I just feel that Bro' either doesn't understand or won't accept the value of torque/rpm analysis. With a proper set-up the drive motor size (within reason) has no bearing on the power it is outputting. The example I gave was doable by most who post on here and it avoids a $2000 dollar investment in the kit needed to use a rotary sensor.
Having said that I really enjoyed the YouTube links Bro' put on. There's a huge amount of skilled work in reconditioning these big motors. I had always wondered how all those coils were put into a motor.I had a go at rewinding a small motor and I managed to get it looking somewhat like although it never ran satisfactorily.
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Originally posted by Quantum_well View PostThis YouTube guy has the right idea. There's no way most of you lot are getting accurate results with drive motor current and it's all too easy to fool yourselves.
https://youtu.be/1Pd0lUKWe7o
I wonder if the video will pass bistander scrutiny?.
I like this guy. He does a nice job. He flies past the dynamometer trunion bearing mounting pretty fast. But I watched his other vid and he covers it in detail. I don't see where he balances (static calibration) the torque arm system, but overall he's got a good system.
Another thing comes to mind. He treats the dynamometer as a motor with his power supply. Realize it is actually a generator so needs an electrical load to apply torque opposing rotation and dissipate power. I've used shunt wound DC motors with an adjustable power supply on the field and big low ohm resistor across the armature. A PMDC motor will work for the dynamometer needing no power supply but using a variable resistance across the armature.
His other vid. * Nice vids from this guy. I approve.
bi
*Hmmm. Edit. Just checked video link. Looks to be same as supplied by q_w. I must have somehow skipped part the first time I viewed it. Oh well.Last edited by bistander; 05-30-2021, 03:05 PM.
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This YouTube guy has the right idea. There's no way most of you lot are getting accurate results with drive motor current and it's all too easy to fool yourselves.
https://youtu.be/1Pd0lUKWe7o
I wonder if the video will pass bistander scrutiny?.
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Originally posted by bistander View Post
Notice the precision popsicle stick shims.
Screenshot_20210529-001620-283.png
Think his core is dead nuts to +/- .001"?
(Images previously posted on this forum by BM.)
bi
What we need is a small record player motor that teeters on the edge of barely turning the rotor BEFORE cogging coils are added one after another. Then you can see slight increases where on a motor this large you might need a 30" rotor with 10-20 one pound magnets to reach this limit. 6.5a X 120v = 780 watts. I run a rotor this size on 10 watts.
And that coil holder bolt will giggle like a Palm tree.
Last edited by BroMikey; 05-29-2021, 10:15 PM.
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Notice the precision popsicle stick shims.
Screenshot_20210529-001620-283.png
Think his core is dead nuts to +/- .001"?
(Images previously posted on this forum by BM.)
bi
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If anybody is interested here is the small school boy machine running at 1750 rpm's showing a 294 hertz or 294 divide by 10 magnet pole X 60 sec to get RPM of of hertz = 1750. Very slow where the big machine uses a 10" rotor with 20 magnet poles and runs at over 4000 rpm.
Last edited by BroMikey; 05-29-2021, 09:42 PM.
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Originally posted by bistander View PostScreenshot_20210527-234008.png
Looks precision?
Please go back to your thread and post the results you've obtained with your machine.
bi
http://flyer.thenetteam.net/3battery...trandcoil4.jpg
Last edited by BroMikey; 05-29-2021, 09:47 PM.
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Screenshot_20210527-234008.png
Looks precision?
Please go back to your thread and post the results you've obtained with your machine.
bi
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Originally posted by bistander View PostThis guy complaining about lack of precision and methods in my test rig posts up an example of his work here:
Take a look and tell me where he gets off ranting at me.
bi
Thanks for asking. See other video's on the 20 magnet rotor setup, not so easy as I make it sound. If alignment is off you may reset all of the locations which I did do a few times till I liked it. Most people just shell out a few grand to the machine shop. Machine shop fees are $75 per hour. Now if I was made out of money like another guy I know.......
The 4th aspect of rotor design is balancing also explained. which is a completely different field of study called mechanical design, not to be short changed. All fields of study hold merit.
Rotor magnet adjustments explained.
Last edited by BroMikey; 05-28-2021, 05:27 AM.
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This guy complaining about lack of precision and methods in my test rig posts up an example of his work here:
Originally posted by BroMikey View Post
bi
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Originally posted by bistander View PostUsing four magnets, all N facing, on the rotor, at 4800 RPM constant
a magnetic circuit using PMs and wide air gaps will fringe and compensate for a great deal of misalignment. It is not like magnetic flux needs straight line pathways.
bi
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Using four magnets, all N facing, on the rotor, at 4800 RPM constant, adding 6 cores, one at a time, showed an increase in prime mover power of 2 watts each. 13 watts was required with no cores near the rotor and 7 watts at zero RPM (PWM energized set at zero duty cycle).
While a single strand conventional wound coil may show some loss when unconnected, I doubt it can be detected at these frequencies with commonly available instruments.
The test fixture can mitigate cogging using an opposition/neutralization magnet at 180°, using 4 or 12 magnets on the rotor, indicating the desired response. Neither the rotor nor stator core or magnet are precision located but are adequately positioned to demonstrate the desired effects. Again, the flux in a magnetic circuit using PMs and wide air gaps will fringe and compensate for a great deal of misalignment. It is not like magnetic flux needs straight line pathways.
bi
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Originally posted by pmgriphone View Post
Exactly. A coil has capacitance and inductance at the same time. So even if it is not connected externally, there is still an internal circuit where current flows and this current will impact the prime mover, especially if it is a resonant circuit where lots of energy piles up (thus high voltage on the capacitance of the coil (dielectric energy) and thus high current when this converts from dielectric field 0.5*C*V^2 into magnetic field 0.5*L*I^2)
Bye can not show the single opposition test because his rotor will not respond the same at 180 degrees. or 90 degrees. He has 4 rotor magnets randomly placed.
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