This chapter examines the operation of different power semiconductor switches currently used for the implementation of different industrial equipment such as electric motor drive systems, electric vehicles, robotics, photovoltaic power generation systems, wind turbine power generation systems, active power factor correction systems, switching power supply systems, and many more. The main use of power semiconductor devices is the implementation of power electronics conversion systems that convert a power source to another. For example, a rectifier converts an AC source to DC and an inverter converts a DC source to an AC source. Moreover, controllable power semiconductor devices can be used to implement power switches. Today, the main power semiconductor devices used in industrial electronics include the Insulated Gate Bipolar Transistors (IGBTs), the Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs), the Bipolar Junction Transistors (BJTs), the thyristors, and the power diodes. Although in this chapter the power Bipolar Junction Transistor is also presented, it has to be noted that today it is not used as a semiconductor switch for the implementation of power electronics topologies due to its low current gain.