gmane.linux.distributions.emc.user

Re: Control of AC motor in antenna rotor

Roland Jollivet wrote:
> Not quite. Most UPS's around 2KVA and below are 'off-line', ie straight
> feed-through. Far far cheaper to make. You pay through your ears for an
> on-line UPS as it requires a full power down and up converter.
> 

Every UPS has a full power down and up converter. How else would it
work? The difference between small and large industrial ones is in their
ability to switch from a UPS mode to feed-through without disrupting the
power to the load. Electronics takers care of the sync between primary
and secondary AC lines. That way you can work on UPS while the load has
full power.

Repaired few small UPS' myself and managed a large one in a computer
center few years ago. Still have to large 100Ah batteries from one time
we replaced 36 of them.

> Regards
> Roland

--
Rafael

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Roland Jollivet | 29 Nov 21:38

Re: Control of AC motor in antenna rotor

There is the wiki on it, but even that does not explain it properly. If you
have a look at this;

http://www.pcrite.com/store/product_info.php?cPath=24&products_id=360

which is typical of what you find in a computer store, you will find a
single, underrated inductor inside. During normal use, the PC is powered
directly, and the the battery is kept topped up by one winding. When the
mains fails, relays kick in, and inverter runs, using the same power
inductor, but other windings. Usually only for a few min otherwise the
inductor would overheat(been there). When mains restores, it takes up to 8
hours to recharge the battery. They really are designed for an unlikely
power outage.

But...... I'm not sure what power rating you are thinking of, or what
country you are in. When I say 'most', I mean the units you find here;

http://www.walmart.be/english/products/oneCategoryProducts.asp?cat=48&catName=UPS

which are usually chinese made.

2008/11/29 Rafael Skodlar <raffi@...>

> Roland Jollivet wrote:
> > Not quite. Most UPS's around 2KVA and below are 'off-line', ie straight
> > feed-through. Far far cheaper to make. You pay through your ears for an
> > on-line UPS as it requires a full power down and up converter.
> >
>
> Every UPS has a full power down and up converter. How else would it

(Continue reading)

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Rafael Skodlar | 30 Nov 05:48

Re: Control of AC motor in antenna rotor

Roland Jollivet wrote:
> There is the wiki on it, but even that does not explain it properly. If you
> have a look at this;
> 
> http://www.pcrite.com/store/product_info.php?cPath=24&products_id=360
> 

You don't put serious servers on such a UPS. I was thinking about smart
UPS that power one or more larger systems in computer rack.

> which is typical of what you find in a computer store, you will find a
> single, underrated inductor inside. During normal use, the PC is powered
> directly, and the the battery is kept topped up by one winding. When the
> mains fails, relays kick in, and inverter runs, using the same power
> inductor, but other windings. Usually only for a few min otherwise the
> inductor would overheat(been there). When mains restores, it takes up to 8
> hours to recharge the battery. They really are designed for an unlikely
> power outage.
> 
> But...... I'm not sure what power rating you are thinking of, or what
> country you are in. When I say 'most', I mean the units you find here;
> 
> http://www.walmart.be/english/products/oneCategoryProducts.asp?cat=48&catName=UPS
> 

You won't find this useful for powering a large computer center where
min of 5 to 10 kW is needed. My guess is we were thinking about
different systems based on previous experience.

> which are usually chinese made.

(Continue reading)