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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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Motor/Generator Analysis
I have measured the DC resistance of a split-phase capacitor run
induction motor's two windings. They are 53 and 35 ohms. The motor is impedance protected. Using the nameplate voltage and current, I have calculated the total impedance at 60 Hz to be 110 ohms. This total impedance is larger than the DC resistance, and so I have algebraically subtracted the resistance from the total impedance to get the inductive impedance, but I don't know if I did that step right: http://users.aol.com/DGoncz/Publicat...orAnalysis.bmp I am pretty sure about R1/R2 = X1/X2 although the winding *are* different colors and could be different gages, but I am not sure about 1/(1/(R1+X1) + 1/(R2+X2)) = 110 ohms I don't know if you can add a resistance and an inductive impedance arithmetically this way. I have seen things like R1 at angle 0 degrees + X1 at angle 90 degrees = sqrt(R1^2 + X1^2) I have invested hundreds of dollars into this motor/generator and while I would like to avoid a rewind, these high resistances make a rewind look inevitable. If I can get a good model, though, I may find a Q1 for some capacitance, and that would indicate, I think, that self-excitation could commence. What is not shown in MotorAnalyis.bmp is R1 in series with L1 and so X1, and R2 in series with L2 and so X2, and R1/L1/X1 in parallel with R2/L2/X2 and the capacitor C. Yours, Doug Goncz Replikon Research Falls Church, VA 22044-0394 |