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Axpert 5KV+, Error 51, overload/surge


Chris Knipe

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Hi,

 

I've had my Axpert for the better part of 7, or 8 years now (when was the Eskom cockup?)... The system has about 270aH batteries (Lead Acid) maintained very well.  PV is (almost) maxed out to the capabilities of the inverter. Up to today, the system has been operating flawlessly and I've not once, had one single issue....

Today in CPT, is a very warm (32C) day after a long, cold winter.  I don't know whether that may be applicable.  My Axpert has shut down twice, with a Error 51 (Overload/Surge), but it doesn't indicate where the the problem is.  My electricity supply has surge protectors (none blown), my PV also has surge protectors (none blown, three separate strings with three separate protectors).  

Anyone know what the cause could be, or what I could / should be looking at?  I'm not 100% but I am pulling 111V currently on the PV, and I am wondering whether the supply from the PV isn't too much for the inverter, although PWM should control that, shouldn't it?  It's been so long since I had to work with these systems, ai, I forgot most of it.

Any help and / or pointers would be appreciated.  I don't think anything is broken, there must be a logical reason why the surges are occurring, and a logical reason how to manage it.

 

FYI:

3 x PV Strings in parallel (3 x 320W I believe), each protected with a 10A fuses, surge protection, and properly earthed.

270aH, 48V battery bank, fuse protected

Single Phase 220V AC Supply, Surge Protected, not fused.

No fuses or surge protection devices triggered with any of the error 51 conditions.  A simple restart of the inverter and everything works 100%.  Few hours (randomly) later, error 51 would reoccur.  Happened twice, hasn't happened a 3rd time yet... 

Edited by Chris Knipe
A bit more details added
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2 hours ago, Chris Knipe said:

My Axpert has shut down twice, with a Error 51 (Overload/Surge),

Hi Chris, welcome here on the forum. 

From what i see in the manual this error could point to an internal issue and  is not imo related to load or feed. 

849223756_errorcode.PNG.2910ddf28d7a7885b50879181fe52799.PNG

I am not sure if its something you could fix. At first I thought its the same error as error 7 (witch is load related). If it happens again, i would recommend that you have the unit checked and serviced. 8 years for that Unit is quite impressive. 

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Touch wood... Hasn't happened again since the 2nd trip (+-2PM local). If one can only find out WHERE the over current / surge occurred or came from, then at least it gives some indication of where to look.  Unless of course it's internal to the unit. Given the inverter isn't under significant load and properly earthed, I doubt any damage to the inverter itself TBH.

And thank you Jaco.  Significant planing and protection went into the designing of the system and it only run on batteries when needed (no PV nor supply available).  So my cycles are really limited.  Day time my load is from PV completely, night time it's back to Eishkom keeping the batteries on standby only to be used in the case of a power failure. After 7/8 years, I still get a solid 2 to 3 hours run-time on my lead acids, just as the day when I put them in, and what I planned for (load shedding).

Maybe next year or the year after, I think it's time for some upgrades and keep the grid purely for a standby.

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Hi Guys,

As summer is starting, it's now starting to happen more and more - so much so that my Inverter is currently switched off, and in bypass (tripped 3 times yesterday, and after firmware upgrades it also tripped once today which prompted me to for now, bypass).  I am drawing close to a conclusion however I think, and I am FAR from convinced that there is any malfunction and/or damage to my Inverter.

The Overload/Surge isn't caused by the load.  I've tested this and by putting on excessive load on the Inverter, I get the appropriate fault code 4, and the Inverter correctly goes into bypass.  

This leaves me with one possibility... The PV power coming into the Inverter. I remember from the past when I did the installation, I am VERY close to the maximum in terms of PV that the Inverter can handle.  I also observe these overload faults only during times when there are exceptional sunlight (extremely warm / sunny days).

I have a 3 x 3 configuration, with the old ReneSola Virtus II 300W panels (http://www.renesola.com/file/Global/product/pdf/Virtus II 305-320(4035) 4BB 1000V US 1606.pdf).  Plugging these numbers into @Chris Hobson 's PV String excel spreadsheet, I exceed Cold Voc and Cold VMP.  Inverter and MPPT Voc is also exceeded according to the spreadsheet.

1) Has anyone here any experience in terms of what precisely the Axperts do when/when the PV Input is exceeded?  Does it by any chance, generate a error 51?  Can anyone test this perhaps, and confirm? We all "assume" the overload condition is related to the load, but I am (and enlighten me here please) assuming that the overload is being caused by PV input. This also means then that the fuses that I have on my PV strings, are too big and aren't providing the required protection quick enough / at the low enough rate to prevent it from exceeding Voc to the Inverter.

