I tried to imagine 8 phase on an oscsillyscope and got seasick.
2 months ago
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How I solved it, is imagining 8 numbered Points on a circle (similar to a clock) and imagining what change I would have to make to change direction. The simplest answer is mirroring. If I align the mirror axis such that it touches the top and bottom points, it leaves them unchanged but there are still 3 points on each side that need to be mirrored, which makes 6 total.
2 months ago (edited) | 77
No paper needed. For an n-phase motor: If n is odd, the number of wire wires that need to change positions is n-1. If n is even, then two windings on opposite sides can remain while others must change, so n-2.
2 months ago | 5
No idea. I didn't even know phases went that high!😂
2 months ago
| 96
Had to answer this question in my advanced motor control class and that's the only reason I remember. Thanks, associate's degree!
2 months ago
| 6
I am a professional electrician with 30+ years of experience who now does EL engineering on medical projects without a PE, and you just managed to ask the least interesting electrical question I could imagine! Congrats!
2 months ago
| 0
Yay, I got it right! I usually don't know the answer to these questions, but i always appreciate them since it gives me an opportunity to learn more.
2 months ago
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Just think of symmetries in phase space! The phases are evenly distributed on a circle. To change the direction of the motor, we need to mirror the points across a line passing through the origin. We're looking for the maximum number of points on this line (the points on the line will not be affected by the mirroring, so the voltages will be the same, no need to rewire). For an odd number of phases, at most one point may be on the line (so n-1 phases need to be rewired). For an even number of phases, 2 points can be on the line (so n-2 phases need to be rewired).
2 months ago (edited)
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It depends on whether the sparky wired them all up with black wire and didn't label them then peeled the winding layout label off the enclosure.
2 months ago | 2
I have spent the past four days on this problem, on and off, trying to imagine how they would reverse order, i tried visualising it with 8 wave graphing calculators, drawing it on papper with a 12 colour pen set, trying to seeing if i could get the right permutation for a full reverse,getting no where, fretting over this, but now this popped up again and I just six on a whim and it was right
2 months ago
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2, 4 ,6, 8!! Who do we appreciate?!!! BigClive!! BigClive!! yyyYyYyYYayyyyy BigClive!!! 👏👏👏
2 months ago
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In Uk we only have 6 wires a 3 phase motor is connected either in star or delta the star connection is sometimes called the low voltage and delta high voltage on small motors on big motors over 10kw they are started in star and then change over to delta once motor is up to speed In that case by changing just 2 phase connection it will change direction ie swap L1 & L2 or swap L2 & L3 or swap L1 & L3
2 months ago | 3
I just looked at it as 4 phases with 4 180 degree out of phase to its pair. Keeping 1 pair as is you would need to change the order of the other 6 (3 pairs)
2 months ago
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Caught me out there. All modern motors are 3 phase, windings can be multiples of 3 to give more speed, like 6, 9, or 12 coils. Never seen an 8 phase motor, it would need a special supply to run. Steppers & other types use 4,6 or 8 poles. I have a 12 pole servo here somewhere :)
2 months ago | 7
Unlike some motor types (like certain single-phase motors), you don't need to make complex wiring changes or adjustments to capacitors. Simply swapping any two of the eight phase wires is enough to change the rotation
2 months ago
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It depends on the location of magnets and type of motor, from none (starting direction only) to eight (optimized for specific direction, maximum efficiency).
2 months ago
| 0
In 3d graphics if you swap the order of any two vertices in a triangle you also reverse its winding order (and thusly it will change from a "front" face to a "back" face or vice versa) Never connected that to motors but it makes sense since theyre both 3s
2 months ago
| 15
bigclivedotcom
With a directly powered three phase motor you can swap any two wires to reverse its direction. But what is the minimum number of wires you'd need to swap to change the direction of a similar eight phase motor? You may need a pen and paper to work that out. This question is mainly a hypothetical brain teaser.
2 months ago | [YT] | 676