The torque on each element is proportional to the power being measured by it. It is designed to explain the students, how total power is measured in a three phase circuit using only two wattmeters. 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. To measure single phase power by using three ammeter method. This method can however be used when the load is balanced two. A special meter movement designed especially for power measurement is called the dynamometer movement, and is similar to a darsonval or weston movement in that a lightweight coil of wire is attached to the pointer mechanism. 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. Now reconfigure the above setup to contain an appropriately inserted wattmeter of at least 1 kw rating. Instructions for the use of weston model 310 portable wattmeters. The traditional form of wattmeter is called as dynamometer wattmeter. In electrical engineering, a wattmeter is a device used to measure the amount of electric power in watts in a given circuit. This page describes different methodologies for measuring power in three phase system or simple measurement of threephase power. The two wattmeter method is commonly used on threephase loads or circuits. In 3phase 3 wire circuits an artificial neutral is created through 3 equal high resistances connected in star.
Two wattmeter method 24 for the load balanced or unbalanced. There are three methods in measuring wattage, the one, two and three wattmeter methods. The method is valid for both balanced and unbalanced circuits with either the load or the source unbalanced. 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. This manual covers direct and general support maintenance for wattmeter me82u fig. The following is a mathematical proof of why the two wattmeter method works on a threewire system.
In general, mphase power can be measured by means of m 1 wattmeters. The power shown by wattmeter thus equal to reactive power. Use pdf download to do whatever you like with pdf files on the web and regain control. The voltage terminals of the wattmeters are connected phase to phase. This method uses two pairs of lineline voltages and lineneutral currents to calculate total threephase power.
Connection diagram to measure the threephase power with two wattmeters. Varmeter single phase and polyphase varmeter electrical4u. Instructions for the use of weston model 310 portable. Why two wattmeters are used to measure power in a 3 phase.
Advantages of two wattmeter method free download as word doc. Pdf basics of electrical engineering a text book for. When using the two wattmeter method, it is important to note that the reading of one wattmeter should be reversed if the power factor of the system is less than 0. If the neutral terminal isnt available and the load is only connected to the three phases, than the neutral cant be used to measure the line voltage. The electronic meter displays the readings on an lcd. Electrical circuit analysis 2 textbook is especially prepared for jntu, jntua, jntuk, jntuh university students. Web to pdf convert any web pages to highquality pdf files while retaining page layout, images, text and. Advantages of two wattmeter method electrical engineering. Now the arithmetic sum of both readings of the wattmeters is equal to total reactive power of circuit. When sum of three currents is zero one of the currents can be expressed in terms of other two currents. Two wattmeter method balanced load condition the two wattmeter method is explained, taking an example of a balanced load. The dynamometer wattmeter works on the motor principle. Where there are nonsymmetrical threephase loads or singlephase loads usually connected to fourwire system, it is necessary to measure power on all three phases it is not possible to measure one phase only and calculate the power of total threephase system. The connections of two elements of a 3 phase wattmeter are the same as that for two wattmeter method using two single phase wattmeter.
The current following through the current coil of the. There are three methods for that are normally utilized such as three wattmeters method, two wattmeters method, and one wattmeter method. Electrical circuit analysis 2 pdf free download electrical circuit analysis 2 pdf free download. Measurement of three phase power two wattmeter method. Therefore, a power measurement in a dc circuit can be generally carried out using a voltmeter v and an ammeter a according to one of the arrangements shown in figure 39. They are generally classified by names descriptive of their operating principles. To study the vi characteristics of an incandescent lamp. Power factor in a singlephase circuit can be measured with the wattmeterammetervoltmeter method. Sep 20, 2017 this three phase circuit video covers the following measurement techniques one wattmeter method two wattmeter method. This three phase circuit video covers the following measurement techniques one wattmeter method two wattmeter method. These power measurement instruments are ideally suited to applications where reliable, precise measurements are required, but where. Induction type wattmeter is used to measure the ac only, while the.
It includes instructions for troubleshooting, testing, and repairing of the me82u, and replacing maintenance parts. Electric power is defined as the electric work done or electric energy dissipated per unit time. However, unlike the darsonval or weston movement, another stationary. In two wattmeter method if one wattmeter shows negative reading then wat is reason. Single and three phase wattmeters and energy meters. Power measurement on fourwire system using wattmeter methods. Measurement of three phase power two wattmeter method objectives 1 apply. Can anyone please tell me that how to measure power factor in. Dc and ac electric power measurement electronics hub. Dynamometer type wattmeter electrical technology s. Jan 02, 2019 this page describes different methodologies for measuring power in three phase system or simple measurement of threephase power. Electrical technology playlist unit 1 millmans theorem. It is considered to be far more accurate and faster compared to the analog meters. A variety of wattmeters are available to measure the power in ac circuits.
