The magnetic field induces by the electromagnet whose strength depends. For low voltage range the power consumption is higher. Construction of attraction type moving iron instruments points. Working principal of moving iron type synchroscope. The iron van is so situated that it can move in the magnetic field produced by a stationary coil. In movingiron instruments the movable system consists of one or more pieces of speciallyshaped soft iron, which are so pivoted as to be acted upon by the magnetic field produced by the current in coil. If it is used at 50 hz, calibration must also be done at the same frequency i. The fixed vane is attached to the coil and moving is attached to the moving spindle. Measuring instruments what is meant by measurement. Torque equation of moving iron instruments electrical. Explain advantages and disadvantages of an induction type wattmeter.
Inside moving iron instruments repulsion type youtube. Jul 21, 2014 the instrument can be constructed to measure current and voltage to an accuracy needed in most engineering works and still be cheaper as compared any other type of a. As the angular deflection of moving iron instrument is proportional to square of operating current, therefore the instrument has basically square law response. List out the instruments used to measure voltage and current. Attraction type moving iron instrument by prof anil.
In fact, its calibration must be carried out at the frequency for which it is used in ac circuit. It consists of a hollow cylindrical coil or solenoid which is kept fixed as shown in the fig. Describe the difference between permanent magnet moving coil and moving iron measuring instrument. In this lesson we learnt following things about moving iron instruments. Moving iron mi instruments generally used to measure ac current or voltage but can measure dc current and voltage without any external circuit pointer is connected to specially designed soft iron that moves according to the intensity of magnetic field acting on it the magnetic field is produced by current carrying coil. Movingiron instruments physics homework help, physics. These instruments are based on the principle that when an unmagnetised soft iron piece is placed in the magnetic field of a coil, then the piece is attracted towards the coil. The most widely used moving iron instruments are switchboard instruments of classes 1. Advantage and disadvantage of repulsion type moving iron. Any instrument in which current is sent through one or more coils suspended or pivoted in a magnetic field, and the motion of the coils is used to measure. The resistance in the circuit of the moving coil of a dynamometer wattmeter. Moving iron instrument working principle and errors. H mi instruments may be seriously affected by waveform both on account of the change in the form of flux waveform and in case of voltmeter, the effect of harmonic upon the inductance.
Moving iron instrument this instrument is one of the most primitive forms of measuring and relay instrument. The force of attraction depends on the strength of the magnet field. There are two general types of moving iron instruments namely i repulsion or double iron type ii attraction or single iron type. There are further two different designs of repulsion type moving iron instruments. Construction of attraction type instrument the stationary coil of the attraction type instrument is flat and has a narrow opening. Attraction type moving iron instrument working principle when a soft iron piece vane is placed in the magnetic field of a currentcarrying coil, then the piece is attracted towards the center of the coil. The force of this attraction depends upon the strength said magnetic field. A hollow circular coil is used and one of the iron pieces is attached inside the hollow coil. Moving iron instruments free download as powerpoint presentation. At this condition, the moving iron type synchroscope behaves as a moving iron type power factor meter. A curved iron of soft iron is fixed to the inside of the bobbin former and another curved iron is mounted on a spindle, which passes axially through the solenoid.
The basic principle of moving iron instruments is it works on. The moving system of the instrument is attached to the soft iron piece and the operating current is passed through a coil placed near it. Classification, absolute and secondary instruments, indicating instruments, control, balancing and damping, constructional details, characteristics, errors in measurement, ammeters, voltmeters. The iron element consists of a moving vane attached to a pointer, and a fixed vane, surrounded by a coil. Its range can be extended by using published on 10 sep 15. The multiplier and the meter coil in a voltmeter are in. At that time the position of the pointer indicates the phase difference. Positive current in the coil has the same pull as negative current. The moving element is the flat disc of the iron core. The instrument can be constructed to measure current and voltage to an accuracy needed in most engineering works and still be cheaper as compared any other type of a. A movingcoil permanentmagnet instrument can be used as fluxmeter. Repulsion or double iron type figure 1 attraction or singleiron type figure 2 the brief description of different components of a movingiron instrument is given below. Apr 20, 2018 the deflection of needle of moving iron instrument is given in terms of rms value of voltage or current.
Explain with neat sketch of moving iron attraction type measuring instrument. Clapper type repulsion design using pivots, hairsprings and jewel movements. Moving iron instruments principle, operation and type, theory of. Moving iron instruments principle, operation and type. Explain the different types of torque in an electrical measuring instruments. Choosing a backup generator plus 3 legal house connection options transfer switch and more duration. When the current to be measured is passed through the coil, then coil produces a magnetic field and attracts the ovalshaped disc, hence disc will swing into the coil.
