startrite 275 3 phase inverter advice

[mainebluedave]

hello guys . Firstly, I would like to announce myself as a new poster here on this great forum. I am usually a read and learn guy and after researching some great topics regarding using inverter to power three phase startrite 275 saw. I am looking to source an inverter to complete the task. after studying input from forum members Ttrees , Ozark and others I conclude.
I can alter motor connections to delta low voltage. then wire inverter to power saw from domestic supply.
Motor on saw is brook 2.2 kw rev 2850 V220-250 / 380 - 420 delta or star
amps 7.9 / 4.55 50hz 3 phase
the last posts I read was referring a Huan yang I have searched eBay and have not found a uk supplier. after searching amazon uk I have found this albeit cheap inverter and was wondering if it would be up to the task.
craftsman168 VFD Inverter Frequency Converter 220V 2.2KW 3hp for Spindle Motor Speed Control Motor Drive

Advice would be great full and of course Thankyou in advance .dave

 

[Ttrees]

ello Dave
I am not familiar with that VFD so can't advise.
I can't see a brand name at a glance, to look it up.
What I will say is before buying any for a tablesaw to make sure the VFD has the capability
for three wire control, and not just two wire control.

Three wire control means a start push button and seperate a stop push button. (momentary signal to the VFD)
Two wire control is like a light switch or toggle switch which is a permanent fixed mechanical method to mimic two wires joined together.

Three wire control is for the likes of a push button station
or if you prefer not to get ripped off paying a score, buying a NO start push button, and a NC stop push buttons instead for the price of a pint and making a box yourself.

Its a lot easier and safer to make a paddle switch for a seperate start and stop button.

PS I would doubt that the seller of the VFD you referred to is in the UK

 

[guineafowl21]

I would go for a slightly higher rated VFD than the power of the saw, because a) it’s best to under-run things, b) the cheaper VFD ratings are likely to be ‘optimistic’, and c) the motor will draw a large inrush current on startup which may overwhelm an exact-rated drive. Say 3 kW.

Another reason for over-rating the drive is that a saw motor, being an inductive load (creates a magnetic field), will appear to be a bigger load than it actually is. The extent to which it does that is given by the power factor, PF or cos(phi).

I run my Multico 500W mortiser on a 2.2 kW drive (at £80 delivered it wasn’t worth going lower) mounted on the machine with the detachable control panel on a bracket facing me. With a saw, you’ll want a chunky stop button in easy reach as Ttrees suggests.

 

[Ttrees]

I don't think there is any point in getting a larger rated unit for a tablesaw as it should never slow down.
But with a mortiser I would expect that it would be a good idea to get a larger rated unit, or Vector drive as it seems normal practice for a mortiser not to run at rated speed all the time.
I could be wrong as I've never used one, but it seems that way since some of them have large wheels to give a bit more oomph.

Beware that there are smaller mini VFD's on the market that are being passed off as the Isacon/Askpower HY02D223B unit.
Look or ask for dimensions before buying.

The Isacon/Askpower drives don't seem to have the common/reset/relay that goes inbetween
start and stop terminals ala three wire control.
This is necessary for individual push buttons rather than a single button for off/on
which might be dangerous or confusing if you have a big paddle like mine.

Look at a paddle designed for a toggle switch (two wire control) in this video
at 5 mins into the video.
It looks a faff and not half as safe more importantly.
[youtube]I1R3kZWJk98[/youtube]
You could do the same with a latching push button as with a toggle switch but if you have a big paddle you might set it off frequently.
The three wire control method is safer because you have to aim your finger through the hole in the paddle to push start, and if your fingers are too clumsy, you will also hit the paddle and the machine won't even think of running.

The Huanyang would be one of the favourites for me because the parameters are known...
and it can be set up for three wire control.
I'm unsure if the Isacon/Askpower has the ability to do so.
(haven't found manual to try, now I know a bit more)

If the fan annoys you, there is a very good video on making the VFD quiet or silent.
I made a thread on sawmill creek titled suitable relay for three wire control if you want to know more.

