The 4600 series was developed to emulate the older electromechanical synchronous motor type of repeat cycle timers. In older electromechanical repeat cycle timers, a cam closed a switch on each rotational cycle of the motor. The cam driven rotational cycle has been replaced by the Repeat Cycle Time portion of the 4600. The switching action of the electromechanical timer has been replaced by a solid state switch energizing on each repeat cycle. This portion of the cycle is referred to as Energize Time.