Best motor type for adjustable 1–24 rpm clay mixer: AC with VFD or DC with controller?

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#1 21666712 22 Feb 2013 12:10

hadi makoui hadi makoui

Anonymous

Post #1
21666712 22 Feb 2013 12:10

Hi,
I need a motor to put it to work on a clay mixer. Rotational speed of the blender must be adjustable between 1 and 24 rpm.
Using a gearbox I can reduce 1420 rpm of 1.5 hp single phase ac motor to 24 rpm but to reduce it up to 1 rpm I have to reduce motor speed without decrease of output power and torque of the gearbox. I have seen a video of a mixer in witch the operator just turns a switch to the right and left and easily that changes rotational speed of motor. any idea how can I do that? Should I use DC or AC motor to have a cheep,user friendly and simple system.
thanks.

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#2 21666713 22 Feb 2013 12:35

Pothuganti Balaiah Pothuganti Balaiah

Anonymous

Post #2
21666713 22 Feb 2013 12:35

I think,a AC motor grinder,one that is used in floor mill for grinding wet rice for making dosa or idle must be right choice for ur clay works..i think a light dimmer circuit can reduce the speed of motor..

Dear experts what u say...
#3 21666714 22 Feb 2013 15:46

Peter Evenhuis Peter Evenhuis

Anonymous

Post #3
21666714 22 Feb 2013 15:46

A light dimmer is for light not for speed control.
But in near all power tools you have a proper speed control or you use one from home cooling fan.

That all incase you want to keep it simple.

but be a where i understand that money is all ways a problem, but please do not for get safety.
if you have clay you have water and water and electricity do not mix but do kill people.
#4 21666715 23 Feb 2013 07:10

David Adams David Adams

Anonymous

Post #4
21666715 23 Feb 2013 07:10

Get yourself a 3 phase motor and then use a variable frequency drive to control the speed. VFD will give you full torque at what ever speed you need - within reason of course.
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#5 21666716 27 Feb 2013 16:22

Frank Bushnell Frank Bushnell

Anonymous

Post #5
21666716 27 Feb 2013 16:22

For an AC motor, the solution is a triac motor speed controller.
For a DC motor, the solution is a PWM DC motor speed controller.
Both are cheap and easily available.
What is the voltage of your main supply ?
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#6 21666717 01 Mar 2013 05:10

hadi makoui hadi makoui

Anonymous

Post #6
21666717 01 Mar 2013 05:10

I'm considering either 1 phase 220v 50 hz or a 3 phase motor and using it with 1 phase 220v 50hz supply.
Is it possible to use PWM with AC motors,if not why?
thanks
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#7 21666718 01 Mar 2013 06:45

Frank Bushnell Frank Bushnell

Anonymous

Post #7
21666718 01 Mar 2013 06:45

A triac AC motor speed controller uses a form of PWM, chopping up the AC waveform in the same manner as the DC PWM controller.

Single phase AC equipment is generally cheaper and more easily available.

For example, to control a single phase AC motor up to 2kW (2.7 hp)
(Copy and paste this in your browser address window):

http://www.ebay.co.uk/itm/2000W-Adjustable-50...ial_Automation_Control_ET&hash=item5d39c6a7f1

This is exactly the same kind of electronic circuit that controls the speed in a mains electric power tool. If you can buy a mains power tool speed controller, you can just plug it in and start working.

As Peter has said, keep all your electrical circuits dry, well proofed against water.
#8 21666719 07 Mar 2013 13:37

Mark Harrington Mark Harrington

Anonymous

Post #8
21666719 07 Mar 2013 13:37

Hi

See the following article from velleman Kits
http://www.esr.co.uk/manuals/k2636.pdf

or consider this link as well
http://www.orientalmotor.com/products/ac-motors/msc-1.html

or this link might also be usefull to you
http://sg.renesas.com/media/applications/motor_control/triacdrive/TriacAppnote.pdf

or

http://www.8051projects.net/news-i188-single-...ac-motor-speed-controller-project-report.html

or

http://www.nxp.com/documents/application_note/APPCHP3.pdf

or

For in depth explanations see the following

http://www.ab.com/support/abdrives/documentation/fb/1024.pdf

Finally for 3 phase motor control see this link

http://cache.freescale.com/files/dsp/doc/app_note/AN1958.pdf
#9 21666720 07 Mar 2013 13:47