3) As things age (specifically PV), what happens in terms of power generation on aged PV panels, vs. new PV panels?  Could the fact that my panels are a bit older now mean that they provide less stable power to the Axpert, and that these fluctuations from time to time, now start to exceed Voc more than what the Inverter would like?  Again, I can understand the Inverter going into an error condition (assuming error 51) when such an overload occurs, but to date (and from what I could google), there's very little if anything, confirming what precisely the error 51 is referring to technically.

2) If my assumptions here is correct, instead of going 3 x 3, I should (theoretically) be OK to go with a 5 x 2 configuration (I have one additional spare panel sitting in my wendy house waiting for better days).

Before I go down this route to rewire / reconfigure everything however, I would appreciate it if someone can please just double check the math and confirm my findings - especially in terms of what the Axpert does in an overload on the PV side. I am possibly asking a lot here, but yes.  I am asking someone to exceed Voc on their inverter and confirm whether they get an Error 51 or not. I can now that I think about it, maybe run in 2 x3 for a few days, and see if the problem persists.  That's a easy matter of just removing a fuse temporarily.

Whilst I am not qualified per say, I do have a fairly decent understanding of what is going on here and what everything means and does.  By all means, there's no need to handle me (or the situation) with baby gloves.  I am FAR from convinced the error is a faulty inverter, and I am much more likely to buy into the suggestion of a overload being created / caused by circumstances (such as sunlight / PV).  I am unfortunately, one of those people that needs a sound technical explanation before just "accepting" something and I am here searching for an explanation as to what is happening, and why.

Some assistance please, and let's see if we can get to the bottom of this.

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3 x 3 Strings

2 x 5 Strings

PV Watts

2700W

3000W

PV Watts (Hot)

2580W

2867W

Voc

134V

90V

Vmp

110V

73V

PV Current

24.6A

41.0A

Voc (Cold)

140V

93V

Vmp (Cold)

116V

77V

 

Inverter Ratings (5KVA-48-PAR-A):

Rated Current: 60A

Voc: 145V

I am thus very, very close to max with a 3 x 3 configuration.  A 2 x 5 not only gives me an additional 300W, but the numbers are much further from the max ratings than with a 3 x 3 configuration.  Oh choices, choices (and might I add, I feel like an idiot for not realizing this when I did the initial installations).

Edited by Chris Knipe
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1 hour ago, Chris Knipe said:

I also observe these overload faults only during times when there are exceptional sunlight (extremely warm / sunny days).

Extreme warm days will reduce your production, not increase it. Excessive production, can be expected under cool cloudy conditions where cloud edge effect is normal. 

 

1 hour ago, Chris Knipe said:

3) As things age (specifically PV), what happens in terms of power generation on aged PV panels, vs. new PV panels? 

It decreases. 

Please remember with exessive heat electronics starts acting up and aging units and most electronics starts showing problems under hotter conditions. 

1 hour ago, Chris Knipe said:

We all "assume" the overload condition is related to the load,

 

On 2018/09/30 at 6:18 PM, Jaco de Jongh said:

From what i see in the manual this error could point to an internal issue and  is not imo related to load or feed. 

I guess if the manual recommends you take the unit in, its the best to do so. 

1 hour ago, Chris Knipe said:

Could the fact that my panels are a bit older now mean that they provide less stable power to the Axpert, and that these fluctuations from time to time, now start to exceed Voc more than what the Inverter would like?  Again, I can understand the Inverter going into an error condition (assuming error 51) when such an overload occurs,

If its PV related I would expect the following errors. 

AAAAA.PNG.17f38518fe86ccdb2c03b07e5dc9b898.PNG

 

I still believe something inside the unit is busy failing, and should be checked out. 

 

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On 2018/10/06 at 4:53 PM, Chris Knipe said:

Before I go down this route to rewire / reconfigure everything however, I would appreciate it if someone can please just double check the math and confirm my findings - especially in terms of what the Axpert does in an overload on the PV side. I am possibly asking a lot here, but yes.  I am asking someone to exceed Voc on their inverter and confirm whether they get an Error 51 or not.

@Chris Knipe, i dont think anyone on this forum will deliberately exceed the VOC of their Equipment just to test something. Lets say this exercise results in damage, who would pay for that. It will mean someone else needs to rewire their system to test something for you, why don't you just rewire your system and confirm your own suspicions. If it doesn't give you the error after the rewire, then you know you found the problem. 

