I. Program background

China is now the largest railway country in Asia and the fourth largest in the world. The electric railway system is an expanding and complex transportation system, and its reliability and safety are very important issues. As an important part of the railway, the catenary mainly provides power for electrified locomotives. Due to the influence of external factors, the connecting parts of the catenary are prone to overheating, which will lead to the interruption of power supply and lead to train shutdown accidents. How to detect the catenary safely and effectively has become the first step to ensure the railway safety. The traditional technical monitoring means have some defects and cannot achieve the effective prevention purpose. The infrared thermal imager can detect the temperature of catenary from a distance to find hidden trouble in time and avoid accidents.

As an important transportation sector of the country, the daily stable operation of the railway system determines the normal operation of national production and life. In addition, the numerous departments, scattered locations and complex site environment of the railway system have become major obstacles to daily maintenance. At present, the railway security monitoring means is still based on regular patrol inspection, which not only costs money and manpower, but also fails to carry out constant monitoring, and hidden dangers still exist. The original technical means has not achieved the effective prevention purpose.

II. The current defects of traditional control and measurement technology

1. Electronic fence technology: This alarm system requires high installation cost, large amount of supporting civil works and power consumption, and it needs to be supplemented by CCTV to check whether the alarm is wrong. At night, it needs to be supplemented by light or infrared lighting.

2. Infrared counter shooting technology: this alarm system is greatly affected by the weather, terrain and other external factors. It is easy to be installed with dead Angle, high false alarm rate, short service life, large loss and narrow protection area.

3. Microwave counter technology: The electromagnetic wave of microwave sensing radiation is harmful to human body and is subject to radar interference, which is not suitable for air traffic and the Ministry of National Defense. The distance between transmitter and receiver affects the detection rate and requires high installation requirements. As for the shortcomings of the above traditional alarm system, infrared thermal camera is used to monitor the image with high visibility: good effect is still maintained when realizing regional alarm and automatic tracking, with little noise, which does not affect the manual interpretation of the image; Is not affected by visibility, in the fog, haze, rain and snow and other weather still maintain a very high effect. Strong anti-jamming capability, obtaining clear images and performing intrusion detection in challenging imaging environments. Infrared features are used to realize the day and night monitoring, automatic alarm and heat tracing based on infrared thermal imaging, and meanwhile, the advantage of high visible light imaging ratio is used to realize the identification of field conditions. A warning signal will be issued as soon as a moving object enters the area.

III. Application of on-line infrared thermal camera system for defect detection

1. Power supply system includes traction substation and catenary. Traction substation all transformers, fuses, circuit breakers and all distribution lines, etc., catenary has many joints, return lines and other equipment. The use of infrared thermal camera can find loose joints or bad contact, casing oil shortage, three-phase load imbalance and other hidden dangers. The transformer box body generates heat due to oil pipeline blockage, eddy current loss, internal abnormality, poor insulation of iron core, etc. The detection of the transformer box body by the infrared thermal imager can keep the transformer box body at normal temperature all the time, so as to avoid damage of the transformer due to excessive temperature. The catenary has many joints, return lines, etc. The traction transformer has transformers, fuses, circuit breakers, and all the distribution lines, etc. Using an in-line infrared imager can reveal loose or poor contact (tap converter), casing overheating, overload, three-phase load imbalance, and other hazards. Its influence is to produce arc, short circuit, burn down, fire.

There are a large number of electrical equipment inside the locomotive and the vehicle. The infrared thermal imager can scan the high-voltage contactor, fuse panel, main power circuit breaker panel, contactor, and all the distribution lines, motors, transformers and other electrical equipment in a short time, quickly and intuitively find fault points and hidden dangers. The vehicle axle temperature is accurately detected to prevent the hot axle accident.

IV. Infrared thermal imaging railway overhead contact network efficient detection system

1. What is an overhead contact network

Catenary is a special form of transmission line set up along the railway line to supply power to electric locomotive. It is composed of contact suspension, support device, positioning device, pillar and foundation part. Contact suspension is set up on the pillar through support device, and its function is to transmit electric energy to electric locomotive.

2. Why should the temperature of the catenary be checked

The catenary connection is prone to overheat due to the interference of external factors, which will lead to power supply interruption and train shutdown accident. The main reasons for overheating of contact net connectors are as follows:

1) Oxidation corrosion: The conductor joint is exposed to the atmosphere for a long time due to external thermal defects

Years by the sun, rain, dust condensation and chemical active gas erosion, resulting in the conductor contact surface serious corrosion or oxidation, oxidation layer will make the metal contact surface resistivity tens of times or even hundreds of times;

2) Loose connector: the conductor connection is subject to mechanical vibration, shaking or wind force for a long time

Loosen the conductor press screw with down swing.

3. How to use infrared thermal camera for catenary detection

Infrared thermal imager detection has the characteristics of long distance, no contact, no disintegration and so on, using infrared thermal imager

During the detection, the point of temperature overheating can be judged by the infrared heat map taken, and the temperature analysis can also be carried out by using the supporting infrared analysis software, so as to find problems and timely repair to avoid safety accidents.

4. Precautions for using infrared thermal camera for detection

1) Avoid direct sunlight during detection, especially avoid detection at noon;

2) Set the temperature range, the measurement result will be more accurate;

3) If there are multiple contact net connectors on site, please compare their temperatures with each other, so that the heating fault of contact net connectors can be found in time.

Using infrared thermal imaging instrument to detect the railway system, find fault points in time to repair, preventive measures, help to reduce the accident rate, to ensure the safety of personnel.

5. Introduction of special thermal imager for railway and rail transit

Yoseen X (Rail Transit) series infrared thermal imager is a high performance and high accuracy on-line temperature measuring infrared thermal imager. Yoseen X series infrared thermal imager adopts imported detector with stable work and excellent performance. Coupled with unique temperature measurement correction algorithm and easy-to-use user interface, X series infrared thermal imager has become the preferred product of the rail transit industry.

Yoseen X (Rail Transit) series infrared thermal imager is compact in size, light in weight and high in frame frequency. It is equipped with a terminal software with rich functions and an easy-to-use SDK package. Whether used alone or in secondary integrated development, it can meet the differentiated application needs of users.