PLEASE NOTE: If you had an account with the previous forum, it has been ported to the new Genetry website!
You will need to reset the password to access the new forum. Click Log In → Forgot Password → enter your username or forum email address → click Email Reset Link.
The issue I had was that the transformer rubber pad PJ put under it was not a large enough diameter I pulled it out and raised up the coil and adding a 3D printed holder with air passageways under it for cooling and insulation. The rubber pad on the bottom was not a large enough diameter so the coils were touching the case in a few spots not a good thing in a vehicle glad I caught it before it rubbed through the enamel.
8 hours ago, Steve said:The outside will offer allot more surface area but the center will be much hotter
Really it needs to have flow on both
I did wonder why the big round flange was used rather than something more breathable.
With the straps, you could almost skip the flange and just use the bolt in the center holding the straps down. With narrow enough straps, good airflow could result, and ideally wide enough to not cut into the enamel.
Maybe they haven't found an economical enough way to rely on the straps to this degree.
I did wonder why the big round flange was used rather than something more breathable.
I have no idea why...and then adding a big rubber pad to that. And in some of the larger PJ inverters, you'll see a triple-cross bracket...
...when the real issue is that the 2-cross bracket isn't tight to the transformer. The moment that transformer starts to move in shipping, it's game over.
With the straps, you could almost skip the flange and just use the bolt in the center holding the straps down. With narrow enough straps, good airflow could result, and ideally wide enough to not cut into the enamel.
That's GS spec: no flange, no big rubber mat on top, etc. I've narrowed out the straps on the GS12 spec--and likely could narrow out the straps on the new GS6 spec if necessary. Biggest difference on the GS spec is that I'm purposely making the transformer straps very difficult to put on--so they hold the transformer tightly as possible.
As a result, if my memory serves me right, we have not had a single incident of inverter shipping damage caused by a transformer bracket failure.
The transformer bracket mounting is not close to sufficient without a center bolt--remove that bolt, and the inverters will be internally demolished during shipping. Probably a main reason that most other inverter companies go with an E-core transformer: those things are SUPER easy to mount!
That's funny, i've looked inside the GS 100 times, and i never noticed that. Indeed, there is no flange. Just a strap with the center bolt holding it true.
I made this change on my U-Power when i had it apart. lol Not sure if i'd trust shipping it this way, i didn't know how much force i could apply on the strap.
i didn't know how much force i could apply on the strap.
Load it down as tight as you dare: the strap is stainless steel, same as the chassis. I don't think you'll be able to break it 😉.
The biggest challenge is the distance between the chassis bolt mounts and the first bend (on the PJ straps)...that large gap WILL bend under strain, and result in an even-looser transformer bracket. Adding insult to injury is that the PJ spec has huge gaps between the strap and the transformer...rendering it basically useless.
Finally got around to checking that bolt. It is slightly warmer than body temp all around the bolt and measures 1.0vac to the case.
The mounting bolts holding the transformer to my rubber pad have gotten hot enough to melt the 1/8" aluminum floor under the mat. They are no longer doing any securement of the inverter other than acting as locator pins.
and measures 1.0vac to the case.
This is exactly as expected (per transformer winding spec). Worth noting that the transformer is all the way around the bolt, so it will warm the case as well.
If the bolt was shorted to the case, it'd cause significant heat in the bolt and case--and also would not measure 1.0v from the bolt to the case.
By "significant heat", I mean....you'll smell the heat within 10 minutes of power-up, and touching any affected metal will burn your finger.
I still do not think the inverter is responsible for the melted rubber pad/damaged aluminum floor. If the inverter was generating that sort of heat, it'd have melted down long ago (as the transformer wires are aluminum!)
Your earlier test results of AC output potentials vs the chassis, and DC input potentials vs the chassis....doesn't turn up anything out of the ordinary.
Unless somehow the inverter is being used as a DC ground path, I don't see anything amiss.
It is possible the cab is using the inverter as a ground path. I'll have to check voltage drop on my negative grounding studs on the cab. It sits on rubber isolators so the only path to ground is those studs....and now the inverter.
On 10/2/2022 at 7:57 AM, Nilao said:L1 to case: 140.7VAC steady
L2 to case: 143.4VAC climbing to 159.8 before dropping to 143.4 and repeating.
N to case: 20VAC dropping to 17 before jumping back to 20 and repeating.
I'm probably missing something, but these readings worry me. I'm surprised the inverter is still running with this going on. I look forward to learning what the problem is in this setup, and hope you solve it soon! (before something blows up!)
I'm probably missing something, but these readings worry me. I'm surprised the inverter is still running with this going on. I look forward to learning what the problem is in this setup, and hope you solve it soon! (before something blows up!)
I don't see why said readings are a concern.
Internally, there's a 10nF decoupling cap from Neutral to the case. This should hold the chassis fairly close to the Neutral potential--which it is (~20vAC). This should reasonably center the case between the two Line outputs--and it is.
Beyond this, if there's external grounding power being routed through the inverter chassis (intentionally or inadvertently), THAT could cause the issues being described here. But at least so far, it does not appear that the inverter itself is responsible.
Please don't misunderstand, I'm not trying to blame the inverter, the installation, or anything else. I'm simply interested in learning what happened here and why it is doing what it's doing.
That said, why does the L1 leg read 140v to the case? Shouldn't it be closer to 120v?
The L2 leg going from 140 to 160v in a cycle is more concerning. Why would it do that? Obviously related is the neutral to case also in a 20v cycle. And why isn't the L1 leg changing in a cycle if the others are?
Inquiring minds want to know....
That said, why does the L1 leg read 140v to the case? Shouldn't it be closer to 120v?
Yes it should...if nothing's connected to the inverter.
But remember, this is a split-phase inverter. Most loads are single-phase 120v--and any connected SMPS units will generally have X and Y caps centered between (L1 - N) and coupled to ground--which will skew the grounding potential slightly. Other SMPS circuitry can easily cause a gentle voltage "pulsing" depending on how they're designed. Worth noting that there will be basically no current behind any of this.
Please don't misunderstand, I'm not trying to blame the inverter, the installation, or anything else. I'm simply interested in learning what happened here and why it is doing what it's doing.
L1 and L2 should be 120V to Neutral. Since Neutral is 20V to the case then it makes sense that L1 reads 140V (120+20) to the case.
Phase offset allows the case to line voltages to exceed line to line voltage
Inquiring minds want to know....
IS your Powerjack neutral to L1 read 20vac ? Maybe GS 6kw is different from Powerjack neutral to case .