FEATURE SWITCHES & RELAYS THE BIG SWITCH ELECTROMECHANICAL STILL BETTER THAN TOUCH


New technology has yet to replace the trusted reliability of traditional electromechanical switches says Mark Mills, distribution sales manager at ZF Switches & Sensors. Here’s more on why?


lectromechanical switches are still the poplar choice probably because of their tried and tested nature especially in industrial applications where safety and reliability are crucial factors, such as when dealing with machinery or factory equipment. But chances are they could well be equalised by the demand for more modern forms such as touch screens, as we as users come to prefer and so expect this functionality in modern devices. But both style of switch still very much has its place. A well designed system that takes into account both form and style can be the key to the next winning electronic device and it’s things like switches, screens and key pads that can give it it’s competitive edge. This is probably more so with


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consumer devices but again it comes down to user interface and how we interact with devices both personally and also in the work place. But consumers and designers of electronic devices and systems are alike in their desire to have access to the latest technologies.


So much so is the trend for ergonomic design that the HMI (human machine interface) is now recognised as a highly specialised arena with an intimately scrutinised relationship between user and device. Previously just a purely functional aspect, the control interface of a device is now a testament to good design and even brand recognition. One thing users have now come to expect when interfacing with a device is a touch screen or tablet type of device. They dominate home automation,m tion, portable electronic products, industrialtrial control and automotive electronics. Such design aspects are often the


mark of quality of a total solution, determined by the sum of its components. A fault in a component, which only costs a few pence can jeopardize everything. Perfection down to the smallest detail is therefore the basis of good device design and is something ZF switches & sensors pay close attention to as a supplier of mechatronic components.


ay 28 SEPTEMBER 2017 | ELECTRONICS Safety – a prime concern for any system


designer. Microswitches can be specified with EN60335-1, a standard for the safety of electrical appliances for household and similar purposes. Battery-operated appliances and other DC powered devices are also within the scope of this standard. Equipment not intended for normal household use but which nevertheless may be a source of danger to the public including appliances intended to be used by people in shops, light industry and on farms, are also within the scope of this standard. Examples of these products include catering equipment, cleaning appliances for commercial use and appliances for hairdressers. Ease of mounting – microswitches may


Figure 1: Microswitches


“Snap action


But modern switch interfaces are not a universal solution for industrial, machine control, security and safety applications. Despite years of rumours that snap action microswitches would be replaced by cutting-edge technologies, sales of these long-established electromechanical products contiproducts continues to boom. Why should this be so in the current age of connected electronic control?


should thi age of


contr microswitches will


continue to be a viable design option. Their low cost, wide availability, service life and flexibility make them indispensable ...”


Industrial applications, appliances, white goods, power tools and


po


industrial linear drive markets have specific requirements which cannot be met by electronic switching


re ca elec systems. The main reasons syste include: inclu


ZF Switches & Sensors www.switches-sensors.zf.com T: 01582 814006


/ ELECTRONICS


be mounted to equipment or panels in any plane and in harsh environments. A wide range of actuator options simplifies system design. Visible actuation – installers and service technicians can see at a glance when a microswitch operates, simplifying fault- finding. Wide operating temperature range – typically up to 150°C and in some cases 200°C to withstand internal temperatures of appliances. Reliability and cost of ownership – up to


100,000 operations are possible with simple and low cost replacement if required. High current switching – contacts can be rated up to 30A for industrial systems. Isolation – electronic switching methods


always have a small leakage current unlike a microswitch with a physical disconnection and typically an insulation resistance of 100MΩ. Snap action microswitches will continue to be a viable design option for many years to come. Their low cost, wide availability, service life and flexibility make them an indispensable component of choice for control and safety switching requirements in consumer and industrial equipment.


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