Author Topic: guess who bought a power jack inverter  (Read 84406 times)

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Offline welshman

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Re: guess who bought a power jack inverter
« Reply #510 on: February 13, 2017, 07:18:43 AM »
I'm amazed, your equipment is in another category of power level. I may have to increase mine also though. Odd, ive got a 24v setup with a 200lb square transformer and it runs 4kw without an issue and very little heat, i turn fan on low just for a little protection.  Now this 48v setup is using 1 original pj toroid with modified windings and it only had to hit 1850w today and the former + heatsi ks got very warm. 3 times it shut off, guessing it was heat because it turned right back on.
It didnt display. Any red lights.

if you have a look at my setup where i have split the pj into seperate parts and put them into an electric wall mount box with fans on the front door. With regards to the temperatures of the individual components. The heatsinks and the fets are by far a lot cooler than the toroids ever are. For example on a 2kw load the heatsinks only get up to about 20 deg c, where as the toroids can reach 50 deg c. At 10kw load the max i have seen the heatsinks is 37 deg, but the toroids can reach 80-90 deg.

Offline oztules

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Re: guess who bought a power jack inverter
« Reply #511 on: February 13, 2017, 02:18:09 PM »
I find the whole thing runs cooler back feeding ( the 8010 ... don't use PJ nowdays ).

The wire insulation is the thing holding the transformer back from destruction, and I would hope that less than 100c would be fine. If it cant take boiling water temp, then there is a real problem.

The hotter it gets, the easier it is to get the joules out of it, as delta T gets bigger....... 80c seems to be the normal getting too hot temp... ie when they normally take steps to ease up a bit.. fans or throttle back in some cases.



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

Offline lighthunter

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Re: guess who bought a power jack inverter
« Reply #512 on: February 14, 2017, 08:48:42 PM »
Lighthunter..... those PJ transformers are only 1kw continuous by my reading........ they do fine with huge loads for short periods, but continuous they are very much under cooked. You will need to wind a 100lb torroid to emulate the 200 lb square one...... and that PJ is not that.

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

Uh, ok, seems like they should do more but from what ive seen, i agree.


It would be perfect to switch the large transformer to the 48v inverter but they arent near each other. The 510AH battery is one frame (2000lbs) is that right? I know its heavy, no chance of getting it in basement.  Moving the large transformer out of basement would be a trick as well. Think i will leave the 24v setup alone, it works too well to mess with.

Heres a couple of photos of another transformer i may be able to use, its only 1/4 the size of the one im using for 24v inv but its still pretty big guess about 50lbs similar to a sack of feed to pick up.
The idle current is around 19w with dual 120v secondaries and a quad 43.5v primary.

I wonder if I couldnt pull some of the wire out of the middle and reduce the 43.5v to 35v??

The primary has 4 parallel  of 10awg square copper
No idea on power handling but would surprise me if it couldnt do 4kw continuous without significant heat.  Thanks everyone for ideas and suggestions.

LH

Offline lighthunter

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Re: guess who bought a power jack inverter
« Reply #513 on: February 26, 2017, 04:18:53 PM »
Hi all! :)  Ive been busy putting up another array, Done with that now, it looks horrible but it puts out power and I got it cheap. Its 3kw rated but bubbles trapped under glass.  Already seen it putting out 2260w so am happy. The catch is the outputs arent uniform so i cant do a string, therefore very large wire 76v and buck mppt.

Anyway, I'm more posting about the interesting transformer in previous post.
It came out of a multi kw UPS and not sure if this transformer was the recharger part of it? It weighs 75lbs or 34kg.   It appears to have been connected as an autotransformer. Has anyone seen this done for a bat charger or inverter?  Certainly it lacks isolation yet wouldnt it boost efficiencies? Interested in your thoughts. I'm attaching a pic showing original design connection and a possible way to use it as a 48v inverter for 120/240 but NOT split phase. There are 6 windings. All are same size wire equivalent of #8awg good for 40amps continuous at least.

