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New drill-1PH to 3PH wiring

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David Siddle 109/03/2019 20:14:18
12 forum posts

Hi. I've just bought myself a decent Fobco Star, fitted with the original dual voltage 3PH motor. I want to be able to run it from my normal 1PH supply through one of the cheap VFD's of the usual auction site. The one i've seen is rated for 0.45kw. My motor is 0.33HP, ie. 0.25kw. Is this OK? Also, I want to add a remote speed and direction control to assist tapping ops, and for convenience. I believe i need to wire the motor delta, but i'm not sure what voltage/current the parts for the remote control box should be. I'm assuming it would be a low voltage circuit? Forgive my ignorance, but i'm not electrically minded, and have never dealt with 3PH before.

Many thanks for any help.

David Siddle 109/03/2019 20:37:51
12 forum posts

Actually, i've just found this guide on-line for a Siemens device. Looks like just the job to me, and the guide answers all my questions.



Anyone agree with me?

Martin Cargill09/03/2019 20:39:55
99 forum posts

First you need to check that the motor on your drill can run at 220 volts three phase. Have a look at the nameplate on the motor and check that the voltage is rated for 400/220 volts. A 0.45 kw drive will be suitable for a 0.25kw motor.

The control circuitry will probably be 24 volt and does not handle any significant current, it is normal to make a control pod with start/stop/ direction and speed control. A light eight core cable is the norm for connecting the pod to the invertor. Your invertor should be mounted somewhere safe (inside a housing )where it will not have any chance of having swarf etc falling into it.


John Olsen09/03/2019 20:42:10
959 forum posts
86 photos
1 articles

The .45 kW inverter will be fine with your motor, a bit of spare capacity is not a problem. The motor will need to be wired delta. This is usually not a problem, unless the star point is buried inside the winding, but since it is a dual voltage motor it must be accessible. There is quite likely a little diagram, maybe inside the cover over the terminal.

The remote control parts will all be low voltage rated. Usually all you need is a couple of switches (forward/reverse and on/off) and a potentiometer for the speed. The latter is probably about 10k ohms, linear, but check what the instructions say, if you can decipher them! I made mine up in one of those small diecast boxes that the electronics shops usually sell.

No switches or plugs on the motor side, and preferably shielded cable there.

If you are not used to this stuff it might pay to find someone who has done it before to help.


David Siddle 110/03/2019 10:10:33
12 forum posts

Thank you both very much for your help. I feel a little more confident now!

David Siddle 110/03/2019 10:26:14
12 forum posts

Does anyone know where i might find a suitable wiring diagram? Off/On, forward/reverse and pot for the speed control?

Thanks again.

Martin Connelly10/03/2019 11:48:45
839 forum posts
93 photos

Wiring for the VFD is dependent on the make and model and is usually given in the associated manual. They are generally available on line.

Martin C

Trevor Drabble10/03/2019 13:52:09
186 forum posts
5 photos

David ,

Sent you a PM .

Trevor .

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