Thread: Speed control alternative to VFD??

I know VFD are popular converting 3ph motors to 240V and you get the bonus of speed control. If you already have a 240V motor and rather than using stepped pulleys is there an easy electronic way to have speed control??


I saw this and thought it sounds like a good plug an play option.
productLarge_13403.jpg

Here is the blurb:

240V 10A Deluxe Motor Speed Controller Kit

Ref: Silicon Chip Magazine May 2009
Another motor speed controller? This one is a little bit different and offers boutique performance in the world of speed controllers. While the simpler circuit of our other motor controller kit (KC-5477) will control a motor's speed fairly well, it can't provide maximum speed as the output voltage is limited to about 160VAC maximum. It also doesn’t provide great speed regulation and torque at low speeds. The deluxe kit addresses all these issues and provides full speed control from near zero to maximum RPM, good speed regulation under load, very smooth low speed operation and is rated for devices up to 2300W. It also has soft-start to eliminate the "kick" from larger power tools and has interference suppression filtering, fuse protection and over-current protection with limiting. This kit really is the duck's guts for motor speed control. The case has the tricky cutouts pre-machined, but a little bit of extra drilling is required to complete the project.

• Overlay PCB and all components.
• Machined case included
Note: This project is designed for brush type motors and is not suitable for induction motors or shaded pole motors.
Note: Not for use with induction motors. See KC-5509 for controlling induction motors.

The most limiting thing is that it's limited to universal or brush type motors which are not commonly used on machinery as they are usually pretty noisy so they're not fund to have in a shed.

That unit and similar been around for a while. I was thinking of getting one to replace the Dimmer switch unit I have driving my welding/spary booth squirrel cage fan as the dimmer runs the fan motor pretty warm.

One another very significant thing about them is that unlike a 3P VFD combo they can't deliver any more speed out of them than the full speed at 50Hz, not to mention the programability aspect of VFDs

I'm basically looking for something cheap to use on a belt grinder like this.
DreamKMG1.jpg

Originally Posted by DSEL74

I'm basically looking for something cheap to use on a belt grinder like this.
DreamKMG1.jpg

Well as long as its universal motor, it should work.

A VFD would be better as it can give you higher speeds which can be useful with different belts/materials.

In the case of a universal motor and the Jaycar speed controller you'd have to adjust your pulley's gears to make sure the setup was arranged to give you the highest speed you needed and the use the speed control to back it down from there.

It would be interesting to test one of those Jaycar units there with my HP rig. I'll have to see if I have a universal motor in my motor stash under the house.

Hi Dale,

I built several of those kits, they are excellent drill speed controllers, probably the best there is... but no good at all for induction motors.

The http://www.jaycar.com.au/productView.asp?ID=KC5509 is the one you want for single phase induction motors...

Ray

I'm guessing I need a 2800Rpm motor and about 0.55kw, I think that translates to 3/4HP.. What is the cheapest VFD that would suit this purpose?

Does VFD work on a 1phase motor, or only a 3phase motor running on 240V?

Could I get a 8" bench grinder to use as the motor?

Originally Posted by RayG

Hi Dale,

I built several of those kits, they are excellent drill speed controllers, probably the best there is... but no good at all for induction motors.

The http://www.jaycar.com.au/productView.asp?ID=KC5509 is the one you want for single phase induction motors...

Ray

$249 that puts a damper on things!! Thanks for the point in the right direction though. Also a kit isn't suitable for me. I think the VFD can be cheaper than that, I was trying to avoid those due to cost.

Hi,
Since we are on this forum.....

Your aiming for a 72" belt aren't you? I have used a little buddy with a 2hp motor and was very underwhelmed by the power. In fact it had less balls than my 1hp grinder and multitool. The bigger the belt the more power needed to just keep it spinning. I would go 2 hp at a minimum, I would recommend 3.
Now I have a 2hp 2 pole 3 phase motor here wired in delta. I can bring it to Phil's on the weekend if you want it. Then all you need is a $150 huanyan vfd off eBay.

Ew

Yep to the 72". other than 2hp & 3ph I have no idea what the relevance of those specs are. 2pole and delta wired.

P.s. are you stalking me

Originally Posted by Ueee

. . . . . Now I have a 2hp 2 pole 3 phase motor here wired in delta. I can bring it to Phil's on the weekend if you want it. Then all you need is a $150 huanyan vfd off eBay.

It not only has to be ∆, is has to be 240V ∆, if its 415V ∆ it will only generate ~ half power on 240v.

Hehe, Ueee the forum stalker.........although I thought you were following me....

2 pole means 2880 rpm, and yes its delta 240v so basically ready to hook up to a 240/220v vfd. You have until thursday arvo to make a decision......

Ew

Ps you can have it for nicks.

2 pole means that it runs at around 2950 RPM, (4 pole spins at 1450 RPM or there abouts), and delta wired is what you want to run most 3 phase motors under about 5 HP if you are using a VFD to generate the 3 phase from 240 V single phase. These motors are usually wound to run on 415 V in star (also sometimes called Y), but they can also normally be connected to run on 240V 3 phase, if they are connected in Delta. Some of these motors have all the necessary wires bought out into the terminal box, and the switch from star to delta or visa versa is done by re-arranging jumper bars within the terminal box. The diagram and accompanying text below come from this link http://www.csanyigroup.com/general-about-motors and more detail is available there if you want.
Voltage
Three-phase single speed motors can normally be connected for two different voltage levels. The three stator windings are connected in star (Y) or delta (D). The windings can also be connected in series or parallel, Y or YY for instance. If the rating plate on a squirrel cage motor indicates voltages for both the star and delta connection, it is possible to use the motor for both 230 V, and 400 V as an example.The winding is delta connected at 230 V and if the main voltage is 400 V, the Y-connection is used. When changing the main voltage it is important to remember that for the same power rating the rated motor current will change depending on the voltage level. The method for connecting the motor to the terminal blocks for star or delta connection is shown in the picture below.

I hope that this helps, Cheers,
Rob
PS much too slow, everyone else answered you first

A way to mechanically vary the speed of a motor driven device is to use a Reeves Drive unit.
You could spend weeks making one and trying to get it to work properly.

We used to use them before VFD's became common, on our Coal Feeders, at work.

Reeves Drive.jpg

Originally Posted by Ueee

Hehe, Ueee the forum stalker.........although I thought you were following me....

2 pole means 2880 rpm, and yes its delta 240v so basically ready to hook up to a 240/220v vfd. You have until thursday arvo to make a decision......

Ew

Ps you can have it for nicks.

OMG me stalking you??? Your a stalker & a narcissis :eek: but a generous one. I'll take you up on that. Be good to meet you...just don't follow me home.