The Advantages of Solid-State Relays

From industrial machinery to sophisticated scientific equipment, relays are found in almost every electronic device. Thanks to their versatility, they are used in many applications.

Usually, each type differs based on how it switches electrical currents on and off. Most are electromechanical relays, which operate by physically opening and closing contacts, thereby establishing or disabling a connection.

While all relays switch the electrical current in a circuit on or off, solid-state relays (SSRs) are unique in that they feature no moving parts, allowing for seamless switching that’s faster and more precise than any other type of relay.

How do Solid-State Relays Work?

Solid-state relays are a switching device that remotely controls the flow of electricity in a circuit, turning it on or off as needed. This is a versatile and essential function for any electronic device.

Unlike traditional electromechanical relays, solid-state relays switch currents on and off without any moving parts. Instead of contacts opening and closing due to electromagnetic force, SSRs use semiconductors – more specifically, photoconductors – that remotely switch on and off in response to electronic signals.

An SSR’s photoconductors isolate input and output signals sent to the relay. By isolating the signals, the photoconductor can turn the current of electricity in a circuit on or off, depending on how the relay’s switching element is set.

Due to their unique switching method, solid-state relays offer numerous advantages over conventional relays.

Among the most important is how they work: using no physical contacts or moving parts.

Why does this matter? Without moving parts, there’s no contact corrosion or wear over time. The result: solid-state relays can perform millions of switches with absolutely no decrease in performance.

5 More Advantages of Solid-State Relays

A near-infinite service life isn’t the only benefit that solid-state relays exert over their electromechanical counterparts. Solid-state relays’ unique design features exclusively use electronic components, which eliminate many of the limitations associated with other types of relays by comparison.

1. Low Power Consumption

No moving parts also means that solid-state relays require very little power to switch, even when handling substantial power loads. Since SSRs don’t need to physically open and close contacts to switch, they consume roughly 75% less energy than electromechanical relays.

2. Compact Size

Solid-state relays’ reliance on semiconductors and other electronic components for switching also means they come in a smaller size. This compact form factor makes them even more versatile than electromechanical relays because they require less space to operate.

3. Silent Operation

Since solid-state relays switch through an electronic process, they operate completely silently. Conversely, relays that operate by physically opening and closing contacts make an audible sound when switching. 

4. Shock and Vibration Resistant

Solid-state relays are entirely enclosed in a durable casing that protects their internal components from damage and wear, making them ideal for harsh environments. Additionally, this design protects them from switching accidentally. Sometimes, vibrations and other factors can cause electromechanical relays to switch unintentionally; however, solid-state relays never switch unless they’re supposed to.

5. High Switching Frequency

Solid-state relays’ semiconductor-based switching method allows power to be applied to or removed from a load much faster than traditional relays. SSRs owe this quick switching property to their lack of moving parts; with photoconductors, switching can happen instantaneously.

Types of Solid State Relays

Solid-state relays are themselves one of many types of relays, but there are also various subtypes of solid-state relays. Each type typically differs in the size of electrical power load it can handle, with single-phase being the lowest and three-phase being the highest. 

The most common types of solid-state relays include:

• Single-Phase Solid-State Relays
• Two-Phase Solid-State Relays
• Three-Phase Solid-State Relays
• Push-in Solid-State Relays

Single-, Two-, & Three-Phase Solid-State Relays

Single-phase, two-phase, and three-phase solid-state relays differ in their capacity to withstand power loads, with three-phase relays being the most powerful. While each has its ideal applications based on the power demands, three-phase SSRs are the most common and relied upon in large-scale industrial applications and commercial buildings.

Why?

Because three-phase SSRs provide a more constant and reliable power delivery, capable of handling large power loads that other relays cannot. They also handle smaller power loads with greater efficiency.

Push-In Solid State Relays

Push-in solid-state relays are another type, available in single-, two-, and three-phase varieties. Most relays are installed to electrical wiring via screws; while offering a durable connection, this can be time-consuming, and makes it cumbersome to remove or change the arrangement of relays. 

Push-in relays offer a flexible solution that’s easier to install, featuring a locking mechanism that securely connects wiring while allowing it to be unlocked with the push of a button. 

Further Reading: Learn more about the available types of solid-state relays and their characteristics by referring to this data sheet. 

Industries & Applications that use Solid-State Relays

Thanks to their durability, extreme longevity, and their ability to perform switches faster than electromechanical relays, solid-state relays are used in a wide variety of applications.

SSRs perform a diverse range of essential functions that industries worldwide rely on, including:

• Manufacturing: Solid-state relays control motors, temperature control systems, furnaces, and a wide range of other automated industrial equipment.
• HVAC: HVAC equipment and appliances rely on solid-state relays for precise temperature control and load switching to operate the motors that power fans, heaters, and other devices. 
• Medical: Medical equipment requires precise motor control, necessitating the use of SSRs on hospital beds, exam tables, and other devices. They’re also helpful for accurate patient monitoring and temperature control for sterilization and incubators.
• Automotive:  Solid-state relays are rapidly replacing traditional electromechanical relays in the automotive industry, particularly in hybrid and electric vehicles. There, SSRs control the flow of power in battery management systems (BMS), lighting, and other automated systems, such as door locks.

Dynamic Electronics: Exclusive Factory Direct Industrial Products

Solid-state relays are a vital component of industrial operations worldwide, and Dynamic Electronics offers the products and resources to consistently provide top-quality custom solutions, procuring the best products for any application.

Whether you need solid-state relays with one, two, or three phases, featuring push-in or screw terminals, we guarantee products that meet the specifications to cater to any manufacturing need. Contact Dynamic Electronics Inc. to learn more; we are the exclusive sales agent for Celduc SSR relays.