Crest factor?

[notme]

I see this term in specs for UPS's. Wikipedia describes it as a ratio of RMS
to peak voltage.

That doesn't "grok" for me.

Help me understand what it means re. a UPS whose output is spec'd to be sine
wave with CF of "up to 5:1".

Does this mean as load increases that he sine wave distorts up to the crest
value of 5:1 (which I take to mean alot)?

Thanks.

 

[Phil Allison]

"notme"

I see this term in specs for UPS's. Wikipedia describes it as a ratio of
RMS
to peak voltage.

** No it does not - it says " waveform ".

Go read it again.

That doesn't "grok" for me.

Help me understand what it means re. a UPS whose output is spec'd to be
sine
wave with CF of "up to 5:1".

Does this mean as load increases that he sine wave distorts up to the
crest
value of 5:1 (which I take to mean alot)?

** Got nothing to do with the output voltage wave

- it has everything to do with the CURRENT draw wave.


The current drawn by loads typically attached to a UPS is anything but sine
wave in shape - it is more like a stream of short pulses in time with the
voltage peaks and with the same polarity as them.

So, in your example, the maker is saying the UPS will supply continuous
current *peaks* of up to 5 times the RMS current rating of the UPS.

Eg Say the UPS is rated at 300 watts at 120 volts, then the RMS current
rating is 2.5 amps.

With a CF of 5, the allowable peak value is 12.5 amps.



..... Phil