Smarter Food Heating Starts with Solid State Relays

(Source: Shubby Studio/stock.adobe.com; generated with AI)

As anyone who has attempted to bake a lemon meringue pie would attest, getting the exact ingredients, mixture, timing, humidity, and temperature are key. All of these elements must be perfect to achieve success. Now, scale this to hundreds or even thousands of pies with repeatable and consistent results.

This is the challenge with food preparation, especially when it comes to heating food and beverages, as errors in heating can rapidly spoil entire batches. Precisely controlling commercial food heating requires reliable switching solutions to selectively activate the heating elements in these industrial machines. Modern food and beverage applications have even more stringent requirements for quality and consistency—often across many different facilities—than ever before.

This blog discusses how the latest high-endurance solid state relays (SSRs) offer an ideal solution for food and beverage heating applications, compared to mechanical relays. Additionally, this blog will explore implementation of these new SSRs.

Solid State Relays vs. Mechanical Relays

Many industrial heating applications are still being controlled with electromechanical switches and relays. Although these legacy mechanical designs were historically the most viable solution for food and beverage heating in the past, modern solid state solutions offer several advantages over mechanical switches and relays, even at comparable power levels.

SSRs operate using integrated circuit-based relays in compact packages that are energy-efficient, silent, fast, and extremely reliable. Legacy mechanical relays use electromagnet solenoids to depress springs, which force mechanical and electrical contact between conductive contactor elements. This process generates substantial noise, requires significant amounts of power compared to SSRs, may create sparks and fire concerns for some applications, and can readily be degraded by debris, corrosion, or humidity ingress that is common to food and beverage processing applications. SSRs, however, do not have these challenges. Therefore, they are ideal choices for demanding food and beverage heating applications, such as espresso machines, warming trays, ovens, stills, and other similar devices.

Meet the SRP1 High-Endurance Series

Even amongst SSRs, not all solid state relays are created equal. For food and beverage heating applications, the switching is often constant in facilities that run 24 hours a day. Food and beverage facilities and equipment put SSRs in an extremely demanding environment, and to avoid downtime and excessive maintenance, the most reliable ones are needed. SRP1 high-endurance SSRs meet the demands of these heating applications by ensuring superior uptime in high-frequency operations. This multipurpose family of SSRs from Littelfuse offers enhanced reliability, with endurance life cycles two to three times higher than those of other relay options in demanding conditions (Figure 1).

These SSRs are purpose-built to function consistently in operations with high-to-continuous uptime. The SRP1 high-endurance models feature a wide voltage range with zero-cross and instantaneous switching, enabling compatibility with a vast selection of single-phase and high-power, three-phase applications ranging from industrial to commercial use. These high-endurance SSRs use Littelfuse’s proprietary IXYS technology and offer advanced thermal bonding techniques to reduce component heat-rise under load when properly installed with heat-sink.

Figure 1: Littelfuse’s SRP1 high-endurance SSRs deliver enhanced reliability, boasting life cycles two to three times higher than those of other relay options in demanding conditions.. (Source: Littelfuse)

In addition to their RoHS/REACH compliance, the SRP1 high-endurance SSRs comply with cЯUus and CE international standards for product safety and quality. The SRP1-CB models are designed for basic SSR requirements, such as quick connectors. The SRP1-CR models are equipped with touch-safe IP20 plastic covers over the terminals and overvoltage protection to handle electrical spikes common in industrial and commercial applications with large inductive loads, such as electric motors and compressors. The SRP1-CBF comes with quick-connect terminals specifically designed for food and beverage applications.

The SSR Advantage

One of the main switching applications in the food and beverage industry involves switching high-power heating elements, such as cooking ovens, hot drink dispensers, coffee machines, fryers, and toasters. The heating elements in these applications are switched frequently throughout the machine's operation, with more refined temperature control requiring higher frequency switching.

Maintaining this precision in electrically noisy, high-vibration, and humid environments is extremely challenging, which is why completely sealed SSRs with no moving parts and rugged internal electronics are the best choice for these applications. Moreover, many of these machines also feature motion control, pumps, or valves that require electrical switching for the motor actuators, for which high-endurance SSRs are also well suited.

Up to the Challenge of Demanding Environments

High reliability and long-life switching capability are extremely critical requirements for commercial kitchens and cafés. These food and beverage applications often run on extremely tight time scales, with machines working from very early in the morning and late into the night, if not 24 hours a day. Additionally, any downtime with the machines in these applications results in direct production losses, and as most of these businesses operate on very narrow margins, this can be a substantial hit to revenue, with raw foodstuff material often having a limited shelf life.

Another demand of these applications is durability, since their operations are usually very rough on the machines, with little to no time for cool-downs and repeated cycling. High mechanical and electrical resilience are essential for these applications, which is why SSRs are preferred over electromechanical relays that suffer from contact bounce and arc and can rapidly degrade in elevated temperatures and high-vibration, shock environments.

Easy to Integrate and Safe to Operate

High-endurance SSRs are also an excellent choice due to their compact design and ease of installation. The electrical contacts are made with simple and reliable screw terminals, and only two mounting screws are needed, allowing for direct mounting to heat sinks or control boards for original equipment manufacturers (OEMs) that build high-quality, long-lasting machines. Touch-safe versions of these SSRs are available for applications where technicians and operators may benefit from the safety of additional electrical isolation.

Conclusion

When it comes to heating control of industrial and commercial food and beverage equipment, the benefits are clear for choosing high-endurance SSRs over less rugged SSRs or legacy electromechanical relays.

SSRs ability to deliver precise, high-frequency switching in harsh, fast-paced environments makes them the ideal choice. For applications that demand consistent reliability, minimal maintenance, and long operational life, high-endurance SSRs like the Littelfuse SRP1 high-endurance series offer the performance and durability needed to keep operations running smoothly.

Jean-Jacques (JJ) DeLisle attended the Rochester Institute of Technology, where he graduated with a BS and MS degree in Electrical Engineering. Before completing his degree, JJ contracted as an IC layout and automated test design engineer for Synaptics Inc. Further pursuing his career, JJ moved to New York City, where he took on work as the Technical Engineering Editor for Microwaves & RF magazine. In the next phase of JJ’s career, he moved on to start his company, RFEMX, seeing a significant need in the industry for technically competent writers and objective industry experts. Progressing with that aim, JJ expanded his company’s scope and vision and started Information Exchange Services (IXS).