Thread: urgent help please with drill and vsd

Originally Posted by scamp

i would get 3 phase installed but as my workshop is about 100 meters from the source and i have to pay for all that cable and also the re wiring and installation of a new power board, meter and sub board, im looking at quotes of 7 grand plus.

i cant believe how expensive it is. but that is what i have been quoted.

I paid $8000 to get 3 phase installed on my place. 200m of bundled aerial cable, 2 private poles installed, share in the cost of the transformer, then the other bits. Worth every cent IMO but I have a lot of 3 phase tooling and I use it a lot.

When I did this in Sydney I think the cost was more like $2K because it was simple, just a domestic dwelling and the cable was easy to run from the main board under the house to the shop.

Generally if you have to upgrade your power board & sub-board, they need it anyway. Mine are all circuit breakers & RCD's on domestic circuits, the original Sydney board still had porcelain fuses etc. I ran all the wires etc, just had the licensed electrician do the hookup & put in for the inspection.

Cable is the cheap part. I paid $7/m for 6mm 5 core orange sheathed fairly recently so you're looking at around $700 to go to your shed, plus conduit if it's got to be buried, or you can run 6mm single insulated in conduit which is what I did for a line to my dam. Cost me about $600 including conduit for 100m 6 years ago (and I've never used it, but I had a trench open at the time so.....). I've got 20A breakers on the 6mm cable over that distance which is reasonably conservative. Same size cable in my barn, 20m run, has a 32A breaker on it to feed my 25HP air compressor motor.

I'd suggest getting more quotes & asking for a breakdown in costs, see what you can do for yourself. VFD's are all well & good, I have a few, but for speed control, not buggering about.

PDW

Originally Posted by scamp

the motor is 4 speed and the gearbox is 2 speed, so 8 in total it also has an automatic reverse function for tapping and and automatic feed mechanism that has its own gearbox with 3 different speed feeds.

I've been thinking about this over the last few days. I'm thinking now the reversing isnt for tapping, its just easier for them to reverse the motor(thereby reversing the feed) than to leave the motor running the same way and reverse the feed.
My reasoning(unless there is something I'm missing), you'd need a feed for each thread pitch, 3 just wouldnt do.

Stuart

p.s. Maybe it would work for tapping if you were feeding manually?

Yeah when tapping, you use the manual feed with auto reverse. This way, the tap controls the rate of feed.

Originally Posted by harty69

Hi Scamp

I have just come in from the shed and I now have 3 phase 415v rotary phase converter for a total cost of $80
bit of work still do in balancing out the phases and the rope start is a bit rough but she works
had the tool and cutter grinder running for about an hour and it worked like a charm
all you need is a old welder (that can be hooked up 250v or415v)and a 3 phase pony motor mine is 5.5hp

here is a link to aussiejoeblows build over at PM

cheers
Harty

Good Work Harty, on your work in progress Rotary Phase Converter. I too am looking for the bit to economically build one, and like your design I would also prefer to generate 415V, 3 phase, just so that any 3 phase machines would hook up with the minimum of fuss, with maximum flexibility and without needing to dig out star points etc. Presently I am researching the various designs to see if I can use an auto-transformer circuit, and still derive a neutral, or do I have to have an isolating transformer as the 240 to 415 step-up transformer to get a neutral link to have a star connection.
Another point of interest is the N.Z. lot who advertise on eBay a kit to build R.P.Cs, which sounds like it switches capacitors in and out to keep the phases balanced with changing loads. They don't give much away in their blurb, and I have heard from someone that their circuit boards have all the component identification Nos. removed to hinder copying of their design. Anyone with knowledge they would care to share is most welcome to chime in, as the ability to maintain phase balance with varying loads does have a certain elegance I think.
Finally, in your quote above you refer to a pony motor, when I think you mean an idler or sometimes referred to as pilot motor, (as the "3 phase generator"). As I understand it a pony motor is a small single phase motor which gets the idler up to speed, before the power is applied to it, so as to prevent high start-up surges which would cause all the neighbours lights to dim as you fired up the RPC, especially if it is a largish idler motor. It also allows you to do away with the rope pull!
Keep up the good work, Cheers,
Rob.

Hi Rob
you are correct it should read idler motor
the current setup I have is unbalanced and i am getting 415v 407v 390v on the 3 legs it does now have a pony motor to replace the rope start
the welder works as a auto-transformer in this setup

cheers
Harty

Originally Posted by harty69

Hi Rob
the current setup I have is unbalanced and i am getting 415v 407v 390v on the 3 legs

Those voltages are not too bad I would have thought Harty. At 390V on the worst case leg, you are within 6% of 415V near enough, and the impression I get is that anything around 10% is normally quite acceptable. Are you planning on fine tuning these voltages when you load up your RPC?
As an aside, I have just received a copy of Three Phase Conversion by Graham Astbury, which is No.47 in the Workshop Practice Series. I am wading through it at the moment, it has some mathematical aspects which I have not seen in any of the other books in this series, but nothing much too difficult to get a handle on. When I have read it I will let you know my considered impressions, but ATM I think that I will find it pretty useful. The cost was less than AU$11.00 , delivered, as are the other titles in the Workshop Series, from the Book Depository in the U.K. It took about 5 days to get here.Three-phase Conversion (Workshop Practice) : Graham astbury : 9781854862624 Looks like they ripped me off, It's even cheaper now!!
Cheers,
Rob.