these instrument are widely used in laboratories and switch boards at commercial frequencies because these are cheaper in cost , robust in construction and can be manufactured with required accuracy.
there are two general types of such instrument i.e (i) the attraction type (ii) the repulsion type . the attraction type instrument operate on the principle of repulsion of two adjacent iron piece magnetised by the same magnetic field. repulsion type instrument are are more sensitive as in these instrument large operating torque is developed by having two iron element positioned close together inside the field coil where the magnetizing effect is maximum. in both type of these instrument the current under measurement is passed through a coil of wire. this current carrying coil sets up the necessary field. depending on the magnitude of the current to be measured the coil may be of a few turns of very heavy conductor or of many turns of fine wire. the instrument to be used as an ammeter is provided with a coil of thick wire in order to have low resistance and carry large current and to be used as a voltmeter is provided with a coil of large number of turns of fine wire in order to have high resistance and draws as small current as possible.
Different b/w a moving coil instrument and a moving iron instrument
moving iron instruments
Moving-coil instruments are polarised, not unpolarised. This is because they are direct current instruments, and the direction of the current determines the direction in which the instrument's point will move. If a moving coil instrument is connected incorrectly, then the instrument will try and read 'downscale' -in other words, the resulting torque will try and move the pointer backwards.AnswerA moving-iron meter operates by the repulsion between a fixed iron pole piece, and a moving iron pole piece to which the pointer is attached. The magnetic polarity of the fixed and moving pole pieces is determined by the direction of current flowing though a coil. The magnetic polarities induced into the fixed and moving iron pole pieces, when the current flows in one direction, are both north; and, when the current flows in the oppositedirection are both south. So the pole pieces always repel each other, regardless of current direction.
What are the advantages and disadvantages manx iron instrument
power must be gotten thru moving parts to the coil slip rings, festoons, tinsel
Different b/w a moving coil instrument and a moving iron instrument
moving iron instruments
If this is a homework related question, you really should consider trying to solve it yourself before looking at this answer. Otherwise, the value of the lesson, and the reinforcement provided by the assignment, will be lost to you.A moving coil measuring instrument has a coil attached to the indicator, surrounded by a magnet.A moving iron measuring instrument has a magnet attached to the indicator, surrounded by a coil.In both cases, the indicator is driven by magnetic torque caused by current flow in the coil.
mic or moving iron coil is instrument type works on ac and dc
mic or moving iron coil is instrument type works on ac and dc
Megger is related to a hot wire instrument with a moving coil. The megger uses a moving coil to measure insulation resistance in electrical circuits and equipment. This type of instrument is specifically designed for insulation testing.
A moving iron instrument works by means of a coil that attracts a moving iron mass that is attached to a pivoted pointer which moves across a graduated scale. The iron mass will be attracted towards the coil, regardless of the magnetic polarity of the coil. So, as an AC current continually reverses the magnetic polarity of the coil, the iron mass is always attracted towards the coil, never repelled by it. Similarly, a moving iron instrument doesn't care in which direction a DC current is flowing. So the instrument works equally well with both AC and DC currents. Moving iron instruments, however, are not as accurate as moving coil instruments which, of course, are sensitive to the direction of current.
Moving-coil instruments are polarised, not unpolarised. This is because they are direct current instruments, and the direction of the current determines the direction in which the instrument's point will move. If a moving coil instrument is connected incorrectly, then the instrument will try and read 'downscale' -in other words, the resulting torque will try and move the pointer backwards.AnswerA moving-iron meter operates by the repulsion between a fixed iron pole piece, and a moving iron pole piece to which the pointer is attached. The magnetic polarity of the fixed and moving pole pieces is determined by the direction of current flowing though a coil. The magnetic polarities induced into the fixed and moving iron pole pieces, when the current flows in one direction, are both north; and, when the current flows in the oppositedirection are both south. So the pole pieces always repel each other, regardless of current direction.
hot wire ammmeter or a moving iron ammeter will work for ac and dc.
moving iron and eletrostatic type
For moving-iron instrument magnetic field is caused when the current (voltage) passes the fixed circle. When the current (voltage) passes the fixed circle,the two iron plates are magnetized ,rotational torque is resulted, the deflection angle indicate measured current. Because the magnetized polarity is same for AC or DC, moving-iron instrument can be used in AC and DC circuit. For permanent-magnet moving-coil instrument magnetic field is caused by the permanent-magnet, When the DC current passes the moving coil, rotational torque is resulted,so the deflection angle indicate measured DC current. As AC current passes the moving coil ,because inertia of moving parts of meter the deflection angle indicate rotational torque average, but rotational torque average is zero in cycle, moving parts of meter is´t deflec,so permanent-magnet moving-coil instrument only is used in DC circuit.
All Moving Iron Type measuring instruments major rms value of quantities.