A wattmeter is an instrument which consists of two coils. If you cannot read the numbers in the above image, reload the page to generate a new one. For obtaining the required phase difference published on 10 nov 15. The traditional form of wattmeter is called as dynamometer wattmeter. Elevation, side view and plan of the object given below. In all induction meter two fluxes are produce by two different alternating currents on its metallic disc. Because for dc supply current coil is short and produced flux is very very small then flux linkage with pressure. 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.
Study of active electric energy meters behavior of induction and electronic types. Originally only a tool of professionals there are now many different types of the device available that are both cheap. In induction type wattmeter both current and pressure coils are required. The resistance in the circuit of the moving coil of a dynamometer wattmeter should be. In case of low voltage circuits three potential coils may. Single phase induction type energy meter consists of four important systems which are written as follows.
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. Jul 25, 2018 which is known as the general expression for the deflecting torque in the induction type meters. Download the book into available format new update. The basic working of single phase induction type energy meter is only focused on two mechanisms.
Working of single phase induction type energy meter the basic working of single phase induction type energy meter is only focused on two. This type of wattmeter works on the principle of torque production by induced currents in a short circuited secondary circuit. Single phase energy meter working of single phase induction. 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. Ac watt meter project 20140908 danger only for the non mains isolated versions important warning. Here we are going to discuss about the single phase induction type in detail.
Why is dynamometer type instrument chiefly used as a wattmeter. The wattmeter is an instrument for measuring the electric power or the supply rate of electrical energy in watts of any given circuit. 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. Nov 29, 2014 the traditional form of wattmeter is called as dynamometer wattmeter.
Measurements and instrumentation objective type questions. 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. So an induction wattmeter can work on ac circuits only. Yes, its right induction type wattmeter cannot work for dc power measurement. Wattmeter types diy electrical electronics projects. Study of single phase induction type energy meter or watt. All electrical parts of the meter are connected to the live mains supply. It has a few decisive advantages like sturdy construction and very long circular scale around 300. Three wattmeter method power measurement in an ac circuit is measured with the help of a wattmeter. Working of single phase induction type energy meter the basic working of single phase induction type energy meter is only focused on two mechanisms. Mechanism of rotation of an aluminum disc which is made to rotate at a speed proportional to the power. 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. Measurement of threephase power with the 2wattmeter. You should also make a dc measurement of stator winding linetoline resistance.
Pdf study of active electric energy meters behavior of induction. Induction type single phase energy meters measure electric energy in. A dynamo meter type watt meter is used in various applications where the power or energy transfer has to be measured. On this page you can read or download advantages disadvantages of electrodynamic wattmeter in pdf format. The principle of operation of an induction wattmeter is same as that of induction ammeters and voltmeters i. Meter with lag adjustment devices low power factor wattmeter. Jun 03, 2017 yes, its right induction type wattmeter cannot work for dc power measurement. Construction and working principle of electrodynamometer type wattmeter.
The fixed coils or field coils arc connected in series with the load and so carry the current in the circuit. Induction type energy meter essentially consists of following components. Spiral coil springs hold the needle to a zero position. Hence it is the working of induction type energy meter, adjustment of induction type energy meter. Jul, 2016 the principle of operation of an induction wattmeter is same as that of induction ammeters and voltmeters i. A wattmeter is an instrument which consists of two coils called current coil and potential coil. Electrostatic type wattmeter for small amount of a. 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. Dynamometer type wattmeter working your electrical guide. Jul 17, 2016 principle of induction type instruments. 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. The current coil having low resistance is connected in series with the load so that it carries the load current. 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. Therefore, this type of meter is also called an integrating meter.
