AC Motor inverter

[Paul VassalloParticipant @paulvassallo49657]

[Paul VassalloParticipant @paulvassallo49657]

I have just bought a Tool and Cutter Grinder and it has a 3 phase motor on it, the options to run it at my workshop, are either I buy a single phase motor, or an inverter. I would prefer to buy an inverter but I do not know how to program it.

Can some body please help.

 

[David Clark 13Participant @davidclark13]

Hi There

Very easy to program.

Buy a Jaguar or similar from Transwave.

5 minute job to program it and they will help if you get stuck.

regards David

 

 

[Les Jones 1Participant @lesjones1]

Hi Paul,

I think most of the suppliers will be willing to advise you on setting up an inverter. Using it on a grinder is undemanding as it will not need to vary its output frequency. You may even get it working well enough just using capacitors to provide phase shift to one of the windings. Using this method the motor would not provide its full torque but this probably does not matter on a tool grinder.

 

Les.

[KWILParticipant @kwil]

Gary Oseman, an advertiser on Homeworkshop.org.uk website will supply already programmed.

[The Merry MillerParticipant @themerrymiller]

I can’t honestly see the need for variable speed on a tool grinder.

 

I assume that the existing motor would run at a fixed speed as most tool and cutter grinders would, if you can establish what that is then select an appropriate single phase motor.

 

You may have to go for a two pole version if the grinding wheels are about 4″ diameter to get the speed you need.

 

Hell of a lot cheaper than an inverter.

 

Len P.

 

 

Edited By The Merry Miller on 19/12/2011 16:09:37

[Paul VassalloParticipant @paulvassallo49657]

Thank all for you help provided.

Les Jones 1

Hi you told me that I can use my present 3 phase motor just by adding a capasitor between phases, can you please be more specific, and giving me the values of the capacitors,and maybe a diagram of the wiring

Thank you

[Les Jones 1Participant @lesjones1]

Hi Paul,

I said you MAY get it working using a capacitor. First the motor must be designed to run in star configuration when run on three phase (415 volts between phases – the normal supply in the UK.) Also the star point must be accessible. This is most likely to be possible if it is designed as a dual voltage motor. Connect neutral to the star point. Connect live directly to one winding. Connect live via a capacitor to another winding. The third winding is not connected. The capacitor must be the type designed for motor start / run application – at least 300 volts AC rating. I would suggest trying a value of between 10 an 20 uf. Once the motor is running it should be possible to disconnect the winding which has the capacitor in series with it. If this works you could design a delay circuit to do this automatically. If you do not understand this then I suggest that you see if anyone lives near enough to you to help you.

 

Les

 

[TerrydParticipant @terryd72465]

Hi Paul,

 

These books by Mr Cox are very well written and with a lot of information regarding electric motors, including the capacitor method of driving a three phase motor from a single phase supply. A friend who was not very knowledgeable about motors managed to successfully use this method from this book to drive a three phase Bridgeport at home. The book was called ‘Electric Motors In The Home Workshop’. The books are very cheap from Amazon.

 

Regards and Happy Yuletide,

 

Terry

[Author]

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