[Nut-upsuser] compaq r3000 triggering the fuse when power is reconnected

[Arjen de Korte]

Citeren Per Jessen <per at computer.org>:

>> That's usually the tell tale sign that the batteries are well past
>> their 'due to replace by' date. When was the last time you ran a deep
>> discharge test on them?
>
> Not sure - I'll have to admit my ignorance and ask what is that?

Never mind, I noticed that the upscode2 driver doesn't seem to support  
this command (yet), so the chances that you actually did a runtime  
calibration are fairly slim (unless you used something else than NUT  
to control it).

[...]

> I have two of these r3000, both with almost exactly the same load
> attached - each is about 2.2kVA.  The other box does not trigger the
> fuse when power is reconnected.

Nominal load depends on the amount of VA (or W) that a UPS sees. It  
makes no difference if this is one load drawing 2.2 kVA or ten each  
drawing 220 VA, the total load will be the same.

Surge (inrush) current is something different. Usually, PC/server  
power supplies will peak around 20..50 A (each), with essentially no  
dependency on the actual load. So there is a huge difference if you  
have one or ten systems connected when it comes to inrush current. In  
many cases, five PC/server power supplies all connected to the mains  
at the same time will be enough to trip the circuit breaker. Adding  
just a single additional one may tip the scale. When it comes to  
tripping fuses, you may be fine if you stay just below a certain limit  
and will only notice a problem if you (just) exceed it.

So basically the only way to check for differences, is to disconnect  
all loads. Don't leave the mains connections attached, the power  
button on a PC/server is just a soft switch, it doesn't actually  
disconnect the mains.

Best regards, Arjen
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