What is non-unity power factor?

Power factor correction increases the power factor of a load, improving efficiency for the distribution system to which it is attracted. 

Linear loads with a low power factor such as induction motors can be corrected with passive network of capacitors or inductors. 

Non-linear loads, such as rectifiers, distort the current drawn from the system. In such cases, active or passive power factor correction may be used to counteract the distortion and raise the power factor. The devices for correction of the power factor may be at a central substation, spread out over distribution system or built into power consuming equipment.

Load Banks can be used for power factor correction to achieve closer to a power factor of 1.0, resulting in greater efficiency, lower line losses, smaller conductors, etc.