Which is known as the general expression for the deflecting torque in the induction type meters. An induction type single phase energy meter, as show in fig. This article is only focused about its constructional features and its working. In 3phase 3 wire circuits an artificial neutral is created through 3 equal high resistances connected in star. The two coils are connected in different circuits for measurement of. Electromagnetic wattmeters are used for measurement of utility frequency and audio frequency power. Costeffective and flexible singlephase energy meter. Induction type wattmeter, watthour meter, and dynamometer type power factor. The following figure shows the dynamometer wattmeter for measuring the power. Single phase induction type energy meters is very commonly used to.
The controlling torque is provided by spiral springs. Refer to the schematic diagram in figure 41 for this description. Electrodynamometer type wattmeter construction and working. 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. What links here related changes upload file special pages permanent. Sometimes it is not possible to have access of the neutral point in the star connection. The dynamometer wattmeter works on the motor principle. Now let us look at constructional details of electrodynamometer type wattmeter.
It is widely use to measure the energy in domestic as well as in industry. The operating principle of the induction type instrument is based on the two pole. Mechanism of rotation of an aluminium disc which is made to rotate at a speed proportional to the. One singlephase wattmeter plus miscellaneous apparatus as needed. Advantages disadvantages of electrodynamic wattmeter. This device is available in a purely electronic form too which is known as digital wattmeter. Study the construction and working of single phase energy. A movingcoil permanentmagnet instrument can be used as fluxmeter. 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.
The movable coil carries a needle which moves over a. 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. Dec 07, 2015 on this page you can read or download advantages disadvantages of electrodynamic wattmeter in pdf format. 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. The two circuits of a wattmeter can be damaged by excessive current. Dynamometer type wattmeter construction and working. A wattmeter is generally used for checking on the power supply of. 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. The two coils are connected in different circuits for measurement of power. Electromagnetic wattmeters are used for measurement of utility frequency. Now there are two types of induction meters and they are written as follows. It consist of a pair of fixed coils, known as current coils and movable coil known as the potential coil.
Be semesteriii electrical question bank electrical and. The induction type voltmeter operates on the either shaded pole method or on. Questions and answers list eie south central railway. Induction type meters electromagnetic induction inductor scribd. Record all nameplate information for the induction motor. Given below is the picture of single phase induction type meter. An 8 bit converter type ad converter makes at least 8000conversionssec.
Electrodynamometer type, induction type, single phase and three phase wattmeter, compensation, energymeters. A wattmeter, measures electric power of the given an electric apparatus or circuit. When a drum or disc of a non magnetic conducting material is placed in a rotating magnetic field, eddycurrents are induced in it. The induction type wattmeter is very simple as construction wise.
Why does induction type wattmeter cant be used for dc. To study the construction and working of single phase energy meter and to find. Conference paper pdf available september 2006 with 238 reads. Measurement of threephase power with the 2wattmeter method. Type k induction integrating wattmeter by fort wayne ind. 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. The movable coil carries a needle which moves over a suitable marked scale.
Unitiv single phase induction type energy meter driving and braking torques, errors and compensation. Overview of single phase induction type energy meter. However, there is one difficulty in this type of connection. 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. 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. As shown in the above figure, the wattmeter has two sets of coils.
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 is an instrument for measuring the electric power in watts of any given circuit. Why does the wattmeter show a negative reading during the no. Single phase energy meter single phase induction type energy meter is also popularly known as watthour meter. Single phase induction type energy meter pdf to understand the basic construction and different components of a single phase induction type energy meter. Driving system consists of two electromagnets on which pressure coil and current coils are wounded, as shown above in the diagram. However, it differs from induction ammeter or voltmeter in so. If you dont see any interesting for you, use our search form on bottom v. Nov 30, 2014 this type of wattmeter works on the principle of torque production by induced currents in a short circuited secondary circuit. Induction type single phase energy meters measure electric energy in kwh var none of the above c 17. The reaction between the rotating flux and the eddy current produced by it creates a torque which rotates the disc or drum. 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.
1053 953 550 1398 107 1337 1393 736 32 216 278 583 957 399 401 234 1070 1251 1456 1106 364 173 1539 407 679 716 470 17 409 950 514