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A n00b trying to get around power outages


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Hi Everyone


There are likely many similar posts already with similar questions and solutions, I have read through some and have a very basic idea / understanding of things.
With that said I am looking for some advise and pointers on a solution I would like to have setup for a small business.


They currently have a small server room that uses +/- 6000watts to 7000watts and 30 to 40 Amps. (Some devices can be shifted around to bring this down closer to 5000watts or less.)

They will need to power this room as well as 1x laptop 40 to 75watts, 5x small form factor PC's 230watts each and 2x standard desktops +/- 500watts each.
They only need to be up for 3 hours at a time for now.

They already purchased a generator on the recommendation of an electrician, 28A, 6800kW petrol generator, it cannot handle the load.

I am thinking of a solution whereby they can run either one large inverter with a battery bank or two inverters in parallel i.e. 1x 3kva + 1x 8kva and a battery bank and then use the generator to charge the batteries once the power has gone out.
Or 1x 10kva or 12kva inverter and battery bank + generator to charge the batteries?

Is it possible to run a generator to charge the batteries?
And if so is there perhaps a recommended brand for this?

Kind Regards

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A good place to start is establishing your exact needs and being able to describe them accurately.

I would hazard to say this has already cost the price of a generator in school fees.

It is a mistake to be use the terms kVA and kW interchangeably. They aren't the same thing.

For instance 6000watts to 7000watts is different to 40Amps which is over 9kVA.

I also know that your generator isn't 6800kW, maybe 6.8kW, or was it actually 6.8kVA? 

At 28A, 230Vac, it is neither, it's less than 6.5kVA. 

Also read up up the difference between kW and kWh, if you're considering batteries.

If these things aren't accurately described, you will get people who will sell you what you say you want, instead of what you really need.

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Hi @phil.g00

Thank you for the feedback.

For the generator I was going on what info I was given, the generator was installed without consulting anyone, and they went ahead based on an electrician they found on-line's suggestions.
I was only told about it after it was installed.

You are correct I went in and checked the Generator it says:
6.8kW
28A
230V

For the server room I worked out the watts load based on the total potential of the device's power supplies MAX ratings all together, but based on the Amps, it looks closer to 8 to 9.5kVA.
For the Amps I took the readings directly from the APC UPS over time so 30 to 40Amps, but it generally stays withing the low to mid 30's.
 

Kind Regards

 

Edited by Mookz
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On 2020/01/09 at 5:37 PM, phil.g00 said:

A good place to start is establishing your exact needs and being able to describe them accurately.

I would hazard to say this has already cost the price of a generator in school fees.

It is a mistake to be use the terms kVA and kW interchangeably. They aren't the same thing.

For instance 6000watts to 7000watts is different to 40Amps which is over 9kVA.

I also know that your generator isn't 6800kW, maybe 6.8kW, or was it actually 6.8kVA? 

At 28A, 230Vac, it is neither, it's less than 6.5kVA. 

Also read up up the difference between kW and kWh, if you're considering batteries.

If these things aren't accurately described, you will get people who will sell you what you say you want, instead of what you really need.

Thx again for the advise.

 

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On 2020/01/14 at 6:57 AM, Mookz said:

For the Amps I took the readings directly from the APC UPS over time so 30 to 40Amps, but it generally stays withing the low to mid 30's.

Whatever you get you have to size for the kVA peaks.

You also should consider future expansion, and then add a margin for safety.

There is nothing wrong using a  correctly sized generator, so long as it is a standby generator and not a portable one.

There are no circumstances that it is legal to use a portable generator as a permanent fixture, it is electrically different to a standby generator and it can be dangerous.

 

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Server rooms are particular to clean power. 

Unless you invest in an inverter generator of sufficient kW output it will not be good enough. And it must be able to start up and supply power immediately, which is not possible in the real world. 

You need to determine how necessary it is to have your system up and running at all times. 

Only then can the financial motivation follow. 

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