Why do autotransformers use fluorescent optical fibers for temperature measurement-INNO

What is a rail transit autotransformer

The AT power supply (autotransformer power supply) method has become the main direction of high-speed and heavy-duty railway construction. The AT power supply method adds positive feeder lines and parallel autotransformers in the traction network, doubling the system power supply voltage. Under the same traction load, the current of the contact network and positive feeder lines can be reduced by half. At the same time, the impedance of the traction network in the AT power supply method is about 1/4 of that in the BT power supply (suction transformer power supply) method, which improves the traction network’s energy transmission capacity and reduces the voltage and energy losses of the traction network. It effectively extends the power supply distance of the traction substation, reduces the magnetic field generated by the traction current in the track, and weakens the interference caused by the magnetic field on adjacent communication lines.

Why does an autotransformer need to measure temperature

In power transmission and transformation systems, power equipment such as current carrying busbars and busbars may experience excessive temperature rise when the load current is too high or the surface is oxidized. Prolonged inactivity can degrade the performance of adjacent live parts, leading to breakdown, fault and power outage. According to data analysis provided by the production safety supervision department, over 90% of major accidents in power transmission and transformation stations across the country are caused by overheating, causing huge economic losses to production and operation, and also threatening the safety of life and property. By monitoring the operating conditions of bus contacts, high-voltage cable joints, and high-voltage switch contacts, it is possible to effectively prevent the occurrence of high-voltage transmission and substation faults, providing effective guarantees for achieving safe production. Yog li ntawd, vim, taking effective measures to monitor the temperature changes of joints in transmission and transformation systems in high-voltage environments is a major issue that urgently needs to be addressed.

As an important component in the power system of rail transit, the safe and reliable operation of autotransformers is closely related to the safety of the power grid and transportation equipment. The fire accident caused by internal faults in transformers is a major hidden danger, so it is particularly important to detect and monitor the temperature of transformers.

The drawbacks of traditional temperature measurement methods

Many busbars are at high potentials (6KV, 10KV, 35KV, 110KV, 220KV, and even higher). Currently, there are many equipment specifically used for measuring high voltage busbars, high voltage switches, and electrical contact heating in China, but there are few measurements of the temperature of busbars in narrow fully enclosed spaces.

Wax stick temperature measurement

One commonly used method for temperature monitoring is to apply a layer of luminescent material with a color that changes with temperature on the high-voltage electrical contact surface, and roughly determine the temperature range by observing its color change. This method has low accuracy and poor reliability, and cannot be quantitatively measured. It is also impossible to observe in a fully enclosed environment;

Infrared thermal imager temperature measurement

Another method is to use infrared thermal imagers with radiation characteristics, which have high accuracy. However, due to the need for optical components, it is not very convenient to use in specific situations. Even if it is reluctantly used, it poses challenges for installation, debugging, maintenance, and equipment power supply, making it difficult to implement and expensive, making it difficult to promote and apply. More importantly, both of the above methods require manual inspection and cannot obtain real-time temperature data. The obtained data is always lagging and cannot function as a real-time temperature alarm.

Wireless temperature measurement

At present, some wireless temperature measurement systems are being put into use, and the stability of the temperature measurement terminals is not sufficient during operation. In addition, most of these products are powered by built-in batteries, and the lifespan of the built-in batteries and the constraints on the appearance and size of the batteries have a greater or lesser impact on the products. At the same time, in environments that are difficult for personnel to reach, maintenance or battery replacement will become impossible.

Fluorescent fiber optic temperature measurement using autotransformer

Basic functions of transformer fiber optic temperature measurement host

▲ Data export

Event recording

▲ Multi level alarm settings

▲ Temperature trend analysis

▲ Historical data callback

▲ Real time data recording

▲ Output: 4-20MA

Multi channel temperature measurement:

Output: RS485

Standard MODBUS protocol;