Variable speed motor/switch

kadman · 21-02-2020 8:14pm #1

I currently have a 2 hp single phase woodworking lathe.

I need to make this a variable speed unit, without messing about with pulley
changes.I want multiple speed choices, while maintaining torque if possible.

What options do i have to make this happen. With or without my existing motor.

I want the best option, rather than the cheapest.

Thanks,
kadman

brightspark · 21-02-2020 8:20pm

Might be helpful if you post details about what type of motor is fitted?

An inverter should be able to provide speed control while maintaining torque, depending of course on the speed ranges.

Changing the motor may be necessary as some are unsuitable for speed control, cooling the motor can also be an issue at lower speeds as the motors cooling fan is also running slower.

kadman · 21-02-2020 9:18pm

Dont mind buying a motor, I just want the best setup
considering I only have single phase supply

adrian92 · 24-02-2020 1:08am

Little help.
Your electrical load for tis motor is about 1.5 kW
Not a problem at single phase at all

Bruthal · 24-02-2020 10:40am

Need to see what type of motor it is.

Probably induction but any specs on it?

kadman · 24-02-2020 1:22pm

Here is the pic, and I think its 3 hp.

Thanks

kadman · 24-02-2020 2:18pm

Just saw Dylan's 12 volt tractor,

fair play, its priceless.:cool::cool:

Bruthal · 24-02-2020 3:41pm

kadman wrote: »

Just saw Dylan's 12 volt tractor,

fair play, its priceless.:cool::cool:

Yea it's a while since I did those now.

On the motor, a VSD might be an option for that. I have not used them with single phase motors myself. Although a single to 3 phase VSD and 3 phase 230v winding motor could be an option too, but there probably are vsd's for single phase induction motors but 3 phase works much better.

Probably expensive though. There are probably dc motor options for lathes too.

brightspark · 24-02-2020 4:11pm

Is there a brake built into that motor? ( I can't imagine the motor being allowed to just spin to a stop, but perhaps that is the case)

The brake (if fitted) will need a separate supply as an inverter may not supply it correctly.

kadman · 24-02-2020 5:16pm

Is a 3 phase arrangement a better option for speed control ??

Bruthal · 24-02-2020 5:31pm

kadman wrote: »

Is a 3 phase arrangement a better option for speed control ??

Yes much better for everything.

24-02-2020 6:07pm

This won’t be cheap but you could buy a variable speed drive that will provide a 3 phase output and connect this to a 3 phase motor. This will provide you with descent speed control.

kadman · 24-02-2020 8:06pm

2011 wrote: »

This won’t be cheap but you could buy a variable speed drive that will provide a 3 phase output and connect this to a 3 phase motor. This will provide you with descent speed control.

I dont want cheap, I want the best solution.How much and where do i shop, and what am i shopping for . Thanks

24-02-2020 8:35pm

kadman wrote: »

I dont want cheap, I want the best solution.How much and where do i shop, and what am i shopping for . Thanks

Start by finding a 2.2 kW / 230V / 3 phase motor.
So a motor designed to be connected with a line voltage of 400V in star would be suitable for a line voltage of 230V when delta connected.

Then consider a good variable speed drive to suit such as ABB, see link.

Obviously the VSD will need to be programmed, wired and mounted. Generally a "pot" can be wired to the VSD, by turning this the motor speed can be adjusted. these units can be programmed to operate in constant torque mode at a variety of speeds.

24-02-2020 8:53pm

I should add:
- It is important to consider how to mount the new motor.
- 3 hp = 2.2 kW (approx)
- It would be best to consider a start, stop and emergency stop buttons
- This type of work is generally more suited to electricians with industrial experience.

kadman · 24-02-2020 9:50pm

Is there a limit to hp size that I can use, given that my supply voltage
is only standard domestic supply.

And are there specific 3 phase motor types that can be used only,
or can I use any type 3 phase motor.

Is there any kit type arrangement, that allows me to take out my single phase motor,
and swap in the alternative 3 phase solution+electrics.

thanks.

adrian92 · 25-02-2020 1:11am

kadman wrote: »

Is there a limit to hp size that I can use, given that my supply voltage
is only standard domestic supply.

And are there specific 3 phase motor types that can be used only,
or can I use any type 3 phase motor.

Is there any kit type arrangement, that allows me to take out my single phase motor,
and swap in the alternative 3 phase solution+electrics.

thanks.

Just on your domestic supply, you have only a few kilowatts, maximum for your motor, so no worries.

(Many domestic supplies have 8 kilowatt showers, for comparison)

25-02-2020 8:04am

kadman wrote: »

Is there a limit to hp size that I can use

Yes but a 2.2 kW motor on a VSD will be ok.

