Types and common fault analysis of high-voltage switchgear

High-voltage switchgear is a very important electrical equipment in the power system. The deterioration of the operation status of the switch cabinet 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

According to the arrangement of high-voltage switch cabinet, it can be divided into outdoor type and indoor type. For 10KV and below, the indoor type is mostly adopted. According to different primary line schemes, it can be divided into incoming and outgoing line switch cabinet, interconnection oil switch cabinet, bus section cabinet, etc. Low-oil circuit breaker or vacuum circuit breaker are mostly installed in the 10KV incoming and outgoing line switch cabinet. The operating mechanism of the circuit breaker is mostly spring operating mechanism or electromagnetic operating mechanism, and some are equipped with manual operating mechanism or permanent magnetic operating mechanism. Different switch cabinets have great 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, the metal armored removable switchgear is developed on the basis of fixed switchgear. The metal-armoured removable switch cabinet is a fully enclosed structure, with each functional compartment separated from each other. The normal operation performance and anti-misoperation function are more perfect and reasonable, and the maintenance is convenient. 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 miniature vacuum circuit breaker technology, the new development of the mid-mounted switchgear as a metal-enclosed armored removable switchgear has developed rapidly. The central cabinet has many advantages. The most important thing is the miniaturization of the handcart and the mechanization of the manufacturing process, which makes the handcart and guide rail more accurate. There are even many manufacturers' products. The handcart, including the main circuit breaker and the cabinet, need not be debugged one-to-one in the factory. It is also easy to debug successfully after the handcart is delivered to the site at the time of delivery, and it can also ensure the flexible and convenient access of the handcart. Because of the good interchangeability of the product, it is little affected by the site ground level conditions. This metal armored removable switch cabinet is safe and reliable in operation and convenient in maintenance. Therefore, more and more power supply systems are used.

2、 Analysis of common faults of high-voltage switchgear

Analyze the causes of high-voltage switch cabinet failures, which mostly occur in insulation, conductivity and mechanical aspects.

（1） Misoperation and misoperation fault

This kind of fault is the main fault of high-voltage switchgear, and its causes can be divided into two categories. One is caused by the mechanical failure of the operating mechanism and transmission system, which is specifically manifested as the jamming of the mechanism, deformation, displacement or damage of the components, loose and jamming of the opening and closing iron core, loose and broken shaft pin, tripping failure, etc. The other is caused by electrical control and auxiliary circuit, which is manifested as poor contact of secondary wiring, loose terminal, wrong wiring, burning of opening and closing coil due to jamming of mechanism or poor change-over switch, ineffective switching of auxiliary switch, as well as operating power supply, closing contactor, micro switch and other faults. WeChat technology training deserves your attention.

（2） Breaking and closing fault

This kind of fault is caused by the circuit breaker body. For the oil-less circuit breaker, the main manifestations are short circuit of oil injection, burning loss of arc extinguishing chamber, insufficient breaking capacity, explosion during closing, etc. For vacuum circuit breaker, it is manifested as air leakage of arc extinguishing chamber and bellows, vacuum reduction, re-ignition of capacitor bank, ceramic tube rupture, etc.

（3） Insulation fault

Insulation level is to correctly handle the relationship between various voltages (including operating voltage and overvoltage), various voltage limiting measures and insulation strength acting on insulation. Strive to make the products safe and economical, and obtain the best economic benefits. Faults in insulation mainly include external insulation to ground flashover, internal insulation to ground flashover, interphase insulation flashover, lightning overvoltage flashover, porcelain insulator bushing, capacitor bushing flashover, pollution flashover, breakdown, explosion, lifting rod flashover, CT flashover, breakdown, explosion, porcelain insulator breakage, etc.

（4） Current-carrying fault

The main reason for the current-carrying fault of 72-12KV voltage level is that the contact is burnt due to poor contact of the isolating plug of the switch cabinet.

（5） External force and other faults

Including foreign body impact, natural disasters, short circuit of small animals and other unknown external forces and unexpected failures.