Watt
A unit used to measure the actual power being delivered in an electrical circuit. To maintain the distinction between actual power and apparent power, actual power is expressed in kW while apparent power is expressed in kVA.

wet bulb temperature
see design wet bulb temperature

wye-delta
A reduced inrush current starting method in which the 3-phase motor stator coils are initially connected in a wye configuration and switched to delta as the motor's speed increases. When an adjustable frequency drive is connected to such a motor it should be permanently connected in the delta configuration.