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Unformatted text preview: 1/30/2011 1 Acknowledgement These handouts and lecture notes given in class are based on material from Prof. Philip Kreins ECE 431 lecture notes. Disclaimer These handouts only provide highlights and should not replace the class notes or course textbook. ECE 431 Electric Machinery Lecture 4 Reactive Power Measurement and Magnetics Review (1) 1 Copyright 2011 Ali M. Bazzi. All rights reserved 1/30/2011 One-Wattmeter Method for Reactive Power Measurement A method using one wattmeter is proposed to measure the three-phase reactive power. The wattmeter must have independent or decoupled voltage and current measurements (Electrodynamometer). Claim: 2 Copyright 2011 Ali M. Bazzi. All rights reserved 1/30/2011 3 3 bc a Q V I = 1/30/2011 2 One-Wattmeter Method for Reactive Power Measurement Proof: 3 Copyright 2011 Ali M. Bazzi. All rights reserved 1/30/2011 3 cos( ) cos( 90 ) but and cos( 90 ) sin( ), then, sin( ) sin( ) 3 3 sin( ) m bc a bc a o ll l o m ll l ll l m ll l P V I V I V I Z P V I V I Z Q P V I Z = = = = = = = = Meters In analog wattmeters, two coils displaced by are used, one for voltage and one for current....
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- Spring '11