Three phase circuit tutorial 1 wattmeter 2 wattmeter methods. This is one of the important subject for electrical and electronic engineering eee students. The schematic diagram for the measurement of three phase power using two wattmeter method is shown below. The matter presented here is prepared by the author for their respective teaching assignments by referring the text books and reference books. Fig 1 the two wattmeter method of measuring three phase power. It is designed to explain the students, how total power is measured in a three phase circuit using only two wattmeters. Apply two wattmeter methods to both balancedunbalanced delta loads. The instrument most commonly used for power measurement is the dynamometer.
Mar 11, 2019 in threephase currents, all three pairs of the linetoline voltages have to be measured accurately in order to determine how much power can be consumed by the threewire load. Two wattmeters method balanced or unbalanced load, figs. Jan 22, 2020 the 2 watt meter approach does not work when you have a 4th wire assuming the 4th wire is used for something more than instrumentation. 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 across the same line and the third line. Electrical circuit analysis 2 pdf free download electrical circuit analysis 2 pdf free download. Similarly the reading of wattmeter two is the product of phase current and the voltage difference v 2 v 3.
Electrical power measurement is a method of measuring the power in a circuit, which is expressed in watts. The dynamometer wattmeter works on the motor principle. In all cases, the total power is the algebraic sum of the two wattmeter readings. This paper presents a design to produce a microcontroller based digital wattmeter that measures the magnitude of power consumption of various loads electronic devices connected through it. 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. The three wattmeter method is used to measure the power in this circuit. 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 twowattmeter method of measuring electrical power based on. The connection diagram for twowattmeter method, along with the relevant phasor diagram for balanced load, is described. What are the limitations of the two wattmeter method in a. Simulation based measurement of three phase active, reactive and apparent power by two wattmeter method with labview article pdf available may 20 with 1,615 reads how we measure reads. So two current coils and two wattmeters are sufficient. To study the vi characteristics of an incandescent lamp. The two wattmeter method of measuring threephase power figure 2 shows a wattmeter connected to measure the power delivered to a load and the equivalent circuit connections of the dai to obtain the same result with the metering system.
Figure 12 threephase, threewire, 2 wattmeter method. A discussion on why the twowattmeter method works on a threephase, threewire load. The current coils of the two wattmeter s are connected in series on any two lines and the third line on which no. Solved a calculate the reading of each wattmeter in the. To determine the active, reactive power, and the power factor of a threephase system. Electrical technology playlist unit 1 millmans theorem. Two wattmeter method can be employed to measure the power in a 3 phase, 3 wire star or delta connected balanced or unbalanced load. As shown in the above figure, the wattmeter has two sets of coils. This is known as the twowattmeter method of measuring threephase power. Soviet industry produces portable laboratory dynamometer wattmeters in efficiency classes 0. Jan 11, 2015 the three line voltages are 220 v and the current in each of the three line wires is 8 a.
Nov 09, 2016 various methods are used measurement of three phase power inthree phase circuits on the basis of number of wattmeter used. To perform short circuit test on a single phase transformer. Wattmeters article about wattmeters by the free dictionary. Obtain a second wattmeter and reconfigure the instrumentation to measure load power using the 2 wattmeter method. A discussion on why the twowattmeter method works on a threephase, three wire load. This three phase circuit video covers the following measurement techniques one wattmeter method two wattmeter method. In this lesson well examine the two wattmeter method used to measure power in balanced and unbalanced 3 phase ac systems. Mar 17, 2017 a calculate the reading of each wattmeter in the circuit shown in fig. Enter your email below to receive free informative articles on electrical. There are three methods for that are normally utilized such as three wattmeters method, two wattmeters method, and one wattmeter method.
The value of z b verify that the sum of the wattmeter readings equals the total average power delivered to the. Why two wattmeters are used to measure power in a 3 phase. Measurement is an act or the result of comparison between the quantity and a predefined standard. Introduction describes the features of the 43 wattmeter, lists equipment supplied and optional equipment, and provides powerup instructions. There are various methods for measuring power such as single and two wattmeter methods etc. Any one of the 3 phases can be used as a reference. This method is commonly used for the power measurement in the 3 phase circuits. Two wattmeter method 3 phase power measurement youtube. This device is available in a purely electronic form too which is known as digital wattmeter. In threephase currents, all three pairs of the lineto. The device consists of a pair of fixed coils, known as current coils, and a movable coil known as the potential coil the current coils are connected in series with the circuit, while the potential coil is connected in parallel. The two wattmeter method is used to measure the power delivered to the unbalanced load in problem 11. Measurement of power in a threephase circuit nptel. 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.