This principle is utilized in the moving iron repulsion type instrument. Home advantages and disadvantages of movingiron instruments. The movement is light, quick acting, but extremely robust. Moving iron types instrument can be classified into attraction and repulsion types. In coaxial vane type the fixed as well as moving vanes are the sections. Thus moving iron instruments are unpolarised instruments i. The current to be measured is passed through the coil, coil produced the magnetic field. Classification of moving iron instruments a media to get. Moving iron type instruments are of mainly two types. Attraction type the construction of an attraction type moving iron instrument. In movingiron instruments the movable system consists of one or more pieces of speciallyshaped soft iron, which are so pivoted as to be acted upon by. The latter instruments may be used for frequencies of up to 800 hertz. There are two general types of movingiron instruments namely.
Construction of moving iron repulsion type instruments in repulsion type instrument there are two irons. The most widely used movingiron instruments are switchboard instruments of classes 1. We can use a moving iron instrument for both ac and dc. Moving iron instruments are generally used to measure alternating voltages and currents. Moving iron instruments principle and operation repulsion type damping torque deflecting torque theory of attraction type moving iron instrument. Jul 25, 2018 this instrument is one of the most primitive forms of measuring and relay instrument. This principle is used in moving iron attraction type instrument. Movingiron instrument article about movingiron instrument. The calibration of these instruments should be done for both ac and dc. Mar 11, 2018 the angular deflection of needle of moving iron instruments is related to the current flowing through the field coil.
Moving iron type synchroscope construction and working. Oct 14, 2017 moving iron instruments repulsion type duration. Suppressed scale ammeters with suppression upto 600% can be supplied in all types. Suppose there is no difference in the frequency between the existing electrical system and the incoming generator. Movingiron measuring mechanisms are also used in ratio meters. Due to this square law response, the moving iron instrument scale is nonuniform. Construction and working of moving iron instruments. Oct 21, 2016 before answering your question let me explain the working principle of both moving coil and moving iron instruments that will give you a basic idea. In attraction type moving iron instruments, an ovalshaped disc made up of soft iron is pivoted on the spindle near the coil.
As the name suggests the electrostatic type instrument use static electrical field to produce the deflecting torque. Because whatever may be the direction of current in the coil, there will always be an attraction force acting on. Moving iron instruments attraction type and repulsion type complete concept duration. There are two general types of movingiron instruments namely i repulsion or double iron type ii attraction or singleiron type. In radial vane type radial strips of iron are used as moving vanes. Due to such deflection, some mechanical work will be done. I and dynamometer type due to high cost of permanent magnets. Electrodynamometer type, induction type, single phase and three phase wattmeter. The pointer is attached to the spindle so that it is deflected with the motion of the soft iron piece. To this iron a pointer is attached so that it may deflect along with the moving iron over a graduated scale.
Due to square low response, the scale of the moving iron instrument is nonuniform. The attraction and the repulsion are the types of the 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. Comparison between attraction and repulsion types of instruments. K l university department of basic engineering sciences1. Principle of attraction type moving iron instrument.
Attraction type the instrument in which the iron plate attracts from the weaker field towards the stronger field such type of instrument is known as the attraction type. Since the stationary parts and the moving parts of the instrument are simple so they are cheapest. These types of instrument are generally used for the measurement of high voltages but in some cases they can be used in measuring the lower voltages and powers of a given circuit. The moving iron instrument is free from the hysteresis loss.
A feature of the moving element is that it is fitted with synthetic sapphire jewels. Movingcoil instrument article about movingcoil instrument. Advantages and disadvantages of movingiron instruments. The moving iron meter was invented by austrian engineer friedrich drexler in 1884. Moving iron instrument working operation electrical edition. Construction of attraction type moving iron instruments. Apr 16, 2017 internal parts of repulsion type moving iron instruments. Whereas the hysteresis loss occurs in the moving coil instrument. Home electrical articles comparison between movingiron m. Construction of moving iron repulsion type instruments.
Attraction type, repulsion type moving iron ammeter pdf. Electrostatic type instruments construction principle torque. Accordingly the attraction force acting on the piece of iron would also be increased and decreased. We are manufacturer and exporter of moving iron ac ammeters. To understand the basic construction of movingiron instrument and its principle. Repulsion type instruments are the most commonly used.
Construction of moving iron repulsion type instruments points. Classification of moving iron instrument moving iron instrument are of two types attraction type repulsion type 4. Moving iron instrument electrical study app by saru tech. Moving iron instruments are generally used for measuring ac voltage and currents. What is the difference between movingiron and movingcoil. Measurements and instrumentation objective type questions. Find powerpoint presentations and slides using the power of, find free presentations research about moving iron instruments ppt. Depending upon this simple phenomenon attraction type moving iron instrument was developed. One of the design objectives of the instrument is to disturb the circuit as little directly drive the hp highspeed digital. Moving iron instruments principle, operation and type, theory. Moving iron attraction type instrument is described clearly with neat diagrams and important formulae for gate and other competitive exams guide to measuring instruments for gate ee 15 lessons 3 h 9 m. Suitable for low frequency and high power circuits. Consider a small increment in current supplied to the coil of the instrument.
