Electricity + Control May 2018

SENSORS, SWITCHES + TRANSDUCERS

The Leuze LSIS 422i reads up to 99 barcodes per image in any format.

Leuze LSC 200 stations with Leuze CML 700i Series light curtains con- tain an integrated web visualisation system.

these applications, a conventional single channel shaft encoder would suffice. However, in applica- tions where excessive vibration is encountered a single channel shaft encoder would be subject to spurious counts and would therefore not deliver the correct accuracy. In this instance a three chan- nel phase shifted shaft encoder would be the cor- rect choice. Fit-for-purpose sensing equipment One can see from the example above that it is not as simple as it would seem when selecting a re- placement sensor. In the example above, the orig- inal single channel encoder may have been part of the original equipment supplied and it was not envisaged that this equipment would operate un- der conditions of excessive vibration. Yet over time it would have become apparent that the encoder was not operating accurately and a sensor special- ist who assessed the application would have been able to advise that it needed replacing. An inex- perienced individual would probably have replaced like encoder with like, and the problem would have continued.

The need to use fit-for-purpose sensing equipment applies to even the simplest of applications, and also relates to the material of construction of a sensor. Installing a sensor made from a perfectly acceptable material in an application for which it is not meant can have dire results. As an example, the correct selection of a prox- imity switch can be of importance when the envi- ronment in which it will operate is taken into ac- count. A conventional proximity switch is generally in a nickel plated brass housing which for certain applications would not be acceptable due to the environmental application. In applications where aggressive materials are present a proximity switch with a Teflon or Hasteloy housing would be more appropriate, thereby ensuring optimum per- formance and longevity of the sensor. Conclusion Staying abreast of sensing technology is the re- sponsibility of the original equipment manufac- turers that produce these sophisticated devices, and this knowledge needs to be transferred to the official distributors of these sensors. Coupled with the knowledge of the latest state-of-the art sensing technology and underpinned by years of in-depth experience in the field, reputable suppli- ers of sensing technology are able to accurately assess individual end user requirements and rec- ommend a fit-for-purpose solution.

Without an in-depth understanding of the application of sensing technology it is almost impossible to select the correct sensor for an application.

Gerry Bryant is the Managing Director of Countapulse Controls. Enquiries: Tel. +27 (0) 11 615 7556 or email bryant@ countapulse.co.za Visit www.countapulse.co.za

6 Electricity + Control

MAY 2018