Determine the power factor of the load and the linecurrent. For star connected load clearly the reading of wattmeter one is product of phase current and voltage difference v 2 v 3. Our aim is to measure th e th ree p hase active, reactive, apparent pow er with the help of two wattmeter method and it is simulated in labview. In two wattmeter method if one wattmeter shows negative. Connection diagram to measure the threephase power with three wattmeters. The voltage terminals of the wattmeters are connected phase to phase. Pdf design and development of a microcontroller based.
For more free online technical training check out the following. Now we will explain the measurement threephase power measurement using three wattmeter method. Therefore, the power measured by the wattmeter, w 2 is given by the equation shown below. Three wattmeter method is used to measure power in 3 phase, 4wire circuits. Therefore three wattmeters are necessary who each measure the power of one phase.
There are three methods in measuring wattage, the one, two and three wattmeter methods. It is true in a three phase three wire circuit only. The two wattmeter method of measuring threephase power for balanced resistive loads, the wattmeter readings are identical. Here, as the name suggests, only two wattmeter are used. Electrical technology dronacharya college of engineering. 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. In any 3 phase circuit, the current coil cc of wattmeter is connected to one of the phases and the potential coil pc between remaining 2 lines. Current through the current coil of the wattmeter, w 2 is given as. 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.
The method of measuring two of the currents and two of the voltages is known as the two watt meter method. Measurements and instrumentation 2 mark questions answers pdf. The two wattmeter method is commonly used on threephase loads or circuits. The potential coil of each wattmeter is connected between the line wire to which its current coil is connected and the common neutral wire. Three phase circuit tutorial 1 wattmeter 2 wattmeter methods solved problems this. The two wattmeter method, when applied to the balanced loads, yields interesting results. Yes, one can measure reactive power using wattmeter. Jun 22, 20 for the two wattmeter method balanced load, you will have a high and low meter reading that correspond to the value of bar angle of your line current. Jan 02, 2019 this page describes different methodologies for measuring power in three phase system or simple measurement of threephase power. Electrical circuit analysis 2 textbook is especially prepared for jntu, jntua, jntuk, jntuh university students.
Please feel free to contact any of us at ohio semitronics, inc. This method can however, be used when the load is balanced. The load isknown to be inductive and fed from a 208120v groundedwye 3phase4wire system. Measurement of three phase power two wattmeter method. In these, two wattmeter is cost effective, time saving measurement of three phase power. Configure the dmms to measure the three load voltages relative to the rheostat common point o. Nov 29, 2014 the traditional form of wattmeter is called as dynamometer wattmeter. The total power consumed by a balanced load can be found by using two wattmeters figs. Ferrodynamic and, less frequently, induction, thermoelectrical, and electrostatic wattmeters are also used. Nvis 7005 power measurement by two wattmeter method is an exclusive and useful product for electrical laboratories. However, this method can also be used in 3 phase, 3 wire delta connected load, where power consumed by each load is required to be determined separately.
Theory of operation describes how the 43 wattmeter works and installation describes how to set up and prepare the 43 wattmeter. The method is valid for both balanced and unbalanced circuits with either the load or the source unbalanced. Labview uses graphical language which allows a natural, error free. To measure single phase power by using three ammeter method. If the load is balanced, then p 1 p 2, hence, p t 2p 1. Measurement of threephase power with the 2wattmeter method. This method can however be used when the load is balanced two. Measuring three phase power electronic measurements. To perform an accurate measurement to threephase power installations the power of all three individual phases must be measured. Two wattmeters method electrical engineering assignment. Also, on analog wattmeters, the potential coil carries a needle that moves over a scale to indicate.
