When most people think of relays, they imagine clunky, old, commodity-like products that have been around for more than 100 years. While it is true that relays have been around for many years, despite their predicted demise, the production and design of reliable relays requires an organization that is dedicated and skillful in design with a commitment to quality. Today’s relays must meet various standards; yet still cost less than they did five years ago. This creates a delicate balancing act for producers and users of relays.

Companies must not only meet the existing international safety standards, but also they must deal with emerging environmental standards such as the RoHS directive. This directive, which becomes effective July 1, 2006, basically outlaws the use of metals such as lead, Hexavalent chromium, mercury, cadmium, and plastics such as PBB and PBDE. Elimination of these materials, particularly lead and cadmium (used as a component in solder and as an arc quencher), make the job of a relay designer even more difficult.

On top of all that, companies must also meet the demands of the market. One of the biggest issues facing relay designers today is the need to reduce the size of the relay. In the past, a panel would be large enough to have literally hundreds of large relays clicking on and off to provide logic. Now, with the logic largely being performed by PLC (or even PC-based) control systems, the role of a relay has shifted to more of an interface between these control systems and the application.

As the price of “real estate” inside a panel becomes greater and greater, designers are forced to look for relays that are small enough to fit into the reduced panel space available. This requirement has lead to the rise of a new class of relays; known as interface relays, which are offered (in conjunction with a terminal block) in sizes as small as 6 mm in width, yet still boast contact ratings up to 6 A.

For example, new relays such as the RJ and RQ Series comply with all existing international safety standards. They also comply with the RoHS standard for “environmental friendliness,” while still boasting a compact width.

The RJ series, like the previously announced RU series ice cube relay, uses a spot welding process to eliminate the need for lead, and also eliminate the need for internal connecting wires. The small size saves valuable panel space, yet still has contact ratings up to 12 A in the single pole version, and 8 A in the double pole version. Finally, an optional non-polarized green LED light can provide a strong visualization that the relay is functioning properly.

Meanwhile, the RQ series complies with RoHS environmental standards, as well as all international safety standards, and can be mounted directly to a PC board or mounted in a socket for DIN-rail applications. These relays boast contact ratings up to 16 A yet, they take up less than 0.25 in. in space by volume.

Finally, we should not forget the role of sockets in the world of relays. Sockets are an integral piece of the puzzle and can come with a variety of terminations and mounting styles. Let’s face it, you may chose the best relay in terms of reliability and contact ratings, but if you skimp on the socket, then all of your best laid plans will have gone for naught. In today’s world, relay sockets are available to mount on a DIN-rail or mount directly to a PC board, but the choices do not end there. Termination styles now include solder connections, screw terminals, and even spring clamps.

In addition, innovative manufacturers have developed relay socket accessories such as jumpering (to reduce repetitive wiring), marking plates for circuit identification, and even sockets that accept plug-in accessories such as lights and surge suppression modules.

So while the concept of an electromechanical relay may be old, today’s relay manufactures have to be aware of existing material and safety regulations, and the needs of industry. In addition, the continued downward price pressure on commodity-like relay products forces manufacturers to further reduce costs by automating production lines, or moving production to countries with lower manufacturing costs. All the while, still maintaining the same high reliability of their previous products. It is truly a balancing act.

Lanny Schuberg holds a bachelor’s of science degree in electrical engineering and an MBA in international business. He has worked for IDEC Corp. for the past 15 years and is presently in charge of the engineering department. IDEC Corp., 1175 Elko Dr.,Sunnyvale, CA 94089, can be reached at 800-262-4332. More information is available at www.idec.com.