base speed
The speed at which a motor will develop rated kW/horsepower at rated voltage.

bipolar transistor
A semi-conductor amplifier device in which a small current between two terminals (the base and the emitter) controls a larger current (between the collector and the emitter).

breakaway torque
The torque required to start a machine from standstill.

bridge rectifier
A full-wave rectifier that conducts current in only one direction. AC applied to a bridge rectifier results in DC at the output.

bypass
In an adjustable frequency drive, a bypass is a means of running the motor at full speed directly from the AC line. This bypasses the drive.