want to attempt some powerjack mods and could use some help. oztules?

[Dr_Zogg]

howdey all,
i have two powerjack inverters here that i am hoping to mod for my off grid setup.
the first inverter is a 6000w with one transformer and a fan.
the second one is a 15000w with 3 transformers and 3 fans.
i am on the hunt for 2 or 3 aerosharp or inspire inverters to do a double or triple? stack for the 15000w.
i have got and stripped down an aerosharp 3.5 with the hope of rewinding just that one single transformer to go into the 6000w?
if that would be a good option would you have some advice on how to go about it?

i have read oztule's other posts a fair few times to try to familiarize myself with it before ashing questions
 the pics show the transformer that i have stripped from the aerosharp 3.5kw it weighs in at just over 22kg

thanks in advance for the help.

[oztules]

I have a few of those 3kw aerosharps  ( haven't  used any of them yet in this application)

If you remove the outer winding (250v I think) you will be left with a 230v winding ready to use.....

I would have no problem using that for the 6kw unit... non at all... will do it easily, as there will not be 6kw on for very long at all, and will run 4kw all day without any real cooling.... a winner.... and even better if you were to wind another 20 turn on it to bring it up to 250... this will lower the idle current a bit more as we move the saturation point further away.

Not as good as winding your own, but very fast. The fact it is not potted in any way, will make it a bit noisy when under full loads is the only difference... and that the life may be compromised like all other commercial transformers of torroid design.. they never pot them... so not a real concern either... just an observation.

So check the voltage on the inner winding... is it 230 or 250v ( hopefuly 250v but I think 230v)

If you use the same box, it will look similar to this  ( this is an 8000w board set in that box)


...............oztules

[Dr_Zogg]

thanks for the quick reply.
sorry to sound like a dumbass, but how do i go about checking the voltage of the inner winding?

Cheers,
           Sam

[oztules]

Look at the label... colour code is there... look where the wires go.

You have to remove the outer winding anyway, so easy to follow the wire colour there..... and see which one your removing.

I think it is 4 in hand 1.6mm diameter for that winding. I unwound one of them a good while back.... but the core is still on the shelf.... and only vauge memory remains. As you can see I used the box, but not that core.

Let us know when you know.


................oztules

[Dr_Zogg]

thanks heaps for that. i must have been having a senior moment haha.
well I'm going to have some dinner and then get started, wish me luck.
i will put up an update and some pics later on.

what size wire and how many turns would you recommend for the primary?
also for the e core is it possible to use one of the rings i have kicking around from pulling these inverters apart instead?

Cheers,
            Sam

[Dr_Zogg]

sorry bout the delay. i got a new phone and it wouldn't play nice with my laptop
well it is all stripped down and damn. you weren't kidding about getting sore shoulders.

i have decided to take your advice and add 20 turns to it. ( if i have gone this far i may as well do it right)
also it will be good practice for the next one.
i presume that i add 20 turns 3 in hand? also as for my  questions in the previous post i have a heap of 4 gauge car audio
amplifier cable is this suitable?

now to go hand straighten this wire

thanks for the help.

Cheers,
            Sam

[oztules]

Sorry I missed that...yes the extra turns the same as the rest of them... 3 in hand.

Fun undoing it isn't it..... use the three bearings to straighten the wire.

For 48v systems:

Audio cable is about 20mmsq.. so if your going to run this thing hard, then two in hand, if you don't expect longish periods over 1- 2 kw, then one in hand will squeak through.

For the primary we want to know the volts/turn... did you happen to get the turns number when you unwound?

If not..... I am guessing it is about 1.1v/turn, so you will want about 30 turns on the primary for 48v... 15 for 24v and definately 2 in hand and more for lower voltages, and more for higher powers too.

To make certain, you can connect 240v into the 230v winding, and wind a few turns on to get the volts/turn on the new turns. You will have to soften the startup as the fuses will likely blow. You can use a globe and then bypass it when operating..... check the voltage on the 230v winding, and the turns on the test winding.... just to make sure 240v is available or thereabouts.
When you get the turns/volt or volts/turn in this case, divide it into 33v to get the turns you want... for 48v system.......... ie 33/1.1v=approx 30 turns   ......scale to match other voltages.

It is a physical thing working on these transformers for sure.



keep at it.



.....................oztules

[Dr_Zogg]

i finally got off of my lazy backside and did some work.
i have straightened the wire and rolled it onto a large cable spool 3 in hand. my hands knew about it after doing that haha
i built a bearing straightener like yours but ended up not having to use it, after wrapping the end of the wire around one of the stumps on my house and giving it a bit of a tug with the ute it ended up dead straight. is that normal?
anyway i have found some large welding cable for the primary. i will measure it later and see what you think of it, and all being well i am hoping to add the turns to the primary tonight.

Cheers and thanks for the help,

Sam     

[Dr_Zogg]

hi,
  i think i understand the principle for checking the volts per turn that i add. but would it be possible for you to show me a sketch just so i can make sure i am thinking correctly? just because the way i am thinking of doing it i would make a giant 240v electromagnet? i just don't want to toast myself or the transformer  .

thanks again,
                    Sam

[Dr_Zogg]

i just measured the welding cable i have and it is 7.5mm across the core. do you think it would be suitable?

sorry for all the questions,

Cheers,
           Sam

[oztules]

Welding cable is fine @ around 35mmsq .. I guess........ for 48v system for the 6000w converter, and even for the 8000w converter will be fine.
For 24v ok if not driven too hard for too long.

The turns per volt is simply running the transformer normally as is............. with the 240v winding to the 240v ac. ( may need a decent  dropping resistor until it gets going..). then having a few turns on it and measuring the voltage for the say 10 ( or whatever you decide to average it out over ) turns you put on.... ie if you get 12v over 10 turns... then 1.2v/turn... I expect near that .. 1.1 to 1.2v/turn.

You could use the power jack for the 240v input.... just hook the output 240v to the 240v winding BEFORE you turn it on.... that way it will soft start the torroid. Hard start will blow your secondary fuses in the PJ for near certain.

Stretching the wire  with a car is normally for the primary

..............oztules

[Dr_Zogg]

oops. i thought i saw somewhere that you stretched the enameled wire. at least i didn't snap it then. worked well though haha.
i should mention that i am building a 48v system.

thanks for all your help Oz, you truly are a credit to the human race with the way you share your knowledge.

Cheers,
            Sam

[Dr_Zogg]

Check out my amazing graphic design skills!! 
does it look correct to you? if not. what have i messed up in this mess i call a brain? haha


Cheers,
           Sam

[oztules]

......well... giving the enamel wire a bit of a tension up is one thing,,, using the ute to do it brings it to a new level

Graphic arts is better than mine.

That gives you the circuit, now wind a few turns around the torroid ( through the center ...) and measure the voltage that gets induced into these new coils.

This will give you the volts per turn in AC rms ( root mean square )... the equivalent of DC in power terms. ( the peak AC voltage will be 1.414 times the rms value... but we won't bother with this at this time). Use a normal multi meter to measure the volts and we will be fine and in AC rms.

I expect to see 1.1 - 1.2v /turn or in that region.
Once it is going, you will need to short out the globe to get the voltage up to 240v or thereabouts.


Proof your graphics are better than mine......




.............

[Dr_Zogg]

thanks heaps for that. i will put the turns on tonight and give it a crack tomorrow when i finish work.

nothing wrong with the artwork mate, get's the point across perfectly.

Cheers,
            Sam