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Fiso TPT-62

Oil Immersed Temperature Sensor

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Key Features
  • For Oil filled transformers
  • High dielectric constant
  • No calibration required
  • No calibration factors
  • Immune to signal attentuation
  • Direct contact

The TPT-62 sensor possesses a resilient construction and has dielectric resistant materials featuring complete immunity to EMI and RFI environments. The heavy-duty version is specifically designed for permanent installation in oil-filled transformers.

The TPT-62 sensor is based on the direct contact of temperature measurement. Traditional temperature sensors like thermocouples and RTDs (resistance temperature devices) work on the same principle. In other words, the semiconducting material must be touching the object or be immersed in the liquid or gas to be measured.The more intimate the contact and the smaller the thermal mass of the sensing tip, the faster the semiconductor will respond to changes in temperature. We then want to be able to deliver light to the semiconductor and measure what is absorbed. That is the function of the optical fiber.

A tiny semiconductor of GaAs semiconductor is bonded to one end of a well polished optical fiber. On one side of this semidonductor, a reflective dielectric film has been installed. Dieletric means it does not conduct electricity. All the materials share this property (“high dielectric strength”), which is one of the principal advantages of our sensor technology over traditional temperature sensors like thermocouples and RTDs (which use wires to convey an electrical signal).

The length of the optical fiber is convered with a PTFE (Teflon®) sheath, making it very resistant to aggressive chemical environments as well, as an additional perforated PTFE sheath (spiral wrap) for added ruggedness and even oil circulation. The entire end assembly (semiconductor and end of the fiber) is then embedded in high temperature adhesive to protect the sensor (the semiconductor) from chemical and mechanical aggressions.Consequently, the only barrier to direct contact is this adhesive.

The position of the absorption shift is determined by using a proprietary signal analysis algorithm and is then correlated to temperature. The computation of the absorption shift does not depend on signal intensity for this particular instrument, but onlythe wavelengths of the light are of interest. Consequently, the various factors that contribute to the attentuation of the optical fiber (fiber length, number and quality of connections, fiver diameter and composition, bending) do not impose any serious constraints to our system. Furthermore, since the semiconductor’s response to temperature is universal, all of our sensors are interchangeable with no need for calibration or entry of factors when swapping sensors. FISO’s approach gives reliable, repeatable temperature measurements without the errors that may result from a loss of power in the connectors or a bending of the optical fiber.


Sensor Specifications

Temperature range -40 to 225ºC
Resolution 0.1ºC
Accuracy ±1ºC
Available length 1 to 15 metres (in. 5m increment)
Sensor dimension 1.1mm
Certification ASTM D-3426
ASTM D-149
IEC 243-1
IEC 243-3
  • TPT-62 Whole
    TPT-62 Whole
  • TPT-62 Wire
    TPT-62 Wire
  • TPT-62 Close-up
    TPT-62 Close-up
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