Active Shield: Reliable measurement despite material build-up - With the RFnivo® Series by UWT

Material build-up is one of the most common sources of interference in level measurement. Whether sticky powders, slurries or conductive bulk solids – as soon as material adheres to a probe, the risk of false switching increases. Moisture or condensation on the sensor probe can also cause capacitive interference.

Active Shield refers to an active shielding technique in which an additional protective field prevents false switching caused by material build-up. This is exactly where Active Shield Technology comes into play: it ensures that the sensor reacts exclusively to the actual medium – not to external disturbances. The result is stable, reliable measurement signals, even under demanding process conditions.

Why do material build-ups cause false switching?
In capacitive or RF-based measurement principles, conductive material adhering to the probe can create an unwanted electrical connection to the vessel wall. The sensor then incorrectly interprets this as a “covered” condition – even though the actual level has not yet been reached. The consequences range from false alarms and process disruptions to unplanned plant downtime.

How does Active Shield work?
Active Shield operates with an additional, intelligently controlled protective field surrounding the sensor probe. Unlike purely passive shielding, this technology actively works with a defined electrical potential and dynamically adapts to the respective process conditions.

Simply explained
• The active electrode generates its own measuring field.
• At the same time, Active Shield creates an identical electrical potential – exclusively as a protective field.
• This protective field prevents material build-up or moisture from forming a conductive bridge to ground (the vessel wall).

• No false signals caused by material build-up or moisture
• Consistent measurement quality, even with challenging media
• Ideal for sticky, viscous or conductive materials
• Reduced maintenance effort and longer sensor service life