Content Level Measurement With Capacitive Measurement Technology
The perfect man/machine relationship is the effective management of scarce resources. This presents a challenge on a daily basis for plant manufacturers and producers. In the area of raw material handling, UWT makes an important contribution:
Is Physics boring? If you don’t take advantage of the knowledge and don’t put physics to good use, then maybe. However, the opposite proves to be the case in the matter of the principle of capacitive measurement. The function of the capacitive switch is based on the change of the capacitive value depending on the type of filling material. A capacitor is formed when a level sensing electrode is installed in a vessel.
The metal rod of the electrode acts as one plate of the capacitor and the tank wall acts as the other plate. As the level of the solid rises, the air surrounding the electrode is displaced by material having a different dielectric constant. A change in the value of the capacitor takes place because the dielectric between the plates has changed. The sensitivity of a capacitive sensor circuit can vary greatly and depends on the dielectric constant (DK value), the sensor diameter, the material and the approximate mass of the material and the mounting position of the sensor. This can be adjusted by a potentiometer or dip switches.
The new Capanivo (CN) 4000 from UWT is suitable for all applications in bulk materials including high temperature, pressure and situations of material build-up such as flour, grain, cement, pellets, powder or coal. The device is available with the housing made of PA6 plastic or aluminum and suitable for use in temperatures ranging from -40 ° C and +180 ° C . A weather protection cover provides additional protection from powerful environmental factors such as rain, condensation, excessive heat from solar radiation and extreme cold in winter.
The device is available for supply voltages of 19-230 V AC and 19 to 50 V DC. Plus the CN4000 is suitable for all materials of a dielectric value of > 1.5. Through the ATEX and IEC Ex approvals, the device can be installed in dust and gas explosive environments.
The advantage of capacitive measurement is that it is a precise and reliable method of point level detection regardless of the varying material properties that are found in all applications across all industries. And crucially, the capacitive principle can be applied both in solids and in liquids.
UWT has overcome the problem of the material build up and caking on the device by the use of UWT’s active shield technology. Thus this material build up and caking are compensated for and ensures the accurate level limit detection by the device.
Other advantages of the capacitive measurement system are:
• An exposed/free standing earthed contact is integrated into the thread. This ensures that the earthing is installed automatically via the metal tank.
• The adjustable delay circuit prevents vibrating switching and allows a hysteresis (the lag in a variable property of a system) of the output signal.
• Multiple shaft lengths allow for complete customisation of the device according to the application’s requirements. The CN4000 is available as standard (CN4020), with extension shaft (CN4030) or with extension rope (CN4050).
• The system offers a cost-effective solution due to the excellent price-performance ratio.
• Precise, reliable level limit control, even with varying material attributes, Capanivo is ideally suited to applications where the product will stick to the measurement device due to the design of the Active Shield Technology.
• Easy installation due to pre-setting, no calibration post-installation.
• Process temperature to 180°C.
Contact:
Graeme Hughes – Sales Manager
UWT (UK) Ltd
20 Main Road
Dorrington
Shropshire SY5 7JW
UK
Tel: (+44) 1743 718883
Email: sales@uwtuk.com
www.uwtuk.com
