Fully Insulated inflatable cabinetsIt is a kind of switchgear with wide application. Due to the design, manufacture, installation, operation and maintenance of some minor problems, occasionally there will be some problems. Most of these accidents occur at voltage levels of 10,000 volts and above, and the consequences are severe. In particular, car switchgear, insulation accident rate is high, and frequent accidents, will endanger the safety of peripheral equipment.

The cause of the accident of the fully insulated inflatable cabinet is analyzed from the following aspects:
(1) Insufficient climbing distance or air gap
Insufficient climbing distance and excessive air gap are the main causes of insulation damage accidents in inflatable cabinets. In particular, the handcart cabinet, in order to shorten the size of the cabinet, greatly reduce the circuit breaker installed in the cabinet, isolating the distance between the plug or the ground distance, but did not take effective measures to ensure the insulation strength.
(2) Poor manufacturing quality and process
Manufacturing quality and assembly quality have a great influence on the overall pressure level of the inflatable cabinet. Some components in the cabinet can pass the voltage test, but the whole cannot pass because the assembly quality is poor. If the fastening screws are irregular, tighten the screws to grow too many nuts, which not only shortens the insulation distance, but also causes the local electric field to be concentrated. In addition, due to the poor quality and poor dynamic stability of the supporting ceramic column, the fracture occurred under the impact of short-circuit current, which led to the expansion of the accident.
(3) Insufficient contact capacity or poor exposure
When the contact capacity is insufficient or the contact is poor, the local temperature rises. When the contact is serious, the carrier part burns, causing grounding or phase flashover, resulting in insulation flashover. It was previously reported that the hot burning of the pile head under the knife gate caused the substation to short-circuit, triggering a fire and explosion accident.
(4) Impact of environmental conditions
The main cause of insulation accident is the environmental conditions of the inflatable cabinet. Air pollution intensifies, gradually polluting the electrical equipment of insulators, casing and busbar.

The design of the fully insulated inflatable cabinet must choose the switching elements with high reliability and sufficient insulation level, so that the inflatable cabinet becomes a maintenance-free switchgear. At the same time, the primary circuit in the inflatable housing is not affected by the external environment. The filled SF6 or nitrogen is oxygen-free, and the water content is controlled at a low level to prevent insulation failure caused by contamination, condensation and oxidation corrosion of metal parts.