OK... Not "just", but not too long ago. 

No outage in the area, plenty in the battery. 

I suspect it was the little PSU for the alarm system. There was that smell you get when smoke escapes. The PSU (16V ac, plugs into the wall) was hot to the touch and there was a scorch mark on the wall behind it. 

OK... So the PSU popped (so it seems). Nothing else is damaged. Goodwe restarted itself. Nothing tripped on the main DB, nor on the AC sub DB for the inverter. 

So it seems the Goodwe will trip faster than the circuit breakers will. Is that so? 

Circuit breakers in the main DB are Onesto. 

3 hours ago, Bobster. said:

OK... Not "just", but not too long ago. 

No outage in the area, plenty in the battery. 

I suspect it was the little PSU for the alarm system. There was that smell you get when smoke escapes. The PSU (16V ac, plugs into the wall) was hot to the touch and there was a scorch mark on the wall behind it. 

OK... So the PSU popped (so it seems). Nothing else is damaged. Goodwe restarted itself. Nothing tripped on the main DB, nor on the AC sub DB for the inverter. 

So it seems the Goodwe will trip faster than the circuit breakers will. Is that so? 

Circuit breakers in the main DB are Onesto. 

Hi @Bobster. Your PSU of your alarm system just failed and possibly create a short-circuit. The inverter have a short-circuit protection and maybe an auto-restart feature. If nothing is damaged on your inverter this is good news. 

This is curius that your circuit breaker doesn't work in this situation. Maybe a bad callibration of the breakers ? How many Amps did you have sized your breaker ? For a standard electric socket outlet, it should be 16 Amps.

Nice to hear from you soon.

Best Regards

Circuit breakers have a trip curve for short circuit protection. This means that in order for them to open when a short circuit occurs, they need 3-5 times thier rated amperage to flow. This depends on the curve type. I think they most common curve type would be C, because B type, which is more sensitive, can cause nuisance tripping when power on large inductive loads (such as motors, compressors, etc...) because of the high initial inrush current needed to start up these loads.

Most HF inverters can sustain a load surge of 200% of thier continuous capacity, but only for a few seconds.

So it seems logical that the inverter tripped first, unless you have B curve breakers.

Fully agree with @meetyg the purpose in general for mcb's is to protect the wiring not as such the appliances connected to the curcuits. Most appliances consist of primary fuses that disconnect the devices in the event of short curcuit across L&N but when it comes to earth faults the RCD disconnect the faulty appliance.

13 hours ago, fhocorp said:

Hi @Bobster. Your PSU of your alarm system just failed and possibly create a short-circuit. The inverter have a short-circuit protection and maybe an auto-restart feature. If nothing is damaged on your inverter this is good news. 

This is curius that your circuit breaker doesn't work in this situation. Maybe a bad callibration of the breakers ? How many Amps did you have sized your breaker ? For a standard electric socket outlet, it should be 16 Amps.

Nice to hear from you soon.

Best Regards

Breakers for the plug circuits are all 20A. The breaker on the output side of the inverter is also 20A.

2 minutes ago, Bobster. said:

Breakers for the plug circuits are all 20A. The breaker on the output side of the inverter is also 20A.

How many plug circuits did you have ? If you have 2 or 3 plug circuits in parralel with a 20A breaker on each circuit, you can use 20A max on each circuit so if each circuit use the max rated power of each breaker you will have more that the 20A fuse of the inverter can support.

Can you share with us a small schema of your installation ? 

Best Regards

5 hours ago, meetyg said:

Circuit breakers have a trip curve for short circuit protection. This means that in order for them to open when a short circuit occurs, they need 3-5 times thier rated amperage to flow. This depends on the curve type. I think they most common curve type would be C, because B type, which is more sensitive, can cause nuisance tripping when power on large inductive loads (such as motors, compressors, etc...) because of the high initial inrush current needed to start up these loads.

Most HF inverters can sustain a load surge of 200% of thier continuous capacity, but only for a few seconds.