Edit; the previous post mentioned 4 parallel primaries, that was incorrect. After cutting leads apart I found windings as drawn in top of pic.
LH

Offline Pete

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Re: guess who bought a power jack inverter
« Reply #514 on: February 27, 2017, 06:09:18 PM »
Lighthunter, auto transformers are generally not recommended for permanent connections. You have mentioned the isolation issue, if the transformer developed a short it could be catastrophic in the least and deadly at worst.
If it were used as a battery charger and developed a short it could destroy the batteries, with catastrophic results and possible fire.
As an inverter, well a short could also put high voltage onto your batteries, panels, and regulators.
I would not use an autotransformer for anything other than test equipment.

Offline lighthunter

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Re: guess who bought a power jack inverter
« Reply #515 on: February 27, 2017, 07:55:20 PM »
Yeah that bothered me too. The unit is better suited for another application (buck circuit). It could still be used for an inverter though, the windings are not internally connected and have paper separating layers, therefore the 30v windings could be isolated from all others giving possibility of 48v /120v isolated conversion.

I had never even thought about how autotransformers work and the whole concept hit me in the face like a wet carp. Turns out the power companies use them extensively where they dont need isolation. One source i found said conversion  losses are .24%. and they use less copper to do it. Better not give pj any ideas or they'll be putting them in their inverters boasting evn bigger watt numbers ;D I shouldnt pick on them, they make a good inverter considering the price.

Thanks for the thoughts! :)
LH

Offline oztules

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Re: guess who bought a power jack inverter
« Reply #516 on: February 28, 2017, 03:07:31 PM »
It is pointless using an auto transformer, as the resistance losses would kill it off too easily.

Remember, you are using a 48v to 240v/120v conversion, so  for whatever the thickness of the secondary winding may be, you should have the corresponding mass of wire on the primary in the ratio of the voltage.... ie if you have 10mmsq of wire in the secondary, you should have at least 80mmsq of wire in the primary ( 240v) It is ok to go as low as 35mmsq of primary if your duty cycle is low... but can you imagine it as a auto transformer? The whole thing would need to be wound at 50mmsq, and it would still get hot under decent load, as there would be 100 turns of wire in there.

So the low losses in coupling would be more than wiped out with all that copper.. if you could fit it in..... not a useful step forward I don't think.

You could perhaps change the winding thickness when you got to the secondary part..... but the isolation would still be nice to have..... if I were to do it, a total rewind would be on the cards, as you have a lot of core there.

The losses will still be about twice for the same power as a toroid one ( twice as much steel)



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

Offline lighthunter

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Re: guess who bought a power jack inverter
« Reply #517 on: March 05, 2017, 06:15:54 PM »
Thanks for the advice oztules.  In case anyone is interested, here are some details of an original pj toroid taken from a 24/110 6000lf.

Primary 12 strand 13awg 23 turns , .756vlts/trn 286uS 17.38AC drive volts .0035R calculated

Secondary 2 strand 13awg 148 turns 8.72uS 112vAC .1146R measured.

Used in 24v application power efficiency/loss @1500w. 
Magnetizing. 15w.
Primary 60A 25v loss 12.6w.
Secondary 13.4A 112v. loss 20.57w.
Total loss 48.17w
Efficiency 96.8%

With primary converted to 48v.
Magnetizing 15w.
Primary 30A 50v loss 6.3w.
Secondary 13.4A 112v loss 20.57w.
Total loss 41.87w.
Efficiency 97.2%

I was surprised to find that it was the secondary that needed more copper.
The primary is good to 2200w in 48v application with less than 15w loss at 45amps.

It looks like 50w of dissipation is enough for this toroid package. Of course with better cooling it could maybe dissipate more. When i used it at 1800w it only got to 160F 71C and it had added windings contributing to heat so in original form with adeqate cooling it may get close to 2kw continuous witbout exceeding 85C

Attached study done on toroid. The example in appendix A shows a 4kva toroid dissipating approx 100w at a fairly warm temp.

