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Forum Index : Electronics : UPS questions

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domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873
Posted: 07:48am 10 Apr 2007
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As there is no manual I am stuck with heaps of questions:

1. Switching the UPS on for the first time, does one connect the mains first, then the batteries or the batteries first, then mains?

2. Is it possible to disconnect the batteries while the UPS is still connected to the main? I may wish to charge the batteries via the windmill and not the mains and have the UPS up when the mains supply fails. I know I could kill a linesman and I would disconnect the grid first via the manual switch!

The UPS is rated at 1500W, any guess how much it draws when the batteries are not connected - if that is possible?

3. When the mains are UP, does the output still come from the batteries or is the UPS bypassing the battery setup and just routes the mains to the output AC leads directly? Or does that depend on the model?

4. A UPS only starts if power is first connected and then fails, then the UPS sounds an alarm and acts like an inverter. Without knowing the circuit, is there a way to make it behave like an inverter and start straight away??

So many questions, so little time!

Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
RossW
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Joined: 25/02/2006
Location: Australia
Posts: 495
Posted: 11:39am 10 Apr 2007
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  domwild said   As there is no manual I am stuck with heaps of questions:
[/quote]

What type and model UPS? There are thousands of them out there, and few are the same!

[quote]
1. Switching the UPS on for the first time, does one connect the mains first, then the batteries or the batteries first, then mains?
[/quote]

Usually, connect the batteries, then connect the mains.
When disconnecting, put the unit into shutdown or bypass, isolate the batteries if they have a switch. If not, kill the mains, then isolate the batteries.

[quote]
2. Is it possible to disconnect the batteries while the UPS is still connected to the main? I may wish to charge the batteries via the windmill and not the mains and have the UPS up when the mains supply fails.
[/quote]

Depends on the UPS. Some are designed for "hot-swap" batteries, some will die quicker than you can say boo.

[quote]
I know I could kill a linesman and I would disconnect the grid first via the manual switch!
[/quote]

I hope not! The load would all come from the output side of the UPS. You most certainly should not be hooking the UPS *directly* onto your supply side.

[quote]
The UPS is rated at 1500W, any guess how much it draws when the batteries are not connected - if that is possible?
[/quote]

Depends if it's standby, online, double-conversion. MSW, full sine. What technology it uses etc.

[quote]
3. When the mains are UP, does the output still come from the batteries or is the UPS bypassing the battery setup and just routes the mains to the output AC leads directly? Or does that depend on the model?
[/quote]

As above. epends.

[quote]
4. A UPS only starts if power is first connected and then fails, then the UPS sounds an alarm and acts like an inverter. Without knowing the circuit, is there a way to make it behave like an inverter and start straight away??
[/quote]

Not all have this behaviour. I have lots that will "black start" - ie, turn on and run from battery alone, without the mains having been present.

 
domwild
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Joined: 16/12/2005
Location: Australia
Posts: 873
Posted: 12:56am 11 Apr 2007
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Ross,

Thanks for that. UPS is an "Accupower Select 2000", a 36VDC version; Emmerson does not reply to emails regarding this model and as it is not a common model, I did not bother to state the model.

Being on the grid and not wishing to float-charge the batteries all the time but having a mill to do that, that is the dream. Dream on!

Thanks.
Taxation as a means of achieving prosperity is like a man standing inside a bucket trying to lift himself up.

Winston Churchill
 
RossW
Guru

Joined: 25/02/2006
Location: Australia
Posts: 495
Posted: 06:44am 11 Apr 2007
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  domwild said   Ross,

Thanks for that. UPS is an "Accupower Select 2000", a 36VDC version; Emmerson does not reply to emails regarding this model and as it is not a common model, I did not bother to state the model.
[/quote]

Not familiar with it, will have a bit of a scratch about, but don't hold your breath!

[quote]
Being on the grid and not wishing to float-charge the batteries all the time but having a mill to do that, that is the dream. Dream on!
[/quote]

It's not an unreasonable request.

Many inverter/chargers will allow you to float the batteries from any available renewable sources you might have. My monster here is a "generator-interactive", not grid-tie. Will charge batteries from the generator (or start the generator if it needs to), will charge the batteries from RE (wind, hydro, solar), and can even shut down the generator if there is enough RE to do the job.

Penalty is price (ouch!)

UPSs (generally) have fairly high "overhead" power consumption in their battery mode, which may render them unsuitable for long-term use in your application.
 
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