Moving iron instruments principle, operation and type, theory. Apr 20, 2019 in my experience, induction ammeters are used with ac circuits. Engineering notes induction type wattmeter engineering notes. Feb 23, 2008 that type of ammeter is widely used in the industry because the measurement is noninvasive. Ammeter means amperemeter which measures ampere value. So an induction wattmeter can work on ac circuits only. The analog electronic voltmeters and ammeters in the form of dc, rectifierbased ac, and true rms. Aug 27, 2014 measurements instrumentation objective questions answers. Moving iron instruments are generally used to measure alternating voltages and currents. The initial readings of ammeter, voltmeter and wattmeter are noted. A clampon ammeter operates by measuring the magnetic flux current.
In the above figure, an ammeter is inserted into the path of a current, that is, in series, so as to carry the current being measured. When a drum or disc of a non magnetic conducting material is placed in a rotating magnetic field, eddycurrents are induced in it. This coreless transformer is used in clamp meters and power monitoring loggers. By increasing the load step by step, the reading of ammeter, voltmeter and wattmeter 7. Some information is given on oscilloscopes as one of the important voltage measuring devices, although they are generally not classified as voltmeters or ammeters. Induction machines are considered relatively reliable and robust due to their simple design and welldeveloped manufacturing technology. Induction type of meters possesses lower friction and higher torqueweight ratio. Apr 15, 2014 types of ammeter by sagar parte rollno. Jul 17, 2016 principle of induction type instruments. Rated voltage of 3phase induction motor, is applied by adjusting autotransformer 5. In 65, only mustang gts and mustangs equipped with the deluxeaka pony interior had an actual ammeter, as opposed to an idiot light. Instrumentation and process control pdf book agrimoon.
An ammeter from ampere meter is a measuring instrument used to measure the current in a circuit. Measurements instrumentation objective questions answers. Used correctly and this tool will become one of your best friends. Single phase induction motor the singlephase induction machine is the most frequently used motor for refrigerators, washing machines, clocks, drills, compressors, pumps, and so forth. Ammeter definition and working principle electrical academia. A wide variety of induction ammeter options are available to you, there are 29 suppliers who sells induction ammeter on, mainly located in asia. The ammeter has a ring extension that closes loosely around one of the ac wires and provides an accurate measurement of the ac current flowing through the wire. Inductive ammeter stuttgart performance engineering. Whatever the type of meter or size of meter movement, there will be a rated value of voltage or current necessary to give fullscale indication. When the energy meter is connected in the circuit, the current coil carries the load current and the pressure coil carries the current proportional to the supply voltage. Repulsion type moving coil permanent magnet type dynamometer. Multiple choice questions and answers on measurement and. Similarly the range of ammeter and voltmeter during no load test should be 5a, 500 v. Instruments used to measure smaller currents, in the milliampere or microampere range, are designated as milliammeters or microammeters.
For example, if we wanted to design an ammeter to have a fullscale range of 5 amps using the same meter movement as before having an intrinsic fullscale range of only 1 ma, we would have to relabel the movements scale to read 0 a on the far left and 5 a on the far right, rather than 0 ma to 1 ma as before. Ammeter design dc metering circuits electronics textbook. Jul 25, 2018 given below is the picture of single phase induction type meter. The reaction between the rotating flux and the eddy current produced by it creates a torque which rotates the disc or drum. Driving system moving system breaking system registering system 2. Early ammeters were laboratory instruments which relied on the earths magnetic field for operation. Induction type energy meter essentially consists of following components. If you continue browsing the site, you agree to the use of cookies on this website. Study of single phase induction type energy meter or watt. Questions and answers list eie south central railway. The singlephase motor stator has a laminated iron core with two windings arranged perpendicularly. If the ammeter resistance is very high, it will introduce high resistance in series with the existing circuit an disturb the circuit conditions.
Resembling a current clamp in appearance and function is the rogowski coil current sensor. The passage of ac through the ring creates a current in the ring via induction that allows for. The speed of the motor, starting and operation, the efficiency of both the motors, its cost, usage, and applications. In a ballistic galvanometer, the deflecting torque is. In a ballistic galvanometer, the deflecting torque is proportional to. Electric currents are measured in amperes a, hence the name. In this article, modern electronic voltmeters and ammeters are discussed. Single phase induction type energy meter consists of four important systems which are written as follows. Dc ammeter are mainly pmmc instruments, mi can measure both ac and dc currents, also electrodynamometer type thermal instrument can measure dc and ac, induction meters are not generally used for ammeter construction due to their higher cost, inaccuracy in measurement. Moving iron instruments are used as voltmeter and ammeter only. Also they are inexpensive and accurate, and retain their accuracy over a wide range of loads and temperature conditions. This type was often used with oscilloscopes, and with highend computerized digital multimeters, however, they are becoming common place for more general use.
