What PF to use in a single phase load calculation

[Elec-Temp]

I have heard to use a PF (Power Factor) of .6 in a single phase load calculation & .8 in a three phase. Any advise or links to help out would be great. Thanks' Rick

 

[iceworm]

I have heard to use a PF (Power Factor) of .6 in a single phase load calculation & .8 in a three phase. Any advise or links to help out would be great. Thanks' Rick

I use 1 for single phase - unless I have reason the think different.

For 3phase, NEC Table 9 uses .85

ice

 

[kwired]

Power factor can be in the formula, but you still need to know what power factor applies to load(s) you have. If it is resistive loads the power factor is 1, which gives same result as if you disregard using power factor in the formula.

Inductive loads will have power factor, will not be same from one load to the next, and will also depend if capacitors are used to correct for power factor.

So there is no general rule of what to use other than 1 if there is only resistive loads.

 

[Hv&Lv]

I have heard to use a PF (Power Factor) of .6 in a single phase load calculation & .8 in a three phase. Any advise or links to help out would be great. Thanks' Rick

Where did you hear .6? Any customer wasting a third of their power should and probably would be charged extra for poor P.F.

Go with unity for single phase loads unless you have special reason to suspect a lot of poor P.F. equipment.


Load Type pf
Ceiling Fan 0.999
Refrigerator 0.875
Microwave Oven 0.998
Vacuum Cleaner 0.951
Fluorescent Ceiling Lamp 0.956 *
Television 0.988 *
Desktop Computer and Printer 0.999 *
* Leading displacement power factor

 

[suemarkp]

Why does it matter? Doesn't the nameplate amps already have the PF accounted for? What are you calculating?

 

[kwired]

Why does it matter? Doesn't the nameplate amps already have the PF accounted for? What are you calculating?

You have a point. Nameplate amps x volts = volt-amps. If nameplate is marked in watts then you need to know power factor to get volt-amps. If power factor is not corrected the conductors, and other supply equipment has to be able to handle volt-amps.