MadModder

Gallery, Projects and General => How do I?? => Topic started by: shipto on June 13, 2013, 04:58:28 PM

Title: 230v dc motor
Post by: shipto on June 13, 2013, 04:58:28 PM

I have a 230v dc motor from a clarke mini lathe. I assume I can run it from the mains with a diode or rectifier in place (please correct me if I am wrong).
Again assuming I can, is there a formula for working out what kind of speed I can expect. The motor is supposed to be capable of 4000rpm which I guess would be a constant smooth supply so a full rectifier will? give me about this maybe more as the voltage will be 240 but a diode would give me 50 hertz at 240 volts and this is the speed I would like to know.
I appreciate any input.

Title: Re: 230v dc motor
Post by: John Rudd on June 13, 2013, 05:15:40 PM

240 volt mains rectified with a full wave bridge (4 diodes) with a reservoir capacitor should realise circa 380v dc.....

(240 * 1.414.....)

The voltage at this level is too high for the motor which is why it is fed with a modified supply from a speed controller....

The voltage rating of these motors is generally around 180 v dc, this is obtained from the speedo which is either mosfet based or thyristor (scr ) based....

If you want to run the motor from the mains I suggest you use a variac and limit the voltage goign to the bridge rectifier ( suitably rated voltage and current wise......)

Title: Re: 230v dc motor
Post by: shipto on June 13, 2013, 05:35:40 PM

Thanks John I guess i will leave it then as I only want it for a single job I wont bother with this motor and save it for a project where it will be worth buying the proper controller. Was a nice thought while it lasted though.

Title: Re: 230v dc motor
Post by: Auskart on June 13, 2013, 10:38:35 PM

If you know what you are doing, you can use the speed controller from an old Treadmill.

Title: Re: 230v dc motor
Post by: Pete. on June 14, 2013, 12:06:23 AM

You want THIS, or something like it. This one is only good for about 1hp:

http://www.ebay.com/itm/221221730576?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649

Title: Re: 230v dc motor
Post by: John Hill on June 14, 2013, 12:14:53 AM

If it is just a single job and you don't care too much about anything a half wave rectifier (i.e. just one diode) might do the trick.

Title: Re: 230v dc motor
Post by: John Hill on June 20, 2013, 06:42:06 PM

Doh! I forget to mention that using half wave rectification would give an effective DC voltage of something less than 230V, depending upon load and capacitance in the circuit etc.

Title: Re: 230v dc motor
Post by: shipto on June 21, 2013, 06:03:10 PM

thanks John but I sorted it with a standard induction motor in the end, just needed to power up lathe to do a bit for the lathe drive belts. working on a new stand for it now.