Electrical soft starters can utilize solid state devices to control the current flow and therefore the voltage applied to the motor. They can be connected in series with the line voltage applied to the motor, or can be connected inside the delta (Δ) loop of a delta-connected motor, controlling the voltage applied to each winding. Solid state soft starters can control one or more phases of the voltage applied to the induction motor with the best results achieved by three-phase control. Typically, the voltage is controlled by reverse-parallel-connected silicon-controlled rectifiers (thyristors), but in some circumstances with three-phase control, the control elements can be a reverse-parallel-connected SCR and diode.

Another traditional and the most reliable way to soft start the motor with reduced current is with the help of series reactor. This method is called as series reactor soft starter, which refers to the IEC standard 60289. If an air core is used for designing the series reactor then a very efficient and reliable soft starter can be designed which is suitable for all type of 3 phase induction motor [ synchronous / asynchronous ] ranging from 25 KW 415 V to 30 MW 11 KV. Using an air core series reactor soft starter is very common practice for applications like pump, compressor, fan etc. Usually high starting torque applications do not use this technology for the starting device. A very famous type of such starters are Harmonics free (due to air core) series reactor soft starter.