Edit, attachment didnt work for some reason. It was a 4kw toroid. Core size 22.86cm OD x 7.62cm H at full load, dissipating 105w at a steady temp of 185F or 85C

The primary resistance was calculated from approx number turns and measuring wire size using 13awg 2.001R/1000feet.  The secondary resistance was measured by using seconday in series with a load and measuring voltage drop. The toroid was not disassembled to obtain information,12 primary windings were counted but 2secondary wdgs is guess based on measured resistance.
LH

Offline elajambejr

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Re: guess who bought a power jack inverter
« Reply #518 on: March 16, 2017, 11:10:56 AM »
I purchased one the these Power Jack inverter (8000w 240v version) about a year ago and I have to say for the money I'm quite pleased. Runs 1500w with room to spare for a fridge or something to startup at the same time without any issue. The one serious drawback is the standby load which I'd like to fix before I take it off grid.

I'm running a split phase 240v 12v version of the Power Jack which have two invertors so I assume I need to choke both sides legs of transformer, correct? Also, could you suggest what size, type, etc. of choke I'd need to build? I know some about electronics but not nearly enough to tackle to figuring out what size of choke I need?

Thanks in advance.

Offline lighthunter

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Re: guess who bought a power jack inverter
« Reply #519 on: March 18, 2017, 12:00:50 AM »
Hi Elajambejr :)  Page 1 of this thread has what you need. Still an Ecore with 3 1/2 turns in series with primary connection to one of the heatsinks. Your specific inverter is not unique to the application of this. One lead wire of your ecore inductor will connect to heatsink while the other wire is connected to one or multiple toroid primaries. With 12v inverter make provision for the necessary current as 1500w equals 125A. If you are seriously considering using this unit for a daily runner off grid you would be doing yourself a favor to upgrade to 24v or higher to reduce problems and increase load capacity.  These units can be converted to a higher voltage quite easily with some electrical ability.

Quote " version of the Power Jack which have two invertors so I assume I need to choke both sides legs of transformer, correct? "

   You do not have 2 inverters with 12v version but you do very likely have 2 toroid transformers (round heavy),   No, you only need choke on one side feeding both transformers.

Have a great day!
LH

Offline Juan Marrero

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Re: guess who bought a power jack inverter
« Reply #520 on: April 11, 2017, 02:43:05 PM »
Hello everyone.
Thanks for all the really useful information.
I request your opinion.
I am aslo an islander (40 x 100 mile island in the caribbean).
I got a power jack low frequency 8000w split phase inverter too.
ac electricity is 60hz here.
I need to hard wire the ac 220-240v to a water pump which is 3 amps but is about 100 feet away off grid.
I checked the terminals and L1+N=110v ac and L2+N=11v ac
I am planing on using a 8AWGauge(3.26 mm or 8.36mm2) to hardwire the connections.
The question is:
1) Do I connect one to each L1 and L2 and the ground to the N?
    or do I just connect the L1+L2 ?
2) Do I use a thicker wire?
3) once I use this hardwire does that mean I cannot use the 110v ac outlet receptacle?
Does anyone have a picture of a hardwired 240v ac power jack inverter?

Offline oztules

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Re: guess who bought a power jack inverter
« Reply #521 on: April 12, 2017, 04:21:37 AM »
Treat the output as 220v center tapped transformer.... so for 220v use L1 and L2 and ignore N completely....it is effectively the center tap. So you can run the pump through L1 and L2, and still use the 110v output to drive different  loads as well.


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

Offline Juan Marrero

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Re: guess who bought a power jack inverter
« Reply #522 on: April 12, 2017, 10:44:18 AM »
hey !  thanks!
I will do just that
You have another's fan in the caribbean .