Author Topic: Another PJ  (Read 517 times)

0 Members and 1 Guest are viewing this topic.

Offline frackers

  • Moderator
  • Full Member
  • *****
  • Posts: 221
  • Karma: +9/-0
  • If it moves - computerise it!
Another PJ
« on: December 29, 2016, 03:43:56 AM »
Nearly finished the OZInverter project but rather than revive a thread that is over a year old, I'll continue here.
Here are pointers to the original item I posted.

The project started with the breaking down of a 5 current transformers. Originally (I think) from 11kV line equipment, they were very old (Imperial sizes) and found in an old oil drum in a scrap yard half submerged in water.

http://www.anotherpower.com/board/index.php/topic,1066.msg10588.html#msg10588

The toroids were rewound

http://www.anotherpower.com/board/index.php/topic,1066.msg10591.html#msg10591
http://www.anotherpower.com/board/index.php/topic,1066.msg10601.html#msg10601

and that is as far as I'd got when I last posted about this project.


Robin Down Under (or are you Up Over!)

Offline frackers

  • Moderator
  • Full Member
  • *****
  • Posts: 221
  • Karma: +9/-0
  • If it moves - computerise it!
Re: Another PJ
« Reply #1 on: December 29, 2016, 03:52:52 AM »
The next part was assembling the (now 5) sections into a single huge (25kg) toroid. This was done with polyurethane glue, and since that requires water to make it 'go off', a contribution from the wifes sewing room with some polyester interfacing (as used in collars etc) to go between sections.

ila_rendered

The polyester was cut to the same size as the core sections

ila_rendered

and each one was dampened, glue spread on the two faces of the cores and it all clamped together in a stack

ila_rendered

Next came the cable for the primary. My mate Andy, champion scrounger par excellence, has scored again!! First with the cores, then the 1.8mm coppper wire for the secondary and now with 13 m of 50 sq mm flexible welding cable for the primary. That's enough for mine and Andy's transformers which will require about 5.5m for the winding so leaves a bit for the tails!

Its double insulated (14.5 mm diameter) so the outer orange PVC will be removed (inner is 11.5 mm) to get the 12 turns into the toroid.
ila_rendered


Robin Down Under (or are you Up Over!)

Offline frackers

  • Moderator
  • Full Member
  • *****
  • Posts: 221
  • Karma: +9/-0
  • If it moves - computerise it!
Re: Another PJ
« Reply #2 on: December 29, 2016, 04:05:25 AM »
First job was to get a layer of mylar on the core

I used some corner pieces to radius the edges (thin irrigation pipe) and set to.

ila_rendered

When it came to epoxying the first winding layer, disaster!! The irrigation pipe corner 'protectors' held the wire out from the core surface and prevented the whole thing holding together. I wasn't very happy with the winding itself either!!

ila_rendered

The result of this was stripping it back to bare metal and starting again having rounded the corners off with a flap wheel

Anyone attempting a rewind might be interested in my 'patented bicycle wheel winder' !! You can see it in action on youtube - first with the mylar

https://youtu.be/RbuXQ005wE8

and struggling with the 1.8mm wire

https://youtu.be/kYtudDVucUo

Having 3 secondary layers onto the core, it was time to check that I had the same number of turns on each one. This is the result of the difference between the first 2 windings with one energised with a 100w bulb in series as a current limiter.

ila_rendered



Robin Down Under (or are you Up Over!)

Offline frackers

  • Moderator
  • Full Member
  • *****
  • Posts: 221
  • Karma: +9/-0
  • If it moves - computerise it!
Re: Another PJ
« Reply #3 on: December 29, 2016, 04:31:26 AM »
Time to put all the bit together on the bench and see if it flies.

Using a 1kw telecom PSU to drive it (my battery bank is set up for 24v at present) I loaded up to the maximum that the PSU can deliver with just over a 1kw. Very happy with this as the heat sinks are only just warm enough to see they are above ambient temperature.

ila_rendered

31kg and the monster is complete. More irrigation piipe, some MD40, to space the primary round the hole!!

ila_rendered

And that is as far as I got by April 2016 when life (visit to the UK, winter, work etc) put a hold on things for a while.
Robin Down Under (or are you Up Over!)

Offline frackers

  • Moderator
  • Full Member
  • *****
  • Posts: 221
  • Karma: +9/-0
  • If it moves - computerise it!
Re: Another PJ
« Reply #4 on: December 29, 2016, 04:42:03 AM »
Summer is here, Christmas holidays so time to put the inverter into a box.

Another trip to the scrap yard for Andy resulted in this  fibreglass electrical panel enclosure

ila_rendered

To carry the weight of the core and hold everything else into place I made a steel subframe.

ila_rendered

This fits onto studs cast into the enclosure and has mounting holds for a wooden panel that holds the main electronics and 10mm nuts welded to the underside to take the toroid mounting bolts.

ila_rendered

Y.M.I.P (Yet More Irrigation Pipe) as spacers for the toroid mounting bolts, exterior plywood to hold but not crush. A pair of Papsp Variofan thermostatically controlled fans, scrapyard again, ex-server rack cooling shelf!

ila_rendered


Robin Down Under (or are you Up Over!)

Offline frackers

  • Moderator
  • Full Member
  • *****
  • Posts: 221
  • Karma: +9/-0
  • If it moves - computerise it!
Re: Another PJ
« Reply #5 on: December 29, 2016, 04:51:23 AM »
I bought a proper E core after messing about with ferrite C cores and managed to get 4 turns through it so happy with that!!

ila_rendered

And finally (so far) MCB and RCB and a couple of sockets (for local use only!!) on the door of the enclosure.

ila_rendered

No monitoring yet, I'm working on a variation of my wind turbine controller to start with, that will only monitor the DC side of the inverter so I'll be re-writing it from an AVR to an STM32 and getting use of all that loverly DMA, 14 bit ADC, USB, super fast FSCM ((flexible static memory controller) for a TFT display and all that good stuff.
Robin Down Under (or are you Up Over!)

Offline bj

  • Hero Member
  • *****
  • Posts: 651
  • Karma: +19/-0
  • Lamont, Alberta, Canada
Re: Another PJ
« Reply #6 on: December 29, 2016, 07:51:04 AM »
As always Frackers, a very nice build.
"Even a blind squirrel will find an acorn once in a while"
bj

Offline oztules

  • Forum Advisors
  • Hero Member
  • ****
  • Posts: 1084
  • Karma: +90/-5
  • Village idiot
Re: Another PJ
« Reply #7 on: December 29, 2016, 03:12:19 PM »
Nice when a plan comes together  8)

You have done this hard Frackers, no-one else has  really built a transformer from scratch scratch... well done

I now pull the centers out to 100mm and add that to the outsides, but thats a long way from a total coil rewind.



.........oztules
Flinders Island...... Australia