System suddendly starts to shut down, when overloading?

Question

question

Minas Papageorgiou asked Sep 22, '22

System suddendly starts to shut down, when overloading?

Hi guys..

I have my off-grid system up and running without a glitch since July 1st.

Today, suddenly it shut down. At that time probably the load was large, but did not get any overload notification. Something smell burned, but could not identify the location, not sure it was from the area the off grid equipment is placed or elsewhere. All devices seem functional.

I played with turning on of devices etc.

Eventually, I realized it shuts down when a "big" load starts. But thing is, all these loads where served perfectly so far.

So when I have a load of ~ up to 800w no problem. when I go over 1.5kw for sure it shuts down.

No errors reported.

I tried to identify which device is causing, but did not. The only thing I identified is the following:

When using an amp clamp I measured the master having increased A drawn when increasing loads while the slave was starting from 0.3A and never went over 0.5A.

When connecting to each device with MK cable, both inverters where identified and seem fine in the app.

About the setup:

2 Multiplus Compact 24v/2000 in parallel. Both AC/DC cables are of equal length to <2mm (what I can measure)

505A 2v lead acid , fully charged when happend.

Bluesolar 150V/70A with 6 panels, 2.670w in parallel/series

Any hints would be helpful..starting with what causes shut off with out error that requires the button to be set to off and on.

THANKS!

shutdown

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Modifications Space

Node Red Space

Answer 1 · 2022-09-22T18:16:23Z

Alexandra answered · Sep 22, 2022 at 06:16 PM

@Minas Papageorgiou

Theory:- Something has worked loose over the operation period.

Check every connection on both AC and DC (including the 2V cell interconnects) to make sure it has the correct torque.

The more expensive alternative answer is the batteries are not ok anymore.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Answer 2 · 2022-09-23T21:26:46Z

Trevor Bird answered · Sep 23, 2022 at 09:26 PM

@Minas Papageorgiou this sounds like a frustrating problem. I have seen devices shutdown under similar scenarios but they do exhibit a fault condition. If the batteries have become slightly aged, perhaps they allow a small amount of DC ripple to appear on the DC bus feeding the Multipluses. If the DC ripple is too high the MPs shut down as high DC ripple is bad for the MPs. This will only happen under increasing load. Perhaps ensure the cable thickness is sufficient to handle the DC current supplying the MPs from the batteries as if it were slightly smaller than recommended, when the batteries age a little the problem would have been exacerbated.

2 |3000

Attachments: Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

question