230V single phase - 3 phase conversion using 2 relays and 3 capacitors on 2 kW motor

[jaymack]

Anyone have a wiring diagram for such an arrangement, using 2 relays and 3 capacitors of rating 200, 60 and 20 microfarad, for a 3 phase motor on an old lathe?

The owner has replaced one relay that was permanently energised with another relay, but the new one gives the same symptoms i.e. it remains enegised but the motor doesn't run at all now. The original fault was that, the motor could only be stopped by switching off the 230V supply. One of the relays appears to be a fleeting start to switch the other capacitor to get the motor running.

Regards

 

[iceworm]

Is the device a one-off fabrication or a manfactured device?

If manufactured, is there nameplate data?

If this is a one-off (no nameplate data) and you are standing in front of it, can you open the covers and do a point to point?

ice

 

[jaymack]

Is the device a one-off fabrication or a manfactured device?
If manufactured, is there nameplate data?ice

It looks like a made up box but could also be professional from 50 odd years ago, there is no information on it.

From a search on the internet, this circuit arrangement is/was very common to give 3 phase power from a single phase supply, albeit that it is very inefficient. I think that the lower values of capacitor, namely 60 and 20 microfarad, are permanently connected across 2 windings, while the largest value of 200 microfarad is switched in just for starting, and is in parallel with one of the other capacitors, although I don't know which one, not being at the site.

If this is a one-off (no nameplate data) and you are standing in front of it, can you open the covers and do a point to point? ice

I am not at the site to do this, although I intend to return after getting more information. The main problem is that I wasn't sure that the owner had reconnected the wiring as it was. :? This arrangement is on the drive motor for an old lathe that the guy uses for his hobby, so I'd like to save him the expense of buying a proper inverter.

Regards

 

[bob]

Check here http://www.metalwebnews.com/howto/ph-conv/ph-conv.html. In the text click on Fig1, Fig2 and Fig7

 

[jaymack]

Check here http://www.metalwebnews.com/howto/ph-conv/ph-conv.html. In the text click on Fig1, Fig2 and Fig7

Thanks for the link, these are more variations to ponder on.

Regards

 

[Phil Corso]

Jaymack...

Is the motor mfgr "Marathon?"

Regards, Phil Corso