FISO
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Utility companies around the world are more than ever working to improve the management of the critical assets that are power transformers. Day to day operation supervision as well as lifetime temperature control can significantly optimize power transformer loading. Maximizing the performance of a transformer by monitoring its true temperature will reduce premature aging and allow for intelligent preventive maintenance planning, directly increasing the return on your investment.
FISO’s proposition to support the effort of utility companies is the Nortech Transformer Winding Hot Spot Temperature Monitoring System. Using proven Fiber Optic technology the Nortech system allows for direct, real-time, and long-term monitoring of power transformers, providing smarter dynamic substation and power grid management. |
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The Nortech Fiber Optic System
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The TPT-62 Fiber Optic Temperature Sensor with the EasyDisk
The TPT-62 family of fiber-optic temperature probes employs industry standard 62.5µm core OM1 optical fiber for vastly improved optical, mechanical, and reliability properties over legacy 200µm core (1st generation) optical fiber sensors.
The EasyDisk sensor tip assembly ensures IEC60076-2 Annex E compliant installation and enables quick insertion of the probes into the spacers within the windings of the transformer.
The EasyDisk sensor tip assembly ensures IEC60076-2 Annex E compliant installation and enables quick insertion of the probes into the spacers within the windings of the transformer.
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EasyDisk Key Features
- EasyDisk installed by FISO prior to shipping
- Yellow Spiral Wrap Cable locked on the EasyDisk
- Total sensor tip protection
- Quick and easy installation in the spacer without adhesive
- Optimal location of the sensor tip on the conductor allowing direct and accurate readings
- Increased robustness and protection during all the manufacturing processes
- TPT-62 and EasyDisk (NOMEXTM material) assembly tested to be fully immune to EMI
The Nortech Fiber Optic Moniotrs
EasyGrid
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EasyGrid LT
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The Nortech family of temperature monitors are provided in two classes: The EasyGrid is a full featured model, while the EasyGrid LT is a more compact model and very cost-effective in low channel count monitoring applications.
Nortech Monitor Key Features
- Up to 18 optical channels
- 1 System Relay, for independent system fail safe alarm
- 0, 8 or 16 form C fully programmable relays
- 1 Analog Output for each optical channel
- Modbus, IEC61850, DNP3.0, Modbus TCP-IP, IEC 60870-5-104 communication protocols
- Large display screen (Colour Touch screen on the EasyGrid)
- Internal data storage and removable media storage (SD Card) for easy data export
- Operation Auto-Diagnostic & measurement Auto-Correct
- Easy front panel wiring
The Fiber Optic GaAs principle and the temperature sensor
The measurement principle is based on white light absorption/transmission by a GaAs (gallium arsenide) semiconductor. The effects of temperature variations on this semiconductor are well known and predictable. As the temperature of the semiconductor changes, the semiconductor’s transmission spectrum (i.e. the light that is not absorbed) shifts also. At any given temperature there will be a wavelength at which the transmission jumps from essentially 0% to 100%. This jump is called the absorption shift, and the relationship between the specific wavelength where the absorption shift takes place and temperature is predictable.
The sensor consists of a tiny GaAs semiconductor crystal bonded to one end of a well-polished optical fiber.
White light launched from the monitor into the optical fiber travels through to the GaAs crystal, passes through it while being partially absorbed, and then is reflected back to the monitor by a mirror at the very tip of the sensor. Light reflected back to the monitor is coupled into an optical spectrum analyzer which then measures the optical power transmission versus wavelength. The position of the absorption shift is determined by the monitor using a proprietary signal analysis algorithm and is then correlated to the temperature of the GaAs crystal.
White light launched from the monitor into the optical fiber travels through to the GaAs crystal, passes through it while being partially absorbed, and then is reflected back to the monitor by a mirror at the very tip of the sensor. Light reflected back to the monitor is coupled into an optical spectrum analyzer which then measures the optical power transmission versus wavelength. The position of the absorption shift is determined by the monitor using a proprietary signal analysis algorithm and is then correlated to the temperature of the GaAs crystal.
Furthermore, since the semiconductor will not change over time, all sensors are interchangeable with no need for calibration or entry of factors when swapping sensors. For the same reason monitors never need recalibration after they leave the factory, while used under normal operating conditions.