TD Guard

Smart Sensors | TD Guard


  • 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

Ultimate solution for transformer monitoring

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.  



TDG-IS consists of a microprocessor-controlled unit supporting sophisticated sensors and conditioning front end.
Fiber optic interfaces allow data download by a standard PC or a server able to record values of Δtan-δ (relative measure) and Capacitance and threshold setting.

TDG-IS has the capability to present two alarm levels, according to a traffic-light approach, using the dedicated LED front lights or activating external alarms media by dry contact interface.
False alarms are avoided through advanced signal processing and field-proven algorithms able to eliminate the effect of noise or other environmental conditions that could lead to wrong diagnosis and inappropriate corrective actions.

“TDG-IS” INTELLIGENT SENSOR implements transformer bushing’s on-line monitoring through Capacitance and relative Δtan-δ measurement.

Smart sensing algorithms are applied to obtain fast response and accuracy.

“TDG-IS” is designed to be used with TECHIMP PD analyzer, as the PDCheck unit and Techimp DGA-IS, providing Global diagnostic coverage and, thus, superior failure prevention.

“TDG-IS” may also be used as a stand alone device to get basic alarms on programmable threshold levels.


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  • TD Guard Full - Datasheet [please login to download or register]
  • TD Guard STD - Datasheet [please login to download or register]
  • TD Guard Lite - Datasheet [please login to download or register]
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