Another 3 phase inverter question: progress update

[Woodmonkey]

This is the badge on the motor for my drill

Am I right in saying its not a dual voltage motor, ie I can't just use a standard vfd like this one
http://www.999inverters.com/our-inverte ... x-040-21-e

I need something that will convert the voltage as well as the phase right?

 

[CHJ]

As constructed 'yes' 415 volt, it may be possible for someone who knows the internals to locate the star point in the windings and rewire to 230 delta. Ask Myfordman.

 

[graduate_owner]

I asked a local electric motor repairers to do this to my 415V motor. It cost me about £30. Much better than arsing about trying to get a different motor to fit, probably cheaper too.

K

 

[graduate_owner]

Also, I did ask the inverter people about running a 380/415V motor on my basic 240V inverter, and they said I would probably lose torque, but would not cause any damage to motor or inverter, so you perhaps could try the motor as it is first and see what happens. I haven't done this with mine yet so no guarantees offered.

K

 

[Woodmonkey]

Cheers, a mate has just recommended a local motor repairs place and also reckons they can just wire in a capacitor so will try that first.

 

[Myfordman]

Your mate is wrong. Adding a capacitor will not enable a 415v star motor to develop any useful power from 240 v .
Your options are
1 Converter static or rotary
2 change the motor to 240 delta and use either an inverter (best) or add capacitors to create the extra phase. With the latter, you are likely to have problems getting it to start with the belts set to higher speeds.

 

[porker]

You could also run off a vfd with voltage step-up. They are expensive though and need wiring direct to the motor so switchgear may need changing.

 

[Myfordman]

You could also run off a vfd with voltage step-up. They are expensive though and need wiring direct to the motor so switchgear may need changing.

I'm not sure if there are any commercially manufactured inverters that do this step up. I modify inverters to do it and do does Dave at Drives Direct in Nottingham which does invalidate the CE marking applied by the original makers (if that is any concern to purchasers).
The modifications either involve de-rating the inverter ie buying one that has twice the power output than the motor or fitting extra components inside (if they fit) or an external "booster box" - both methods lead to an increase in prices compared to a standard model.
If you or anyone else has any pointers to inverter makers who make voltage converting inverters as standard products in their range, I'd be interested to hear please.

 

[porker]

The reason I knew about this option was that I incorrectly ordered one from Direct Drives and subsequently found I didn't need to so swapped it our for a standard vfd to run my Bridgeport mill and reconfigured the motor to delta. It may have been modified but it looked like it had been manufactured that way and he still claims CE compliance.

I see he still has these as an option but it is expensive and I would probably look at the other options myfordman has suggested before considering this,

http://www.ebay.co.uk/itm/TECO-SING...585?pt=LH_DefaultDomain_3&hash=item58c1ae1da1

 

[Woodmonkey]

Your mate is wrong. Adding a capacitor will not enable a 415v star motor to develop any useful power from 240 v .
Your options are
1 Converter static or rotary
2 change the motor to 240 delta and use either an inverter (best) or add capacitors to create the extra phase. With the latter, you are likely to have problems getting it to start with the belts set to higher speeds.

When you say change the motor to 240 do you mean that the motor can be rewired or the motor needs to be swapped out for a 240 motor? The high speed thing is not so much of an issue as it will only be used for wood working so if it can be done just by adding capacitors it would be preferable as obviously this would be a lot cheaper

 

[Myfordman]

I meant modify the motor from star so it can be wired in delta. if this sounds like chinese to you, then you should get this done by a motor specialist as referred to earlier in the thread.

You then need to be able to wire up some push buttons, capacitors and relays to a circuit diagram and do this in a safe manner.
It is not difficult but some people have a phobia and freeze mentally when it comes to electrics getting themselves into a "can't understand - won't understand" state. Forgive me if this sounds blunt but you need to be confident about wiring things up and buying the correct parts.
I can give you the circuit but you need to do the work.

 

[Woodmonkey]

No worries I will take it to the motor specialist and get him to do it. Thanks for the advice

 

[woodpig]

Yes, I'd get the motor repair shop you mentioned earlier to have a look at it.

Ask plenty of questions if they can help and let us know how you get on, it could help someone else on here.

 

[Woodmonkey]

Update: removed the motor and took it to the motor guys this morning. He said he couldn't put a capacitor in as there is only 3 contacts rather than 6, then tried to sell me a 240 motor for £160 +vat, he said in fairness that I could find a cheaper motor but it would be metric sizes on shaft and mounting points so would be more complicated to get it to fit. So more than I was hoping to spend really. My workshop is actually being rewired at the moment so I will have a word with the electrician and see how easy it would be to get a three phase supply put in, the workshop next door has it so there is a 3 phase supply to the building. If not I guess I will have to bite the bullet and get a new motor ( to be honest even £160 isn't bad to get a top notch pillar drill)

 

[dickm]

Don't forget there is a secondhand market too. Try the homeworkshop site - all sorts of useful stuff advertised there and you could well get something a lot better quality than some modern motors.

 

[Myfordman]

I did try and suggest how to approach this.
You want the rewind man to open up the star point and re configure it to delta or to find someone who will.
Then you need to build a phase converter / starter in a box that I referred to and could give you a circuit for.

I doubt very much if a motor specialist would take the whole job on - it would not be economic.

 

[woodpig]

It will also be easier to move it on when the time comes if it's 240V. :wink:

 

[Woodmonkey]

I did try and suggest how to approach this.

Yes you did, and I did try to do what you suggested, just that the chap was either unable or unwilling to do it. Anyone know anyone in the Bristol area who might be able to help with the star/ delta thing?

 

[graduate_owner]

The firm I used is in Llanelli. Not close, but a possibility if you are unable to find a local one.

K

 

[Myfordman]

I did try and suggest how to approach this.

Yes you did, and I did try to do what you suggested, just that the chap was either unable or unwilling to do it. Anyone know anyone in the Bristol area who might be able to help with the star/ delta thing?

Sorry - only just seen your reply. There is a member in the Bristol area who almost certainly has the knowledge/ability to do this mod. Depends if he has seen this thread or indeed has the time/inclination to get involved. It would not be fair of me to name him.

Googling brings up loads of motor places in the Bristol area I'm sure one will do it for you, try the smallest, scruffiest one man band places. Ask them if they will "open up the star point of a fixed 415v motor and reconnect the motor in permanent 230v delta" and give them the make and size of the motor.
I can do it but shipping it two ways is going to make it expensive.