Dynamometer type wattmeter construction and working. When a drum or disc of a non magnetic conducting material is placed in a rotating magnetic field, eddycurrents are induced in it. So an induction wattmeter can work on ac circuits only. The current coil having low resistance is connected in series with the load so that it carries the load current. Jun 08, 2019 dynamometer type wattmeter works on very simple principle and this principle can be stated as when any current carrying conductor is placed inside a magnetic field, it experiences a mechanical force and due to this mechanical force deflection of conductor takes place. On this page you can read or download advantages disadvantages of electrodynamic wattmeter in pdf format. Measurement of threephase power with the 2wattmeter. In two wattmeter method the current coils of the wattmeter are connected with any two lines, say r and y and the potential coil of each wattmeter is joined on the. Jul, 2016 the principle of operation of an induction wattmeter is same as that of induction ammeters and voltmeters i. Induction type energy meter essentially consists of following components. This article is only focused about its constructional features and its working. Therefore, this type of meter is also called an integrating meter. Mechanism of rotation of an aluminium disc which is made to rotate at a speed proportional to the. Study of active electric energy meters behavior of induction and electronic types.
Single phase energy meter working of single phase induction. The wattmeter is an instrument for measuring the electric power in watts of any given circuit. Record all nameplate information for the induction motor. A wattmeter is generally used for checking on the power supply of. Refer to the schematic diagram in figure 41 for this description. The basic working of single phase induction type energy meter is only focused on two mechanisms. The fixed coils or field coils arc connected in series with the load and so carry the current in the circuit. Induction type single phase energy meters measure electric energy in kwh var none of the above c 17. A wattmeter is an instrument which consists of two coils called current coil and potential coil.
The two circuits of a wattmeter can be damaged by excessive current. Induction type siqgle phase and three phase energy meter. Download the book into available format new update. Im considering that the question intends to understand about why a watt meterone of two shows a negative reading with induction motor on noload using two watt meter method. The following figure shows the dynamometer wattmeter for measuring the power. The traditional form of wattmeter is called as dynamometer wattmeter. Why is dynamometer type instrument chiefly used as a wattmeter. Measurement of power 150910 usaid sarienergy integration. The principle of operation of an induction wattmeter is same as that of induction ammeters and voltmeters i. Sometimes it is not possible to have access of the neutral point in the star connection. Electrodynamometer type wattmeter in general, a watt meter is used to measure the electric power of a circuit, or sometime it also measures the rate of energy transferred from one circuit to another circuit. The operating principle of the induction type instrument is based on the two pole. To study the construction and working of single phase energy meter and to find.
All electrical parts of the meter are connected to the live mains supply. The two coils are connected in different circuits for measurement of. Why does the wattmeter show a negative reading during the no. It has a few decisive advantages like sturdy construction and very long circular scale around 300. However, it differs from induction ammeter or voltmeter in so. In 3phase 3 wire circuits an artificial neutral is created through 3 equal high resistances connected in star. In case of low voltage circuits three potential coils may. Like in the one wattmeter methord, where the wattmeter is connected in one phase, in the three wattmeter method, it is connected in all 3phases. Study of single phase induction type energy meter or watt. Meter with lag adjustment devices low power factor wattmeter. Jul 25, 2018 which is known as the general expression for the deflecting torque in the induction type meters.
Working of single phase induction type energy meter the basic working of single phase induction type energy meter is only focused on two mechanisms. This type of wattmeter works on the principle of torque production by induced currents in a short circuited secondary circuit. Nov 30, 2014 this type of wattmeter works on the principle of torque production by induced currents in a short circuited secondary circuit. Dynamometer type wattmeter works on very simple principle and this principle can be stated as when any current carrying conductor is placed inside a magnetic field, it experiences a. Induction type wattmeter requirement of phase difference. The resistance in the circuit of the moving coil of a dynamometer wattmeter should be. Induction type wattmeter, watthour meter, and dynamometer type power factor. Electromagnetic wattmeters are used for measurement of utility frequency. Ac watt meter project 20140908 danger only for the non mains isolated versions important warning. If you cannot read the numbers in the above image, reload the page to generate a new one. Measurement of power in 3 phase circuits 3wattmeter method the method is applicable in 3phase 4 wire circuits, works well for balanced and unbalanced loads. Single phase energy meter single phase induction type energy meter is also popularly known as watthour meter.
Jul 17, 2016 principle of induction type instruments. Electromagnetic wattmeters are used for measurement of utility frequency and audio frequency power. Conference paper pdf available september 2006 with 238 reads. Why does induction type wattmeter cant be used for dc. Single phase induction meters are a popular type of meters, because of its wide application as energy meter or watthour meter. Because for dc supply current coil is short and produced flux is very very small then flux linkage with pressure coil is very very small then needle will remains at zer. In all induction meter two fluxes are produce by two different alternating currents on its metallic disc. An 8 bit converter type ad converter makes at least 8000conversionssec. Single phase induction type energy meter consists of four important systems which are written as follows. A movingcoil permanentmagnet instrument can be used as fluxmeter. Three wattmeter method power measurement in an ac circuit is measured with the help of a wattmeter. Two wattmeter method of power measurement two wattmeter method can be employed to measure the power in a 3 phase, three wire star or delta connected the balanced or unbalanced load.
