Fiber optical temperature solutions for generator and transformer

GERMANY --- Due to the growing demand of energy, existing power plants and grids are stretched to their limits. To ensure operati­onal safety, critical factors such as temperature has to be monitored in generators and transformers. High power ge­nerators are often filled with hydrogen in order to cool effectively. Besides the heavily contaminated electromagnetic environment the risk for explosions is high.

Optocon AG offers a variety of fiber optic temperature measuring devices, fiber optic temperature sensors and accessories for temperature monitoring in oil-filled power transformers. One can enjoy all the benefits of the fiber optic measurement principle. The outer jacket of the fiber optic temperature sensor is made out of PTFE, at the sensor tip a GaAs-crystal (gallium arsenide) is attached. The GaAs based technology is ideal for smart grid temperature monitoring in transfor­mers. The sensor is completely non-conductive. Optocon’s fiber optic temperature sensors offer complete immunity to RFI and EMI emissions with high temperature operating capability, intrinsic safety, and non-invasive use. The fiber optic temperature sensors are also designed to withstand harsh and corrosive environments.

Starting at a light wave length of 850nm/Kelvin, the measurement device contains a light source and a device for spectral detection of the band gap. These guarantee fast, repeatable and reproducible measurements.


The FOTEMP temperature signal conditioners are user-friendly and easy to operate. The system standard deviation of +/-0,2°C as well as fast sampling rate per channel offer reliable real-time temperature results. With our wide portfolio of signal conditioners a versatile usage is possible, e.g. the FOTEMP1-H allows walk-as-you-go temperature validation of the transformer assembly. Our FOTEMP transformer device is specifically adapted to the requirements of temperature measurement in the transformer. FOTEMPTrafo provides reliable results with an excellent accuracy. It can be equipped with standard analog outputs, USB, WLAN, SD-Card, RS232 and RS485 to allow quick and easy integration into existing communication networks. Via the selectable interfaces and thanks to its accompanying software “FOTEMP Assistant”, measurement results can be easily controlled, monitored and logged.


The fiber optic temperature sensor provides accurate, stable and repeatable measurement results. Optocon’s sensors offer complete immunity to RFI, EMI, NMR and microwave radiation with high temperature operation capability, int­rinsic safety and non-invasive use. The TSNano temperature sensor stands out for its miniature size and can be self assembled with the NANO-Kit. The spacer provides a simple, fast and non-adhesive attachment of the sensor directly between the windings. Thereby the protection of the sensor is guaranteed and so perfect measurement results can be reached.


Optical feedthroughs are specially designed for installation on tank walls and oil transformers. They have a leak-proof interface and require no maintenance. On both sides are standard ST connectors attached. There are no moving parts or loose optical cables. They can withstand up to max. 16bar (200psi). The stainless steel tank wall plate is installed outside the transformer wall and to protect and guard the fiber optic measurement assembly. The rough extension cables can be used on all fiber optic temperature probes.

Optocon AG has been developing measurement devices for fiber optic temperature measurement and fiber optic temperature sensors since 1993. In 20 years of business experience, the focus of the company is to provide customers innovative and individual solutions for their fiber optic measurement projects. From the office in Dresden, Optocon AG has established itself internationally and delivers products anywhere in the world.

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