The Working Principle and Applications of Solid State Switch

What is a solid state switch?

A solid state switch is an improved form of a relay. It is made up of solid state materials which have better characteristics than the typical relay. Relays are used for automatic switching of power, to eliminate the need for manual and difficult to handle typical switch technology. A solid state switch is a non-contact switch. The manufacturing material for solid state switch is a solid state element. The biggest advantage of using solid state elements is that they can control bigger load currents with smaller control signals. In solid state switches, as a result of the characteristics of the solid state elements used in relays, sparks cannot be generated. It is easy to achieve a solid state switch's open and closed states. Solid state relays have different characteristics: they contain no mechanical components, the voltage rise is extremely low, and zero-crossing technology is used for solid state relays.

The working principle of solid state switch

The working principle of solid state switch can be understood by dividing them into two types: AC solid state switches and DC solid state switches. The programmable RF switch consists of an input and an output terminal. The relay's input and output are connected to the designated terminals. When a specific control signal is provided to the input terminal of the solid state switch, the ON and OFF functions of the output terminal will be executed accordingly, and when the function is achieved, the switch function of the relay will be turned on. A coupling circuit is formed between the input and output of the relay with the aid of the coupling circuit in the solid state switch.

In the event of unwanted or uncertain initial settings before installing the relay, the coupling circuit also performs a cut-off function. Optocouplers are used in the coupling circuits of solid state switches. Optocouplers have good sensitivity, higher response speed, and higher input and output insulation levels. The load used in the solid state switch is an LED, which is used to match the input signal level. The output of the solid state switch is "0" or "1". The output terminal of the solid state switch, also known as the 4 state switch, is connected to the computer for interface.

In the case of DC solid state switches, there are no buffer circuits or zero-crossing control circuits. Transistors with higher values are used for switch in solid state switches. The other workings of the relay are the same as the above-mentioned working principle.

Applications of solid state switch

The most common application of a solid state switch is load switching for AC loads. Many household appliances have solid state switches for AC load switching. Solid state switches have different applications in power control. In addition, different solid state switches are used for heater control, such as ovens (e.g., baking ovens), robots, machinery tools, and molding machines.