Jürgen Skowaisa, product manager Radar at VEGA Grieshaber KG in Schiltach, Germany, speaks about their new series of sensors
What applications can the sensors be used for and what makes them different?
Jürgen Skowaisa: Radar sensors are designed for a wide pressure and temperature range, which is what makes them expensive. In a lot of applications, there are no high temperatures or pressures, but radar would still be the ideal technology. Those are the applications we are focusing on with the new radar devices. Our main focus is the water and wastewater industry, where ultrasonic is still the most commonly used technology. But there are many other applications in which radar has often proved to be the best choice, e.g. in power plants, small chemical tanks and in applications in the food & beverage industry that have lower demands on hygienic design. We also see great potential in the bulk solids industry, from building materials to various applications in pet food production.
For the new series, you designed a completely new radar microchip. How long did that take and what features did you focus on in the design process?
JS: Radar is being used more and more in the automotive industry. There are now radar modules for use in simple distance measuring systems. However, these modules are not suitable for radar level sensors that have to meet the high demands of industrial process automation. Their power consumption is too high and their frequency ranges don’t fit. That’s why we decided to design our own radar chip optimised for level measurement. Working with a microwave semiconductor design company and a semiconductor manufacturer with broad experience in high frequency technology, it took us three years to create the final version of our own radar chip – perfectly designed for a new generation of radar sensors. During its development, our main focus was on low power consumption, an optimised frequency range for level measurement as well as high accuracy.
What are the main advantages of these sensors from a technological point of view?
JS: There are many differences between sound waves and electromagnetic waves. Sound waves are strongly influenced by temperature, pressure and different gases. If an ultrasonic sensor is mounted outdoors, it needs a sun shield or an external temperature sensor to compensate for the heat generated by sunlight. In bulk solids applications, dust and filling noise cause huge problems for ultrasonic measurement because dust absorbs the sound waves and the intense noise makes it difficult to detect the echoes. Radar signals, on the other hand, are not influenced at all by such conditions. This makes radar sensors universal, highly reliable and extremely accurate.
What’s the difference between the new sensors and the other radar sensors produced by VEGA up to now?
JS: Our typical radar sensors are always customised to meet the requirements of the particular application and industrial sector, for example when it comes to process fittings, and also to fulfill the special wishes of our customers. The sensors come with the certifications and approvals required by each individual industry. We offer standard plastic housings as well as metal housings of aluminum or stainless steel. But no so-to-speak ‘standard sensors’ are kept in stock. The new radar devices are made for standard applications with standard process conditions.
In what environments can the new sensors be used and what are the interfaces you can provide?
JS: Even in simple applications, it is sometimes absolutely necessary to use an Ex- approved sensor. VEGA provides all essential approvals for use in hazardous areas, for gas and dust applications. The encapsulated sensor for gas ex applications in Zone 1 or 2 is completely new. With this version, it’s not necessary to provide an intrinsically safe power supply. The sensor can be directly connected to a PLC without any barriers, which makes it very easy to use a radar sensor. A loop-powered analogue signal of 4 … 20 mA is perfect for more than 90% of all applications. VEGA also provides Modbus and the SDI-12 standard protocol for the hydrological market.