And are there specific 3 phase motor types

Any "standard" 3 phase induction motor will be ok

Is there any kit type arrangement, that allows me to take out my single phase motor,
and swap in the alternative 3 phase solution+electrics.

I think that mounting a replacement motor may be a challenge. You will need to consider this including the dimensions of the motor shaft.

Also motors can overheat when running at lower speeds (as the cooling fan is mounted on the motor shaft). This is normally dealt with by de-rating the motor i.e. select a 3 kW motor but only use it up to 2.2 kW.

Bruthal · 25-02-2020 8:14am

The 3 phase motor should have 230v windings to use on 230v single to 3 phase VSD.

If a 400v one is used, it will only have 1/3 of the power.

2.2kw 3 phase will have a lot more torque throughout its rotation than the single phase one. Cooling shouldn't be too much of a problem when used on a lathe. It will have to be running at a reasonable enough speed and won't be a fixed full mechanical load on it.

25-02-2020 8:31am

Bruthal wrote: »

The 3 phase motor should have 230v windings to use on 230v single to 3 phase VSD.

400V star windings / 230V delta. Check the name plate.

If a 400v one is used, it will only have 1/3 of the power.

Yes, that is an important point.

Bruthal · 25-02-2020 8:59am

2011 wrote: »

400V star windings / 230V delta. Check the name plate.
.

400v star means the windings have 230v across them.
So if the motor had 230v rated winings, it can be connected 400v star or 230v delta for the full power output.
If it is 400v windings, 400v star gives 1/3 power. 400v delta gives full power.

For the op it might be confusing so any potential motors, post details up and we can check them.

25-02-2020 9:17am

Correct.

See link
This gives a clear example of what I am talking about.

However if the motor is designed to be connected in delta to a 3 phase supply with a 400V line voltage then if a 230V line voltage is used instead then the power will be reduced by a factor of 3.

Bruthal · 25-02-2020 9:46am

It's around in circles saying the same thing.

kadman · 25-02-2020 10:02am

I have been offered a 5.5hp motor, a 7hp motor and a 3/4 hp motor, all 3 phase.

Which is the best option.

No doubt you have already guessed, I know sweet FA about electrically:D

brightspark · 25-02-2020 10:14am

kadman wrote: »

I have been offered a 5.5hp motor, a 7hp motor and a 3/4 hp motor, all 3 phase.

Which is the best option.

No doubt you have already guessed, I know sweet FA about electrically:D

I very much doubt if any of them can physically fit your machine without some new mountings/couplings.

You need to get pics of the data plates to know what voltage ranges they have.

25-02-2020 10:25am

+1

I think you need to get a competent electrician electrician on board really. It would be almost impossible to progress this much further on a forum like this.

I think that the biggest issue will be finding a suitable motor and working out how to mount it and how to connect the motor shaft in a robust manner.

kadman · 25-02-2020 12:35pm

Fitting the motor is going to be the easiest issue.

Machine in question is the largest Centauro woodturning lathe.
Full cast iron construction.

Lathe head costruction is a hollow cast iron construction, with ample room access.

I can fit the motor , either inside the tower, or outside. Its simple for me.

I have the necessary mechanical skilset, as well as all the necessary tooling,

to either fit the motor inside, or fabricate an arrangement to fit it outside

the tower, and accomodate the beltdrive through access to the drive shaft.

The headstock of the drive shaft is a horizontal shaft , with bearing mounts each end.

That will be my area of expertise. Simples to me.

BUt I am not very leccy savvy, thats you guys department:D

Thats why I have come to the experts. You

I am not stupid enough to gather bits of info , and try wiring it my self,
and I have already written off my single phase existing setup as unsuitable .

I would rather you guys spec the ideal motor and matching switch, that I can have onsite for the sparks when he arrives.

I will post up the details of the 3 phase motors available to me as soon as I can.

Trust me, I wont be wiring ****, I got electrocuted when I was 10 years old. And its not nice:eek:
Thanks for all your help,
kadman

kadman · 25-02-2020 12:52pm

My lathe is this model, but with the additional outboard turning section,
for turning up to 44" diameter. Which adds another 3' to the length.

kadman · 25-02-2020 1:55pm

Looks like i can't progress on this, as i have just got the motors, with no detail plates
attached ,

Big Motor

Small motor.

So I am at a standstill until I know what motor to buy, and what switch.
All advice welcome, thanks.

kadman · 25-02-2020 2:44pm

These motors are from a Lazzari panel saw that was converted to single phase.
Manufacturers spec puts them at 5.5hp and smaller motor at .75hp.

kadman · 25-02-2020 7:36pm

Maybe the best solution is for someone to spec exactly the motor I need to work with this,

https://www.jfkelectricalni.com/product/2-2kw-3hp-ip20-single-phase-240v-ac-motor-inverter-variable-speed-drive/

Thanks,
kadman

Variable speed motor/switch

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