Vab v vbc v vca v w1 w w2 w pt w free node a b c experiment no. Apply two wattmeter methods to both balancedunbalanced delta loads. In this lesson well examine the two wattmeter method used to measure power in balanced and unbalanced 3 phase ac systems. This method can however, be used when the load is balanced. Measurement of power in a threephase circuit nptel.
Measuring three phase power electronic measurements. In such a case, the leads of one wattmeter may have to be reversed in order to get a positive reading. Wattmeter article about wattmeter by the free dictionary. Measurement of 3phase power using 2 cts and 1 wattmeter. Two wattmeter method 3 phase power measurement youtube. In case of low voltage circuits three potential coils may. Design and hardware implementation of a digital wattmeter. Figure 2 three watt meters connected to monitor power taken by a threephase load. The above picture illustrates the 3 phase 3 wattmeter method of power measurement. Users are not authorized to download it, change it, or charge for. In this paper, design and hardware implementation of a digital wattmeter have been presented with detailed functional description of individual component forming the total circuitry. As shown in figure 318, it consists of a pair of fixed coils, known as current coils, and a moving coil, called the voltage potential coil. In our design, the role of current and potential coil has been served by using ic ade7751.
Two wattmeter method for balance or unbalanced load figure 8, shows how the current coils of the two wattmeters are inserted in any two lines and their potential coils joined to the third line. Nice powerpoint template in a gray color palette will be good choice for presentations on measuring devices, measurement of electrical power, control mechanisms work, etc. As shown in the above figure, the wattmeter has two sets of coils. In this method the current coils of the two wattmeters are inserted in any two lines and the pressure or potential coil of ach joined to the third line. Increase each rheostat to maximum resistance in order to provide a load resistance of approximately 24 drive the apparatus at 60 hz with a variac. Two wattmeters method electrical engineering assignment. First,forthepowerexpendeduponthe fixed coil ofthewattmeter, which is measured alongwith thatof the condenser,and,second,forthechange of phase of the potentialcur. This is the easiest to understand as the power analyzer. This dual wattmeter method can always be applied, even for an inaccessible neutral conductor, phase imbalance, or fluctuating power. These are provided to assist the user in formulating acceptance criteria, determining applications, and for periodic recalibration of the instrument. Can anyone please tell me that how to measure power factor in a single phase connection.
Wattmeters these instruments are similar in design and construction to electrodynamometer type ammeters and voltmeters. Two wattmeter method 24 for the load balanced or unbalanced the wattmeters are from eso 210 at iit kanpur. Three phase circuit tutorial 1 wattmeter 2 wattmeter. In balanced threephase circuit the reactive power can be determined by using one wattmeter. Wattmeter electric power is measured by means of a wattmeter. The authors of this book clearly explained about this book by using.
The two coils are connected in different circuits for measurement of power. In this, we have to prove that the power measured by the two wattmeter i. When using the twowattmeter method, it is important to note that the reading of one wattmeter should be reversed if the power factor of the system is less than 0. Similarly the pressure coil of wattmeter 2 is connected showing same voltage equal to line voltage but differ in phase and this difference in phase is equal to again 90 o. With this product, student can study the power flow in three phase system and correspondingly. Single phase power measurement instruments are made up of rugged electronic instruments designed specifically for use in the harsh electrical environment common to many utility and industrial applications. It is true in a three phase three wire circuit only. The method of measuring two of the currents and two of the voltages is known as the two watt meter method. Nov 05, 2015 introduction to electric power power is defined as the work performed in a specific time or simply a rate of doing work. The fundamentals of threephase power measurements threephase threewire connection two wattmeter method where three wires are present, two wattmeters are required to measure total power.
This document was uploaded by user and they confirmed that they have the permission. This is known as the twowattmeter method of measuring threephase power. Two wattmeter method balanced load condition circuit globe. Wattmeter design dc metering circuits electronics textbook. The current coil is inserted in one line and the pressure coil is connected across the other two lines. In two wattmeter method if one wattmeter shows negative. Nvis 7005 power measurement by two wattmeter method is an exclusive and useful product for electrical laboratories. This is one of the important subject for electrical and electronic engineering eee students. Dont even think of downloading it and uploading to your own channel.
The fixed coils or field coils arc connected in series with the load and so carry the current in the circuit. Measurement of threephase power with the 2wattmeter method. Measurement of power 150910 usaid sarienergy integration. Nov 09, 2016 various methods are used measurement of three phase power inthree phase circuits on the basis of number of wattmeter used. This device is available in a purely electronic form too which is known as digital wattmeter. The load isknown to be inductive and fed from a 208120v groundedwye 3phase4wire system. Measurement of three phase power by two wattmeter method. Power measurement on fourwire system using wattmeter. 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 same line, the third line i. Therefore, a three phase wattmeter has two elements. Wattmeter is a device for measuring real power of a load. Measurement of threephase power with the 2wattmeter.
326 503 1353 937 1408 473 919 1397 498 493 688 704 397 378 381 34 1068 385 386 857 528 305 252 1217 614 545 601 1066 33 81