What is the principle of working of moving iron instruments?
Definition: 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.
What is the principle of operation of the moving coil meter?
Construction of Moving Coil Meter The moving coil instrument works on the principle of the DC motor (electrodynamic effect). It operates by the interaction of the magnetic field produced by a movable coil due to the flow of current with the field of a permanent magnet. It uses a coil for measuring voltage and current.
What are the types of moving iron instruments explain one of them?
Moving iron type instruments are of mainly two types. Attraction type and repulsion type instrument. Whenever a piece of iron is placed nearer to a magnet it would be attracted by the magnet. The force of this attraction depends upon the strength said magnetic field.
What is torque equation of moving iron instrument?
Td = (1/2)I2(dL/dƟ) From the above torque equation, we observe that the deflecting torque is dependent on the rate of change of inductance with the angular position of iron van and square of rms current flowing through the coil. In equilibrium state, deflecting and controlling torque shall be equal as below.
What is moving iron?
Moving-iron instruments are generally used to measure alternating voltages and currents. In moving-iron instruments the movable system consists of one or more pieces of specially-shaped soft iron, which are so pivoted as to be acted upon by the magnetic field produced by the current in coil.
Which type of scale is used in moving iron instrument?
From the figure, the shape of the scale of moving iron instruments is a rectangular hyperbola and it is clear that the scale is cramped or compressed at its lower and higher ends.
What is moving iron type?
What is the difference between moving coil and moving iron instruments?
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 are the advantages of moving iron instrument?
The main advantage of Moving Iron Instrument is that it can measure AC as well as DC quantities. Though this instrument is responsive to DC, it suffers from hysteresis error which causes an appreciable error in the measurement of DC. Therefore, it is rarely used for DC applications.
Why moving iron instruments have non linear scale?
Answer. Answer: As the angular deflection of Moving Iron Instrument is proportional to square of operating current, therefore the instrument has basically square law response. Due to this square law response, the Moving Iron Instrument Scale is non-uniform.
Which damping is used in moving iron instruments?
The moving iron instrument uses the air friction damping while the moving coil instrument uses the eddy current damping system. The damping is the phenomenon through which the amplitude of the oscillations decreases. 6. The moving iron instrument consumes more power as compared to the moving coil instrument.
What are the applications of moving iron instruments?
Moving iron instruments are used as Voltmeter and Ammeter only. Both can work on AC as well as on DC.
Why air damping is used in moving iron instrument?
Right Answer is: When the pointer deflects, the vane in the sector also moves. The air in the sector produces friction in the movement of the vane and thus necessary damping torque is obtained. Eddy Current Damping: It is used in a strong operating field e.g., PMMC (Permanent Magnet Moving Coil instrument) type.
What are the advantages of MI instrument?
Advantage of Moving iron Instrument
- It is a universal instrument which can be used for the measurement of AC and DC quantities.
- These types of instruments have high value of torque to weight ratio.
- It is very cheap due to simple construction.
- These instruments are quite robust due to its simple construction.
What type of damping is used in moving iron meter?
Air friction damping
Air friction damping is used.
Which damping method is common in moving iron instruments?
eddy current damping
In the moving coil instrument type instruments, damping is provided by eddy current damping.
What causes errors in moving iron instrument?
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 are errors in Mi instrument?
Hysteresis error is a serious type of error in MI instruments. The effect of this error is that the readings are higher when the current increases than when it decreases. Stray magnetic field error may be serious because of the weakness of the operating magnetic field.
What is the working principle of moving iron instruments?
Working Principle of Moving Iron Instruments: In Moving Iron Instruments, a plate or van of soft iron or of high permeability steel forms the moving element of the system. The iron van is so situated that it can move in the magnetic field produced by a stationary coil. Figure below shows a simple moving iron instrument.
What is the controlling torque in a moving iron instrument?
In moving iron instruments, the controlling torque is provided by spring. Controlling torque due to spring is given as In equilibrium state, deflecting and controlling torque shall be equal as below.
What are the main errors in moving moving iron instruments?
The following are the main errors in moving moving iron instruments, when these are used either on DC or AC. Error due to hysteresis: Because of hysteresis in the iron parts of the operating system, the readings are higher for descending values but lower for ascending values.
What is the working principle of iron vane?
One iron vane is held fixed to the coil frame and other is free to rotate, carrying with it the pointer shaft. Two irons lie in the magnetic field produced by the coil that consists of only few turns if the instrument is an ammeter or of many turns if the instrument is a voltmeter.