Quantcast
  • We invite you to join UKWorkshop.
    Members can turn off viewing Ads!

bandsaw three phase to single phase conversion

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

froggyie

Member
Joined
20 Jul 2020
Messages
5
Reaction score
0
Location
ENGLAND
Hi,

As I am not a technical person, am looking for advice !

I have a 3phase 400v JET JWBS 18 bandsaw and would like to connect it to a single phase 240v supply, I was under the impression that by buying a digital VFD would do the trick ??

Enclose photo of the plate and wiring, I was told that it can only do 3 phase and it's not a dual motor ?

Any expert advice would be welcome!

Thanks
 

Attachments

guineafowl21

Established Member
Joined
28 Oct 2015
Messages
328
Reaction score
51
Location
Inverness
A standard inverter drive/VFD will only put out 230V 3ph, whereas yours requires 400V 3ph, so what you’ve been told appears correct. You have a few options:

1. Fit a 1ph motor.
2. Take the motor to a rewind shop to have the star point extracted, then run on a standard VFD.
3. Run existing set-up on a step-up VFD (230V 1ph -> 400V 3ph) - google Drives Direct.
4. Research rotary, static and digital phase converters.

Option 2 probably your best bet, if there is a nearby motor shop. 3 and 4 could get expensive.

Regarding option 3, someone on here found a cheap step-up VFD on ebay. I don’t know of anyone who has tried one yet. You’ll need one rated to at least the full load amps, in your case 5A.
 

Ttrees

Iroko loco!
Joined
18 Nov 2012
Messages
2,278
Reaction score
69
Location
In me workshop
Forgive me for I have some questions in my writing, aswell as some options.

That's a lot of terminals coming out from that box,
Some of those wires are thinner gauge than others,
I wonder what Bob (myfordman) would make of it?
Could it actually be a dual voltage afterall?
If you can't find him here, then look on the "would haven two" website said in code as software dosen't like competition.
His google document is worth reading concerning motors and VFD's.


Guineafowl21's knowledgeable comments are worth going over,
and to try and delve in a bit further, some other questions could be answered
to make your options a bit more simple.

Are these extra terminals for a motor brake I wonder, and can that be disabled?
I would have thought safety interlock switches were on the switch/isolator side of things.
(safety interlock swithes are so you can't open doors while machine running, or could be for a foot brake also)
Can you trace the micro switches to the on/off isolator switch?

I seem to recall that some of those Jet bandsaws has the option for cutting metal,
I thought that would not be anything to do with the electrical side of things, and is a manual change of the belt onto a different pulley.
It is a four pole motor running at 1440 RPM, so that would suggest it can be used for both metal and wood.

Has a 4 pole motor less starting inertia, i.e easier on the supply to start?

It says its a 2.2kw on that motor sticker, or 3hp motor, which is stated either on my machine or the rated VFD/inverter @ 11 amps rating, presumably for startup or full depth cutting only, and not 5 amps what's written on the motor sticker.
Presuming there is no other diagrams of anything on the inside of the lid you took off?

As said above, a motor swap to single phase is one option,
Have you got a 16a socket in the shed, or any plan to run a dust extractor with machinery together in the workshop?
Then ideally you might want to just swap it for a single phase motor which has the same 3 hp/ 2.2Kw rating, which is a 4 pole motor running at half
If so make sure you get the same shaft size, research if it's foot mounted, face mounted or flange mounted motor also as that pulley could be double the width and need the right motor mounting,
i.e the motor might need to be tight against the machine cabinet to account for this.

If you have only 13 amp sockets, with a suitable beefy line going to the house, and it is not an option to get an electrican to hook up 16a outlets, then I would think
2 hp might be as powerful a motor you can install on a 13a household plug.
I could be wrong though, and am interested if that 4 pole motor will be less consumptive on startup.
i.e wont blow fuses on the household plug.

The other option of a cheapo step up to 400v drive might be interesting in this regard also...
It would be interesting to know if that voltage step up might be a challenge for the cheapie VFD's all the time, or if it may be more likely to fail with a 2 pole motor during startup.

Another thing that would be interesting to know is if the star point could be more of an easier job than some motors, but that requires some knowledge to do, and ideally a megger which aint cheap.

Sorry I can't be of more help, but it might make way for more knowledgable folks than a numpty like myself, and hopefully yield a pleasing outcome by getting the ball rolling.

Tom
 
Last edited:

guineafowl21

Established Member
Joined
28 Oct 2015
Messages
328
Reaction score
51
Location
Inverness
It says its a 2.2kw on that motor sticker, or 3hp motor, which is stated either on my machine or the rated VFD/inverter @ 11 amps rating, presumably for startup or full depth cutting only, and not 5 amps what's written on the motor sticker.
Full load amps (per phase) for a three phase machine is:
P/sqrt3.V.cosphi

In this case, 2250/1.732x400x0.8 gives you about 4 amps. The rest is most likely allowance for efficiency.


There’s quite a tangle of wires in there, but I assume if it were dual voltage it would be on the plate. That said, it’s a US company, and they have a bewildering array of voltage and phases. I can’t find any manuals for this saw version, so that strengthens the case for option 2, the motor shop, as they will be able to establish the winding arrangement.

It’s possible, for example, that the motor is set up in series star, which could be re-jigged to parallel star for a lower voltage. These normally have 9 terminals, however.
 

Spectric

Established Member
Joined
19 Feb 2015
Messages
375
Reaction score
96
Location
North Cumbria
Hi

Your cheapest and easiest option is to just replace the motor, it saves all the hassle of convertors and motor wiring. If it is only 400 volt three phase then if you went for the digital convertor, not invertor then you could also power other machines from it as well providing you get one with the power needed. Search these forums, there is another guy who is running a convertor on a farm who is supplied from an overhead supply.
 

guineafowl21

Established Member
Joined
28 Oct 2015
Messages
328
Reaction score
51
Location
Inverness
thanks for all your advice, it has been taking onboard !

The model number is actually JWBS 18 T and enclose more pics....
Yes, I got as far as that model number, but still couldn’t find a manual for it. It might be worth contacting Jet UK, but in the end I think you’ll end up with one of the original options above.

If you go for 1ph motor swap, @Myfordman has a link to a document he wrote with lots of useful info on motors, particularly selecting the right frame type.
 

Spectric

Established Member
Joined
19 Feb 2015
Messages
375
Reaction score
96
Location
North Cumbria
Hi

If they sell a single phase version of the machine which looking at your photos they do then it is even easier as you just buy that motor. It looks like it bolts onto an adaptor plate, does this provide the belt tension?
 

Myfordman

AKA 9Fingers
Joined
19 Jan 2013
Messages
2,290
Reaction score
96
Location
Southampton area
My motor paper and many other useful links are listed in the one stop reference links here
 
Top