question

guillem-636 avatar image
guillem-636 asked

Generator size and harmonics (THD)

Greetings,


I would like to know what is the minimum size of generator that can work without problems with a Victron Multiplus 48/5000/70.

I know the following link:

https://www.victronenergy.com/live/multiplus_faq#generator_sizing

in which it is recommended that the minimum power be 8 kVA, but below the data table it is indicated that """if your generator is smaller than the recommended size for your inverter/charger, you will definitely need to adjust the settings ...""". From this, I can deduce that a smaller generator can work properly.

I cannot find the minimum value from which the system will work correctly.

On the other hand, I can choose between two generators: one with a THD<5% and the other with a THD slightly greater than 7%. (There are other features to consider, of course)

Is there some recommended maximum level of Total Harmonic Distortion?

Thank you for your attention.


Generator
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @Guillem_636

The magic number for your 5kVA Multi is 3.9 Amps (at 230V, so ~900W). It's possible to go lower than that by turning off PowerAssist, but you really might miss that feature. Yes, an acceptance limit can be set in the Multi.

Generators come in many types (& capabilities), and it's good form to oversize it to a good degree. Inverter gennies won't tolerate spikes, and need headroom there.

I've never seen a Victron-published THD figure, but there's more to it than that anyway. See this article.. https://www.victronenergy.com/live/multiplus_faq

If you do ever need to activate the 'Weak AC' setting, I've found that my own 5kVA Multi will then only charge up to ~1800W, but will pass through much more than that to loads. My limit there is 14A, as more will trip the plug-in genny breaker. I could rewire the genny, but it's enough for me.

Good luck choosing..



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