A magnetic field is set up and the soft iron piece is magnetized which is attracted towards the center of the coil. Jan 28, 2019 friends is video me ham moving iron instrument ke bare me discuss kar rahe hai, is video me apko moving iron instrument ke working principle, construction, advantage and disadvantages ke bare me. The electromagnet is the temporary magnet whose magnetic field strength increases or decreases with the magnitude of the current passes through it. In this video we will learn about moving iron instruments construction and working principle in hindi. You cant see it but its there neverthelessand you can. Construction and working principle electrical concepts.
The work carried out by the department of measuring devices of the kiev polytechnical institute has shown that the frequency range of movingiron instruments. Soft iron core provides formation of uniform magnetic field. Moving iron instruments are of two types i attraction type. The basic construction of attraction type moving iron instrument is illustrated bellow a thin disc of soft iron is eccentrically pivoted in front of a coil.
Advantages and disadvantages of movingiron instruments. 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. The basic construction of attraction type moving iron instrument is illustrated bellow. Moving iron type instruments are mainly two types of instrument. I instrument the most common ammeter and voltmeter for laboratory or switch board use at power frequency are the moving iron instruments. Pmmc instrument explained permanent moving coil instrument. A galvanometer works as an actuator, by producing a rotary deflection of a pointer, in response to electric current flowing through a coil in a constant magnetic field. The moving coil is either rectangular or circular in shape. The construction of a photo transistor is just like a conventional npn transistor with a little hole made on the surface mean to collector base junction. The coil is suspended so that it is free to turn about its vertical axis. Moving iron instrument working operation electrical edition.
Moving iron instruments construction and working principle in hindi duration. Movingiron instruments construction and basic principle operation movingiron instruments are generally used to measure alternating voltages and currents. The field winding is a threephase winding, with the phases connected to both the running and incoming sources through a phaseshifting impedor network containing resistors, capacitors, and inductors. Moving iron instrument types construction and working self. This iron tends to move inward that is from weaker magnetic field to stronger magnetic field when current flowing through the coil. Construction of attraction type moving iron instrument. 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. A coil of thin wire is mounted on an aluminum frame spindle positioned between the poles of a u shaped permanent magnet. Working and construction of photo transistor blogger. Advantages, disadvantages, errors in moving iron instrument. The basic construction of pmmc is shown in above fig. Moving iron instrument types construction and working.
K l university department of basic engineering sciences1. It consists of permanent horseshoe magnets, coil, soft iron core, pivoted spring, nonmetallic frame, scale, and pointer. Permanent magnet moving coil mechanism pmmc mathematical. When a currentcarrying coil is suspended in a uniform magnetic field it is acted upon by a torque. 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. Moving iron instrument this instrument is one of the most primitive forms of measuring and relay instrument. Moving iron instruments principle, operation and type, theory of. The working principle of pmmc instruments are same as that of darsonaval type of galvanometer, difference being that a direct reading instrument is provided with pointer and scale. Permanent magnet moving coil instrument pmmc working and.
The moving coil is wound either as a selfsustaining coil or else on a nonmetallic former. The instrument in which the moving iron is used for measuring the flow of. The moving iron instruments use the stationary coil of copper or aluminium wire which. A small lens is fixed on this hole for allowing a focused light beam to concentrate on the collector base junction. The strength of the magnetic field induces by the electromagnet is directly proportional to the current passes through it. Multiple choice questions and answers on measurement and instrumentation. Types of inverters, principles of working, basic principle of working of cyclo converters. The moving iron instruments use the stationary coil of copper or aluminium wire which acts as an electromagnet when an electric current passes through it.
Moving iron instruments principle, operation and type. Moving coil galvanometer is an electromagnetic device that can measure small values of current. In the moving iron instrument, an iron vane is mounted on a shaft along with the pointer. Electrodynamometer type instruments construction and operation. A hollow circular coil is used and one of the iron pieces is attached inside the hollow coil. Moving iron instruments attraction type easiest explained. If you send an electric current down a metal wire, you create a magnetic field around the wire at the same time. Movingiron instruments are generally used to measure alternating voltages and currents. This instrument is one of the most primitive forms of measuring and relay instrument.
When the movement is used in an instrument calibrated to read current, most of the current flows through a resistor in parallel with the movement. Click here to download the pdf of this topic moving iron instruments. Moving iron instrument working principle, construction, advantage. Dec 30, 2019 in this article, we shall study principle, construction, working, sensitivity and accuracy of the moving coil galvanometer. Movingcoil instrument article about movingcoil instrument. Range extension of ammeters voltmeters your electrical. If you know how one of those works, understanding a meter is easy. Whenever a piece of iron is placed nearer to a magnet it would be attracted by the magnet. Under the action of this torque, the coil rotates and the deflection in the coil in a moving coil galvanometer is directly. Moving iron instruments are used as voltmeter and ammeter only.
