Inverter RS 48/6000 MCB type and size

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wanek asked Dec 19, '23

Inverter RS 48/6000 MCB type and size

Hello!

Could you please advise for MCB amperage and tripping curve (B or C) should I use with the RS Inverter 48/6000?

In the users manual and datasheet it tells lots of scenarios regarding AC output capacity, so it is not very easy to decide:

users manual, chapter 2.3 says:
- peak power: 9000W (50A) for 3 seconds - which is kind of controversial, because 9000W / 50A is 180V, not 230V...

- cont. power: 5300W

- cont. power with solar boost: 5800W

datasheet:

Maximum continuous inverter current: 25 Aac

Peak power: 9000W for 3 seconds, 7000W for 4 minutes

Short-circuit output current: 45A this info is also controversial, because in the manual it says peak power 50A for 3 sec...

So, what MCB should I use? C25A would be suitable?

Thank you!

Best regards,

inverter rs

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Answer 1 · 2023-12-19T17:26:34Z

Alexandra answered · Dec 19, 2023 at 05:26 PM

@wanek

FYI that is the inverting rating. So what the inverter can supply, aka it cannot invert more than that from the battery (note it's rating is also based on battery voltage) and solar.

The 50A input allows charging, full loads on the AC1 output and some loads on AC2 output. So you can pass more through the unit and have solar contribute to non essentials.

50A at 180v is obviously less passthrough that 50A at 230v. And not everyone's grid is at 230v. So a realistic rating there.

Use a 50A input. Wiring sized accordingly. If wiring is smaller use a smaller MCB.

25A output on AC1. Sized with the wiring of course to match.

Curve rating choice is usually based on local law.

And a breaker never trips at its rated current. Look at the trip curves on c and b related mcbs. The inverter will shut down safely (if battery is correct) before the breaker trips in almost all scenarios.

I have seen 9500w pull through a 32A breaker and it never tripped.

Nothing there is controversial here. Just need to know how to design and dimension an electrical system. In the inverter world everything is amps based, voltage affects power output.

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Answer 2 · 2023-12-19T22:32:31Z

wanek answered · Dec 19, 2023 at 10:32 PM

Hi!

Thanks for the prompt reply! First of all, I apologise if my question was not very clear: I was asking about this product:

Inverter RS 48/6000 230V Smart Solar

https://www.victronenergy.com/inverters/inverter-rs-smart-solar#pd-nav-secondimage

As you can see, this device has no such thing as AC input, neither multiple AC1 nor AC2 outputs.

It has just a single mains AC output, which, according to the users manual chapter 2.3, it can provide "peak 9000W or 50A AC".

What I do not understand, however, how is that 9000W or 50A calculated? As we are talking about a 230V device here, I assume it is a realistic expectation that the inverter output voltage should be all the time close to 230V. But doing the math: 9000W/50A, it gives only 180V, which means either there is an error in the documentation, either the inverter will have a significant - 28% - voltage drop at 50A load.

What are the maximum acceptable voltage deviations for these inverters at while they are still considered functional? In the datasheet it says "Output voltage: 230 VAC ± 2 %", so I would assume that for all the provided peak power values this should be valid, until otherwise noted.

Also, stating in the datasheet "Short-circuit output current 45A", then stating in the users manual "peak 9000W or 50A AC" for me it is controversial. How can a device output 11% more curent then the official 45A Isc?

Thanks!

4

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Alex Pescaru commented · Dec 19, 2023 at 10:53 PM

Let's think practical...

The inverter can supply, in ideal conditions (25*C), a continuous 5300W.

Are you planing to draw more than that? If yes, then it's the wrong inverter for your application.

So, use a 25A breaker, that means 230x25 = 5750W, well within that maximum output.

Or use a 32A breaker to cover that 7kW for 4 minutes peak power. But this is over-realistic, because the inverter will quickly heat up and the max power will derate.

Both above options will function OK and break the circuit and will provide protection BEFORE that 45A internal short circuit limitation will step in.

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wanek Alex Pescaru commented · Dec 19, 2023 at 11:11 PM

Thanks for the tip!

The 32A MCB I think would be too much anyway: Normally, if we check the graphs, a 25A MCB should be able to withstand the 1.5x of its nominal value for 500 sec (about 8 minutes), that is 37A. Still more than the 7 minutes at 7000W.

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wanek Alex Pescaru commented · Dec 19, 2023 at 11:16 PM

"Both above options will function OK and break the circuit and will provide protection BEFORE that 45A internal short circuit limitation will step in."

...nahhh, probably not. A 25A MCB, according to the graph, it will need around 50sec at 45A to trip... The qestion is, how bad is that for the inverter?

So, maybe a 20A MCB would be suitable for these inverters?

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Alex Pescaru wanek commented · Dec 20, 2023 at 07:15 AM

You maybe right.... The theory is good. It only remains to be put to practice.

So, trial and error, here you come. :-))

In the end, you know better than anyone which will be the range(s) your inverter will work and which equipment you'll be using and how.

Don't worry, the inverter, if it's built OK, will protect itself. And you, in 99.9% of the cases, will use it well within the limits.

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