Four particular varieties of motor starters are: Across-The-Line, the Reversing Starter, the Multispeed Starter, and the Reduced Voltage Starter.
Direct On Line (DOL) is the most commonly used general purpose starter. This starter connects the incoming power directly to the motor. It can be used in any application where the motor runs in only one direction, at only one speed, and starting the motor directly across the line does not create any "dips" in the power supply.
The Reversing Starter or Full Voltage Reversing (FVR) reverses a motor by reversing any two leads to the motor. This is accomplished with two contactors and one overload relay. One contactor is for the forward direction and the other is for reverse. It has both mechanically and electrically interlocked sets of contactors.
Soft Start/Stop is used in applications that typically involve large horsepower motors. The two main reasons to use a reduced voltage starter are to reduce the inrush current and to limit the torque output and mechanical stress on the load. Power companies often won't allow this sudden rise in power demand. The reduced voltage starter addresses this inrush problem by allowing the motor to get up to speed in smaller steps, drawing smaller increments of current. This starter is not a speed controller. It reduces the shock transmitted to the load only upon start-up.
Variable Frequency/Speed Drive is designed to be operated at constant frequency and voltage. There are two ways to change the speed of an AC motor: Vary the frequency of the current applied to the motor or use a motor with windings that may be reconnected to form different number of poles. The multi speed starter uses the latter option to change speed.