A moving iron meter doesnt have a permanent magnet it relies on the magnetic attraction from the current in the coil to pull a piece of iron. View and download powerpoint presentations on moving iron instruments ppt. There are two general types of moving iron instruments namely. This type of meter responds to both direct and alternating currents as opposed to the moving coil ammeter, which works on direct current only. Well formed and valid documents namespaces dtd xml schema xfiles. Moving iron instruments are most common for laboratory or switchboard and used at power frequency. The basic working principle of these instruments is very simple that a soft iron piece if brought near magnet gets attracted by the magnet. The instrument which uses the soft iron piece as a moving element such type of instrument is known as the mi instrument. It is clear that whatever may be the direction of the current in the coil of the instrument, the iron vanes are so magnetized that there is always a force of attraction in the attraction type and repulsion in the repulsion type of instruments. Construction of attraction type moving iron instruments the simplest form of attraction type moving iron instrument uses a solenoid and a moving oval shaped soft iron pivoted eccentrically. Moving iron instrument type iqe type iqe 72 iqe 96 front flange mm 72 x 72 96 x 96 housing mm 66 x 66 89 x 89 class 1. Advantage and disadvantage of moving iron instrument. Read here moving iron instrument working operation click here. The construction of the attraction type moving iron instrument is shown in the below figure.
Feb 15, 2012 there are further two different designs of repulsion type moving iron instruments. It works on the principle that the iron place near the magnet attracts towards it. A small piece of soft iron in the form of a vane or rod. Whenever two pieces of iron are kept side by side and a magnet is brought nearer to them the iron pieces will repulse each other. Construction and working of repulsion type moving iron construction and working of repulsion type moving iron. Moving iron ac ammeters and voltmeters frequency meters. Moving iron instruments measuring instrument electromagnetic. Whenever a piece of iron is placed nearer to a magnet it would be attracted by the magnet. Induction type single phase energy meters measure electric energy in.
Construction of attraction type moving iron instrument. Moving iron instrument moving iron instrument for both ac and dc measurement. Jul 25, 2018 working principle of electrostatic type instruments. What is the important of gate time in frequency counter. Accuracy for all suppressed meter is 2x accuracy for the normal range. Classification of moving iron instruments a media to. Derive the torque equation of a moving iron instrument. Moving iron instruments construction and basic principle operation in moving iron instruments the movable system consists of one or more pieces of speciallyshaped soft iron, which are so pivoted as to be acted upon by the magnetic field produced by the current in coil. Moving iron measuring mechanisms are also used in ratio meters. In both the attraction and repulsion type moving iron instruments it is found that for a given position of the moving system, the value of the deflecting torque is proportional to the square of the current, so long as the iron is working below saturation. Electrical instruments and measurements learning objectives absolute and secondary instruments deflecting torque controlling torque damping torque moving iron ammeters and voltmeters moving coil instruments permanent magnet type instruments voltmeter sensitivity.
An oval shaped soft iron pieces is attached to the spindle in such a way that it can move in or out of the coil. The moving iron instrument can be used as an ammeter, voltmeter and wattmeter. Show the constructions detail of an attraction type moving iron instrument. Attraction type moving iron instrument by prof anil brahmin eee1 duration.
Find details of companies offering moving iron ammeter at best price. Advantages, disadvantages, errors in moving iron instrument. What does the moving iron voltmeter measure in a circuit. Ferromagnetic materials magnetize in the direction of a magnetic field, therefore, if they are brought near one end of a current carrying coil, poles of opposite polarity are induced in them. Attraction type moving iron instruments these instruments use soft iron which is a ferromagnetic material. Apart from the movingcoil instruments, there is another important class of meters known as movingiron instruments. Electrical technology playlist pl5fcg6tovhr493p0pd6m1uyh4yfbjozgj unit 1 millmans theorem. The angular deflection of needle of moving iron instruments is related to the current flowing through the field coil. Advantage and disadvantage of repulsion type moving iron instrument. Working principle of moving iron instruments electrical. In moving iron instruments the movable system consists of one or more pieces of speciallyshaped soft iron, which are so pivoted as to be acted upon by the magnetic field produced by the current in coil. Both moving coil and moving iron instruments are used measure the voltage and current of circuits. This instrument is one of the most primitive forms of measuring and relay instrument. The deflection of moving iron instruments is independent of direction of current, because the needle of the moving iron instrumen.
Why do moving iron instruments measure both ac and dc. Apr 20, 2018 in moving iron instruments, a van of soft iron forms the moving element of the system. Moving iron instruments are suitable for low frequency application. The current flow through the stationary coil produced the magnetic field which attracts the iron coil. Capable of giving an accuracy within limits of both precision and industrial grades. We are well known in the market for moving iron ac ammeters. Iron vane ammeters and voltmeters depend for their operations on the. Questions and answers list eie south central railway.
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