# Some basic technical doubts about UPS



## patkim (Nov 13, 2015)

Friends..I have some  basic questions about UPS, would be glad to seek clarification on following

The rating of UPS is shows as VA / Watts. say 600VA / 360W.  However I am unable to get layman understanding of this term VA. Does it mean it can provide 230V x 2.6A = 600 VA? If so will it get overloaded if the load is to draw more than 2.6A?

The Overloading of UPS, does it come into effect when Mains is OFF and UPS is providing power or will it affect even otherwise when Mains in ON as well? In short when Mains in ON can I connect more devices / load to UPS output without overloading?


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## icebags (Nov 14, 2015)

# U.P.S = Uninterrupted Power Supply i.e. supply even when mains goes off. it's used is for backup purposes.
# u simply don't overload an ups, internal circuitry may have protections, so, a fuse may go off or so. if there is no protection and it's a crappy ups, accidents may happen.
# VA or Volt-Ampere rating is a term used for AC devices, for power rating specification purposes, but its not exactly same as Watts. Watts is used for DC devices. 
The relation between VA and Watts is quite complex, and varies device wise. This relation is called Power Factor. linear loads, for example incandescent bulbs *s.yimg.com/lq/i/mesg/emoticons7/58.gif , have power factor=1, i.e. 60W bulb = 60VA bulb.

# switching devices like computer smps, mobile chargers, transformer based voltage converters, electronic fan regulators/dimmers, and other non linear appliance stuff etc have less than 1 pf values. they vary a lott, a same device may have different pf for different loads, but to get a general idea, u normally multiply VA rating with 0.6, to get an watt estimate, but it's not correct.

# so, if u have a 600W psu, get a 600/0.6=1000VA ups. have 360W psu, then get 360/0.6=600VA ups.


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