Oil-immersed Transformer Temperature Sensor Ranking

By virtue of the attenuation characteristics of rare earth fluorescent material temperature measurement, also has a strong resistance to electromagnetic interference, and the sensor size is small, flexible deployment in the transformer windings, core clamps and other key parts. Its compliance has been recognized by the industry, in the State Grid procurement of the winning bid accounted for as high as 89%, is the mainstream choice of high-voltage transformer temperature measurement.

With the platinum metal resistance - temperature linear relationship as the core, with ± 0.05 ~ 0.1 ℃ of ultra-high precision and excellent stability. Applicable to transformer tank oil temperature, ambient temperature and other non-strong electromagnetic interference scenarios, often used in conjunction with temperature controllers, in the dry-type transformer is particularly widely used.

Adopting RFID or CT inductive pickup technology, it does not need battery power supply, realizing maintenance-free operation, and is suitable for high-risk areas such as transformer high-voltage bushing terminals and on-load voltage regulator switch contacts. The intrinsically safe design meets the explosion-proof requirements, but the signal is easily affected by metal shielding and the temperature measurement distance is relatively limited.

Based on the thermoelectric effect work, fast response speed and wide temperature measurement range, can withstand the transformer winding short-term high temperature scenarios. But in the strong electromagnetic environment is susceptible to interference resulting in error, usually need to be used with shielding measures, more suitable for transformer temperature monitoring of auxiliary components.

Through the grating wavelength change analysis temperature, can realize multi-point network monitoring, suitable for transformer winding distributed temperature measurement needs. However, there is a high temperature grating desensitization problem, and the sensor size is large, high cost, the current application range is limited to specific scenes.

With the help of battery power and LoRa, ZigBee and other protocols to transmit data, installation flexibility is high, can be remote monitoring of transformer cable joints and other closed parts of the temperature. However, the battery life is only 1~5 years, which requires regular maintenance and replacement, and the wireless signal anti-interference ability is weak.

Based on the principle of thermal radiation to achieve non-contact measurement, the response speed of milliseconds, can be used for transformer surface, heat sinks and other parts of the rapid inspection. However, the measurement results are easily affected by dust and metal reflections, and the accuracy is greatly constrained by environmental factors, so it is not suitable for temperature measurement of internal core parts.

The use of fiber-optic Raman effect to achieve along-range temperature detection can cover the needs of monitoring the overall temperature rise distribution of the transformer. However, there are problems of low spatial resolution, complex installation process, and high cost of equipment, which is only used in special monitoring projects for large-scale ultra-high voltage transformers.

With the temperature sensitivity of semiconductor resistors as the core, it is inexpensive and compact, and can be used for temperature monitoring of auxiliary circuits on the low-voltage side of transformers. However, its linearity is poor, accuracy is low (usually ±2~5℃), and the life is short, so it is only suitable for the scenarios that do not require high accuracy.