Jun 03, 2017 yes, its right induction type wattmeter cannot work for dc power measurement. The wattmeter is an instrument for measuring the electric power or the supply rate of electrical energy in watts of any given circuit. Questions and answers list eie south central railway. Measurements and instrumentation objective type questions. A wattmeter is used to measure the voltage in an electronic circuit. Nov 29, 2014 the traditional form of wattmeter is called as dynamometer wattmeter. Given the two wattmeter readings from the two wattmeter method used on a threephase balanced load, it is possible to find the tangent of the phase impedance angle as times the ratio of the difference between the two wattmeter readings and their sum, based on equation 4. The movable coil carries a needle which moves over a suitable marked scale. Elevation, side view and plan of the object given below. Im considering that the question intends to understand about why a wattmeterone of two shows a negative reading with induction motor on noload using twowattmeter method. Induction type single phase energy meters measure electric energy in. Mechanism of rotation of an aluminum disc which is made to rotate at a speed proportional to the power. Electrodynamometer type wattmeter construction and working.
Electrostatic type wattmeter for small amount of a. What links here related changes upload file special pages permanent. Single phase induction type energy meter pdf to understand the basic construction and different components of a single phase induction type energy meter. A wattmeter is an instrument which consists of two coils. However, there is one difficulty in this type of connection. Yes, its right induction type wattmeter cannot work for dc power measurement. If you dont see any interesting for you, use our search form on bottom v. It consist of a pair of fixed coils, known as current coils and movable coil known as the potential coil. Construction and working principle of electrodynamometer type wattmeter.
Induction type meters electromagnetic induction inductor scribd. This device is available in a purely electronic form too which is known as digital wattmeter. A wattmeter, measures electric power of the given an electric apparatus or circuit. The basic dynamometer type wattmeter working principle is that when a current carrying moving coil is placed in the magnetic field produced by the current carrying fixed coil, a force is exerted on the coil sides of the moving coil and deflection takes place as shown in figurea. Driving system consists of two electromagnets on which pressure coil and current coils are wounded, as shown above in the diagram. Given the two wattmeter readings from the twowattmeter method used on a threephase balanced load, it is possible to find the tangent of the phase impedance angle as times the ratio of the difference. It is widely use to measure the energy in domestic as well as in industry.
Single phase induction type energy meters is very commonly used to. Dynamometer type wattmeter working your electrical guide. As shown in the above figure, the wattmeter has two sets of coils. Electrodynamometer type wattmeter in general, a watt meter is used to measure the electric power of a circuit, or sometime it also measures the rate of energy. Overview of single phase induction type energy meter. One singlephase wattmeter plus miscellaneous apparatus as needed. Pdf study of active electric energy meters behavior of induction. Wattmeters these instruments are similar in design and construction to electrodynamometer type ammeters and voltmeters. Here we are going to discuss about the single phase induction type in detail. Wattmeter types diy electrical electronics projects. Advantages disadvantages of electrodynamic wattmeter. Now there are two types of induction meters and they are written as follows.
Costeffective and flexible singlephase energy meter. Given below is the picture of single phase induction type meter. The two coils are connected in different circuits for measurement of power. The movable coil carries a needle which moves over a. Dec 07, 2015 on this page you can read or download advantages disadvantages of electrodynamic wattmeter in pdf format. Hence it is the working of induction type energy meter, adjustment of induction type energy meter. Which is known as the general expression for the deflecting torque in the induction type meters.
Because for dc supply current coil is short and produced flux is very very small then flux linkage with pressure. Originally only a tool of professionals there are now many different types of the device available that are both cheap. Type k induction integrating wattmeter by fort wayne ind. Be semesteriii electrical question bank electrical and. The induction type voltmeter operates on the either shaded pole method or on. However, it differs from induction ammeter or voltmeter in so far that separate two coils are used to produced the rotating flux in place of one coil with phase split arrangement. Working of single phase induction type energy meter the basic working of single phase induction type energy meter is only focused on two. If two coils are connected such that, current proportional to the load voltage, flows through one coil and current proportional to the load current, flows through another coil, the meter can be calibrated directly in watts.
The dynamometer wattmeter works on the motor principle. For obtaining the required phase difference published on 10 nov 15. Originally only a tool of professionals there are now many different types of the device available that are both cheap and easy to use and available for home use. Unitiv single phase induction type energy meter driving and braking torques, errors and compensation. Spiral coil springs hold the needle to a zero position. The induction type wattmeter is very simple as construction wise. The controlling torque is provided by spiral springs. The ammeter and voltmeter are both vulnerable to overheating in case of an overload, their pointers will be driven off scale but in the wattmeter, either or even both the current and potential circuits can overheat without the pointer approaching the end of the scale. Electrodynamometer type, induction type, single phase and three phase wattmeter, compensation, energymeters. Now let us look at constructional details of electrodynamometer type wattmeter. You should also make a dc measurement of stator winding linetoline resistance. The reaction between the rotating flux and the eddy current produced by it creates a torque which rotates the disc or drum. A dynamo meter type watt meter is used in various applications where the power or energy transfer has to be measured. An induction type single phase energy meter, as show in fig.