MCCB Inverter / MPPT Charger

ArranP

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Nov 5, 2020
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Newly purcahsed MCCB 125A DC Breaker has "Line" & "Load" connections.

I am using combined inverter / MPPT charger.

I have assumed that the "Load" should be connect to my inverter and the "Line" to my battery, however I have checked online and one photo shows the "Line" being connected to the Inverter ?

My Inverter is combined Inverter / MPPT charger so I am uncertain as to which way around it should be wired.

Thank you for the feedback.
 

MichaelK

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Could you provide a link to the exact model of charger/inverter you are talking about?
 

MichaelK

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Well, even at the company website, I find an appalling lack of documentation. I did find this one diagram which I think can help you with your connections. All the wiring terminals appear to be on the bottom of the unit. There appears to be a set of terminals on the far right of the bottom for the battery connections. Let's hope they are color coded. Red will be positive, and Black will be negative. I would assume the terminals accept very thick wire, perhaps as thick as 12mm or so. That's about the size of 4/0 (0000) wire in the US, what I'm using for my battery to inverter connection. But, it might be as small as 5mm, which is about the size of US 4 gauge wire.

The set of two terminals on the far left appear to be for a grid connection. You connect those wires to incoming AC you might want to buy from the local utility. In the US we would call that AC in. They might be labeled L and N, or maybe L in and N in? Finally, the two middle terminals marked load are for your connection to your main house electrical panel. In the US, we would call that AC out. They might be labeled L and N, or maybe L out and N out? It's the AC out terminals that power all the electrical items in your house, like the lights, TV, washing machine, ect. The AC out wires would go to the main electrical panel where the power is divided up into individual circuits, each controlled by an individual breaker.

What I do not see however is how the incoming DC solar is connected to the unit. It will NOT be at the same terminals as the battery. They might actually be side by side with the battery terminals, but they will be a separate set. If you can take pictures of the actual unit and post those, it might be more apparent.
1634092268346.png
 

Bud Martin

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Since the Battery is connected to All-In-One SCC/Inverter that means you will have current flowing BOTH ways between SCCINVERTER and the Batteries so you will need Non-Polarized DC circuit breaker instead of Polarized DC circuit breaker.
I cannot tell from the website you provide to tell me if it is Polarized or non- polarized DC breaker of not.
Are you in Thailand?
 

ArranP

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Nov 5, 2020
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There is just one set of terminals for battery in & mppt charger out.

The question I have is regarding the breaker.... should the "Line" or the "Load" be connected to the battery ?
 

ArranP

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Since the Battery is connected to All-In-One SCC/Inverter that means you will have current flowing BOTH ways between SCCINVERTER and the Batteries so you will need Non-Polarized DC circuit breaker instead of Polarized DC circuit breaker.
I cannot tell from the website you provide to tell me if it is Polarized or non- polarized DC breaker of not.
Are you in Thailand?
yes in Thailand.
 

Bud Martin

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The thing is, the DC polarized DC breaker will be marked with Positive and Negative symbol, I have never Line and Load label on DC breaker, I do see Line and Load label on AC circuit breaker.
Can you ask the seller for full spec of the breaker?
 

MichaelK

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There is just one set of terminals for battery in & mppt charger out.

The question I have is regarding the breaker.... should the "Line" or the "Load" be connected to the battery ?
You don't seem to understand anything I stated in the post above. Line and Load are AC in and AC out terminals. Do NOT connect them to the battery. Most likely that could destroy the unit.

I found another Easun unit for sale on Ebay, and I got more information there then I did the company webpage. Here is a pic of the underside of the unit I found. Does it look the same as your unit? As I thought, they are identified as AC input (#7) and AC output (#8). AC input (#7) corresponds to "Line". AC output (#8) corresponds to "Load". The battery wires only get connected to the #10 terminals. The incoming solar DC is connected at the #9 terminals.

If you still don't understand this terminology, I would strongly suggest you hire a qualified electrician to do these connections for you.
1634097388547.png
 

ArranP

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Nov 5, 2020
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You don't seem to understand anything I stated in the post above. Line and Load are AC in and AC out terminals. Do NOT connect them to the battery. Most likely that could destroy the unit.

I found another Easun unit for sale on Ebay, and I got more information there then I did the company webpage. Here is a pic of the underside of the unit I found. Does it look the same as your unit? As I thought, they are identified as AC input (#7) and AC output (#8). AC input (#7) corresponds to "Line". AC output (#8) corresponds to "Load". The battery wires only get connected to the #10 terminals. The incoming solar DC is connected at the #9 terminals.

If you still don't understand this terminology, I would strongly suggest you hire a qualified electrician to do these connections for you.
View attachment 68622

Michael,

My question pertains to the "Line" and "Load" terminals on the DC breaker.

The breaker connects to #10. Battery input on the inverter.

However as the inverter is also an mppt charger, as Bud Martin correctly states "that means you will have current flowing BOTH ways between SCCINVERTER and the Batteries so you will need Non-Polarized DC circuit breaker instead of Polarized DC circuit breaker."

So now I have approached the supplier of the dc breaker to establish the specification.
 

DJSmiley

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Aug 13, 2020
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484
Line is the source, load is the output (the inverter) on the breaker

However, is there a specific reason why you would want this breaker?

It does look a Chinese OEM. And as with a lot of other high current stuff from China, I doubt their reliability.

I personally won't prefer a breaker, but a regular (decent) Class-T fuse. If you really want to be able to disconnect the battery, use the BMS, an external contactor or external disconnect switch. Go, especially with high currents, for well-known brands. Its easy to cause the most random issues due to bad contacts with cheap shit, or even worse.

For contactors, look eg at Gigavac, for switching you can look into BlueSea systems, or for example ABB or Schneider.

Note: DC current disconnect is something completely different than AC, take good care and look for DC current and DC disconnect capabilities!
 

MichaelK

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Michael,

My question pertains to the "Line" and "Load" terminals on the DC breaker.

The breaker connects to #10. Battery input on the inverter.
That is reassuring. Sorry I did not understand what you were asking.
 
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