Mark Harrington Mark Harrington

Anonymous

Post #9
21666720 07 Mar 2013 13:47

Not altogether correct Peter they can be used for motor control see below for link that explains this in more detail

http://www.mouser.com/catalog/specsheets/stevalill004v1.pdf
#10 21666721 07 Mar 2013 13:55

Mark Harrington Mark Harrington

Anonymous

Post #10
21666721 07 Mar 2013 13:55

For DC motor speed controll see the following
http://www.hitex.com/fileadmin/img/download/B...PID_Control_With_The_Infineon_C167_Family.pdf

or you could use for dc motor control HIP4080AIP "Interesting !" or if you like one of the first projects I put together quite some time ago which you can re apply to DC motor control with code pcb layouts etc plus digital readout

By the way this includes memory for storing last set value and recalling last set value i wrote a small bit of VB code for rapid application development so I could work out how to move up the scale and down the scale which I used VB6 for but its all there for you if you want to use it (feel free)

Its original intention was for dimming interior lights in cars ideally suited for these long vehicles for the show offs You know the cars I mean, those long things that look like sausages you can drink in and get very drunk in the rear of the vehicle , normally driven by chauffeurs , the uh bald headed type “Britain’s well ard men, you know well ard !! “ the drivers of these vehicles typically wear huge rings and lots of metal chains around there necks and have to have a kidbney belt to stand up straight when they get out of the car due to the weight of the gold , They are a bit like Rocky blab alot boa without the hair The Long Ford’s etc they use for weddings but alas hum ha no interest was shown typical !! I’m really thoroughly jarred off

Any way heres the link

http://www.harrington.force9.co.uk/Projects/LightsController/LightsController.htm
#11 21666722 08 Mar 2013 15:37

hadi makoui hadi makoui

Anonymous

Post #11
21666722 08 Mar 2013 15:37

Hi;
Thank you for sharing all these . I'm new on this area but your post is quite helpful.
thanks again.
#12 21666723 08 Mar 2013 16:23

Mark Harrington Mark Harrington

Anonymous

Post #12
21666723 08 Mar 2013 16:23

Welcome Hadi
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Topic summary

✨ The discussion addresses the choice between AC and DC motors for an adjustable-speed clay mixer requiring 1–24 rpm. A 1.5 hp single-phase AC motor running at 1420 rpm can be geared down to 24 rpm, but achieving 1 rpm requires motor speed reduction without torque loss. For speed control, single-phase AC motors can be managed using triac-based speed controllers, which modulate the AC waveform via phase angle control (a form of PWM), suitable for motors up to about 2 kW. These controllers are inexpensive, user-friendly, and commonly used in power tools. DC motors require PWM DC motor speed controllers for efficient speed regulation. Three-phase AC motors combined with variable frequency drives (VFDs) offer precise speed control with full torque across a wide speed range but may be more complex and costly. Safety considerations emphasize protecting electrical components from moisture due to the wet clay environment. Several technical resources and application notes on triac controllers, VFDs, and DC motor control circuits were shared to assist in implementation.
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FAQ

TL;DR: Need 1–24 rpm? “Rotational speed … must be adjustable between 1 and 24 rpm.” Use a geared drive plus either a VFD on a 3‑phase motor or a proper AC/DC controller, not a lamp dimmer. [Elektroda, hadi makoui, post #21666712]

Why it matters: This FAQ helps makers choose a safe, torque‑capable, low‑speed drive for clay mixers.

Quick Facts

Target: 1–24 rpm from a 1.5 hp, ~1420 rpm motor requires heavy reduction and electronic control. [Elektroda, hadi makoui, post #21666712]
3‑phase motor + VFD: “full torque … within reason,” ideal for low‑speed mixing. [Elektroda, David Adams, post #21666715]
Single‑phase AC: use a triac motor speed controller; tool‑type modules are common and low‑cost. [Elektroda, Frank Bushnell, post #21666716]
Example single‑phase controllers exist up to about 2 kW for simple retrofits. [Elektroda, Frank Bushnell, post #21666718]
Safety: water and electricity don’t mix—use proper enclosures and keep circuits dry. [Elektroda, Peter Evenhuis, post #21666714]

What motor type works best for a clay mixer at 1–24 rpm?

