The reversal of +/- on each side just considers which way you use as In/Out. So there shouldn't technically be a Line or Load side as long you connect the right polarity at your chosen In. You are right, totally confusing, these DC breakers.

Thanks Mate. It will be invested in a new fuse/breaker solution for the battery bank

Matthew, I know you are still waiting for the SPD video. Will be next ;)

@@RolandW_DIYEnergyandMore Thx. Much appreciated. I trust your correct wiring tutorial over other online sources. Funds ready to deposit once video is uploaded and explains proper connection of AC and DC SPDs.

@@Matthew_Australia the video is already finished. I am planning it to release on 2nd. Before nobody will look it anyways because of the holidays. OK with you?

@@RolandW_DIYEnergyandMore Okay with me. :)

Happy new Year to you and your family as well!

Yes. I will surely replace the set of breaker there. You have the fortune to live in a country where manufacturers where already forced to switch their products. Here I just cannot find any! non-polarized breakers, not even on AliExpress. The selection of fuses are thin as well. Non is really made for such battery-bank distributions. So, yeah. I am trying to find the best solution. Will get what I need eventually.

@@RolandW_DIYEnergyandMore Roland, regarding your setup in the resort; the way you had wired the polarized breakers to offer fault protection is correct, so long as you do not disconnect (i.e. manually trip) those breakers under normal load and operation. The plastic case of the polarized DC breakers will deform and break down internally due to excessive heat whenever they are manually tripped, until eventually the device will have a catastrophic failure.

@@RolandW_DIYEnergyandMore I bought most of my non-polarized DC MCB breakers from EBAY, even though Australia has some local suppliers and retailers of the device. Trusted brands are NOARK (number one pick), ZJ Beny (sometimes marketed as just "Beny"), Suntree (sometimes rebadged as "Renogy").

OK, will try to find something

For my chargers; what would you say to RT18, DC fuses, 14x51? They are available in 40-63A. I would use 40A for ech of the chargers. Because that have DIN rail holders

Correct. Well said. Temperature does affect the bimetal thermal strips within breakers. I partly agree with the edited post of yours, regarding AC breakers can be safely used for low voltage DC applications.

Where I live in Australia, it is typical for the outside ambient air temp to be over 40°C for a few weeks each year, with the highest so far being 48.5°C.

I agree with you, that you can use an AC breaker, but only if it has an adequete arc chute chamber to extinguish the DC arc. In your scenario, you are better off using an actual polarized DC breaker (if used between a solar string and a charge controller). If the breaker does not have any rating for DC, then it is not rated for DC. Derating is a fallacy, as it does not matter if the DC voltage is low, damage still occurs on the arc contacts and bimetal strip and internal housing if the arc chute is inadequete in dissipating the heat from the DC arc. An arc is formed when you pull the contacts away from each other, regardless of DC voltage, and this needs to be thoroughly directed into the arc chute chamber to avoid internal damage. Just because most AC breakers do have a bi-directional electromagnet to direct AC arcs (that self extinguishes anyway), this of itself is not the only requirement for a DC breaker. The DC arc needs to dissipate the heat over a larger surface area within the splitter plates of the arc chute. DC breakers have larger arc chutes that can effectively reduce the internal heat to reduce damage and failure. If the marketed AC breaker does not have any DC rating (such as detailed in spec sheets), then nobody should be derating as a solution. There are sound reasons why MCCB DC breakers are larger and heavier than common household AC breakers.

@@Matthew_Australia I have used a branded quality AC-breaker (ABB, the Company I've learned mechatronics). The main reason for fires are wrong connected polarized DC-breakers when comming with the source from below, cause then the + must be connected on the side where a - symbol is printed on top of the breaker. This is not pointed out enough, drown in all the other expert stuff, unfortunately.

@@topeye4202 That is because those types of breakers are polarized (i.e. they only offer protection for current going in one direction).

