Fiber Optic Temperature Sensor OTG-T

Gallium Arsenide-Based Fiber Optic Temperature Sensor for Distribution Transformers

OTG-T: GaAs based Fiber Optic Temperature Sensor View
OTG-T: GaAs based Fiber Optic Temperature Sensor Head View

Key Features

  • Sensing body encapsulated in uniform protective tubing provides a robust and small size sensor
  • Well defined round openings for proper oil wetting and best cable strength
  • Offered with our standard 62.5 micron optical fiber
  • Compatible with LumaTEST and LumaSHIELD Gallium Arsenide (GaAs) Semiconductor Band Gap (SCBG) signal conditioners.


LumaSense Technologies’ OTG-T fiber optic temperature sensor offers the highest reliability and robustness in the industry. It uses the well proven technique based on the temperature-dependent bandgap of Gallium Arsenide (GaAs) crystal as the temperature transduction mechanism. Its sensing GaAs crystal encapsulated in uniform protective tubing provides robustness and small size and ensures full protection against mechanical stress that may cause sensor damage when installed in the transformer isolation spacer.

The OTG-T comes with a specially designed fiber optic cable for oil wetting in the transformer. Welldefined round openings evenly spaced along the cable ensure proper oil wetting and provide the best cable strength.

The OTG-T is offered with our standard 62.5 micron optical fiber.

Note: See the Transformer Hot Spot Temperature Monitoring Fiber Optic Sensor brochure for more information.

Typical Applications

  • Hot spot temperature monitoring of power transformer windings
  • Temperature monitoring of power transformer top oil
  • High voltage environments


Technical Data


Temperature Operating and Calibrated Range

-40 to +230°C

Measurement Accuracy ±0.8°C (Total system accuracy at typical transformer operating range including both signal conditioner and sensor errors)
Resolution 0.1°C

Response Time

0.5 s Typical

Operating Humidity Range  0 to 100 %
EMI/RFI Susceptibility Complete Immunity
Physical Characteristics  

See Drawing Below

Optical Connector ST

Monitor Compatibility


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