Letter V

Var

The basic unit for reactive power. Shortened from volt-ampere
reactive.

Variable Frequency Drive (VFD)An electronic device used to control the speed a of an AC
motor. A VFD controls the motor speed by varying the
frequency and voltage applied to the motor. Also called an AC
drive.


Variable Speed Drive An electronic drive device used to control the speed of an electric motor. This term applies to both AC Drives and DC
Drives.

Vector Control
A technique employed by some variable frequency drives that
involves calculations of AC motor current vectors and precise
control of motor flux to provide excellent speed and torque
control.