@@taiwanese002 hi, those are switching my high power AC chargers. using 12v DC to switch 230V AC

If fluctuating current inrush is really an issue, than more caps can of course help to stabilize the voltage. But usually the battery is a very powerful source and should keep DC bus voltage quite constant. Do you have such long cabling on the battery side? or is the battery bank relatively small? or are you pulling so huge power changes on the AC output? The only problem big capacitors are making, is the initial charging when they are depleted. That inrush or pre-charging should be done via a resistor. But once the caps are at charge it shouldn't make any problems to the BMS. I do not think that additional caps are required on the PV input. The inverter or charge controller should be designed in a way to manage the PV array for which they are designed for. I have never heard of someone adding caps anywhere. Would be really interesting if you share your experiences if you decide to give it a try...

@@RolandW_DIYEnergyandMore The battery I have is with 560Ah (16x280Ah 2p 8s) strong enought and the cabling is just one meter with 32sq.mm, but as I mentioned the SCP of BMS was triggered. I have some peaks on the AC consumption, i guess they come from a inverter fridge or the Inverter it self need some spikes to keep the waveform smooth with force, which he does really good. The seccond issue I try to eliminate with the additional caps is, cause I have beside the hybride Inverter a additional MPPT which is feeding into the same battery, so the hybrid Inverter switch into floating charge even the Battery is not fully charged. Short voltage spikes comming from the MPPT are maybe enough for the Inverter to think the battery is already full. The BMS (200A) seems to have too much resistance, so the battery is not able to iron the voltage on the other side of the BMS. By the way the cheap good lookin PowMr hybride inverter performs quite good. The efficiency is surprisingly good, he dont produce a lot of heat and delivers the rated 4500Watts constantly. The cooling is made quite good with the three fans on top and cause its a slim costruction the airstream inside is quite fast. I ordered a second one, so I can easy swap and have time for service or repair in case. The App they have is rubbish and it allways works like a UPS if mains are connected, even the priorities can be changed in menu (at this time they are not able to solve this issue, the lady from the surprisingly good customer service said). I just let it run without Mains backup now, thats no problem at all and the fast ATS will switch over, when the battery is empty. For monitoring the grid consumption if have added a small kilowatt hour meter anyway in my main distribution box. They gave me a 10% voucher... for 240 € I cant complain 💁

This topic is above my pay grade, but I am interested.

@@RolandW_DIYEnergyandMore Now I came to the conclusion the shorts came from the H-bridge and i've found a study where they add a capacitor too, to improve the system: quote: The performance of converters has improved considerably using high switching frequency, which leads to a significant improvement in a power converter’s performance. However, the high dv/dt through a fast-switching transient of the MOSFET is associated with parasitic components generating oscillations and voltage spikes having adverse effects on the operation of complementary switches, thereby affecting the safe operation of the power devices. In this paper, the MOSFET gate-driver circuit performance is improved to suppress the H-Bridge inverter’s voltage spikes. The proposed technique is a simple improvement to the gate driver based on the IR2112 driver (IC) by adding a capacitor to attenuate the effect of parasitic components and the freewheeling current, suppressing the negative voltage spikes. end of quote Maybe my capacitors will help too, even its not directly connected to the gate driver. The tiny voltmeter i have at the battery input of the inverter is constantly fluctuating up and down while the voltmeter at the battery is absolutely stable. The capacitors will calm down the whole system of the complex (maybe cascaded multilevel-) H-bridge and will help to make it more stable and smooth I hope. Now I mesured the ripple, its nearly 3 Volts! , looks like rectified 50Hz AC voltage without smooting cap, a wavy jagged round hill every 10 ms. I didn't expect such a blockage through the BMS : /

@@topeye4202 how old is your inverter? maybe the internal caps are not good anymore? I have to change my power supply caps on the MUST inverter again soon. The AC output is becoming irregular again. Changed them 4 years ago last time. But must say that I never had to change a cap on the power lines yet. But here in Thailand, electrolytic capacitors are aging and dying very quickly due to the climate.