About Multi, Quattro, etc. PowerAssist

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Yonas Kiflom asked Oct 26, '19

About Multi, Quattro, etc. PowerAssist

Hello,

My question is about the inverter/charger’s PowerAssist. Multi, Quattro, etc. In the Victron datasheets, it’s specified: "Where peak power is so often required only for a limited period". It’s about the "peak power only limited period" that I would like to understand with the example below. I can test it but I would first be sure of my understanding of the “peak power only limited period” specification. Victron products are great but the documentations/manuals aren't really clear (sometimes, even some answers from Victron's direct technical support).

Grid 230V/16A/50Hz.

Motor 4kW (active power, not apparent in VA) AC sigle phase.

@ 25°C, the MultiPlus 1600VA gives 1300W.

In this case, without taking into account the motor starting characteristics and losses, etc., can the MultiPlus 1600VA handle (by combining grid + battery) the total power of 4000W (calculation below) continuously ? For example, for a duration of 30 minutes to 1 hour or even more?

Total power handled by the Multi = battery power (via inverter) 1300W + grid power 2700W = 4000W.

I’m trained in power electronics, active in renewable energy’s field and design currently many installations (off-grid, grid-tied & Self-consumption & energy storage) with Victron, Studer, etc. converters. The limited period, I understand as very short so no more than a few seconds or fraction of a second or can be last at most 1 minute.

Thank you in advance for your help & your contributions.

Yonas K.

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Answer 1 · 2019-10-26T13:25:02Z

JohnC answered · Oct 26, 2019 at 01:25 PM

Hi Yonas. Don't read too much into that 'peak power' written thing. That Multi has a 16A transfer switch, same rating as your supply, and can pass that through all day (3680W). Can be limited in the Multi if you want.

The inverter under PowerAssist that is adding to it, just go by the spec sheets, it's just additional power available for whatever time it says.

Starting spikes from a 4kW motor is something out there in unknown territory.

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Yonas Kiflom commented · Oct 27, 2019 at 07:57 AM

@JohnC, Many thanks for your prompt, short and lucid answer. You're right about starting spikes. However, I just wanted to get a simple answer (like yours) about the term "only limited period". Some people tend to go too far without really answering the question. FYI: Swiss grid is good quality and, almost anywhere, is 16A. The actual motor is an asynchronous three-phase 5kW and is equipped with a softstarter or star-delta starter system. (the customer isn’t from technical field and doesn’t really know the exact name of the starter system). We know that the star-delta starter system reduces the starting current to 1.5 - 3In and starting torque to 0.5 - 1Tn. The starting current and torque are even smaller with other systems like a softstart system. The rated current of the 5kW motor being 12.6A/phase and assuming a star-delta starter system, our network can easily handle 3In (=3x12.6A). Thanks again & have a nice day.

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