The basic working principle of these instruments is very simple that a soft iron piece if brought near magnet gets attracted by the magnet. Light but rigid construction is used for the moving coil. Ammeter working principle and types of ammeter ammeter. Figure below shows a simple moving iron instrument. To understand the basic construction of a permanent magnet moving coil. Permanent magnet moving coil mechanism pmmc in pmmc meter or darsonval meter or galvanometer all are the same instrument, a coil of fine wire is suspended in a magnetic field produced by permanent magnet.
The construction of the attraction type moving iron instrument is shown in the below figure. Moving iron instrument working principle, construction, advantage and. This iron tends to move inward that is from weaker magnetic field to stronger magnetic field whencurrent flowing through the coil. Apr 20, 2018 working principle of moving iron instruments. The instrument consists of two high intensity, high coercive force magnets or a big ushape magnet based on design. This light rectangular coil carries the current to be measured. Moving iron instruments principle and operation repulsion type damping. Jul 25, 2018 the basic construction of attraction type moving iron instrument is illustrated bellow a thin disc of soft iron is eccentrically pivoted in front of a coil. The pointer is attached to the spindle so that it is deflected with the motion of. Types of converters, working of ac regulators and choppers.
Suitable for low frequency and high power circuits. It states that if the thumb, the forefinger and the middle finger are held in such a way that they are mutually perpendicular to each other makes 90 of angles, then the forefinger points the direction of the field, the thumb points the direction of motion of the conductor and the middle finger points the direction of the induced current from emf. It consists of a hollow cylindrical coil or solenoid which is kept fixed as shown in the fig. Moving iron instruments construction and working principle. Jan 15, 2019 a permanent magnet moving coil pmmc meter also known as a darsonval meter or galvanometer is an instrument that allows you to measure the current through a coil by observing the coils angular deflection in a uniform magnetic field.
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. Jan 29, 2019 pmmc instrument explained permanent moving coil instrument explain in hindi pmmc construction and working principle construction and working principled in details in hindi in this video we. In movingiron instruments the movable system consists of one or more pieces of speciallyshaped soft iron, which are so pivoted. Construction of moving iron instruments, torque equation of moving iron. The basic construction of attraction type moving iron instrument is illustrated. A metallic former cannot be used as eddy currents would be induced in it by the alternating field. Working principle and construction of pmmc polytechnic hub. In moving iron instruments, a plate or van of soft iron or of high permeability steel forms the moving element of the system. The dynamic microphone consists of a magnet, and a diaphragm to which a coil is attached. The dynamic or moving coil microphone relies on the fact that if a wire held within a magnetic field is moved then an electric current is induced. Motors by using converters and choppers, speed control of induction motor by using ac voltage regulators vf control, switched mode power supplies smps, ups. In attraction type moving iron instruments, an ovalshaped disc made up of soft iron is pivoted on the spindle near the coil. In these wattmeters, the field produced by the currentcarrying moving coil tries to come in line with the field produced by the currentcarrying fixed coil, and a deflecting torque is exerted on the moving system.
May 12, 2018 permanent magnet moving coil or pmmc instruments are the most accurate type for the measurement of dc current or voltage. When this happens there will be a small deflection d. The iron van is so situated that it can move in the magnetic field produced by a stationary coil. Figure 2 attraction moving iron instrument measurement of electric voltage and current. Nov 02, 2019 movingcoil meters work in a similar way to electric motors. When the instrument is connected in the circuit, the operating current flows through the stationary coil. Whereas in moving coil instrument the conductor coil is used for dc measurement. The instrument can be constructed to measure current and voltage to an accuracy needed in most engineering works and still be ch. The current to be measured is passed through the coil, coil produced the magnetic field. Dynamometer type wattmeter working your electrical guide. 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 type instruments are of mainly two types.
Construction and working of repulsion type moving iron construction and working of repulsion type moving iron. Dec 25, 2014 construction of attraction type moving iron instruments points. This is the same effect as seen in an electric generator and many other items. Always connected in series with the circuit and carries the current to be measured. Capable of giving an accuracy within limits of both precision and industrial grades. Construction of attraction type moving iron instruments. Deflection torque is proportional to the square of the current. It is an instrument for detecting and measuring electric current. A galvanometer is an electromechanical instrument used for detecting and indicating an electric current. According to the fundamental law of electromagnetic force, the coil will rotate in the magnetic field when it. The moving iron instrument uses the stationary coil as an electromagnet. Since the stationary parts and the moving parts of the instrument are simple so they are cheapest. Construction and working of moving iron instruments. Attraction type, repulsion type moving iron ammeter pdf.
453 106 41 646 1036 261 280 1089 1528 1090 283 344 1302 1162 1234 241 1088 360 911 1316 516 1383 309 831 473 546 229 1114 1460 130 966 822 316 1121 760 1152 1163 523