What will happen if the contact of the high-voltage switchgear heats up

The relationship between the causes of faults in high-voltage switchgear and the heating of contacts

High voltage switchgear is indispensable in all aspects of production, transmission, supply, and utilization of electrical energy, with a very high utilization rate. The transmission, distribution, and adjustment of electrical energy can be achieved through high-voltage switchgear, which has a high position in various aspects related to electrical energy. The key factor to whether it can safely and stably achieve these functions is whether the electromagnetic interaction environment inside is stable. So, if the high-voltage switchgear is in a high heat state and its professional handling is not timely enough, it will cause serious faults in the high-voltage switchgear, which will have a significant impact on various aspects of electrical energy. According to the statistical results of past faults in high-voltage switchgear, it can be seen that the main cause of faults is their contacts. If a heating type fault occurs, it not only causes serious damage to the working performance of the facility itself, but also due to the complexity of its internal structure, the repair time will be long, affecting normal use and restricting the economic development related to electricity. The process of heating failure in facilities is accumulated over time, such as being in an abnormal operating environment for a long time or damage to its own structure, which can cause a sudden increase in the temperature of its contacts. An in-depth analysis is conducted on the actual situation of heating faults in high-voltage switchgear, as well as the causes and corresponding preventive measures.

What will happen if the contact of the high-voltage switchgear heats up

At present, many high-voltage switchgear cabinets used in the power industry are small car type adjustment power supply facilities, which have complete functions and good working performance. Based on past work operations, it can be seen that the most common malfunction of the small car type adjustment power supply facility is caused by the heating of its contacts. The contact heating causing equipment failure is a series of processes, not sudden, but caused by long-term incorrect operation of the facility or damage to the components of the facility itself. The probability of this phenomenon occurring is very high, leading to a significant impact on the economic development of various fields related to electricity production, supply, and industrial and agricultural production. Its adverse effects mainly include the following:
Firstly, increase the number of damaged facilities. If the contacts of the facilities do not generate heat in a timely manner and corresponding measures are not taken, it will lead to the gradual accumulation of heat from the contacts, which will be transmitted to other components of the facilities through copper busbar components, causing damage to the insulation parts between the facilities, leading to the occurrence of insulation breakdown accidents. There is also a high probability of causing serious facility damage accidents such as explosion damage to high-voltage insulation components, melting and deformation of various connecting wires, and explosion and fire of similar current sensors.
Secondly, the maintenance cycle of the facilities is too long. The internal structure of the small car type high-voltage switchgear is completely enclosed, and the variable frequency distribution equipment is disposable. If the facility malfunctions or is damaged due to heating, it needs to be completely powered off during maintenance, and multiple components need to be replaced, including the inner contacts, insulation components, auxiliary switches, etc. The space inside the high-voltage switchgear is very small, making maintenance and replacement very laborious, resulting in a long maintenance cycle of the facilities. Due to the constant power outage environment during maintenance, the power supply system is very unstable. Thirdly, it causes significant economic losses to the enterprise. If the high-voltage switchgear malfunctions or is damaged due to heating, it will not only cause significant economic losses to the power enterprise, but also lower the overall evaluation index of the power enterprise. Sudden power outages can also cause damage to many mechanical facilities, damage to production products, and confusion in production processes.

What are the reasons for contact heating in high-voltage switchgear

（1） The tension of the fixed spring on the outer edge of the plum blossom contact is insufficient
The fixed spring on the outer edge of the plum blossom type contact usually has insufficient tension due to factors such as its own material or not selecting a suitable model according to the joint form. The spring coil is not tight, and the resistance received by the contact increases, making the contact extremely prone to heating; After the contact heats up, the spring also heats up, and the elasticity of the spring coil increases, causing the heat of the contact to increase. If the contact heating phenomenon is caused by this reason, the edge spring and plum blossom contact should be replaced in a timely manner, and the truly suitable plum blossom contact made of excellent materials should be selected according to the joint situation. The tension of the edge spring should not be missed during the scheduled maintenance period of the circuit cutting facility.

（2） The connection between the transmission arm and the plum blossom contact is loose
The plum blossom contacts configured in circuit cutting facilities are usually connected by transmission arms and bolts. In daily work, due to the influence of electrical power and other factors, it is easy for the connection structure bolts to loosen to varying degrees, causing the received electrical resistance to increase, and the temperature of the connected part to rise. Heat is then transferred to the plum blossom contacts, causing the temperature of the fixed spring to increase. If the fixed spring is always in this operating state, the tension of the fixed spring will not be insufficient, and the spring spiral body is not tight, leading to the occurrence of plum blossom contact thermal accidents. During maintenance, it was noticed that both the fixed spring and the plum blossom contact in a high load cut-off circuit facility had blackened and heated up. Further inspection revealed that the connecting positions of the power transmission arm and the plum blossom contact were severely loose. The plum blossom contact showed a sliding ring phenomenon with a light touch. After reinforcing the bolts connecting the plum blossom contact and the power transmission arm, the overall heating problem was effectively controlled. For the heating phenomenon caused by problems in the connected part, it is necessary to strictly check whether there is any looseness in the connecting part between the plum blossom contact and the power transmission arm during the scheduled maintenance period of the circuit cutting facilities. If there is any looseness, it should be reinforced in a timely manner.

（3） The material of the fixed spring on the outer edge of the plum blossom contact does not meet the standard requirements
According to the design and practical application requirements of high-voltage switchgear, the fixed spring material on the outer edge of the plum blossom contact must be non-conductive magnetic material. The selection of this material can effectively prevent the heating phenomenon caused by the vortex flow of carrying current on the fixed spring during normal operation. Heating will increase the elasticity of the fixed spring, decrease the tension, and the tightening force of the spiral body is not enough, resulting in an increase in electrical resistance, causing the plum blossom contact to turn black and hot, and in severe cases, damage may occur. For the heating phenomenon caused by incorrect selection of fixed spring materials, it is necessary to require that the fixed spring material on the outer edge of the contact is non-conductive magnetic material when selecting high-voltage switchgear or purchasing plum blossom contact components to prevent the occurrence of heating phenomenon.

（4） Poor contact between the stationary contacts of the switchgear and the dynamic contacts of the circuit breaker facilities
The reason for this phenomenon is that during the installation process of the switchgear, the accuracy is insufficient or the precision of the various components of the produced switchgear cannot meet the actual set standards, resulting in varying degrees of displacement of the fixed contacts of the switchgear, leading to poor contact between the fixed contacts of the switchgear and the dynamic contacts of the circuit breaker facilities. At the same time, mismatched models of backup circuit breaker facilities can also cause this phenomenon to occur. For the phenomenon of poor contact between fixed and dynamic contacts, the production enterprise should first be required to strictly control the accuracy and installation technology of various components of the switchgear. When installing fixed and dynamic contacts, a model that completely matches the switchgear should be selected. If it is necessary to use backup cut-off circuit facilities with different models during actual operation, the first step is to ensure that the steady-state and static contacts can conduct contact well, and to strictly control the resistance value at the connection.
In the daily work of various facilities related to electricity, it is necessary to first avoid heating of the contacts of high-voltage switchgear. If the contact generates heat, it will have a significant impact on the load capacity of the entire electrical energy system, and in severe cases, it may even lead to damage to high-voltage switchgear, circuit breaker facilities, etc. Timely measures should be taken to address the specific reasons for the increase in contact temperature of switchgear, in order to minimize the adverse consequences caused by heating. At the same time, it is necessary to use the temperature measurement device of the switchgear to monitor the temperature of the switchgear contacts in real-time, fundamentally reducing the incidence of heating accidents.