High voltage switchgear is a very important electrical equipment in the power system. The deterioration of the operating status of the switchgear is one of the reasons for power system failures. So, what are the common faults of high-voltage switchgear?
(1) Outdoor and indoor.
From the placement of high-voltage switchgear, it can be divided into outdoor and indoor types, with indoor types mostly used for 10KV and below. According to different primary line schemes, it can be divided into incoming and outgoing line switchgear, interconnecting oil switchgear, busbar segmented switchgear, etc. The low oil circuit breaker or vacuum circuit breaker is installed in the 10KV incoming and outgoing switchgear. The operating mechanisms of circuit breakers are mostly spring operated or electromagnetic operated mechanisms, as well as manual or permanent magnet operated mechanisms. There are significant differences in the structure of different switchgear cabinets, which can affect the selection and installation of sensors.
(2) Fixed and movable.
From the use of high-voltage switchgear, it can be divided into fixed and separated types. In the past, the power system of power plants used to use separate switchgear, while the power system used more fixed cabinets. With the progress of technology and the successful development of new products, many habits are also changing. For example, the metal armor separation switchgear was developed on the basis of fixed switchgear. The metal armor separation cabinet is a fully enclosed structure, with each functional room separated from each other. The normal operation performance and misoperation function are perfect and reasonable, and maintenance is convenient, greatly improving the safety and reliability of operation.
(3) The development of high-voltage switchgear.
In recent years, with the development and promotion of small vacuum circuit breaker technology, the new development of central switchgear as metal enclosed armored switchgear has been rapid. The intermediate cabinet has many advantages, the most important of which is the miniaturization of the handcart and the mechanization of the production process, making the production of the handcart and guide rail more accurate. Even many manufacturers' products, including main circuit breakers and cabinets, do not require one-on-one debugging at the factory. After delivery to the site, the commissioning is also easy to succeed, which can also ensure the flexibility and convenience of handcart access. Due to good product exchange, the impact of on-site ground level conditions is minimal. The metal armored switchgear operates safely and reliably, with convenient maintenance. Therefore, more and more power supply systems are being used.
Analysis of the causes of faults in high-voltage switchgear often occurs in insulation, conductivity, mechanical and other aspects.
(1) Refusal to move, malfunction.
This type of fault is the main fault of high-voltage switchgear, and the reasons can be divided into two categories. One is caused by mechanical faults in the operating mechanism and transmission system, specifically manifested as mechanism jamming, component deformation, displacement or damage, loose switch core, jamming, loose shaft pin, tripping fault, etc. Another type is caused by electrical control and auxiliary circuits, manifested as poor secondary wiring contact, loose terminals, wiring errors, mechanism jamming or burning of transfer switches, poor switching of auxiliary switches, operating power supply, switch contactors, microswitches, and other faults. WeChat skill training is worth your attention.
(2) Switch failure.
This fault is caused by the circuit breaker body. For low oil circuit breakers, the main manifestations are fuel injection short circuit, arc extinguishing chamber burning, insufficient opening capacity, and explosion during closing. For vacuum circuit breakers, it is manifested as air leakage in the arc extinguishing chamber and bellows, reduced vacuum, reignition of the capacitor bank, and ceramic tube rupture.
(3) Insulation fault.
The insulation level is the correct handling of the relationship between various voltages (including operating voltage and overvoltage) acting on insulation, various voltage limiting measures, and insulation strength. Strive to make the product both safe and economical, and achieve better economic benefits. Insulation faults mainly manifest as external insulation flashover, internal insulation flashover, interphase insulation flashover, lightning overvoltage flashover, porcelain bottle bushing, capacitor bushing flashover, dirty flashover, breakdown, explosion, lifting rod flashover, CT flashover, breakdown, explosion, porcelain bottle fracture, etc.
(4) Current carrying fault.
The main cause of load failure at voltage levels of 72-12KV is poor contact of the isolation plug in the switchgear, which leads to contact melting.
(5) External force and other faults.
Other external forces and unexpected failures include foreign object impact, natural disasters, small animal short circuits, etc.
