Power Factor - a good explainer ?

[paulscottrobson]

Good afternoon everyone,

I've had a Shelly EM monitoring my input line for a couple of weeks, and I'm very happy with it and it seems pretty accurate.

I'm not quite sure what the Power Factor is , and if it is important. If someone could point me to a good explainer on this I would be grateful.

My PF seems to vary between about -0.7 and -0.8 ; I got the impression this was an indicator of low efficiency ? What would people advise ?

Many thanks in advance,

Paul Robson

[thgoebel]

The power factor is - like voltage and current - a significant quantity in power measurement with AC systems. Please have a look at Wikipedia:

https://en.wikipedia.org/wiki/Power_factor#Importance_in_distribution_systems

 

 

[terae]

Capacitive - / inductive + which means effective power without reactive power amount... so if you need for example 1000W power to do work and PF is -0.7 or +0.7 then you actually need over 1400W worth of Amperes through wiring but only 1000W does work. cos φ = P / S = P / (U·I)

Negative value means you make the extra from devices to grid, compensating the positive at grid side. Other way you need to transfer that from grid. Amount is same, direction isn't. Compensation should be at close as possible to devices needing it. That's why power factor correction.

[tavi]

Not quite something to bother with in rezidential setup.