V and inverted v curves of synchronous motor

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1. V and Inverted V Curves of Synchronous Motor Explanation. Circuit Diagram V curve and Inverted V curve Kongunadu College of Engineering & Technology V and Inverted V curves of Synchronous Motor

2. Explanation When the excitation of a three phase synchronous motor taking constant power P from constant voltage supply main is varied, the power factor of the motor changes. The power drawn by a 3 phase synchronous motor is given by, P= VIcosφ . Since input power P and supply voltage V are constant, decrease in power factor causes increase in armature current and vice-versa. Kongunadu College of Engineering & Technology V and Inverted V curves of Synchronous Motor

3. Circuit diagram Kongunadu College of Engineering & Technology V and Inverted V curves of Synchronous Motor

4. Hence variation in excitation or in field current causes the variation in armature current and curves drawn between armature current and field current for different power inputs are known as “V – curves”. On the other hand ,if the power factor ( cosφ ) is plotted against the field current, the graph looks like an inverted V. The following figures shows the experimental setup to obtain V curves. The three phase supply is given to stator. The two wattmeter method is used to measure the input power. Here the rheostat is used in the field circuit to adjust the excitation to operate the motor under variable excitation. Kongunadu College of Engineering & Technology V and Inverted V curves of Synchronous Motor

5. V and Inverted V curve Kongunadu College of Engineering & Technology V and Inverted V curves of Synchronous Motor

6. conclusion V curve V curve is the graph showing the relation of armature current as a function of field current in synchronous machines keeping the load constant. The purpose of the curve is to show the variation in the magnitude of the armature current as the excitation voltage of the machine is varied. Inverted V curve The Inverted V Curve is a graph showing the relation of power factor as a function of field current Kongunadu College of Engineering & Technology V and Inverted V curves Synchronous Motor

7. references Kongunadu College of Engineering & Technology V and Inverted V curves Synchronous Motor S.No Book s / Web Sources 1 A.E. Fitzgerald, Charles Kingsley, Stephen. D. Umans , ‘Electric Machinery’, Tata Mc Graw Hill publishing Company Ltd, 2003. 2 D.P. Kothari and I.J. Nagrath , ‘Electric Machines’, Tata McGraw Hill Publishing Company Ltd, 2002. 3 P.S. Bhimbhra , ‘Electrical Machinery’, Khanna Publishers, 2003. 4 M.N.Bandyopadhyay , Electrical Machines Theory and Practice, PHI Learning PVT LTD., New Delhi, 2009. 5 K. Murugesh Kumar, ‘Electric Machines’, Vikas Publishing House Pvt. Ltd, 2002. 6 Syed A. Nasar , Electric Machines and Power Systems: Volume I, Mcgraw -Hill College; International ed Edition, January 1995. 7 J. Ganavadivel , ‘Electrical Machines II’, Anuradha publications, Fourth edition, 2015. 8 U.A.Bakshi & M.V.Bakshi , ”Electrical Machines II,” Technical Publications, Second revised edition, 2016. 9 Google and Wikipedia