Quote:
Originally Posted by e*clipse
Ok,actually this question applies to any 3 phase motor: The ORNL test said that the BEMF was averaged line to Neutral for the three phases. Assuming a wye connected motor (the MGR is wye connected) how do you find the neutral? I've looked for a common connection point, and can't find it, even when I took the motor apart. Also, if it is line to neutral, isn't that just the Vdrop of one phase??
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L - N can be a theoretical measurement. If your three phase transformer is Y connected, then there really is a neutral point and you can measure to it. If ORNL used an isolation transformer between their controller and the motor (not a normal method, but I've seen it used) then a 460V controller can boost up the output voltage to say 600V. If the transformer is Delta-Y, then the output voltage could be measured at the transformer terminals, Line to neutral.
Each phase is measured line to neutral, so it's the measurement of each .. I guess. Line to line measurements is OK when you have sine waves. When you use pulsed output from a controller, the waveform does NOT look like a sine wave until you put the motor/load on the output terminals. But the line to neutral doesn't really look much better ...
