Re: Rotary phase converter

the measurements, are they with the motor load applied, or are they looking at the unloaded phase converter? sam mayberry

Hi all > > I am happy to say that I am still in one piece after experimenting with > building a rotary phase converter from a 3-phase 4 H.P. motor, a > single-phase supply, several metres of cooker cable and a stack of motor > 'run' capacitors. I have successfully had the motor pull up to speed > and run on a single-phase supply without blowing anything, but I suspect > that the currents in the motor are out of spec (too high) because of the > heating effects I'm seeing... I await my clip-on ammeter from Screwfix > with bated breath :-) > > The motor I'm using is a Crompton-Parkinson machine with six terminals - > A1, A2, B1, B2, C1 and C2. I've assumed that the same letter is common > to a winding, so that A1 and A2 are just opposite ends of the same > winding. This being the case, I have currently got it connected in > 'star' with the '2' ends of each winding commonly connected but > otherwise 'floating': > > A1 ~ 240 ~ B1 > |\ / > | \ / > | \ / > | \ / > = \/--- A2, B2, C2 > | | > | | > |_____| > C1 > > I'm supplying 240V single-phase across A1 and B1 and have a capacitance > across A1 and C1. I have successfully managed to run my 3-phase pillar > drill from the convertor for about five minutes but the contactor > tripped due to heating from current imbalances. > > I'm seeing the following voltages across the motor for a given > capacitance: > > microfarads A1-B1 B1-C1 A1-C1 > 60 240 489 255 > 70 240 427 184 > 80 240 382 139 > 90 240 349 111 > 100 240 330 93 > 110 240 319 76 > > I have a few questions: > > Has anyone else (reading this group) done this successfully? I know > that it's been done by our American brethren - most of the background > info I found on Google was from US websites - but I'm not sure that they > have quite the same single-phase supply that we do (isolated WRT earth > so that neither Live nor Neutral on their own have a potential WRT earth > springs to mind). > > Should I be feeding just one phase, e.g., A1 to star point (A2)? > > Dare I try this in delta connection? > > My concern is to reduce the high voltage on the B1-C1 leg - I need to > see more or less balanced voltages across all three lines. I'd be > grateful for any tips or help and beer would be indicated for anyone > able to assist :-) > > Regards > > Pete > > PS Need to view this fixed-pitch, 72 chars wide. > -- > Peter Scales
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sammmm
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In message , sammmm writes

Unloaded.

Pete

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Peter Scales

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