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Any experiences of 3 phase converters?
v8kid - 13/7/12 at 12:35 PM

I've bought a largish 3 phase lathe (Colchester Triumph) and would like to keep the motor which is a delta connected 400V spec. The motor is quite difficult to change due to the clutch/brake arrangement (so I am told).

Have any members experience with single phase to 3 phase converters?

I'velooked at the Clarke PC40 (£322 ouch!) and the cheaper versions on ebay.

The Clarke gives the full 415V 3 phase whilst the cheaper ones on closer reading only give 240v three phase for star connected motors (which my 1950 Brookes is not).

There are also more expensive ones from Direct Drives at £450 which vary the frequency (and hence the speed) but I'm not sure I really need this.

What experiences have you guys had? Is there a reliable and smooth locost option.

Oh yes I forgot I live in the country and the local transformer is single phase so its megsabucks to get a 3 phase supply installed.

Cheers!


Theshed - 13/7/12 at 12:59 PM

I use inverter phase converters on all my machines - being able to change the speed digitally is great. You are right that the 415v units are much more expensive. On many motors you can dig out the star point from the windings to convert to dual voltage - google this.

I have only used a static converter for 5 mins - it all ended in smoke...you have to match the capacitors to the motor - that said people have used them for years. If you want to build your own I still have a very large 240/415v auto transformer cluttering up my shed - lots of plans on the interweb


AdrianH - 13/7/12 at 01:28 PM

I have a 3HP motor on a Herbert Flashcop that I managed to change from 415 to 240 by selection of links in a junction box. That changed it from 415 star winding to 240 Volts delta. A Mibsbusi VFC drive runs that now from a 13 amp socket.

I have also made a 240 Volt static converter to drive a Harrison vertical mill. That needed the star point digging out and making into a Delta motor.

What I have stuck under a work bench is a 240 to 415 Static converter that I have had for years, with switchable caps for 2 HP, 3 Hp and 4 HP I think!

If you wish to have a play with it to check things out you are welcome, you just have to get it from Blackburn to where ever you live. I am sure that can be done in a sort of relay locost style.

You will need a heavy mains supply suggest around 30 Amp to it.

I would also suggest if possible you run an idle motor, this allows easier switching in and out of your lathe motor.

Adrian

I might even have a 415 VFD some where sat on a shelf, can you understand German, that needs 415 supply.


mark chandler - 13/7/12 at 04:58 PM

I had a 3hp donkey saw, star wired and loaded the 3rd phase with capacitors, extra ones to start it which I switched out when running.

Once I got them balanced it did not stall easily, just a bit of faffing about. Downside is you lose power, so just go slowly


Wadders - 13/7/12 at 05:24 PM

Here you go mate

http://www.homeworkshop.org.uk/index.php?option=com_adsmanager&view=show_ad&adid=12061&catid=2


theprisioner - 13/7/12 at 07:31 PM

Hi,
I have one of these on my Meddings pillar drill. Absolutely fabulous. Changing speed no problem. Bit of a bitch to program, the chap gave be a hand over the phone telling me which buttons to press. Had it for years, soft start etc etc

see: http://www.motors-direct.co.uk/index.php?_a=category&cat_id=123

No sure if this supplier I used but similar.


v8kid - 20/7/12 at 11:32 AM

Thanks for all the advice. As well I also considered a three phase petrol generator but decided in the end to fit a single phase motor.

Even allowing for fitting a 75% larger motor it was the cheapest option and on further investigation it is quite easy to change motors on these lathes despite what the inverter salesman said

Cheers!