Nearly every electrical device has at least one switch. We take their safe, efficient and reliable operation for granted, but selecting the correct switches can be confusing for the designer and engineer.
Incorrect specification can have serious consequences for product reliability and reputation. Toni Hankins, MD of Rowe Hankins Components, the UK distributors of Marquardt switches offers the following guide.
* Safety first - select a reputable manufacturer with proven ability to design, deliver and supply product that meets relevant European, North American and national test and accreditation standards. Select a switch with the correct electrical rating and characteristics, including factors such as correct resistive and motor loads and tolerance of transient in-rush current on start up.
* Environment - what kind of environment will the switch be in? Will it be exposed to exceptional temperature, humidity/moisture, dust or other hazards? Switches can be specified with heat resistant and even flame retardant cases and with dust and splash protection or to meet specific IP criteria.
* Style - for appliance, automotive, medical devices and many other applications, think carefully about shape, size, colour, texture, switch action and markings. These are more than just aesthetic considerations and can affect the usability, appearance, and user's perception of the quality and value of the device.
* Assured performance - any switch that has more than 2000 annual operation cycles must be tested for 50 000 cycles, look for the 5E4 marking. For reliability it may be even more important to have gold-plated contacts on switches that are infrequently used.
* Status - decide if the application requires a positive indication of on/off status and whether this is best achieved by colour reveal/conceal (with a slider switch, for example) or by internal illumination or LED.
* Mode of operation - consider carefully what mode of operation meets the need best - rocker, toggle, pushbutton, slide, rotary, open or closed snap action or footswitch. Do you need single, double or multipole switches?
* Production - correct specification can be an aid to productivity. Consider carefully the benefits of standardisation of switch types, the ease of fitting the correct choice of terminals to suit the production method.
If all this sounds confusing then seek advice from your local distributor. "It is in our interest to supply a switch that is safe, effective and reliable and meets the needs of the application. Failing to address needs properly can lead to premature failure, higher service costs, outages for the user and ultimately loss of goodwill and reputation," advised Hankins.
For more information contact Tony Hankins, Rowe Hankins Components, +44 (0)161 765 3000. Marquardt is distributed in South Africa by Avnet Kopp, +27 (0)11 809 6100, [email protected]
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version