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What is the reason for using MI instrument on both AC and DC?
Universal use – The MI instrument is independent of the direction of current and hence used for both AC and DC. Less Friction Error – The friction error is very less in the moving iron instrument because their torque weight ratio is high.
Can the same moving iron instrument be used for both DC and AC measurements?
Measurement of Electric Voltage and Current. Moving iron instruments are used as Voltmeter and Ammeter only. Both can work on AC as well as on DC.
Why Pmmc is used to measure DC and moving iron instrument is used to measure both AC and DC?
So unlike moving coil instruments moving iron instruments are not affected by the direction of electric current as it will produce a magnetic field regardless of its direction, while moving coil instruments rely mainly on the current direction that they can’t be used in AC measurements.
What causes error in moving iron instruments?
Error in moving iron instruments due to change in frequency: The change in frequency produces a change in impedance of the coil and change in magnitude of eddy currents. The increase in impedance of the coil with the increase in frequency causes serious errors in case of voltmeters only.
What is difference between PMMC and MI?
The moving iron instrument uses the air friction damping while the moving coil instrument uses the eddy current damping system. The moving iron instrument is used for measuring both the direct and alternating current whereas the moving coil is used for the DC measurement.
What is difference between moving iron and moving coil?
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.
Why is Pmmc only used for DC?
These types of instruments are only used for measuring the DC quantities as if we apply AC current to these type of instruments the direction of current will be reversed during negative half cycle and hence the direction of torque will also be reversed which gives average value of torque zero.
What is the difference between moving coil and moving iron instruments?
What instrument is used to measure AC current?
Ammeter
Ammeter, instrument for measuring either direct or alternating electric current, in amperes. An ammeter can measure a wide range of current values because at high values only a small portion of the current is directed through the meter mechanism; a shunt in parallel with the meter carries the major portion.