Publication date: 23 March 2010
Electromechanical switch and relay demand is recovering as the wider electronics industry recovers, but there is no doubt that customer needs have changed. In medical, remote energy monitoring, security and to an extent HVAC and white goods, the requirement tends to be for a solution that offers a very specific performance within a tight size and cost envelope. A standard catalogue of quality parts is no longer enough to secure the sale. The 2010 relay customer is looking for products adapted to his specific niche or application, then further customised to suit his needs.
A great many industrial applications use relays of a standard footprint, but welcome space savings in terms of the height of the component. Relay manufacturers have made huge strides in this direction, producing 8A, 250VAC relays for boiler controls with heights of just 12.3mm, such as Omron’s (Fig 1) G6RL-1(A) relay – some 20% lower than the previous generation. Customers are also looking for specialist product variations that address the design challenges in specific markets. These might include versions with higher switching performance, higher reliability to meet P1 load conditions, higher shock resistance or fully sealed type. Cookers and similar control applications will demand higher temperature variants (Fig 2). More recently, manufacturers have begun adopting physically smaller devices with a smaller footprint also offering a combination of high current capacity, long lifetime and low cost.
Renewable energy is spawning growing interest in DC power relays, previously a relatively small market. Relay vendors such as Omron have responded with designs featuring gas-filled construction, which provides an arc cooling effect, and allows space savings by reducing the need for arc space. Omron’s solutions feature a patented design of the contact switching component together with the use of a permanent magnet to stifle the arc, and can eliminate the need for polarity in the main circuit. Relays weighing just 135g, and with dimensions of just 25 x 60 x 58mm can now interrupt up to 25A at 400VDC – this is about half the volume and a third of the mass of similar, earlier relays.
Manufacturers of boilers and controls require relays to meet numerous criteria, including compliance with relevant IEC standards for performance and safety, as well as high dielectric strength, high switching capacity, and high endurance with inductive and resistive loads.
One of the most challenging aspects of relay performance for the boiler-controls market is durability. European regulations for boilers stipulate a minimum lifetime of 250,000 electrical cycles at normal load, according to the standard EN298-2003 for gas-fired boilers. Although the EN298 standard applies to boilers, and not to individual components, the boiler’s ability to meet the standard is closely linked to the performance of the relays used. Relay manufacturers work with their customers to ensure the standard can be met. In practice a target well above 250,000 cycles is usually set, and some boiler producers are requesting lifetimes as high as one million cycles.
To deliver a cost-effective solution to these demands, relay designers are using a number of techniques such as optimisation of the relay mechanism, and high-performance, RoHS-compliant material technologies delivering increased hardness and conductivity to prevent welding of internal electrical contacts.
Most of the above issues apply equally to switches, but here customers have even higher needs for customisation, as switches are normally integral to the user interface and the enclosure of a system. In addition to meeting the core performance, size and cost requirements, switch manufacturers now need to offer a high degree of customisation, as well as cable harnessing and other capabilities. Modifications might range from the development of an alternative lever, to redesign of the case, terminals or wiring harness where the customer and the volume permit. For high volume opportunities, switch manufacturers such as Omron will even develop custom solutions in Europe.
This final customisation normally needs to be handled in Europe, locally to the customer, to speed the dialogue between the design teams at the supplier and the customer end, and to ensure prompt turn-around of sample requirements. The ideal combination is engineering resource located in Europe but drawn from the vendor’s manufacturing location to ensure appropriate expertise, associated with local assembly to ensure that products are assembled to the relevant European standards.
Manufacturers are continuing to evolve their switch portfolios, adding new variations and versions to address specific market needs and opportunities. Omron, for example has recently added a new compact, sealed detection switch (Fig 3), featuring a self-cleaning slide contact, a new waterproof tactile switch and an extended range of ultra-miniature DIP switches (Fig 4).
The relay and switch supply chain is currently operating at maximum efficiency. Buffer stocks are low throughout, so that new demand from the end customer immediately creates opportunities right down the supply chain. Relay and switch vendors need to deliver components that are adapted to the needs of specific markets, and support them with customisation options and services to address customers needs exactly.
