Electricity and Control February 2022

SENSORS + SWITCHES

High-tech sensors for process automation in Ex areas The dynamic world of factory automation relies on sensors with a range of technologies. If these sensors can meet the requirements for hazardous areas, a number of them could be valuable in process automation. Pepperl+Fuchs has developed a range of high-tech sensors that have proven themselves in discrete applications.With explosion protection, they are also suitable for process engineering in zones 1/21 and 2/22.

T he digitalisation of process information forms the basis for modern automation and Industry 4.0 solutions. It enables remote access to data and device parameters, predictive maintenance, and data-based process optimisation. The basic data is largely supplied by sensors. The sheer variety of these devices in the world of factory automation is almost unmanageable. They are adapted to the highly differentiated technology of discrete manufacturing processes, and their development mirrors the short-term cycles and high dynamics in this field. The process industry may be focused on considerably longer cycles, but it can benefit from the technological progress in sensor technology for factory automation. It is important to ensure mechanical integration of the

these appliances, experts from Pepperl+Fuchs helped to transfer a proven process from the non-hazardous area to the hazardous area. The R2000 2-D laser scanner is mounted under the platform railing and its scanning field is directed toward the vehicle area. If the lifting platform is lowered too close to the tanker below it prior to the filling process, the sensor triggers a dual warning signal – a flashing light and an audible signal. At the same time, the platform is automatically stopped. This protective circuit reliably prevents damage to the platform and tanker and avoids hazardous situations for operating personnel. For use in hazardous areas, the laser scanner has been placed in a pressure-resistant aluminium enclosure with an integrated viewing window. It is approved for explosion protection zones 1/21 and 2/22. To prevent scattering and distortion of the signals by refraction, the sensor is mounted in the enclosure at a 15° angle. Access control Safety is a priority for oil platforms at sea. Safety measures include access restrictions and residence documentation in critical areas. Pepperl+Fuchs has developed an automated solution for this in cooperation with a supplier that specialises in tracking software. Employees wear RFID tags, which can be integrated into items like key rings or badges. Each employee’s access rights to specific areas are stored on the tags, which are read by a RFID sensor at the access point to the specific areas. This read/write head is housed in an Ex-d enclosure and is approved for use in hazardous areas. A human-machine interface (HMI) connected to the cen- tral computer is used for software visualisation. Employees are recorded every time they enter an area. The information stored in the tag enables track-and-trace evaluation of in- dividual employees. The software determines whether the employee is authorised to access the area in question. If so, the software unlocks the relevant cabinets and doors. It simultaneously documents where exactly the employee is located, which is particularly important in emergency situa- tions and in the event of an evacuation. Object detection Sensors that use the time-of-flight recording method (Pulse Ranging Technology, PRT) are ideal for quick and reliable

sensors is as simple and standard- ised as possible. Reliable explo- sion protection for the devices is a prerequisite for their broad and flexible use in process technology. The acquisition and servicing costs for sensors usually play only a mi- nor role in large plants in process industries compared to the outlay for permits and certifications need- ed in explosion protection. The sen- sors are often required in especially exposed areas, which creates ad- ditional challenges. The potential of devices originally developed for factory automation can best be il- lustrated by way of case studies.

Simple design, standardised as far as possible, makes the sensors easy to integrate into operational equipment.

Collision protection When tankers are being filled with chemical fluids or oil products, person- nel must be present on a moving platform above the vehicles. This workspace needs to be protected against collision risks to prevent damages to equip- ment or people. Working with a manufacturer of

High-tech sensors, proven in discrete applications, also hold potential for use in process automation.

20 Electricity + Control FEBRUARY 2022