Thus, unbalanced loads can give erroneous readings. 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. The following is a mathematical proof of why the two wattmeter method works on a threewire system. 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. The basics of singlephase and threephase ac circuits for. Video lecture on two wattmeter method of power measurement of chapter three phase circuits of subject basic electrical engineering for firstyear engineering students. Measurement of 3phase power using 2 cts and 1 wattmeter. In two wattmeter method, a three phase balanced voltage is to a balanced three phase load where the current in each phase is assumed lagging by an angle of o behind the corresponding phase voltage. Measurement of three phase power wattmeter methods. Our aim is to measure the three phase active, reactive, apparent power with the help of two wattmeter method and it is simulated in labview with two different windows one is its block diagram window shown in figure 2 and results are indicated in front panel window shown in figure 3. Aug 20, 2016 video lecture on two wattmeter method of power measurement of chapter three phase circuits of subject basic electrical engineering for firstyear engineering students.
Two wattmeter method balanced load condition circuit globe. Considering either balanced wye or deltaconnected loads, with the aid of the corresponding phasor diagrams drawn earlier for the phase sequence abc figures 4. Two wattmeter method of power measurement three phase. How to measure reactive power using a wattmeter quora.
Therefore, the power measured by the wattmeter, w 1 is. 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. The traditional analog wattmeter is an electrodynamic instrument. The authors of this book clearly explained about this book by using. Two wattmeter method measurement of three phase power. To measure the single phase power by using three voltmeter method. Go back to three phase power measurements three phase threewire connection three wattmeter method although only two wattmeters are required to measure total power in a threewire system as shown earlier, it is sometimes convenient to use three wattmeters. Now visualize a load connected from that neutral to the v3s phase. Solved a calculate the reading of each wattmeter in. In centrifugal pump applications, electrical power is measured using electrical and mechanicalelectrical methods. Power measurement and the twowattmeter method mcgrawhill. What are the limitations of the 2 wattmeter method of a 3.
V vbc v vca v w1 w w2 w pt w free node a b c experiment no. For dc circuits and purely resistive ac circuits, power is product of voltage and current. Download cbse notes, neet notes, engineering notes, mba notes and a lot more from our website and app. Electrical technology playlist pl5fcg6tovhr493p0pd6m1uyh4yfbjozgj unit 1 millmans theorem. Review of 3phase ac circuits university of nevada, las. In electrical engineering, a wattmeter is a device used to measure the amount of electric power in watts in a given circuit. In general, mphase power can be measured by means of m 1 wattmeters. Threephase power measurement objective to measure power in a threephase circuit using the two wattmeter method. An ac wattmeter has a potential coil and a current coil and responds to the product of the effective voltage. Thus the total power of the circuit is sum of the reading of both the wattmeters. Pdf basics of electrical engineering a text book for. 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.
In this, we have to prove that the power measured by the two wattmeter i. Figure 2 three watt meters connected to monitor power taken by a threephase load. Aug 20, 2016 video lecture on two wattmeter method of power measurement for delta connected lagging pf inductive load of chapter three phase circuits of subject basic electrical engineering for firstyear. Measurement of three phase power by three wattmeters method. Figure 2 shows three watt meters connected to a threephase load with a voltage coil in each connected to a phase line and the other side of the voltage coils connected to a common point x as. Two wattmeter method can be used to measure the power in a 3. In such a case, the leads of one wattmeter may have to be reversed in order to get a positive reading. Using 2 wattmeters as a method of power measuremen. Video lecture on two wattmeter method of power measurement for delta connected lagging pf inductive load of chapter three phase circuits of subject basic electrical engineering for firstyear. Measurement of three phase power two wattmeter method objectives 1 apply. For star connected load clearly the reading of wattmeter one is product of phase current and voltage difference v 2v 3. Request pdf the twowattmeter method of measuring electrical power based on tms320f2812 application of tms320f2812 in the power metering system. Pdf simulation based measurement of three phase active.
With this product, student can study the power flow in three phase system and correspondingly. The current coil of wattmeter 1 is placed in line aa and that of wattmeter 2 is placed in line. A34a34m06 standard practice for sampling and procurement testing of magnetic materials a34003a2011 standard terminology of symbols and definitions relating to magnetic testing a341a341m002011e1 standard test method for. Similarly the reading of wattmeter two is the product of phase current and the voltage difference v 2v 3. Neither wattmeter will read the power through that load. Two wattmeter method of power measurement delta connected. Basic three phase power measurements explained in details.
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