Genset frequency at 53.1Hz. Multi does not turn on

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Lyndsay Cotton asked Apr 2, '21

Genset frequency at 53.1Hz. Multi does not turn on

I have a client installation which is a pretty standard 48/5000 Multiplus 2 with ESS.

There is a changeover switch from a genset which is manually operated in the event of a prolonged national grid failure.

For all intents and purposes the Genset is installed as if it is the national grid.

Except, - The Multi does not recognise the Gender and sees the Grid as failed. The genset output is 23x volts and 53.15 Hz at no load

Out National grid code NRS097 stipulates the Multi to disconnect at low Hz 47 and high Hz 52

I suspect that due to the Genset output being 53.15Hz that the Multi recognises this as out of the acceptable parameters.

How can I fix this?

Can I create an identical Grid code but with high Hz cut off being say 54Hz?

Multiplus-II genset multiplus

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wkirby ♦♦ commented · Apr 02, 2021 at 07:51 PM

What did the generator manufacturer say? I'd follow their advice on how get it fixed.

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Lyndsay Cotton wkirby ♦♦ commented · Apr 03, 2021 at 08:34 AM

I tend to agree with you. Due to the long weekend and my limited knowledge of the Genset, I was hoping to rather just solve on the Victron side

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Matthias Lange - DE ♦ Lyndsay Cotton commented · Apr 03, 2021 at 08:39 AM

Maybe you can try to connect a small load directly to the generator?

A classic light bulb maybe. This could be enough to pull down the frequency.

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Lyndsay Cotton Matthias Lange - DE ♦ commented · Apr 03, 2021 at 08:45 AM

Haha... Thanks. I tried that with the oven - nope (:

It is a 12KVa gender- dropped by 0.3Hz

My "lightbulb moment" was dashed into oblivion

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Modifications Space

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Answer 1 · 2021-04-03T04:19:30Z

Paul B answered · Apr 03, 2021 at 04:19 AM

Hi Lyndsay, I would Guess and say that you are correct in that the Quattro is complying with the country code selected.

So one posiable option is to reduce the Generators RPM so that the hz goes below 52 Hz , (Thats if its NOT a inverter generator that is), As normaly the larger generators Hz is controled by its RPM to get the Hz Frequency correct, now some generators when under load don't hold there RPM well and then it becomes a balancing act between two high a frequency and too low a frequency

or MAYBE TOTALY and AT your discretion as you have to comply with your local countrys laws.

Change or try changing the country code to Other, and see if you then get a connection. or set it to NONE , this will all depend on what other assistants you are running and what they require as well. etc

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Lyndsay Cotton commented · Apr 03, 2021 at 08:41 AM

You are correct wrt to the Genset settings rather being corrected. It has a very good quality alternator and due to its size, I doubt if the Hz will reduce by anything more than 0.3 Hz. I switch the oven on to its highest setting and the units Hz dropped by only 0.3Hz

As per @wkirby that is probably the answer but I was hoping to set the Multi parameters by SLIGHTLY modifying the Grid code parameters

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Paul B Lyndsay Cotton commented · Apr 03, 2021 at 08:44 AM

the only way it will reduce (If its the NON inverter type that is) is to reduce the main engines RPM until the hz drops to below 52hz , It should be set to around 50hz anyway. It should be a easy adjustment on the engines injector pumps governer

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Lyndsay Cotton Paul B commented · Apr 03, 2021 at 08:53 AM

Thank You. I will try that. It was serviced recently and I wonder if the technicians did not focus properly

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Lyndsay Cotton Paul B commented · Apr 04, 2021 at 11:40 AM

Hi Paul.

I went back to my customer today and I set the genset speed to match a very stable 50.15 Hz. The Multi did not react. Whilst I was monitoring the frequency, we dropped the genset frequency to just under 50Hz and the Multi then reacted as to be expected - trying to syncronise to the "grid".

This it tried a number of times but only once did it syncronise to this "genset grid"but very shortly went into overload. I am going to assume that this is unrelated and purely co-incidental.

Repeated tries thereafter with genset being set just marginally over 50hz elicited no response from the Multi. However immediately on setting the genset output to slightly under 50Hz got the Multi "recognising"a "grid"and attempted the switchover process. The Multi however refused to accept this genset grid and although it tried a number of times - was not successful.

Switching the mains on caused the genset to recognise the mains, changeover and power then was obtained from the national grid.

As expected the Multi did its tests, eventually took on the national grid and shortly thereafter activated AC2 relay as well.

Please note that I am using a Mutliplus 2 48/5000 and not a Quattro. Reason being that when installing the Victron solution, the client was intending to remove the genset. Due to an increasing prolonged periods of the national grid being down, the client decided to keep the genset, it already having a ATS.

So some questions then;

1. Does the Multi then "refuse" to use a genset input on AC In ? It just will not syncronise. Or is it due to, (excuse my ignorance for the incorrect term) lack of "back pressure"from the genset which the grid offers. Why I say this is when the Multi tried to accept the "genset grid", I noticed a MARGINAL spike in the frequency.

or

2. Does the Quattro INPUT 2 AC accept a poorer voltage / frequency on its second input and will thus take power from a potentially lower quality source.

AND, therefore if having a genset, - the only option is a Quattro??

or

3. Is it a voltage issue as well (although I seriously doubt it)

- Genset output was a very stable 230v whereas

- Grid input was around 240V

After Paul (and others) earlier responses I was convinced the problem was solved - however that was not to be

Any other answers to this? I am stumped

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Answer 2 · 2021-04-04T16:40:26Z

Daniël Boekel (Victron Energy Staff) answered · Apr 04, 2021 at 04:40 PM

Please read this document:

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

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