How to deal with faults in 10kV switchgear

10kV switchgear structure

The 10kV switchgear used in the mine is generally composed of two main parts: circuit breakers and cabinets. The cabinets are physically divided into busbar room, control room, outgoing room, and circuit breaker room. Due to the harsh mining environment and heavy loads, there are higher requirements for the reliability of equipment operation. Its notable features are narrow space and compact structure.

Common faults of 10kV switchgear

With the rapid development of science and technology, the quality and reliability of 10kV switchgear have been significantly improved, and the failure rate of equipment has been greatly reduced. However, due to the large load in the mine and the harsh environment, as well as the 10kV switchgear working in high voltage and high current environments, it is difficult to avoid equipment failures.

Among the common faults of 10kV switchgear, heating, insulation, and component failures account for the top three, accounting for 48.15%, 27.78%, and 11.11% respectively, totaling 87.04%. The occurrence of these faults has serious adverse effects on the power supply safety of the mine, and effective technical measures must be taken for prevention and treatment. Although mechanical and other faults account for a small proportion, their occurrence has a very adverse impact on the normal production of the mine.

Analysis of the causes of faults in 10kV switchgear

10kV switchgear heating fault

During the operation of the switchgear, the main sources of heat generation come from the conductive circuit, specifically from the joint position, conductor heating, eddy current heating, and other parts. If the heat generation of the equipment is higher than the heat dissipation of the switchgear, it will cause the temperature of the switchgear to increase, and in severe cases, it can cause malfunctions. Joint heating mainly occurs at knife switch joints, joint positions, transformer connecting plates, and other locations where there may be poor contact, or due to electrochemical corrosion, the equipment may have poor contact, resulting in sparks or heating. The main reason for conductor heating is the heating of the busbar in the busbar room. The busbar passes through a high current value for a long time. When the switchgear load is high, the heating of the busbar is more obvious. Due to the limitations of production technology and conditions, it is difficult to avoid impurities in the produced busbar, which increases the resistivity value and also increases the heat generation of the busbar. Eddy current heating is mainly caused by the circulating current of the load current due to the partition effect of the steel plate inside the switchgear, causing heating. The larger the load current, the more severe the eddy current heating phenomenon.

Insulation fault of 10kV switchgear

Insulation discharge is the main factor causing insulation faults in switchgear, such as ground flashover, conductor phase to phase flashover, and pillar porcelain bottle flashover. When the insulation strength of the insulation or gap between the insulators inside the switchgear is insufficient to meet the insulation requirements, discharge may occur during operation in a high-voltage environment. In severe cases, direct penetration of the insulation may occur, leading to insulation faults. The harsh operating environment of 10kV switchgear in mines is an important reason for insulation faults, with the most typical being the occurrence of pollution flashover. There is a large amount of dust in the mining environment, and due to the accumulation of time, there is a lot of pollution in the insulators, sleeves and other components inside the switchgear. When the air humidity is high and the insulator support is close to the leakage point, it is extremely easy to cause pollution flashover.

10kV switchgear component failure

There are many precision components inside the switchgear, which are prone to malfunctions under long-term high load operation. Among them, the probability of live displays malfunctioning is relatively high, and many 10kV switchgear live displays in mines are in a faulty state, which is virtually non-existent and cannot be used on site; The main reasons for the failure of voltage transformers are due to equipment installation and debugging, equipment quality, equipment overvoltage, and short circuits on the secondary side; The main causes of lightning arrester failure are seal failure, porcelain contamination, and aging of valve plates due to prolonged equipment operation. When the seal fails, it will cause moisture and dust from the external environment to enter the interior of the lightning arrester, causing insulation degradation and accelerating the aging process of the valve plate. At the same time, when the porcelain sleeve is contaminated, it will cause uneven voltage distribution inside the resistor plate and intensify the aging of the resistor plate.

Mechanical failure of 10kV switchgear

The most common mechanical faults that occur in switchgear include broken pull rods, bent or deformed operating components (or localized fractures), broken transmission pins, and broken pull rods. These mechanical faults can cause the connecting rods to fall off, resulting in short circuits in the internal circuits of the switchgear and single-phase grounding accidents. In severe cases, it can lead to insensitive operation of the entire switchgear, and even the inability to close or open the switch. In addition to the above faults, the main reasons for other faults in the switchgear are operator and maintenance personnel’s misoperation, or snakes, mice, etc. entering the switchgear, causing equipment short circuits.

