Speed control of hysteresis synchronous motors.

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gkh6
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Speed control of hysteresis synchronous motors.

Post by gkh6 » 01 Jul 2019 20:38

Hi all. I am trying to figure out how control a motor from a Ampex reel to reel with a small invetek AC drive. I think I should be able to do it. Has anyone else tried to "repurpose" one of these motors?

JoeE SP9
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Re: Speed control of hysteresis synchronous motors.

Post by JoeE SP9 » 01 Jul 2019 21:43

The rotational speed of almost all AC motors is determined by the frequency of the AC line signal.

gkh6
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Re: Speed control of hysteresis synchronous motors.

Post by gkh6 » 01 Jul 2019 21:55

I agree, By varying the frequency to the motor I should be able to control the speed no? I just dont understand how to apply this drive: https://www.invertekdrives.com/client-u ... _Guide.pdf to the motor. Has anyone tried this? I would have to parallel the windings and I think I would need to remove the capacitor from the circuit.

Coffee Phil
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Re: Speed control of hysteresis synchronous motors.

Post by Coffee Phil » 01 Jul 2019 23:12

You are correct that the speed of an AC synchronous motor is determined by the frequency, however you can't put the windings in parallel. These are either two phase or three phase motors. The capacitor is to shift phase between the windings.

Phil
gkh6 wrote:
01 Jul 2019 21:55
I agree, By varying the frequency to the motor I should be able to control the speed no? I just dont understand how to apply this drive: https://www.invertekdrives.com/client-u ... _Guide.pdf to the motor. Has anyone tried this? I would have to parallel the windings and I think I would need to remove the capacitor from the circuit.

Dimal
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Re: Speed control of hysteresis synchronous motors.

Post by Dimal » 02 Jul 2019 07:09

G'day... :)

As per attached copy from Manufacturer's Installation Manual, you need to take note of the section highlighted and the section above too probably. I doubt that the motor you're referring to would satisfy the requirements and would risk burning out the Start Winding at least. :(

Mal.
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gkh6
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Re: Speed control of hysteresis synchronous motors.

Post by gkh6 » 02 Jul 2019 23:21

I seem to have overlooked that. I think I'm just going to go the DC route. Thank you all for your input. It is much appreciated.

Gavin

rgonsalves
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Re: Speed control of hysteresis synchronous motors.

Post by rgonsalves » 20 Nov 2019 00:01

I am looking for a solution for my Empire Troubadour 598 III turntable. It is a belt driven unit with a hystersis synchronous motor that drives the platter by a belt. I have tried every possible belt size sold for empire turntables but my unit still runs 1 rpm too fast. I have been able to get obtain 33 1/3 speed with a smaller belt, but it won't stay on the motor shaft. Is there a unit out there that can be used to reduce or increase the frequency on incoming a/c power that will allow the turntable to run at the proper speed? I am looking for a simple solution.

Thanks,

Bob Gonsalves

Alec124c41
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Re: Speed control of hysteresis synchronous motors.

Post by Alec124c41 » 20 Nov 2019 01:49

The relevant dimension of the belt is the thickness, not length or width. A thinner belt of the correct length and width would be what you are looking for.
If the motor draws 3 watts or less, you could use the Music Hall Cruise Control 2, or a similar regenerative power supply. This would allow you to control the speed quite accurately.

Cheers,
Alec

LesE
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Re: Speed control of hysteresis synchronous motors.

Post by LesE » 20 Nov 2019 14:28

rgonsalves wrote:
20 Nov 2019 00:01
I am looking for a solution for my Empire Troubadour 598 III turntable. It is a belt driven unit with a hystersis synchronous motor that drives the platter by a belt. I have tried every possible belt size sold for empire turntables but my unit still runs 1 rpm too fast. I have been able to get obtain 33 1/3 speed with a smaller belt, but it won't stay on the motor shaft. Is there a unit out there that can be used to reduce or increase the frequency on incoming a/c power that will allow the turntable to run at the proper speed? I am looking for a simple solution.

Thanks,

Bob Gonsalves
Esoteric Sound True Speed Belt
Esoteric Sound wrote: TRUE SPEED BELT for Empire 498/598/698 Troubador turntables. 31.2 inch circumference. This belt was designed by Esoteric Sound and custom made for us to provide accurate speed. Speed within 0.3% accuracy.
https://www.esotericsound.com/access.htm

KentT
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Re: Speed control of hysteresis synchronous motors.

Post by KentT » 20 Nov 2019 15:48

What LeeE said. This is the only belt I've ever seen work well on an Empire. Empires are very demanding about belt quality (as bad as Thorens is). Cheaping out doesn't work. Nor does the belt last as long.

ralphfcooke
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Re: Speed control of hysteresis synchronous motors.

Post by ralphfcooke » 20 Nov 2019 17:07

Here are a couple of methods that will allow accurate speed control of 2 and 3 phase motors:-

https://www.diyaudio.com/forums/analogu ... ay-41.html
and
https://www.diyaudio.com/forums/analogu ... drive.html

both appear to be very good solutions, but equally both need a certain amount of background knowledge.

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