Centec 2B power feed

[David PyeParticipant @davidpye61505]

I acquired a Centec 2B a couple of months ago and am in the process of part stripping and cleaning. I have removed the power feed gearbox from the table (thanks to some helpful info on this forum) and am now getting ready to re-assemble. Two questions: the whole box was full of grease when I opened it up. From the manual it appears the rear part (next to the table) should contain a light oil, for which it seems to be designed. The manufacturer's lubrication plate specifies a grease to be used in the "worm box". Now the table gear box is the only worm I can see so would people use suitable grease to lubricate this part? It doesn't really look designed to take oil in this section.

The previous owner had a 220v inverter wired to what appears to be the original table motor which is 3phase 400/440v. Any comments on driving a 400v motor from a 220v inverter?

[David PyeParticipant @davidpye61505]

[peak4Participant @peak4]

Posted by David Pye on 26/04/2017 16:00:19:

The previous owner had a 220v inverter wired to what appears to be the original table motor which is 3phase 400/440v. Any comments on driving a 400v motor from a 220v inverter?

Has the previous owner dived into the windings to find the star point, and re-wired it as delta?

If so, it would effectively be a 220v motor.

I've got exactly that job to investigate myself when I get more time.

 

You could have a read of this post and see if you can find out how the OP got on.

http://www.model-engineer.co.uk/forums/postings.asp?th=123870

 

Edited By peak4 on 26/04/2017 21:30:14

Edited By peak4 on 26/04/2017 21:30:41

[not done it yetParticipant @notdoneityet]

The previous owner had a 220v inverter wired to what appears to be the original table motor which is 3phase 400/440v. Any comments on driving a 400v motor from a 220v inverter?

 

It was either seriously down on power, or someone had delved into the motor to split the star connection and then connected in delta configuration. Latter would be the better option, but it may have worked adequately (just?) at the lower voltage in star connection.

 

Edit – Peak4 keys in faster than I do!  Gary Wooding is the member who has done it already.

Edited By not done it yet on 26/04/2017 21:28:52

[David PyeParticipant @davidpye61505]

Thanks. The connections brought to the outside world did not appear to have been disturbed, so I presumed it was unmodified. I have now had chance to open it up. All the windings are very neatly, tightly and comprehensively bound. There is no sign of disturbance. Neither is then any sign whatsoever of where the star point may be located.

The manufacturer's label states it is made by The English Electric Co. Ltd. The one Gary pictures is by Brooks Ltd and the windings do not look as "encased" as mine. Certainly there is nothing like the star point he shows.

Guess I just use it as is if it works (I did see it move the bed before I bought it).

[Brian OldfordParticipant @brianoldford70365]

Posted by not done it yet on 26/04/2017 21:26:09:

The previous owner had a 220v inverter wired to what appears to be the original table motor which is 3phase 400/440v. Any comments on driving a 400v motor from a 220v inverter?

It was either seriously down on power, or someone had delved into the motor to split the star connection and then connected in delta configuration. Latter would be the better option, but it may have worked adequately (just?) at the lower voltage in star connection.

Edit – Peak4 keys in faster than I do! Gary Wooding is the member who has done it already.

Edited By not done it yet on 26/04/2017 21:28:52

I did a similar mod to an old Brooks Gryphon motor that was wired for 415V only. I acquired it for very much the right money. Older motors are probably easier to mess with because they are less likely to have "epoxy potted" windings.

One thing to be vigilant about is to ensure all three windings are connected with the correct polarity i.e connect the star point of winding 1 to what was originally the outer point of winding 2, the star point of winding 2 to what was originally the outer point of winding 3 and the star point of winding 3 to what was originally the outer point of winding 1.

Don't ask how I know about such things. . . . . . . . .

[Neil FazakerleyParticipant @neilfazakerley]

Posted by David Pye on 26/04/2017 16:00:19:

… The previous owner had a 220v inverter wired to what appears to be the original table motor which is 3phase 400/440v. Any comments on driving a 400v motor from a 220v inverter?

Old star wound 440v motors will usually work okay from a 220v inverter, but at about half their normal power. E.g. a 1/2hp motor will effectively become a 1/4hp one. I use an old high speed bench drill this way and it's fine on smaller drills (which is all I use it for).

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