PFC Power Supplies

[mpparent]

With today's advent of power factor correcting power supplies, I wondered how many of you out there(that have raised floors and UPS backup), have seen increasing leading power factor? I have heard of static UPS's dumping the critical load once the power factor starts to go leading.

Mike

 

[jbartos]

Suggestion: The leading power factor may lead to oscillations or resonances that are causing problems.

 

[electricuwe]

Please consider that there are two different power factors:

fundamental power factor: cosphi

and true power factor: lambda

Terms as leading and lagging can only be applied if you are talking about fundamental power factor.

In the case of power computer powers supplies discussions on fundamental power factor are not worth the time spent because low power factor is mainly caused by harmonics.

 

[rbulsara]

Most modern UPS (like Liebert and Powerware in the USA) incorporate automatic means of disconnecting the capacitors at low loads. (drop caps below 25% of ragted load and pick up again at 30% or more ).