High-voltage switchgear is a very important electrical equipment in the power system. Deterioration of the operating state of the switchgear is one of the reasons for the failure of the power system. So, what are the common faults of high-voltage switchgear?

(1) Outdoor and indoor

In terms of the placement of the high-voltage switchgear, it can be divided into two types: outdoor type and indoor type. For 10KV and below, the user's internal type is mostly adopted. According to the different primary circuit schemes, it can be divided into incoming and outgoing line switch cabinets, contact oil switch cabinets, bus section cabinets, etc. More oil-less circuit breakers or vacuum circuit breakers are installed in the 10KV inlet and outlet switch cabinets. The operating mechanisms of the circuit breakers are mostly spring operating mechanisms or electromagnetic operating mechanisms, and there are also manual operating mechanisms or permanent magnet operating mechanisms. . Different switch cabinets have big differences in structure, which will affect the selection and installation of sensors.

(2) Fixed and removable

From the use of high-voltage switchgear, it can be divided into fixed type and removable type. In the past, the auxiliary power system of power plants used to use removable switch cabinets, while the power supply system used more fixed cabinets. With the progress of science and technology and the continuous development of new products, many idioms are also changing. For example, metal armored removable switch cabinets are developed on the basis of fixed switch cabinets. The metal armored removable switchgear is a fully enclosed structure, and the functional compartments are separated from each other. The normal operation performance and anti-misoperation functions are perfect and reasonable, the maintenance is convenient, and the safety and reliability of its operation are greatly improved.

(3) Development of high-voltage switchgear

In recent years, with the development and promotion of small vacuum circuit breaker technology, the new development of middle-mounted switchgear as a metal-enclosed armored removable switchgear has been rapidly developed. There are many advantages of the middle cabinet. The most important thing is the miniaturization of the handcart and the mechanization of the production process, so that the production of the handcart and the guide rail is more accurate. There are even many manufacturers’ products. Their handcarts, including the main circuit breaker and the cabinet, do not need to be debugged one-to-one in the factory. After they are shipped to the site at the factory, they are easy to debug successfully, and the handcart can be flexibly and conveniently in and out. . Because the product has good interchangeability, it is not affected by the ground level conditions on site. This metal armored removable switchgear is safe and reliable in operation and convenient for maintenance. Therefore, more and more power supply systems are used.

2. Analysis of common failures of high-voltage switchgear

Analyze the reasons for the failure of high-voltage switchgear, mostly in insulation, electrical conductivity and mechanical aspects.

(1) Failure to move or malfunction

This kind of failure is the most important failure of high-voltage switchgear, and its causes can be divided into two categories. The first type is caused by mechanical failures of the operating mechanism and transmission system, which are specifically manifested as mechanism jamming, component deformation, displacement or damage, loosening and jamming of the opening and closing iron core, loose shaft pin, and tripping failure. The other type is caused by electrical control and auxiliary circuits, manifested by poor secondary wiring, loose terminals, incorrect wiring, opening and closing coils burned due to jamming of the mechanism or poor transfer switches, poor switching of auxiliary switches, and operation Failure of power supply, closing contactor, micro switch, etc. Wechat technical training is worthy of your attention.

(2) Breaking and closing faults

This type of fault is caused by the circuit breaker itself. For a low-fuel circuit breaker, it is mainly manifested as a short circuit of fuel injection, burning of the arc extinguishing chamber, insufficient breaking capacity, and explosion during closing. For vacuum circuit breakers, the performance is air leakage in the arc extinguishing chamber and bellows, reduced vacuum, reignition of the capacitor bank, and rupture of the ceramic tube.

(3) Insulation failure

Insulation level is to correctly handle the relationship between various voltages (including operating voltage and various overvoltages) acting on the insulation, various voltage limiting measures, and insulation strength. Strive to make products safe and economical, and get the best economic benefits. Insulation faults are mainly manifested as external insulation-to-ground flashover breakdown, internal insulation-to-ground flashover breakdown, phase-to-phase insulation flashover breakdown, lightning overvoltage flashover breakdown, porcelain casing, capacitor bushing , Pollution flashover, breakdown, explosion, lifting pole flashover, CT flashover, breakdown, explosion, porcelain bottle fracture, etc.

(4) Current-carrying fault

The main reason for the current-carrying faults in the voltage level of 72～12KV is the poor contact of the switchgear isolation plug, which causes the contacts to melt.

(5) External forces and other failures

Including foreign body impact, natural disasters, short-circuiting of small animals and other unknown external forces and accidental failures.