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Jaco,

Not wanting to argue with you, but I've got the service manuals here too.  Not even the service manuals, have any reference to the Error 51.  Taking it in to the supplier (out of warrantee too, might I add), they aren't going to do jack because the manuals don't tell them what to do.  The fault is also VERY intermittent, and we all know the inverter is just going to be tested, after which it's going to be "oh there's nothing wrong with it." We all know how this works, especially in South Africa... If I have to buy a new unit, then everything is just frankly going to be placed on hold until I have time and money to upgrade the entire system and go off-grid (Eskom is making that SO easy these days).

13 & 14 that you posted above, is an Error condition.  51 that I am talking about, is a Fault condition.  I hear what you are saying however.  Surges (and especially Overloads), comes from somewhere.  They don't magically invent themselves. Something is causing, and triggering this.

No, I'm sure no one would deliberately exceed Voc, and sorry if it came out that way.  However, there must be someone that has previously (whether deliberately, or by accident) exceeded Voc?  And what happened in those cases?

As you say yes, I can (and more than likely will) re-wire things myself and see whether the problem persists or not.  One of the reasons one comes to a forum (and the benefits thereof), is to find out whether someone ELSE experienced something similar or not, and whether there is meaningful inputs that can be delivered.  I guess, that is obviously not the case.  No worries then...   You and I aren't going to get anywhere TBH as you've pretty much up your mind it's the inverter, and I've pretty much made up my mind it isn't.  So unless there is someone else with some inputs, that's it then I suppose.  No point in going around in circles.

 

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https://forums.aeva.asn.au/viewtopic.php?t=4332&start=1600#p64122

Assuming that there aren't such currents about, even for short periods of time, the fault would seem to be associated with that current measurement. So some current shunt (which may be an area of printed circuit trackwork), or filter components associated with that measurement. Likely there is also an op-amp to amplify the small shunt voltages to the three volts or so that represent full scale on the DSP analogue inputs. Any components around this op-amp could cause such trouble.

---  @Coulomb Your own words... 

 

https://forums.aeva.asn.au/viewtopic.php?t=4332&start=1600#p64350

I have a MPP Solar branded 4048 with an Error 51, for me it must be related to PV input current - as the error doesnt re-occur with PV input switched off, but all other connections active. (and now re-occurs within an hour if PV input is on, even with half the panels disabled)
My setup is 2x 3KW arrays of PV connected to 2x parallel PIP-4048MS into 24x 2v 800AH SLA batteries.

---

Pretty much also maxed out like me.  Think I'm going to remove my PV from the Inverter and see whether the problem persists over a period of a day or three, and then gradually bring PV back.

Long and short of this, we can BOTH be right, we can BOTH be wrong.   It's a very rare error (from what I can gather), and there isn't a lot of information available about it.  So yes, the idea with me coming here was to try and pick the brains of those that may know just that little bit more than me...  Nothing more, nothing less.  Don't mean any harm or foul.

 

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Yup. I've read it all.

And the second post I posted a link to, actually states that the problem did NOT re-occur when the PV was disconnected.

Going to try run a few days / weeks without PV and see what happens (not that doing that will solve anything as it defeats the whole purpose)... At the end of the day, regardless of what the issue / cause, it does look like a new inverter will need to be purchased at the end of the day.

No point in continuing here with the he said / she said thing... Fact is, no one knows definitively what the cause is, and no one knows definitively what the resolution is.  We can sit here and speculate and argue until kingdom come, but it ain't going to help anyone.

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10 minutes ago, Chris Knipe said:

speculate and argue

Why do you argue? or who argues? you are trying to find a solution or answer, I am trying to help you find an answer ( I thought that is what the forum is for)) Why ask if you dont want answers and Ideas? For 7 to 8 years your system has run on the current setup, with no problems. Why should the setup become a problem now. All, Rhetorical questions, no answer needed, no argument, just a thought... 

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The thing is, without knowing what causes, and what happens when a error 51 is triggered, I don't think anyone is going to know what the problem is.

If it is the battery current sensor (and heaving forbid, why can't it be the PV current sensor too for that matter), why does it only occur during day time, under heavy sunlight?  Why, absolutely never ever at night (for argument's sake). Why only between +- 11AM and 3PM on excessively warm (30C+) days? If this was battery related the fault condition should occur at any time, day or night... That's just what makes logically sense to me, and that is why I am hammering on PV, instead of Inverter.

