Status Instruments Ltd. - PRODUCT NEWS

Digital-Analogue hybrid in-head temperature transmitters go from strength to strength.

In-head temperature transmitters play a small, yet vital, role in many industrial processes and despite the growth of ‘smart’ digital transmitters, Status Instruments, the UK’s leading manufacturer of temperature transmitters, firmly believe that digital-analogue hybrid devices, combining the best from both technologies, have a strong future.

Strong market pressures on manufacturers to reduce size and cost, whilst improving performance and flexibility, have had a major impact over the last few years, with customers ever-looking for a low ‘cost of ownership’ product. Significant investment and ingenuity is now needed to stay ahead in this highly competitive market place, especially where products must meet the latest requirements for EMC compliance.

Simple analogue devices are still widely used and it is generally accepted by engineers that these offer the user simple, reliable technology at low cost. Unfortunately, standard analogue transmitters are limited in their flexibility as Status’ managing director Ian Pullin explains: "Typically, standard analogue units are made to order or require individual set-up via solder links and potentiometers. Set-up may appear to be straightforward, but trying to solder links in a plant where the transmitter may be two metres off the floor can be extremely inconvenient and this is a far cry from controlled workshop or laboratory conditions. What’s more, units are specifically designed for particular temperature sensors only. These shortcomings increase stock holding and spare part inventory for distributors and users, as well as increasing delivery times. Quite simply, the perceived low cost factor soon pales into insignificance! "

Most manufacturers have therefore tended to neglect analogue transmitter development in recent years, preferring to focus their efforts on digital technologies, whereby a single transmitter can be programmed by a laptop computer to suit a wide variety of applications. Against this trend, Status Instruments, have recognised the importance of the analogue market sector and made a significant breakthrough by producing the first digital-analogue hybrid, combining the performance of a digital device with the simplicity of re-ranging, resulting in their model SEM203; a low cost versatile transmitter.

Early analogue transmitters were ‘hand built’ using conventional components and were relatively bulky due to component size and technology. Advances in surface mount technology and new component designs have allowed Status engineers to reduce the overall size, allowing the transmitters to be manufactured to the same dimensions as a standard DIN connecting block. This ensures they still fit within an industry-standard temperature probe housing.

The ingenious part of 203P, which uses the latest surface mount technology, is the unique push button set-up feature. As Pullin continues: "The push button feature sets us apart from other manufacturers. Instead of having to manually solder links inside the unit to select the temperature range and then adjust potentiometers, calibration is achieved simply and swiftly via an internal push button switch. The built-in LED indicates correct set-up. A thermocouple version achieves full galvanic isolation through the use of an internal transformer.

The primary advantage over the digital programmable versions is that complete re-ranging can be done without resource to a computer, whilst the advantage over the pure analogue types is in the speed of set-up and that the linearisation is performed digitally for high accuracy, drift-free operation. The set up time of the SEM203 is seconds compared to minutes and without the need for an additional PC, laptop, soldering iron and continued patience! "

Remarkably, the 203P is a low cost product priced below many simpler analogue units. Extensive sales in Europe, North & South America, South Africa and the Far East, confirm that it is a very competitive product both technically and commercially, taking the headache and frustration out of on-site configuration. Status have also still found the room to incorporate physical barriers for the all important input-output isolation, ensuring that none of their designs can malfunction through ground loop errors. Many transmitter manufacturers, especially in the low cost sector, still rely on the probe itself to provide the isolation.

For more information, please contact :-

Status Instruments Ltd
Green Lane, Tewkesbury, Glos GL20 8DE
Tel: +44(0) 1684 296818
Fax: +44(0) 1684 293746

May 2007

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