VFD conversion and getting a 110v supply for power feed

[Phil Crossley 1Participant @philcrossley1]

Hoping someone can advise …

In the cabinet of my bridgeport clone, there is a transformer that uses 2 phases (L1 and L2 in )and has 110v an 24v out (power feed and work light). can i simply connect live and neutral single phase to those so the power feed etc still work while the VFD runs the main motor?

Thanks

[Phil Crossley 1Participant @philcrossley1]

[Joseph Noci 1Participant @josephnoci1]

No, you cannot..

Between L1 and L2 lies 400v AC. Between Live and Neutral is 220V AC. Connecting this to the 400V input of the transformer will not cause any damage, but will drop the 24V output to around 14v AC; likewise the 110v AC output will drop to around 60 volts. Way to low for the feed and light..

What shape is the transformer? If normal 'E-I' type core, most likely the primary winding is one winding on the centre core , with the secondaries, and you are euchred.. If a 'C' core, ie, a square or rectangular 'ring', the primary is sometimes split in half, with one winding on one leg of the core, and the other half on the opposite leg, and then wired in series for 400VAC. If this is so you can disconnect the series connection, and put the two halves in parallel , which will be a 200 volt winding – this will work on 220volts in the transformer is reasonably beefy, but now you out put voltages will become 26VAC and 120VAC, the latter being 'within' the max specified upper limit for 100volt AC mains..

Joe

[Phil Crossley 1Participant @philcrossley1]

I've managed to get a photo, which shows it better than i could explain i think.

[Phil Crossley 1Participant @philcrossley1]

[Chris Evans 6Participant @chrisevans6]

I have fed my Bridgeport transformer with 240 volt ac and the 110 output works as does the 24volt. I believe it was from instructions posted by Clive Foster he will probably confirm at some stage. This was to get the power feed and Lovo light working. I will take a look in the Bridgeport cabinet next time I am in the workshop.

[Joseph Noci 1Participant @josephnoci1]

Phil, what does the legend beneath the wire lower left in your pic say? – Just above the 0V legend. Does that say 220V? If so, you are in luck! Neutral on the 0V and Live on that input and it will work fine.

Joe

[Phil Crossley 1Participant @philcrossley1]

Thanks for the replies folks. And Joe – I checked another picture and it does indeed say 220v. I missed that, and that makes sense as it’s currently wired L1 and L2 to 0v and 415v.

[Phil Crossley 1Participant @philcrossley1]

Well, after a great deal of staring and continuity testes i've managed to not just get the power feed working off 240v single phase, but the lamp and every single contactor and button on the mill too. And with ONE simple wire change ….. move the wire on the transformer from 415v to 220v. and thats it.

I think they designed it to be easy to convert from three to single phase. saves any extra costs.

Well happy with that now, and i'll feed the VFD off the main motor contactor so the emergency stop kills that as well as the power feed.

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