AC/DC SR 49C all-voltage sensors now suitable for outdoor use

Inside of automated systems, a voltage supply of 24V DC has become common due to the high degree of integration of control technology, whereby regional differences with regard to the interfaces and switching outputs are typical. What is more, optical sensors must ensure reliable signal transmission and exhibit great insensitivity to fluctuations of the supply voltage - even with long cable lengths.

These two aspects become particularly important when in extensive systems, i.e. with long cable lengths, the signalling can only be assured with a single switching contact. This occurs frequently on the periphery of systems, for example at the end of a highly-automated high-bay warehouse and picking systems, and in distribution and truck loading areas. At the ends of such lines the supplied voltages are generally low.

Another interesting example of the typical demands of certain sectors - in this case with low control density - are the packaging systems and wood working industries. Here too, the existing cable lengths are a prevailing issue, but simple switching signals are much more common - usually with AC voltage because of the large drives. Accordingly, sensors with relay switching outputs and which cover the widest possible voltage range are required. These are referred to as UC (Universal Current) or AC/DC sensors.

The stated conditions place demands on the sensor technology which are not to be taken lightly: on the one hand, an evident tolerance for fluctuations in the supply voltage, on the other hand an uncomplicated connection technology and interference rejection because of the frequently harsh environmental conditions.

Drawing on their many years of industrial experience and vast application know-how, Leuze electronic developed an apt approach to meet these demands. The rugged SR 49C AC/DC series proves itself convincingly over very long operating ranges (operating range limit up to 150m, effective operating range up to 120m) and features that make deployment both reliable and simple. The series consists of throughbeam and retro-reflective photoelectric sensors, as well as light scanners; there are both red light and infrared models. All of the sensors are mounting compatible with many other market-standard sensors and with the 96 and 46B series. Alignment is a quick and simple matter, thanks to the very bright light spot of the red light version and an alignment aid for the infrared devices.

Easily accessible terminal compartment

What is immediately noticeable on the sensors is the easily accessible terminal compartment on the front. It simplifies mounting and expands the deployment possibilities, as it allows the installation in very confined installation spaces or in corners. Connecting the devices is easy: open the housing cover and push in the wires. Hooking up wires is easy. The cable itself is fed into the sensor from below or the rear at a 45 degree angle. And that, thanks to the spring terminals, is exactly what saves a lot of space and spares the electrician straining and fiddling around with screws when mounting and dismounting units. Status LEDs which are highly visible from all directions facilitate the alignment and diagnostics.

The SR 49C is characterised by state-of-the art sensor functionality, for instance the adjustable (by teaching) light/dark switching and the adjustable switching delay for the switching behaviour of the outputs (0.5s). The sensitivity of the sensor adapts to the respective application by means of a potentiometer. What is remarkable here is the ALC automatic sensitivity readjustment. To the greatest extent possible, it prevents the total reflection at close distances to the reflector. If contamination build-up begins, the optics still consistently maintain their sensitivity, switching point and function reserve.

Optional integrated optics heating ensures the reliable detection of objects - particularly in material flows, in transitional areas between inside and outside, or in varying temperature zones - where fogging or condensation can occur. High degrees of protection of up to IP 69K, made possible by the new housing design, are especially valuable in such applications. The firmly cast-in sensor circuit board withstands perceptible vibrations. The SR 49C scores high with longevity in outdoor use and deployment in environments with slight soiling. Consequently, the series is suitable for systems in the wood-working industry, car parking systems, packaging plants and applications in material flows, for example in crane systems.

To learn more about the AC/DC SR 49C all-voltage sensors please visit www.leuze.com.