[kwlug-disc] (question) Which UPS to buy?

[John Johnson]

On 2014-06-02 12:32, L.D. Paniak wrote:
> component failure (fun having a 6kVA inverter blow up in your face!).
> Maybe it is just a fact of life when it comes to power electronics.
>
> That said, they are a necessary evil.  I have had reasonable luck with
> Eaton/Powerware UPSes.
Earlier Andrew described component failure in the insulation of the 
internal wiring in motors being driven from VFD drives, where the output 
is not dissimilar to that of a UPS.

Add this to component stresses due rapid and continuous cycling of 
voltages that cause can stresses in the components and possible failure.
Some of this is, as said, above a 'fact of life when it comes to power 
electronics'.

This can be addressed by what is sometimes called 'over-engineering', 
e.g. using components with a higher margin of 'safety', better 
mechanical design including better heat sinks, etc.

But this increases cost and this and other drivers conspire to remove 
the 'over-engineering' and with that an acceptance, by the manufacturer, 
of a certain failure rate.

Note: APC and Eaton are leaders in this field.

jsquared

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