Induction type of energy meters are universally used for measurement of energy in domestic and industrial a. This type is easy to use, cannot be damaged by misconnection and will not damage the vehicle wiring. An ammeter from ampere meter is a measuring instrument used to measure the current in a. The operation of induction type instruments depends on the production of torque due to reaction between two magnetic fluxes having some phase difference or reaction between flux of an ac magnet and the eddy current induced by this flux. Wattmeter types diy electrical electronics projects. Types of ammeters, voltmeters electrical instruments. 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. Step1 to 6 is repeated till the ammeter shows the rated current of 3phase induction motor. Movingiron ammeters and voltmeters there are two basic forms of these instruments. Given below is the picture of single phase induction type meter. Induction type instruments, working principle of induction.
This type of meter movement is extremely common for both ammeters and other meters derived from them, such as. This paper aims to represent routine test performing in three phase induction motor. Sep 05, 2012 induction type instruments the principle of operation of induction instrument is similar to that of induction motor. Difference between induction motor and synchronous motor difference between induction and synchronous motor is explained with the help of various factors, like the type of excitation used for the machine. Difference between induction motor and synchronous motor. These types of instruments are used only foe ac measurements. Induction type wattmeter, watthour meter, dynamometer type power factor meter. Induction instruments differ from other types of instruments in that they can be used in ac circuits only for one specific frequency. Multiple choice questions and answers on measurement and instrumentation.
Routine test of three phase induction motor vishant naik1, saurabh k singh2, sahil chawhan3. Ammeter working principle and types of ammeter electrical4u. Driving system consists of two electromagnets on which pressure coil and current coils are wounded, as shown above in the diagram. How to test amperage flow usage with an inductive ammeter. Feb 15, 2014 induction type measuring instrument energy meter 1. Moving ironelectrodynamo meter and induction typeextension of range.
Sep 15, 2014 an ammeter is used to measure the current flows through the circuit. If an ammeter is of dc type, then it has polarity signs on it for ensuring appropriate connection for an upscale indication. Nov 30, 2014 this type of wattmeter works on the principle of torque production by induced currents in a short circuited secondary circuit. Induction motor is one of the most important motor used in industrial applications. Induction type siqgle phase and three phase energy meter, compensation. Always connected in series with the circuit and carries the current to be measured. Disadvantage is that you cannot measure small currents and wires must not be close together because the field around adjacent wires influences the meter readings. Short cut notes rapid fire notes best theory of measurement and instrumentation, electrical engineering multiple choice questions objective type questions, mcqs, with question and answers, download free pdf, electrical engineering, multiple choice questions, objective type questions, electrical engineering short notes, rapid fire notes, best theory.
Collections of diagram of induction type wattmeter. Basic effects of electromechanical instrumentsammeter and voltmetermoving coil. In electromagnetic movements, this will be the fullscale deflection current necessary to rotate the needle so that it points to the exact end of the indicating scale. This is a very useful tool for diagnosing problems in the electrical system that cannot be found easily by any other method. Ammeters and voltmeters are classed together because the principle involved is same. Part6 mcq in electrical measurements and instrumentation 1 a 10mhz cro has. You can check amperage by wiring an ammeter into the circuit also called inseries, or you can detect current by clamping an induction meter around a wire. When the wattmeter is connected in the circuit to measure a. The two fluxes produced by the magnets induce eddy currents in the aluminium disc. Jan 15, 2020 current is the measure of the flow of electricity through a circuit in amperes amps by a device known as an ammeter.
The principle of working and construction of induction type meter is very simple and easy to understand thats why these are widely used in. Examples of such instruments are voltmeter, ammeter and wattmeter etc. Moving iron ammeters and voltmeters there are two basic forms of these instruments. This was an induction loop ammeter, not the shunt type ammeter that was used in 66 models and beyond. It has a few decisive advantages like sturdy construction and very long circular scale around 300. Oct 23, 2017 dynamometer type wattmeter electrical technology duration. This current flowing through the coil produces the desired deflecting torque.
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