1、 What does GIS switchgear mean? The definition of GIS is: metal enclosed switchgear that uses all or part of the gas instead of the air under atmospheric pressure as the insulating medium, also known as gas filled switchgear. GIS is a high-voltage switch cabinet composed of 7 kinds of high-voltage electrical appliances, including circuit breaker, bus, disconnector, voltage transformer, current transformer, lightning arrester and bushing, which is called fully insulated and fully enclosed metal switchgear. The GIS gas filled cabinet uses SF6 gas with excellent insulation and arc extinguishing performance as the insulation and arc extinguishing medium, and seals all high-voltage electrical components in the grounding metal cylinder. Compared with the traditional open high-voltage switch cabinet, the GIS high-voltage switch cabinet has small floor area, all components are sealed and free from environmental interference, high operation reliability, convenient operation, long maintenance cycle, small maintenance workload, rapid installation, low operation cost No electromagnetic interference and other advantages. After years of development, GIS gas filled cabinet has matured in technology and gradually become the mainstream cabinet type in the high-voltage switchgear market.
2、 The difference between GIS switch cabinet and AIS switch cabinet. There are three types of high-voltage power distribution devices we commonly use: the first is a conventional air insulated power distribution device, referred to as AIS, whose bus is exposed and directly contacts with the air; The second is the hybrid power distribution device, referred to as H-GIS. Busbars are open type, and others are sulfur hexaoxide gas insulated switchgear; The third is sulfur hexaoxide gas insulated totally enclosed power distribution device, referred to as GIS. Now let's understand the difference between GIS switchgear and AIS switchgear.
(1). The structure of GIS is different. In terms of the shell structure, GIS is divided into three phases, simplified and compound. The shell of GIS has developed from phase separation to three-phase common simplification, which further miniaturizes GIS. At present, 300 kV all three phases have been simplified internationally, and 550 kV bus three-phase has been in the same barrel.
(2). GIS switchgear with different areas has small floor area, small volume, light weight, and all components are sealed without environmental interference. The operating mechanism is free of oil and gasification, and has high operation reliability. GIS is transported in one piece, which is convenient for installation, short in cycle and low in installation cost; The maintenance workload is small and the time is short. Three phase mechanical linkage is adopted for the common box GIS, so the mechanical failure rate is low.
(3). The circuit breaker with superior breaking performance adopts a self energy arc extinguishing chamber based on the new arc extinguishing principle (a hybrid structure of self energy thermal expansion and auxiliary air compressor), which makes full use of the energy of the arc itself. Gas insulated totally enclosed combined electrical apparatus. The enclosed electrical apparatus mainly include circuit breakers, disconnectors, grounding switches, buses, lightning arresters and other primary equipment. The switchyard of many power plants and substations is made of GIS, which covers a small area and is easy to maintain. It is different from high-voltage switchgear.
(4). Low loss and noise The induced magnetic field on the GIS enclosure is very small, so the full current loss is very small, reducing the power loss. The use of the barrel mechanism makes the operation noise very low.
Disadvantages: GIS has the disadvantages of high price, inconvenient installation and testing, poor flexibility, and inconvenient maintenance and expansion. It can be seen that although GIS performance is better than AIS, AIS will not completely exit for quite some time due to differences in cost and management capability.
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