Robust electronic relays boosting connections for industrial and railway applications

The market for robust relay modules is growing rapidly on the back of rising demand from heavy duty industrial and infrastructural applications. Relays come in a variety of styles and technologies and it is important to match the one that best suits their designated application. According to a white paper from National Instruments, the UK technology solutions provider, the most common types of relays used in automated test equipment (ATE), are: Electromechanical Relays (EMRs); Reed Relays; Solid State Relays (SSRs); and FET Switches.

EMRs are made of a coil, an armature mechanism and large electrical contacts. And they are typically the most robust and widely used relays in ATE applications today. A recent industry report forecasts a CAGR of 4.10% in the EMR market, to $8.537 billion by 2023. This is an increase from the $6.708 billion that the market was worth in 2017. However, despite their popularity a major drawback is that they are relatively slow devices. They also have a typically shorter mechanical lifetime than other types.

Reed relays meanwhile, with their smaller, less massive contacts, can switch about 10 times faster than an electromechanical relay with equivalent ratings. However, they are susceptible to contact damage. SSRs are a faster alternative to electromechanical relays and are useful for high-voltage applications. SSR growth is particularly strong in Asia Pacific Excluding Japan (APEJ), with Western Europe the second largest market by geographical region.

But like reed relays SSRs are not as robust as electromechanical relays. They are also highly susceptible to surge currents when used at signal levels above their rating. FET switches, meanwhile, are the fastest of the five switches. They have no mechanical parts or LEDs and can be very small. They do though have one major drawback. They lack a physical isolation barrier and therefore may only be used with low-voltage signals.

A number of companies such as Menlo Microsystems, WAGO Contact Technology GmbH & Co. KG; Weidmuller; Kissling Elektrotechnik; and E-T-A Elektrotechnische Apparate GmbH recently unveiled new products to support the strengthening relay market. Menlo Microsystems, launched in 2016 as a spin-out from General Electric, showcased its innovative Digital-Micro-Switch (DMS) platform. It claims that it is “a reinvention” of the electromechanical relay. The platform operates up to 1000 times faster than a typical mechanical switch with 1000 times the lifetime. It can also handle hundreds of watts of power.

In May, WAGO announced the arrival of a new easy to plug-in relay module from its 2042 series. Because it is built to “withstand high vibration and shock loads” it is suited for industrial and railway applications. An added feature is that the relays are plugged directly on to the base terminals of the Topjob S terminal block system, thereby saving the user an extra level of wiring.

Fellow German company Weidmueller is targeting demanding industrial applications with its long service life D-series SSR industrial relay modules. The modules come with a wealth of accessories that improve flexibility in use. Convenient operation is ensured by an optional LED status display and optional test button.

Kissling Elektrotechnik has put on the market a new multi-function signal switch. With up to seven different functions, bi-colour lighting as well as other design features there are plenty of options for customisation. As with the company’s other relays, the multi-function switch features advanced stable insulating materials that are suitable for operating in extreme environmental conditions. It also has robust contacts for a long contact lifecycle.

The Nuremberg based E-T-A Elektrotechnische recently added its EPR10 electronic SSR to the company’s existing suite of products. The device is designed for applications where standard solid state and mechanical relays are not ideal. It is on the market specifically for special vehicles, such as those used in agriculture, and construction machinery. Design features include a compact size, which is 80% smaller than conventional solid state relays and sealed circuitry to protect the device from dust and humidity. The relay is also cost effective as it eliminates the need for heat sinks used in solid state relays. The protected version also eliminates the need for blade fuses.

Sensata Crydom Inc. has introduced its CX Series SIP SSR. It is suited for high density PCB applications where a maximum of 5A of current is required. The AC or DC relay has a high surge current rating and is available with a zero voltage or instantaneous turn-on output. Other relay offerings are available from ABB Ltd., International Rectifier, Infineon Technologies AG, Carlo Gavazzi Holding AG, Vishay Intertechnology (Siliconix), Fairchild Semiconductor, STMicroelectronics, Texas Instruments Incorporated, Rockwell Automation, Inc., Linear Technology & others.

As society becomes increasingly electrified, the market for electronic relays will rise in lockstep. The pressure is on though for the suppliers to drive down their unit prices, even as they strive to make their relays ever more robust and durable.

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