Common troubleshooting measures for 10kV switchgear

Carry out equipment installation and debugging work well

When the 10kV switchgear is transported to the mine surface substation, installation and debugging work should be strengthened to lay the foundation for the continuous and stable operation of the equipment in the future. The complete debugging of the switchgear is an important means of preliminary troubleshooting of equipment faults. When debugging the switchgear, it is necessary to eliminate whether the insulation gap inside the equipment meets the requirements, whether there is jamming in the transmission, and other situations that do not meet the requirements, in order to create good conditions for future equipment operation. When equipment malfunctions are found during the installation and debugging process, the installation and debugging personnel should immediately report to the mine management personnel and communicate with the equipment manufacturer for handling.

Improve the insulation performance of switchgear

Due to the harsh environment in which the mine is located, high equipment workload, and the need to work for a long time in a high-voltage environment, higher requirements are placed on the insulation performance of the switchgear. Mining 10kV switchgear should pay attention to the insulation performance of the equipment in the early stage of material selection. High standard and high-quality materials can make the switchgear work better and reduce the probability of insulation failure of the equipment. When selecting a switchgear, the first thing to choose is to use an organic insulation material with better insulation performance. At the same time, the components used inside the switchgear should have better insulation performance, and there should be a flame retardant partition in the middle. The voltage transformer should pay special attention to its volt ampere characteristics. For switchgear that has been in service for a long time, attention should be paid to equipment cleaning to minimize the possibility of switchgear failure caused by dust.

Seal the switchgear properly

The sealing performance of switchgear is closely related to its safe operation, and good sealing is an important condition to ensure the safe and efficient operation of switchgear. Firstly, the protection level of the internal partitions of the switchgear should be strengthened. The internal structure of the switchgear mainly includes circuit breakers, busbars, and cables. These components are divided into small compartments using flame-retardant insulation partitions. If a compartment malfunctions, it will not cause adjacent compartments to malfunction, preventing the fault from expanding. The plugs used inside the equipment should be covered with insulation to protect the safety of operators and maintenance personnel.

In terms of mechanical operation of the switchgear, it is necessary to strictly observe according to regulations and replace it in a timely manner when problems are found.

Strengthen the regular maintenance and management of switchgear based on the actual situation of the mine. Based on the specific model and service life of the equipment, a reasonable equipment maintenance and repair plan should be formulated. In the specific implementation process, targeted maintenance and repair should be carried out according to the actual situation of the equipment, while following the rules and regulations. When maintaining the equipment, pay attention to observing whether the switchgear has any odor, color, sound, vibration, or other abnormalities. After discovering the above issues, it is necessary to conduct a comprehensive investigation of the switchgear.

Strengthen the inspection of the switchgear and timely grasp the operating status of the switchgear. During the inspection process of the switchgear, be careful and meticulous. Sometimes, a small discharge inside the switchgear may turn into an insulation accident during the next inspection. At the same time, infrared equipment is used to detect the conductive lines and connections inside the switchgear that are prone to temperature abnormalities. Once abnormalities are detected, the working load of the switchgear should be appropriately reduced to avoid further temperature rise and cause faults.

Develop preventive measures

For the malfunction of 10kV switchgear caused by misoperation, on the one hand, the mine should establish reliable and complete rules and regulations, and strictly implement them. On the other hand, it should strengthen the training of switchgear maintenance and repair personnel, improve their professional skills, and prevent misoperation. During the daily inspection of the switchgear, any problems found should be promptly reported and dealt with.

10kV switchgear is widely used in mines, and due to the harsh mining environment, the switchgear operates at high loads for a long time. The problems and types of faults that occur during operation are also diverse. Therefore, the author has conducted a statistical analysis of common faults in switch cabinets in mines in recent years, summarized the common types of faults, and proposed targeted measures from the installation and debugging of switch cabinets, improving insulation performance of switch cabinets, doing well in switch cabinet sealing, strengthening regular maintenance and management of switch cabinets, and formulating preventive measures to reduce the possibility of faults in 10kV switch cabinets and improve mine power supply safety.