HUIMULTD E-blog: Solid State Relays Introduction - 7.What is the Application of The Solid-State Relays

§7. What is the Application of the Solid State Relays

Through this chapter you will learn where to use solid state relays and what is solid state relay used for.

Lighting Control System:

The fast switching, long life and high reliability of solid-state relays make themselves excellent in the light control system. In the field of traffic lights, the working environment of traffic lights is complicated, but solid-state relays with excellent characteristics (moisture proof, explosion-proof, anti-corrosion) can face it. And the solid-state relays can meet the requirements for sign/signal flashing traffic lights which are frequently closed and open, because they can maintain switching intervals of 10 milliseconds or longer. And in stage lighting control systems (usually applied to the production of theatre, dance, opera and other performance arts), solid state relays can work with the computer system to control multiple lights, and implement complex lighting effects to increase the atmosphere of the stage.

Remote Control System:

Remote control systems typically require small current signals to control high power equipment, such as electric motors, pulse valves, and other machinery. As an electronic switching element without mechanical contacts, solid state relays are widely used in remote control systems with excellent advantages: flexible control, high reliability, high durability, no spark, no noise, fast switching, high operating frequency, strong anti-interference ability, etc.

Computer Numerical Control Machinery:

Many traditional mechanical relays in Computer Numerical Control machinery (CNC machine) are gradually being replaced by the solid-state relays. On account of the excellent durability and high sensitivity abilities, the solid state relays are applied to ensure the high precision and high quality of CNC machining. In the servo system of CNC machine, the solid state relay can receive the control signal continuously, and control the processing machine accurately.

Heating/Cooling Equipment:

Normally, there are three ways to control the heating /cooling equipment: solid state relay (SSR), thyristor module (SCR module), and AC contactor. Currently, solid state relays and SCR modules are very common in cooling/heating equipment, but in contrast, SCR modules are not cost effective, so solid state relays are most common in heating/cooling equipment, such as electric ovens, coffee machines, vending machines, griddles, Fryers, air-conditioner, refrigerator and etc. The solid-state relays also perform well in temperature control equipment. The timer control SSR, the microcontroller control SSR and PID control SSR (proportional–integral–derivative controller) are used in the temperature control device to maintain temperature stability of the device, like HVAC (Heating, Ventilation, and Air Conditioning).

Medical Devices:

In the field of medical equipment, the equipment has strict requirements of operating frequency and precise operations, so the components of medical equipment should have nice performance (high precision, durability, etc.). Solid state relays can meet these demands of most medical devices, for example, the infrared radiation devices have a huge thermal inertia, but by connecting the solid-state relays to the radiation plate, it becomes very easy to control the temperature of the infrared radiation device through the solid state relays.

Electric Vehicles:

Solid state relays are widely applied in the field of electric vehicles. For example, the explosion-proof solid-state relays are used in the fuel-cell vehicles (hydrogen fuel cells) to avoid electric arcs and incorrect operation during vibration. As well as, each high-voltage power unit is protected by the combination of multiple solid-state relays, fuses and filter capacitors.

Chemical and Mining Industry:

Considering the complex working conditions and special requirements (the explosion-proof, moisture-proof and anti-corrosion abilities) of the chemical and mining industry, the traditional mechanical relays cannot meet such requirements, therefore lots of solid-state relays are used to the intermediate controllers of the major mechanical equipment, such as the solid state relays equipped in large coal mining elevators.

Computer Control System:

The computer control system (including the computer peripheral devices) have high requirements of relays, but types various of solid-state relays can help the computer devices control assorted power units to drive the large mechanical automation equipment, or hydraulic and pneumatic equipment, because solid state relays have the characteristics: zeroing-crossing, nice electromagnetic compatibility, high sensitivity, fast switching speed, low level control signals, compatible with logic circuit (TTL, CMOS, DTL, HTL) and even can be directly connected to the micro-computer control device, and so on.