Thread: VFD / inverter feedback / advice

It's a very close match to a Huanyang vfd i fitted to a Drill Press, i did have trouble with mine but a lot of guys have had no trouble with then at all. Search Vfd's in the Metalwork forum plenty of information there, do you know about the Star and Delta windings in your 3ph motor that's a added expense if you have to change anything.
I don't think i would fit another Vfd over changing to a 1ph motor but the motor was a flange mount and dearer to source, if you go to the vfd get one with a speed pot.you will need one for sure.

Thanks whitey. Ill have a look in the metalwork forum too.

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Yeah the Huanyang are the ones I'd been looking into as well, they seem fairly common amongst the DIY crowd.

I have 7 Huanyangs (my oldest one is ~6 years old) on machines in my shed and for the price I reckon they are fine. I have not had any trouble with any of them in that time

Amrjon. You motor is a Y (star) connected motor.
If you connect that to a 240V 3Phase VFD you will only get half the power between about 50 and 100Hz, i.e. 3/8HP
Below 50 Hz the power drops proportionately - i.e. at 25 Hz it will be 1/4 power (3/16 HP) , at 12.5 Hz it will be 1/8th power.
Above 100 Hz the power drops off more slowly - typically it drops by 20% at about 120Hz and another 20% at 140 Hz.

To get original power it needs to be converted to ∆ (delta) connection. Most modern motors have that capability in the motor connection box but I have yet to see that on the small Cadet motors like yours.
Doing it yourself is not for the faint hearted and if you are not familiar with Mains electricity and don't have all the right testing gear I strongly recommend against doing it.
You can take it to a motor rewinders and get them to do it but it may cost about $150 so not worth it because of the lack of power below 50Hz.

What you need is 1.5 or 2HP 240V 3Phase ∆ connectable motor.

A 2HP motor will have 1HP at 25Hz and still have 3/4 HP at 18.7 Hz and have more than 1HP even up around 140Hz.

So you are up for another motor as well as VFD.

But it does not end there. The cadet will have a 5/8" diameter bore pulley whereas a modern ∆ connectable 2HP motor will have either a 19 or 24 mm pulley.
The original pulley may not have enough metal to enable it to be bore out so you may need a new pulley.

Now its OK if it is a single pulley because you can easily but a replacement 19 or 24 mm pulley but if it is a stepped pulley you cannot rely on the VFD alone to give you the speed range on a lathe so you will still need the stepped pulley - or at least a couple of steps.

A good WW lathe will have a set of pulleys that provide speed range of about 20:1.

Using a 2HP VFD would enable you to run from 12.5Hz up to about 125 Hz or a speed range of 10:1 but I would be wary of running a motor at such low speed for two long because it may overheat )fan is not providing enough air) so its more like about 20 to 120 Hx or 6:1 - what this means is you will still need a pulley with at least a couple of steps.

There's a heap more I could tell you about but it may just cloud the issue and so I will stope here.

A VFD has a number of other features that are well worth having but its not quite as straight forward as it seems.

Thanks Bob. I was doing some reading and just realised my motor is Y connetced.
I have a gearbox on the lathe so speed contorl isnt my main goal with the vfd and after a bit of reading tonight I think im swaying back to picking up a new 240v motor.
I do have another 3/4 hp 3 phase motor but I don't know how that one is connected. Id need to pay for someone qualified to check it out and change it if necessary, so again its starting to sound easier and cheaper to get a new 240v motor.

Thanks for the replies fellas.

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Originally Posted by Amrjon

Thanks Bob. I was doing some reading and just realised my motor is Y connetced.
I have a gearbox on the lathe so speed contorl isnt my main goal with the vfd and after a bit of reading tonight I think im swaying back to picking up a new 240v motor.
I do have another 3/4 hp 3 phase motor but I don't know how that one is connected. Id need to pay for someone qualified to check it out and change it if necessary, so again its starting to sound easier and cheaper to get a new 240v motor.

Sometimes it is indeed just easier to do this.

It's a good idea to change your location in your ID to something more specific than Australia and you may be able to get help from a local member.