Loads - Scenario 4
This post is inspired by Problem 31, Chapter 14 (Synchronous Motor) of "Textbook-Reviewer in Electrical Engineering, 1st Edition" by Professional Electrical Engr. (PEE) Marcialito M. Valenzona. SITUATION A Y-configured, three-phase synchronous motor draws its rated current of 70 Amperes at a leading power factor of 0.8, with 6.6 kiloVolts at its terminals. If each phase has 2 ohms armature resistance and 20 ohms synchronous reactance, what is the induced electromotive force between the lines? ANALYSIS 1.) One-line diagram: o|---V,load,LN---R,ar,1ph---X,sy,1ph---EMF,load,LN---|> -V,load,LN-> + i,load-> (R,ar,1ph +j X,sy,1ph) + EMF,load,LN-> = 0 EMF,load,LN-> = V,load,LN-> - [ i,load-> (R,ar,1ph +j X,sy,1ph) ] EMF,load,LN-> = V,load,LN-> - [ i,load-> (Z,load,1ph) ] 2.) Armature resistance, 1-phase: R,ar,1ph = 2 ohms 3.) Synchronous reactance, 1-phase: X,sy,1ph = 20 ohms 4.) Load impedance, 1-phase: Z,load,1ph-> = R,ar,1p