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Multiplus-II goes into overload at grid failure (UPS)


Crankshaft
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Hi

Last night was the second time this has happened:

Multiplus-II as a UPS with 4 x 100AH SLA batteries.

Minimal load connected, a handful of LED lights.  At the moment of grid failure the inverter turns off with the red overload LED on.

Turning the inverter off and on restores proper operation.

Anyone else experienced this problem?

 

 

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  • 2 weeks later...

@Crankshaft - YES!!!  It happened to me this morning as well, much to my very unhappy surprise.  At the time - it was 6:00 in the morning - there was very little load on the system; about 250 watt maximum.  I am running a MultiPlus-II 48/3000/35-32, on firmware 2628465.  It is also running in UPS mode - no solar panels yet.

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image.thumb.png.7567eef321c25a8837184f70925b0511.png

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Yep that is a recent issue with my Multiplus 2, started like 2 weeks ago after all the power outages.

Checked wiring on my side, all good.

Suspect issue on Munic side.

2 solutions:

1.An isolation transformer providing a new neutral.

2. Timer activated contactor, when.ac in is on, delays ac out for 2 minutes.

Pondering which one. Best I can get an isolation transformer is R4000, timer contactor should be cheaper if only I can find a supplier that has some grey matter

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In 99% of cases an error 11 or an error 8 has to do with bad wiring.

On the GX device, select the Multiplus from the Device List, then navigate to Alarm Status → VE.Bus Error 11 report, that should tell you what went wrong. Very often it is a neutral sitting on the wrong neutral bar.

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Unfortunately I have nothing in the "error 11 report" area on the gx device.  Also, my Multiplus II has been running happily since October 2019, and this is the first time it had done that.  Would a neutral on the wrong bar suddenly start doing this out of the blue?

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10 hours ago, admiral said:

nothing in the "error 11 report" area on the gx device

I think the last error clears if the Multi was reset (turned off and back on, ve.bus reset, etc). Also, you need firmware newer than 459 (I think?) otherwise it is simply not supported.

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1 hour ago, plonkster said:

I think the last error clears if the Multi was reset (turned off and back on, ve.bus reset, etc). Also, you need firmware newer than 459 (I think?) otherwise it is simply not supported.

I was running 465, but I did have to reset the multi to get it out of the "overload" condition - so probably lost the status message there.

I however did *not* have the correct grid code set;  it was set to "other", so I have changed that to South Africa.  I am wondering if the "loss of mains" detection could have gone wrong with it being set to "other" grid code?

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  • 6 months later...

Have seen a few of these now.

In many cases its actually a low battery issue. Some background required. The way the Multi knows it is overloading, is if it cannot produce 230V into the output for some amount of time. It uses a 20khz PWM signal to form the sine wave, and it cyclically adjusts the duty cycle of the PWM signal to form a 50Hz sine wave and to hit 315V (ish) at the peak of the sine wave. If at max duty cycle it cannot hit the peak, it knows it is overloading. Now the battery voltage itself also plays a role, that is to say, at lower battery voltages and higher loads it will overload faster (also because higher currents are involved on the primary side of the transformer). In these cases the overload often coincides with a low battery alarm.

There are also still a few 5kVA models made in mid 2019 out there that has a manufacturing defect, causing it to overload and/or overheat at lower power values. If you have one of those, simply have your installer RMA it and swap with a new unit under warranty.

I have one case which is neither of these, but I'm still waiting for the support guy to explain his thinking to me. And it involves large Quattros, not pedestrian multis... 🙂

So long story short, make sure your DC voltage on the terminal of the Multi isn't sagging excessively under load.

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1 hour ago, plonkster said:

There are also still a few 5kVA models made in mid 2019 out there that has a manufacturing defect, causing it to overload and/or overheat at lower power values. If you have one of those, simply have your installer RMA it and swap with a new unit under warranty.

Already went through that.. 😥 

@plonkster I realise there are a lot of variables and you always give an additional view of how/what/why, which all of us in the blue corner really appreciate!  Just feels like something that should work. 

1 hour ago, plonkster said:

Now the battery voltage itself also plays a role, that is to say, at lower battery voltages and higher loads it will overload faster (also because higher currents are involved on the primary side of the transformer). In these cases the overload often coincides with a low battery alarm.

image.thumb.png.37bee7c98ee58fa664f3b506c867bd8d.png

 

 

 

image.png

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On 2020/09/04 at 9:33 AM, plonkster said:

Have seen a few of these now.

In many cases its actually a low battery issue. Some background required. The way the Multi knows it is overloading, is if it cannot produce 230V into the output for some amount of time. It uses a 20khz PWM signal to form the sine wave, and it cyclically adjusts the duty cycle of the PWM signal to form a 50Hz sine wave and to hit 315V (ish) at the peak of the sine wave. If at max duty cycle it cannot hit the peak, it knows it is overloading. Now the battery voltage itself also plays a role, that is to say, at lower battery voltages and higher loads it will overload faster (also because higher currents are involved on the primary side of the transformer). In these cases the overload often coincides with a low battery alarm.

There are also still a few 5kVA models made in mid 2019 out there that has a manufacturing defect, causing it to overload and/or overheat at lower power values. If you have one of those, simply have your installer RMA it and swap with a new unit under warranty.

I have one case which is neither of these, but I'm still waiting for the support guy to explain his thinking to me. And it involves large Quattros, not pedestrian multis... 🙂

So long story short, make sure your DC voltage on the terminal of the Multi isn't sagging excessively under load.

How can I check if I have a faulty one? Mine was installed last year end July, so I might have the faulty version. I have seen a few times the overload issue, With my batteries  at around 30%. I have notified my installer but he said he did not see anything wrong. And with what happened the other day when loadshedding started and my inverted did not switch over, maybe it is related to a faulty unit.

Edited by isimobile
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1 hour ago, isimobile said:

How can I check if I have a faulty one?

There is a way to look through the bottom vents and look for a bolt, whether it's the right one. If you see a round-headed bolt, you have one with a manufacturing defect. Ask your installer to have it RMA'd. In this piecure you can actually see the bolt glowing red. It's the wrong material bolt.

306823322_WhatsAppImage2019-10-27at19_03_20.thumb.jpeg.9a823390c5a25766ff8ca09640be48d7.jpeg

 

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