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8 Solid State Relay Applications And Uses

Solid state relay for air conditioner
Solid state relay for air conditioner

SSR relays are used in many electrical and electronic circuits, given its superior performance in most situations. Here are some of the most common solid state relay applications as well as reasons for use:

What is a Solid State Relay Used For?

Solid state relays are electronic switches that utilize semiconductor components to provide switching between two points, without the use of any moving parts. This design results in a switch that is much more durable, can operate at faster speeds, and requires less power than a standard mechanical relay.

A solid state relay is, therefore, used to control circuits with AC or DC signals, by switching the load current on or off. The load can be anything from a low-power light bulb to a high-power electric heater. In essence, the application of solid state relay modules allows small inputs to control much larger output signals.

Wiring a solid state relay for installation
Wiring a solid state relay for installation

Solid State Relay Applications

Solid state relay uses are many and varied, ranging from home automation to industrial motor control. Here are some of the most common applications. Note that the list is almost endless, and we only picked the most popular uses of the device today.

1. Solid State Relays for Motor Control

One of the most common solid state relay applications is motor control. You can use SSR to control both AC and DC motors, from the small motors in home appliances to large industrial motors.

The main advantage of using SSRs to control motors is the lack of moving contacts, which means no arcing or sparking. This results in less wear and tear, as well as a longer lifespan for the motor.

Solid state relays for motor control can also be designed to switch the load when the AC power supply is at its peak, thereby preventing damage to the motor by inrush current.

2. Solid State Relay for Lighting Control

Solid state relay applications also include switching loads such as light bulbs and LED arrays. In these applications, these relays offer the advantage of fast switching speed, which can be important for certain lighting effects.

Another advantage of using SSR for lighting control is the lack of moving contacts. This means that there is no risk of arcing or sparks, which could be a fire hazard. Additionally, there is no contact bounce, which can result in flickering lights.

Because SS relays can work with low-voltage DC control signals and logic circuits, they are often used in conjunction with microcontrollers to create complex lighting effects. Such situations include stage lights systems, traffic lights, and other similar systems where precise timing is important.

3. Solid State Relay Heater Control

Solid state relays are widely used in the heating (and cooling) systems of air conditioners, electric ovens, and industrial heaters or furnaces. Other devices may also be used. However, SSRs offer the advantage of being able to handle fairly high voltages while still being compact in size.

SSR devices also allow these systems to be highly automated, such as when using a solid state relay thermostat. That’s because the relays use semiconductors and can be controlled by microprocessors or other electronic devices.

Because SSRs do not generate sparks or arcs, they are a safer option than their electro-mechanical counterparts. Additionally, they can be designed to switch the load only when the AC power supply is at its peak, further protecting the load from damage.

4. Solid State Relays in Medical Devices

Medical devices, due to their critical nature, require specialized control systems to switch their power supplies on and off. A controller with solid state relay switcher fits the bill perfectly, and will be highly reliable and use very low input signals.

Another reason for solid state relay use in medical devices is their quiet operation. With no moving parts, these relays do not produce noise, which is important in medical rooms.

SSR relays can also be designed to provide zero crossing switching. That means low electrical noise, which essential when the relays have to work in the proximity of computers and other sensitive medical equipment.

5. Automotive Solid State Relays

In the automotive world, SSR relays are important switching devices. They are quickly replacing older, mechanical relays in engine management systems, headlight dimming circuits, and fog light control applications.

Automotive solid state relays allow for more precise control of loads, as well as greater levels of automation in vehicle systems. Other solid state relay applications in the automotive industry include daytime running lights, power windows, and power seats.

In electric vehicles, SSRs are being used to ensure explosion proof switching since they do not arc or spark, among other benefits such as low operating noise, low power consumption, and long life.

6. Solid Sate Relays for Water Pump

Water pumps contain an electric motor that needs to be switched on and off as needed and other systems. You can use an AC solid state relay to do that.

One of the benefits the SSR would offer the advantage of being able to switch the load only when the AC power supply is at its peak. This further protects the load from damage.

Other advantages of using a solid state relay for water pump control include the lack of moving contacts, which means no arcing or sparks, and no contact bounce

7. Solid State Relays for CNC

CNC stands for computer numerical control and refers to the process where computers are used to automate machine tools. This technology is used in a variety of industries, such as woodworking, metalworking, and plastics processing.

Solid state relays are often used in CNC automation systems for a variety of reasons. First, they can switch loads on and off quickly and precisely. Second, they can be controlled by low-voltage machine tools.

In these applications, high sensitivity and switching speed are of the utmost importance too, and solid state relays are used to deliver these features. Other benefits of using SSRs for CNC applications include reliability and long lifespan.

8. Solid State Relays for Communication

Communication systems require fast and reliable switching of high currents and voltages. That’s why solid state relays are often used in these applications, owing to its better features and capabilities.

Unlike solid state relay alternatives such as EMRs, you would not need to worry sparks or arcs. This makes the SSR a safer option for communication systems. And that’s in addition to allowing for more precise control.


As you can see, the list of solid state relay applications is quite long. They fit most switching requirements and can be used in almost every electrical system. When picking or selecting an SSR or SSR for your specific needs, be sure to consider both the pros and cons of using it over conventional mechanical types. That’s because, depending on the application, one type may be better than another.

Picture of William

I am William, Electrical Engineering Author. Dedicated to writing technical articles on Timer Relay, Monitoring Relay, Surge Protection Device and other electrical devices. With 7 years of writing experience, I am committed to providing accurate and in-depth expertise to my readers.


    Please could you advise if I can use ssr’s to built a dc motor inversor control? ( a autopilot build to control two solenoids but instead it have to control a reversible dc motor )
    Thank you in advance
    Have a nice New Year 2023
    Kind regards
    Afonso Indias Zagalo

      We have received your message and our product specialist will contact you as soon as possible. Thank you for contacting GEYA.Have a good day😀

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