Use a 3‑phase induction motor with a VFD plus a gearbox. The VFD gives controllable speed and strong low‑speed torque. Add mechanical reduction to hit 1–24 rpm without stalling. “VFD will give you full torque … within reason.” [Elektroda, David Adams, post #21666715]

Can I slow an AC motor with a light dimmer?

Do not use a household lamp dimmer. It is not designed for motor loads, has poor control, and creates safety risks. Use a purpose‑built motor controller instead. “A light dimmer is for light not for speed control.” [Elektroda, Peter Evenhuis, post #21666714]

How do I control speed on a single‑phase AC motor?

Use a triac‑based AC motor speed controller. These phase‑angle controllers are common in power tools and available as plug‑in modules, offering simple, low‑cost adjustment. [Elektroda, Frank Bushnell, post #21666716]

How do I control speed on a DC motor?

Use a PWM DC motor speed controller. PWM varies the average voltage while keeping efficiency high, giving smooth, wide‑range speed control and good torque. [Elektroda, Frank Bushnell, post #21666716]

What is a VFD and why choose one here?

A Variable Frequency Drive changes the frequency and voltage to a 3‑phase motor, letting you dial speed and maintain torque. It’s well‑suited to mixers needing low, adjustable rpm. “Full torque … within reason.” [Elektroda, David Adams, post #21666715]

Will a triac controller keep torque at 1 rpm on an induction motor?

Not reliably. Phase‑angle control reduces voltage and torque, which can cause stalling at very low speeds. For strong torque near 1 rpm, use gearbox reduction plus a VFD. “Within reason” applies at very low rpm. [Elektroda, David Adams, post #21666715]

Is PWM the same idea as chopping AC with a triac?

Yes, in principle. A triac controller “chops” the AC waveform similar to PWM on DC, altering effective voltage to change speed. [Elektroda, Frank Bushnell, post #21666718]

What gearbox ratio do I need from 1420 rpm to 24 rpm?

Approx. 59:1 (1420 ÷ 24 ≈ 59). Add more reduction for a 1 rpm minimum while keeping the motor in an efficient speed range. [Elektroda, hadi makoui, post #21666712]

What mains supply should I plan around?

Design for single‑phase 220 V, 50 Hz if that’s your available supply. You can also consider a 3‑phase motor with appropriate control hardware. [Elektroda, hadi makoui, post #21666717]

Are off‑the‑shelf single‑phase speed controllers available for retrofits?

Yes. Example tool‑style controllers exist for single‑phase AC motors up to about 2 kW and can be used in simple builds. [Elektroda, Frank Bushnell, post #21666718]

What’s the cheapest path to variable speed right now?

For simplicity and low cost, use a triac AC controller for single‑phase motors or a PWM controller for DC motors. Both are widely available and inexpensive. [Elektroda, Frank Bushnell, post #21666716]

How should I approach safety around wet clay and electrics?

Keep all electrical parts dry and sealed. Use proper enclosures, strain relief, and ground fault protection. Water and electricity together can kill. [Elektroda, Peter Evenhuis, post #21666714]

Can I adapt a power‑tool style controller to my mixer motor?

Yes, many power tools use similar triac speed controls. A compatible module can provide knob‑type adjustment for AC motors. Ensure current rating matches your motor. [Elektroda, Frank Bushnell, post #21666718]

Which controller should I avoid for induction motors?

Avoid plain lamp dimmers. Use controllers designed for motor loads. Dedicated triac motor controllers address phase control, surge, and protection. [Elektroda, Mark Harrington, post #21666720]

How do I set up a simple AC speed control safely? (3‑step How‑To)

Choose a triac motor controller rated at or above your motor’s current.
Mount it in a ventilated, splash‑proof enclosure with strain relief.
Wire line‑in and motor‑out per the module diagram; test at no‑load, then under clay load. [Elektroda, Frank Bushnell, post #21666718]

What power level am I dealing with at 1.5 hp?

About 1.12 kW (1 hp ≈ 0.746 kW). Ensure controller and wiring comfortably exceed this rating plus startup surge current. [Elektroda, hadi makoui, post #21666712]

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