 

[kinsella]

Dave
Check out how i converted the saw with an invertor.
3-phase-to-single-phase-startrite-275-conversion-from-3-ph-t91106.html

 

[mainebluedave]

Thanks guys for reply . The device had next day delivery from rain forest (Your account does not have permission to post links or domain/page references) As reference to size ..what should i be looking at here. Thanks in advance again .dave

 

[mainebluedave]

i have pics here

 

[Ttrees]

That looks to be a standard sized one.
Some 2.2KW drives are little bigger than the control panel but have pictures of the standard size units.
I suggest when searching for a VFD is to know if you can use push buttons rather than only a toggle switch.
This might not matter if you don't plan on making a paddle for your machine.
On the recent sawmill creek thread one member was thinking of making a relay for his Isacon/Askpower drive, utilizing some components from a guitar amp.
I won't pretend like I understand.

If your having doubts because there is no search results of folks using that VFD,
Seek out downloading the manual for the one you want,maybe off of the seller if need be, and if that answers little, download the Huanyang HY02D223B manual and see if there are swappable function ports in the small group of external terminals for switches.
Read the sawmill creek thread to see if there is ports that change functions,
should one of the three ports necessary for three wire control for the start button, stop button and common/RSTreset/relay terminal fail, you can just use another one instead.

Tom

 

[mainebluedave]

thanks tom for very good advice here. on the startrite saw there is a Kick stop at the bottom of saw .I dont know weather this is standard as it dose not show in the Startrite T/a 275 manual I have downloaded. this has a N/O contact. wired in series with a key switch contact which was close to the old ,now removed contactor. I will contemplate reusing the same setup with the inverter. Even though the vfd instructions are very detailed and simple to wire up they dont give straight forward setup procedure for the application I require for saw. So its back to saint google for now....

 

[Ttrees]

Are the buttons a standard size?
You will be looking for an NO for the start and a NC for the stop push buttons for your three wire control proposition.
Seems simpler to gut the switches if you can, as I think I've read that some of the newer VFD's are about half as expensive again as the budget ones.
What would be nice would be an easy swap to 3 wire control, (dependent if you would think of selling it again without any effort to refit switches , I suppose)
Even if the buttons were a smaller size you can cap the housings and redrill them for the suitable sized push buttons.

A momentary push button will need the common/reset/relay, otherwise you would have to keep your finger held on the on
button, and when you'd take it off the machine would stop.
Without the common, this is two wire control and it needs a toggle or fixed position switch to make a mechanical join.

You can't do a toggle fixed switch ala Holmgren if the paddle is too low, so you would ideally want a start button at a better location at a suitable height.
As said you could buy any VFD and just use two wire control with a latching switch for your paddle, but you'd have to kick it to start it
and that probably would be quite dangerous.( I don't know how easy these press)

Two momentary signal buttons is what your after, a NO button of your choice, (I would favour a LED one in your case, unless some child had a terrible fascination with such things) green for start might be a good choice.
If this was a concern though, you could fit/hide as many twistlock switches (below) as you like...
With a twistlock switch its a mechanical break in the connection even though the actual button is a momentary signal push button.

And a regular NC push button for the stop paddle, doesn't have to be red if its behind the paddle.
My cheap ones seem tough enough, it only would take a frogs weight to activate it, and won't need the Onzlow treatment.
The common gets the signal that the buttons have been pressed, rather than breaking any connection via mechanical switch methods.
So make sure the VFD you choose has a common/RSTreset/relay.

If the start switch is too complicated if you were to gut it, you will need to fold a bit of sheet to make a box
Otherwise what possibly would work, (never tried it) is buying an emergency stop twistlock switch with a box

and replace it with an NO start, you can get ones with a LED light to let you know its on.
All these buttons are cheap as chips
Tom