So it seems logical that the inverter tripped first, unless you have B curve breakers.

Thanks. This is the idea that I had very fuzzily in my brain. You have expressed it with greater clarity.

I opened up the PSU out of curiosity. There's not much in there. A transformer. An LED off the output side of the transformer. And a small cap across two of the output terminals.

I had a replacement PSU. This one has dual outputs - 12 and 16 V AC. But do they make it easy for you by labelling the outputs? They do not. So I first figured out which of the four was earth (dead short to the earth pin on the plug), then measured across the others until I found pins 3 & 4 (left to right) measured 12, and 2&4 measured 16. I am guessing that 4 is the neutral. Nothing has blown up yet.

I'm going to amuse myself by taking the one that failed back to the store where I bought it, but I expect that there's no guarantee because of lightning, eskom surges etc.

1 minute ago, fhocorp said:

How many plug circuits did you have ?

Three. And one on the sub-db in the outbuildings (had no role here)

1 minute ago, fhocorp said:

If you have 2 or 3 plug circuits in parralel with a 20A breaker on each circuit, you can use 20A max on each circuit so if each circuit use the max rated power of each breaker you will have more that the 20A fuse of the inverter can support.

I'm aware of that. There's some extremely bad wiring in the roof (doesn't surprise, actually) and the wiring is being redone next month and then the whiole place will be COCed again, so if that's a concern then the electrian will discuss it with me. 

I am not thinking nice thoughts about a certain class of electricians who will just write out a COC for a few K without actually inspecting anything.

1 minute ago, fhocorp said:

Can you share with us a small schema of your installation ? 

Best Regards

I don't think I have those skills. I would be guessing if I told you how the inverter supplies the main DB.

2 minutes ago, Bobster. said:

Three. And one on the sub-db in the outbuildings (had no role here)

I'm aware of that. There's some extremely bad wiring in the roof (doesn't surprise, actually) and the wiring is being redone next month and then the whiole place will be COCed again, so if that's a concern then the electrian will discuss it with me. 

I am not thinking nice thoughts about a certain class of electricians who will just write out a COC for a few K without actually inspecting anything.

I don't think I have those skills. I would be guessing if I told you how the inverter supplies the main DB.

Ok. From my end, i had to create an electric schema for one of my clients that had outages due to insuficient power. Very useful to emplain to him the issue. His inverter could only deliver 20A max output, and all the protective circuit breakers were overrated in relation to the inverter's power rating. The inverter tripped several times before going out of order. As I couldn't come to his place, I sent him a new inverter with the appropriate circuit breakers.

9 minutes ago, fhocorp said:

Ok. From my end, i had to create an electric schema for one of my clients that had outages due to insuficient power. Very useful to emplain to him the issue. His inverter could only deliver 20A max output, and all the protective circuit breakers were overrated in relation to the inverter's power rating. The inverter tripped several times before going out of order. As I couldn't come to his place, I sent him a new inverter with the appropriate circuit breakers.

We had a lot of trips early on. Though again I'm surprised that the MCB didn't trip before the inverter now I think of it. The plugs in the kitchen are all on one circuit. A favourite early morning combo was kettle, microwave, toaster & dishwasher all running at the same time.

I don't know how MCBs for kitchen plugs don't trip more often. Not just in my house, but in general. 

3 hours ago, Bobster. said:

We had a lot of trips early on. Though again I'm surprised that the MCB didn't trip before the inverter now I think of it. The plugs in the kitchen are all on one circuit. A favourite early morning combo was kettle, microwave, toaster & dishwasher all running at the same time.

I don't know how MCBs for kitchen plugs don't trip more often. Not just in my house, but in general. 

@Bobster.Your kettle, microwave, toaster and dishwasher problably have a electric resistor inside. This is probably inductive load, and you had type C breakers that work better than type B breaker like @meetyg said. That probably explain why they didn't trip on your installation. Also, the power rating of your devices used at the same time maybe not exceed 20A.