Hypothetically speaking (again, we wont know the answer as we cant reproduce the error on demand), but it could be the inverter's own internal temperature causing the sensor(s) to go way wire?  Every time I get to the inverter to restart it for example, fans are ramming air as fast and loudly as possible.  Now, this COULD be because the inverter overheated, or it could be a result of the error whereby the inverter after the error occurred, increase the fan speed to max.  

The fact is, we simply do not know.  I don't think any one knows. Not you, not I, not @Coulomb, and I doubt a reseller / distributor will know either. I know that much, the one or two resellers / distributors I know in Cape Town, I will be wasting my time, money, and energy to go to them for assistance. It's a bit late now, but I think first things first I'm opening the Inverter tomorrow to inspect for visible damage, and failing that I will try to put it to the test without PV for a while to see if the error reoccurs.  At least then, the problem can be pin pointed and it can be said with surety it is SOMETHING on the PV side, or it isn't.  

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8 hours ago, Chris Knipe said:

Every time I get to the inverter to restart it for example, fans are ramming air as fast and loudly as possible.

So that sounds like you are already running 73.00 or later, or at least running firmware that works the fans harder will have no effect.

When you open it up, you might find something is blocking the air flow. Cleaning dust out of the heatsink fins etc might help to keep things cooler.

10 hours ago, Chris Knipe said:

as the error doesn't re-occur with PV input switched off, but all other connections active. (and now re-occurs within an hour if PV input is on

The above is actually from a post you quoted, i.e. from the other person having this error 51 / overload issue. The "within an hour" suggests a moderately long time constant, which might be the time it takes for excess heat from the SCC to transfer to parts on the main board. A bit of a long shot, but another indication that heat is the root cause.

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On 2018/10/06 at 4:53 PM, Chris Knipe said:

 

I have a 3 x 3 configuration, with the old ReneSola Virtus II 300W panels (http://www.renesola.com/file/Global/product/pdf/Virtus II 305-320(4035) 4BB 1000V US 1606.pdf).  Plugging these numbers into @Chris Hobson 's PV String excel spreadsheet, I exceed Cold Voc and Cold VMP.  Inverter and MPPT Voc is also exceeded according to the spreadsheet.

Hi Chris

Welcome. You 3 x # configuration is same to 0°C. So depending on you location it may be safe or not. If you get frost it is likely that it could exceed your inverters PVmax.

You are you in Cape Town?  I have someone in Cape Town that has experienced several Error 51's in the last couple of days. It may be from your supply.

 

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2 hours ago, Chris Hobson said:

You are you in Cape Town?  I have someone in Cape Town that has experienced several Error 51's in the last couple of days. It may be from your supply.

 

 

Hi Chris,

Yes Cape Town... I'm in Bothasig (Milnerton / Panorama / Welgelegen area).  Eskom supply, not CoCT.  That, is VERY helpful now indeed...

Have you found out anything useful about this?  What are the options?  Just to restart the inverter every single time, or did you actually start to replace units?  

Sorry guys, I pulled an all nighter last night with some other stuff that I was busy with, so didn't get the time today as I hoped to get into the unit and see what's going on inside.  Will try to do so on Monday.

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On 2018/10/07 at 5:59 AM, plonkster said:

You could point a heatgun/hairdrier at some temperature sensors inside and see if the error shows up...

Also, once it is showing, you could try squirting "can of cold" at various components as well. [ Edit: assuming you can safely run it with the cover off. The blue hall effect sensor would be my first target. ]

Edited by Coulomb
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1 hour ago, Coulomb said:

There is a restart on overload option, which defaults to off.

Doesn't restart on a 51... Tried that already.  

51 needs ALL power removed (even batteries) in order to get the inverter started again.  It's a nasty error to have.  My poor battery fuse's contacts are so burned I would more than likely need to replace the fuse by the time that this is finished.

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Assuming the fans are clear, nothing really changed, Eskom did not cause any damage, another point to ponder is that I have come across electrical devices that just become erratic overnight or in higher temps. When you take it back to the supplier, you may be told that the electrical parts inside have reached their intended design life read, time to replace. Very very annoying.

 

FWIW. Axperts have not been around 7-8 years, we've discussed this before. In 2010/2011 there where no Axperts in SA that I ever saw. First ones came about 4-5 years ago when Mustek (being one of the first) brought them in due to some serious UPS shortages. I was selling UPS'es at the time and wondered why on this earth would you put in such a small PWM controller on a UPS, seeing that "UPS with solar panels and Eskom as fallback" was not a new concept by then.

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