Single Phase or Inverter?

[julianthegypsy]

I've just acquired a nice Corona high speed drill. It's actually quite small as these things go, and high speed, with the lowest speed being 660 rpm. This on a machine that stands three feet high and takes two people to lift. My kind of kit really :-) The thing is, it has a 1/2 hp three phase motor, which is a nuisance for me as I only have the one three phase socket in the corner of the shop...as against twelve single phase sockets. The three phase motor is quite compact and I am tempted to mount an inverter on it rather than swap the motor as that way it would be running as it was designed, but I know nothing of inverters, what type to get, etc etc. I've seen a few second hand on ebay but don't know enough to dare put a bid on. Any thoughts?

 

[doubleboost]

Is the motor wired 220 / 440
220 3 phase digital drives are very good
I have one on my lathe speed control and reverse (be good for power tapping)

 

[daleyd]

If you have a piccy of the motor plate that would help a lot. I would have thought as long as the motor is 220/240 compatable and you get an inverter with enough output you should be fine (the motors usually have 2 ratings, one for 400v and one for 220/240)

 

[julianthegypsy]

Aha. I shall have a look at the motor plate tomorrow and I'll try and get a piccy if it's clear enough. So if it just says 380V for example, what would that mean in terms of the inverter? Many thanks for the replies incidentally.

 

[Wendelspanswick]

Aha. I shall have a look at the motor plate tomorrow and I'll try and get a piccy if it's clear enough. So if it just says 380V for example, what would that mean in terms of the inverter? Many thanks for the replies incidentally.

A digital inverter normally takes 240v single phase in and changes the phase by 120 deg twice to give you 240v 3 phase out. Basically 240v single in and 240v 3 phases out.
If you have a motor that will only run on 380-415v the inverter needs a transformer in it to step the voltage up as well as producing the 3 phases - available but more expensive.

 

[J.B. Welding]

Extension lead for the 3 phase?

 

[daleyd]

Extension lead/ spur off the 3 phase would be an easier solution if it's possible. A bit of cable should be cheaper than an inverter. You would just need to check capacity of existing supply.

If the motor has a 220/240 rating then you should be able to run with just the inverter but as wendelspanswick has said if not then you will need extra bits.

 

[julianthegypsy]

Extension lead/ spur off the 3 phase would be an easier solution if it's possible. A bit of cable should be cheaper than an inverter. You would just need to check capacity of existing supply.

If the motor has a 220/240 rating then you should be able to run with just the inverter but as wendelspanswick has said if not then you will need extra bits.

Thanks. I got sidetracked today and forgot to check. The three phase socket is a 32 amp and is mainly used for my 320 amp mig welder, but I also use it via an extension cable to run the capstan lathe and occasionally my little tapping machine. It's a pain changing it over to the extension because the socket is behind the forge in the corner, and then I have to swap the other end between the capstan and the tapping machine. I'm sure the supply is fine as there's only me in the workshop so I can't be welding, turning, tapping and drilling all at the same time, but its not ideal.

 

[ford34/2]

seriously consider a spur or extension from the existing, a sparky will be cheaper in the long run and the supply a lot more convenient.
Stan

 

[brightspark]

just spur off the existing 3 phase socket with a 4mm 4core steel wire armoured cable to a switchfuse and then in to your drill, just down rate the fuses to suit drill in switchfuse. much cheaper and a better result

 

[julianthegypsy]

I had a look at it today, it says 380/420V and its 2850rpm. So it would need a transformer as well as an inverter if I went down that route?

 

[daleyd]

Yeah, looks like it. Normally they will have a separate rating for 240 if they are able to be run off 240v.

 

[shenion]

At only 1/2HP you should be able to find an inverter that drives 415V.

At 1/2HP or less here, 120 single to 208 3-phase are common and cheap. I have one on my lathe. No step up needed, just 120V to DC, then 3 120V drivers to generate 208V 3-phase.

 

[daleyd]

At only 1/2HP you should be able to find an inverter that drives 415V.

At 1/2HP or less here, 120 single to 208 3-phase are common and cheap. I have one on my lathe. No step up needed, just 120V to DC, then 3 120V drivers to generate 208V 3-phase.

I've seen these but never used them, however I don't think they are that common over here. (Cue loads of people writing to say well I've got one )

Certainly by the time you have forked out a couple of hundred quid for one of these and got a sparky to wire it in and set it up, it would be cheaper to pay said sparky to fit a spur to your existing 3 phase.

 

[julianthegypsy]

The other problem is that I have absolutely no idea what to search for on evilbay! I'm beginning to think I should swap the motor!

 

[mike k]

I'm in the same boat as you, bought a spray booth with 3 phase motor powering the extractor. It's 2hp so a inverter from direct drives is £200 if it is the correct one or seen replacement non brand motors for around the £100 mark but also checked youtube as I heard you can convert 3 to single phase

http://m.youtube.com/results?q=converting 3 phase to single phase&sm=1

http://m.youtube.com/results?q=single phase to 3 phase part 2&sm=3

http://m.youtube.com/results?q=single phase to 3 phase part 2&sm=3

http://m.youtube.com/results?q=single phase to 3 phase part 2&sm=3

http://m.youtube.com/results?q=single phase to 3 phase part 2&sm=3

I think I've linked all the videos, looks like it's a route I might take - bit old school and me spark mate says to just buy a different motor but worth a shot.

mike

 

[julianthegypsy]

My problem ended up being solved in quite a different way. My landlords offered me a huge pollard geared head pillar drill for a bargainous price, so I sold the small one and a nice backgeared meddings and now have more space and can drill virtually anything. Still running off a long lead but I shall put a box on the wall at some point. First time I used the opowered downfeed I had my heart in my mouth I have to say, but its brilliant!

 

[Henrik]

Just a note on the 3 phase motors;

Even if the label says 400/415 or whatever, it is quite possible to bring out the extra tails from the windings so that the motor can be connected in delta instead of star.

Doesn't work on all motors, but e.g the two pillar drills I bought last year were both marked as star (415) only, yet all it took to bring out the other tails was to open up the motor case and look for the "star point", break it up into three and re-assemble.