15 hours ago, fhocorp said:

@Bobster.Your kettle, microwave, toaster and dishwasher problably have a electric resistor inside. This is probably inductive load, and you had type C breakers that work better than type B breaker like @meetyg said. That probably explain why they didn't trip on your installation. Also, the power rating of your devices used at the same time maybe not exceed 20A.

Well they tripped the Goodwe, which is limited to 20A. It will burst to 30A for 10 seconds. 

20A is 4.6kW. A kettle alone can account for 3. 

"Twenty amps" sounds a lot if you say it quickly, but in reality it's very easy to overload a 4.6 kW inverter.

1 hour ago, Bobster. said:

Well they tripped the Goodwe, which is limited to 20A. It will burst to 30A for 10 seconds. 

Yes, your inverter is 20A continuous and 30A surge.

1 hour ago, Bobster. said:

20A is 4.6kW. A kettle alone can account for 3. 

"Twenty amps" sounds a lot if you say it quickly, but in reality it's very easy to overload a 4.6 kW inverter.

Yes, of course, that's why i have 5Kw inverter in my installation for more flexibility.

On 2024/12/27 at 1:29 PM, Bobster. said:

I'm going to amuse myself by taking the one that failed back to the store where I bought it, but I expect that there's no guarantee because of lightning, eskom surges etc.

So I went back to the store, and they said the importer only gives them two weeks from date of purchase for manufacturing faults, otherwise they presume misuse or a power surge. So I said well it failed on the 14th day. But of course that day was a public holiday.

Anyway, he asked me to describe the symptoms, said it sounded like a genuine failure but, you know, 14 days... 

So he sold me a replacement at cost. They are marking up just over 100% when they sell to the likes of me, maybe a bit less if you're in the trade and have an account with them. 

Anyway, I thought giving me one at cost was not too unreasonable considering all the possible misadventures that could have befallen that PSU. 

Edited December 28, 20241 yr by Bobster.

3 hours ago, Bobster. said:

So I went back to the store, and they said the importer only gives them two weeks from date of purchase for manufacturing faults, otherwise they presume misuse or a power surge. So I said well it failed on the 14th day. But of course that day was a public holiday.

Anyway, he asked me to describe the symptoms, said it sounded like a genuine failure but, you know, 14 days... 

So he sold me a replacement at cost. They are marking up just over 100% when they sell to the likes of me, maybe a bit less if you're in the trade and have an account with them. 

Anyway, I thought giving me one at cost was not too unreasonable considering all the possible misadventures that could have befallen that PSU. 

Ok. So did they keep the out-of-order one, or did they just sell you an identical new one?

If the case you keep the failes one, i can try to repair him, if possible.

11 hours ago, fhocorp said:

Ok. So did they keep the out-of-order one, or did they just sell you an identical new one?

If the case you keep the failes one, i can try to repair him, if possible.

That's very kind of you. They handed me a replacement over the counter, and didn't take the blown one back.

I didn't tell them, of course, but I had opened the one that blew and there is very little inside. The output is AC, so there's not even a bridge rectifier inside. There is a transformer, a little paper capacitor, and an LED. I presume the smell had been awful things happening to the transformer. It give no output now, just gets very hot, very quickly (though doesn't show as short circuit when I measure it with my multimeter). 

As I said, they gave me a replacement at cost. The failed one had been a replacement for the original PSU which had blown in a power surge (I think, several other devices got taken out). I took them both down to Pikitup for recycling as e-waste. A staff member took them (they look perfect from the outside) and I pointed out that I wasn't throwing them away because they worked. 

Edited December 29, 20241 yr by Bobster.

28 minutes ago, Bobster. said:

It give no output now, just gets very hot, very quickly (though doesn't show as short circuit when I measure it with my multimeter). 

Failed electronic component that create resistance on the circuit.

28 minutes ago, Bobster. said:

I took them both down to Pikitup for recycling as e-waste. A staff member took them (they look perfect from the outside) and I pointed out that I wasn't throwing them away because they worked

Ok no problems 😄 At your disposal if needed 😇