exposure for large duration.
If radio frequency is applied then due to high frequency, these induce large amount of flux , thus more induced emf, thus more Eddy current, thus more heating of the iron disc , and it may happen that, there is wear and tear in the disc,or the disc mat burn also ,when exposure for large duration.