Fiber optic temperature sensor

An innovative patented probe design gives transformer manufacturers probe robustness and ease of installation. Transformer operators then get reliable and long-term temperature data, essential for precise transformer aging evaluation.

  • Optimised for easy installation on oil-insulated and dry-type transformers and reactors
  • Rugged construction built to last the life of the transformer
  • Exceptional repeatability, zero-drift GaAs technology
  • 9 mm fixing disc design, suitable for all transformer positions (windings, cores, busbars, tap changers, etc.)
  • Resistant to solvents and chemicals

Product Features

The Rugged Monitoring Tsens probes have been designed and built so they can be incorporated into your transformers to give precise results (direct measurements of temperature). The sensing technology is based on the proven zero-drift GaAs technology. They are completely built using first quality materials, all with very high dielectric strength, so your transformers can benefit from accurate temperature readings, which is essential to a good knowledge of transformer aging rate. During factory heat run tests, these probes will give both transformer manufacturer and operator invaluable information regarding the transformer's expected MVA performance. The patented tip construction makes them extremely robust and easy to install in radial spacers or other pressboard material (such as for temperature measurements in cores or other transformer components). This tip, along with a 200  Ø fiber offers the highest probe pulling force in the industry. The spiral-wrap cable is specially constructed to allow complete oil penetration so you can be assured that no air can be present. All materials used in the probe construction are compatible with high-temperature kerosene desorption processes.


  • Power transformers, oil-filled and dry-type
  • Ideal for direct measurements of temperature
  • High voltage environments (1 MV, or more)
  • Suitable for HVDC windings
  • Mounts in standard radial spacers
  • Withstands kerosene desorption
  • Compatible with all types of transformer oil, including ester-type
  • Compatible with all Rugged Monitoring instruments


  • Sensors do not require any calibration, ever
  • No shift over time, high stability
  • PTFE Teflon spiral-wrap reinforcement
  • Robust fiber optic temperature sensor tip
  • Available with disc and without disc
  • Surpass ASTM D2413 and D149 standards
  • Very low PD performance
  • Designed to exceed transformer life
Temperature range-200 °C ... +250 °C (optionally cryogenic range 4 K)
Repeatability0.2 °C
Accuracy absolute temperature±0.8 °C
Accuracy relative temperature±0.2 °C
Probe sheathing materialTeflon spiral-wrap
Tip materialTorlon (with disc) or Polyimide (no disc)
ConnectorStainless alloy ST with zirconia ferrule (Optional: Dielectric Torlon ST with zirconia ferrule)
Probe length

up to 25 m

Response timeup to 0.2 sec without disc. About 2 sec with disc
LongevityProbe accuracy and repeatability constant over time

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