Why Are Solid-State Relays Preferred in Certain Industrial Applications?

In many systems, relays are responsible for controlling power and safeguarding equipment by allowing circuits to be switched and isolated as needed. Among the various relay variants available on the market, solid-state relays (SSRs) have become an increasingly popular choice, as their design addresses certain challenges that other options face in automation, manufacturing, and other demanding applications. In this blog, we will discuss everything you need to know about how SSRs operate and why they are often the preferred option in industrial settings.

What Is a Solid-State Relay?

SSRs are a type of electronic switching device that is designed to perform the same role as relays with controlling power flow to a load, though they do so without relying on moving parts. Instead, they employ semiconductor components like thyristors, triacs, or MOSFETs to manage current.

In a standard SSR, a control signal is transferred to the switching element through a light-based link, typically created by a small LED inside the device. This optical coupling keeps the low-voltage control side safely isolated from the high-power output side while still allowing the input to activate the switch. When the input signal is applied, the semiconductor path conducts and current flows to the load. Once the signal is removed, the path is blocked.

The Benefits of Solid-State Relays

SSRs display a variety of characteristics that make them well-suited for many demanding environments, including:

Reliability and Longevity: No mechanical contacts means that SSRs are safe from wear or failure that results from mechanical fatigue. Generally speaking, SSRs can handle millions of cycles without degradation.
Vibration and Shock Resistance: With no moving parts, SSRs are able to hold up well to damage from vibration and shock.
Faster Operation: Switching in an SSR occurs anywhere from microseconds to milliseconds.
Noise-Free Switching: SSRs switch silently, eliminating the audible click common with mechanical relays.
Electrical Isolation: SSRs transfer signals with light instead of a direct electrical path, preventing high voltages or fault currents on the load side from reaching sensitive electronics.
Lower Electromagnetic Interference (EMI): Because SSRs switch electronically rather than through physical contacts, they produce less EMI to help protect nearby sensitive equipment and maintain signal integrity.

Drawbacks and Considerations

While solid-state relays offer many advantages, there are also some factors that must be considered when selecting them for industrial use. For example, the main drawback of these devices is that they generally have a higher on-state voltage drop compared to mechanical relays, which results in additional heat generation during operation. For high-current applications, this requires the use of heat sinks or derating to ensure safe and reliable performance.

In addition, SSRs usually carry a higher upfront cost than electromechanical relays. However, their long service life and minimal maintenance requirements can essentially offset these costs over time.

Where SSRs Are Preferred

High-Cycle or Continuous-Duty Applications: Due to their lack of moving parts that wear down, SSRs excel in systems that switch frequently or run continuously, such as conveyor lines.
Precision and High-Speed Switching Tasks: In automation processes that require tight timing and repeatability, SSRs provide exceptionally swift response times.
Harsh or Mobile Environments: Resilience against vibration, impact, or temperature extremes means SSRs can serve vehicles, mobile machinery, or outdoor enclosures.
High-Frequency or Snubber-Sensitive Circuits: For circuits where EMI must be minimized, such as sensitive instrumentation, data communication systems, or medical equipment, SSRs offer cleaner switching.
Safety-Critical or Isolated Control Systems: With built-in optical isolation features, SSRs protect low-voltage control circuits from high-voltage load side faults. This galvanic separation makes handling safer for operators and shields equipment like PLCs and microcontrollers from electrical damage.

Explore an Expansive Selection of SSRs on Industrials 360

In all, solid-state relays present multiple benefits in challenging environments, enabling far smoother operation and reduced maintenance demands. Whether an SSR or another type of relay ends up being the best switching solution for your system, securing quality options is vital. Industrials 360 stands out as a one-stop shop for relays and various other parts, everything on this website being strictly sourced from reputable manufacturers.

As a platform owned and operated by ASAP Semiconductor, those who shop with us can expect to benefit from more than top-notch products, as our team regularly leverages competitive pricing and swift shipment options to best benefit customers. Combined with convenient search tools and easy ways to request quotes for desired items, the process from perusing to final delivery is near-effortless. To see how we can match you with procurement options tailored to your distinct needs, get in touch with our team at your convenience.