Power factor: What it is, why it's important
In electric motors, power factor varies with load (although not directly). A motor running without a load will have a very low power factor, whereas at full load, the power factor may be relatively high. A facility that has a very low power factor in the total system may be charged a penalty by the power company for "borrowing" the power without fully using it. This is because more current is being transmitted than is actually doing any useful work.