TD Guard Intelligent Sensor is an on-line CONTINUOUS Capacitance and tan-δ monitoring system for transformer bushings. TD Guard Intelligent Sensor is the first and only instrument on the market providing absolute Tan-δ measurement in on-line permanent monitoring of transformer bushings, granting the best level of diagnostic leverage and reliability. Sensitivity better than 10-4.  
 
First instrument on the market measuring absolute Tan-δ values in on-line permanent monitoring
Innovative instrument for Capacitance, Tan-δ and Δtan-δ recording, storage & processing
Zero drifts, innovative design for high thermal stability levels without drifts
Fast response and accuracy