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13-08-2010, 13:53   #1
Carlow52
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Wiring a 3 phase motor for 240V

Following on from this thread:
http://www.boards.ie/vbulletin/showt...php?p=67406117

It seems that most good quality 3 phase motors can be wired for either 240V or 415V, if the 6 wires are in the connector box.

Would be obliged for some pointers on:
1: how do you know it will take 240 or 415 by looking at the plate
2: how to establish the full load current
2: where to find the relevant wiring diagrams.

All the stuff on the web is dominated by the US market, with 120/208 voltage and the Wye and Star configurations
Thanks
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13-08-2010, 16:09   #2
Solair
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Minor note :

It would be 230V or 400V in Ireland.
Or, even 220V and 380V.

240/415 is the old GB/Aus/NZ standard.
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13-08-2010, 19:22   #3
brightspark
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Wye (Y) and Star are both the same.

The other connection is Delta (looks like a triangle)

Found this guide on line

http://www.drivesdirect.co.uk/Downlo...otorWiring.pdf

The Full Load Current is written on the plate (usually).



Just noticed that on the thread you refered to you linked to this a couple of days ago.

http://homepage.ntlworld.com/bob.min...-%20Issue2.pdf

It seems to have plenty of information. What exactly did you need to know?

Last edited by brightspark; 13-08-2010 at 19:32. Reason: spotted link by OP in referred thread
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13-08-2010, 19:43   #4
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If you connect a 3 phase motor in star then you are applying the phase voltage across each winding (230 volts in ireland). If you connect the same motor in delta you then apply the line voltage across each winding (400 volts in Ireland).

Does that answer your question?
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14-08-2010, 14:21   #5
M cebee
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the first 2 should be on the 'nameplate'

you can google the wiring diagrams

star/delta or soft start can be used -depending on the supply and starting torque needed
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15-08-2010, 11:09   #6
Hoagy
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Quote:
Originally Posted by Carlow52 View Post
It seems that most good quality 3 phase motors can be wired for either 240V or 415V, if the 6 wires are in the connector box.
They're still three phase, though, no help if you're thinking about a single phase supply.
Dual voltage motors are connected to suit the local three phase voltage.
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15-08-2010, 11:22   #7
brightspark
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Originally Posted by Hoagy View Post
They're still three phase, though, no help if you're thinking about a single phase supply.
Dual voltage motors are connected to suit the local three phase voltage.


Unless you're using an inverter with 230V single phase input and 230V three phase output.
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15-08-2010, 12:01   #8
Hoagy
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Quote:
Originally Posted by brightspark View Post
Unless you're using an inverter with 230V single phase input and 230V three phase output.
Yes, but following from the original thread you might suspect that the OP is maybe thinking that he might not need a converter if he got a dual voltage motor.
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15-08-2010, 12:22   #9
Carlow52
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Thanks for all the replies, my post was not clear

it seems 2XX single to 2XX 3 phase inverters are more accessible, cheaper and more reliable than the few 2XX single to 4XX 3 phase inverters.
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18-08-2010, 16:58   #10
crowbar27
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any one know where you get a drawing to make your own single phase to three phaze inverter ?
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18-08-2010, 19:16   #11
brightspark
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any one know where you get a drawing to make your own single phase to three phaze inverter ?
Why would anyone want to?

I doubt if the components required could be sourced any cheaper than buying a complete unit (nevermind the time involved in assembly).

If anyone wanted to build it as a project, I would expect that they would already have such an understanding of electronics that they would be able to design the inverter themselves.
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19-08-2010, 01:38   #12
crowbar27
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cheapest inverter you can get with a good amps rating is around 1100 euro . And it is a home project my dad and I want to do as we have must of the gear about yard. i know the basics for the building one with the ratios and the stepping up of the windings. any help would be great
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19-08-2010, 08:31   #13
Carlow52
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Quote:
Originally Posted by crowbar27 View Post
cheapest inverter you can get with a good amps rating is around 1100 euro . And it is a home project my dad and I want to do as we have must of the gear about yard. i know the basics for the building one with the ratios and the stepping up of the windings. any help would be great

Depending on your needs 1100 will go a long way here
http://www.inverterdrive.com/default.aspx
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19-08-2010, 11:12   #14
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Quote:
Originally Posted by brightspark View Post
Why would anyone want to?

I doubt if the components required could be sourced any cheaper than buying a complete unit (nevermind the time involved in assembly).

If anyone wanted to build it as a project, I would expect that they would already have such an understanding of electronics that they would be able to design the inverter themselves.
It can be done without electronics, a 3 phase motor is used with L & N to 2 of the phase connections on the motor and the 3rd phase is generated by the motor itself on the 3rd phase connection. A capacitor is needed to initially start it, and so there is 230v 3 phase produced between the L-N-3rd motor connection. I put one of them in a workshop before, and it also had a step up transformer from 230v to 400v. Different size capacitors were needed between the L and produced phase and also between the N and produced phase to balance the phase angle, this part was done by the commissioning fella who supplied the invertor.

To run a small 3 phase motor from single phase it can also be done by connecting L and N to 2 phases of the motor and the 3rd phase is produced for the motor operation by connecting the right size capacitors from the Live to the unconnected phase, and the Neutral to the unconnected phase. A 230v line voltage motor would be needed connected in delta for a 230v single phase supply.

Last edited by Bruthal; 19-08-2010 at 11:26.
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19-08-2010, 13:58   #15
Carlow52
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Quote:
Originally Posted by robbie7730 View Post
It can be done without electronics, a 3 phase motor is used with L & N to 2 of the phase connections on the motor and the 3rd phase is generated by the motor itself on the 3rd phase connection. A capacitor is needed to initially start it, and so there is 230v 3 phase produced between the L-N-3rd motor connection. I put one of them in a workshop before, and it also had a step up transformer from 230v to 400v. Different size capacitors were needed between the L and produced phase and also between the N and produced phase to balance the phase angle, this part was done by the commissioning fella who supplied the invertor.

To run a small 3 phase motor from single phase it can also be done by connecting L and N to 2 phases of the motor and the 3rd phase is produced for the motor operation by connecting the right size capacitors from the Live to the unconnected phase, and the Neutral to the unconnected phase. A 230v line voltage motor would be needed connected in delta for a 230v single phase supply.
AFAIK, for what its worth, using a 3 phase motor in the rig as described above gives what is referred to in the trade as a converter and not an inverter.

The difference is explained in the links in post 3 above.
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