Electricity and Control July 2021

MEASUREMENT + INSTRUMENTATION

At a glance  Ma-estro designs automation and optimisation systems for production processes in quarries, mines and recycling facilities.  Sensor technology plays a major role in the monitoring and optimisation of the crushing machines.  Continuous monitoring of process steps in the production chain is aimed at reducing the load on machine components, to protect the equipment, save energy and deliver a higher quality product.

The automation system used by Ma-estro optimises material flow to the hopper and adapts immediately to load problems and material changes. is used to measure material in crushers and mills, and it also warns of screen clogging and measures the level of water used for washing the material. Other examples are the VEGA sensors located at the opening of the press to control the level in the machine, on the conveyor belts to measure the load, and in the storage containers to measure the quantity of the end product. Depending on the load, various adjustments to the machine are made automatically in order to achieve optimum results in each case. The sensors Ma-estro had previously used from other manufacturers had been expensive to integrate into the existing automation systems and, contending with the conditions typical to the stone crushing industry, had delivered inaccurate measurements. Measuring the level in crushing machines is in general not an easy undertaking because, despite all the electronics and digitalisation, the conditions in Ma-estro’s field of activity are typically dusty, dirty and gritty. Intense vibration is also a factor. Consequently, dust, residual material and moisture cause a lot of interfering reflections. Installed as a test instrument – now permanent To begin with, some VEGA sensors were installed for test- ing. From the start of the project, everyone was convinced the technology would deliver the desired result, and once that was confirmed, the sensors found a permanent place in the crushing systems. The measurement engineering team was especially impressed by the simple configuration of the instruments. Thanks to the plics ® concept – that is, the standardised user interface independent of measuring principle – the team didn’t have to re-familiarise themselves with the different sensor types over and over again. Setup and commissioning were easy. The company’s metrology experts were also enthusiastic about the VEGA engineers’ understanding of the process and the partner-like relation- ship between customer and supplier. However, the reliability and accuracy of the measured values was the decisive factor. VEGAPULS 69, in particu- lar, delivered consistently reliable measured values – an important prerequisite in optimisation of the crushing pro- cess. Its small beam angle of only 3° is responsible for the high accuracy measurements. The radar level transmitter

VEGA sensors in the crushing machines transmit the correct level at all times. operates with a transmission frequency of 80 GHz and has an antenna diameter of about 75 mm. The 80-GHz beam thus bypasses anything that could otherwise get in the way, such as internal fixtures or build-up on the vessel wall. What is more, it easily penetrates thick dust clouds. This makes measurement more accurate and reliable, especially in the harsh environment found in comminution systems. The VEGAPULS 69 radar sensor also has very good sig- nal focusing and a wide dynamic range. In radar sensors, dynamic range indicates which applications a sensor can be used in. It describes the difference between the largest signal and smallest signal that can still be detected by the radar system. In practice this means the greater the dy- namics, the broader the application range of the sensor. With its large, 120 dB dynamic range, the VEGAPULS 69 can pick up and measure even the tiniest reflections. The instrument has a measuring range of up to 120 m, a reac- tion time of less than 1 s and an accuracy of ± 5 mm, pro- viding sufficient performance reserves to handle the most challenging applications. Another feature that delighted the Italian company was the option of wireless communication via Bluetooth. This is particularly useful for hard-to-reach areas, in harsh indus- trial environments and hazardous Ex zones. The user can configure and parameterise plics ® sensors from a safe dis- tance using a smartphone or tablet, whether an Apple or Android device. Fast, user-friendly display and diagnostic functions are also available. VEGA technology thus fits well in Ma-estro’s optimisation environment. □

For more information visit: www.vega.com

Electricity + Control JULY 2021

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