Abstract: in 1987, technical committee 17D of International Electrotechnical Commission (IEC) drafted a technical document entitled "requirements on insulation coordination in Supplement 1 to iec439", which formally introduced insulation coordination into low-voltage switchgear and control equipment. As far as the actual situation of our country is concerned, the insulation coordination of equipment is still a big problem in high and low voltage electrical products, and since the concept of insulation coordination is formally used in low-voltage switchgear and control equipment, it is only in recent two years. Therefore, it is an important problem to correctly handle and solve the insulation coordination problem in products.

Abstract: insulation coordination is an important issue related to the safety of electrical equipment products, which has always been paid attention to from all aspects. Insulation coordination was first used in high voltage electrical products. In China's electrical products, the accidents caused by insulation system account for 50% - 60%, and since the concept of insulation coordination is formally used in low-voltage switchgear and control equipment, it is only in recent two years. Therefore, it is an important problem to correctly handle and solve the problem of insulation coordination in products, which should be given enough attention.

Under the sea crossing bridge connecting Beilun District and Meishan island free trade zone in Ningbo, Zhejiang Province, six "electric silver snakes" meander along the bridge towards Meishan island port area. In June this year, with the commissioning of the 110kV Qixing power transmission and transformation project, this cross sea power channel will send a continuous stream of power to the port area.

The cable branch box belongs to the floor type box, with small volume and small floor area. If some branch box covers an area of 0.65m2, the floor area with SF6 switch is only 1.45m2; the appearance is beautiful and will not cause damage to the appearance of the town.

American cable branch box is a kind of cable engineering equipment which is widely used in North American power distribution network system. It is characterized by one-way door opening and transverse multi-channel bus bar. It has the advantages of small width, flexible combination, full insulation and full sealing. According to the rated current, it can be divided into 600A main circuit and 200A branch circuit. The 600A main circuit adopts screw in bolt fixed connection; the 200A branch circuit adopts plug-in connection, and can be pulled and inserted with load. The cable joint used in American cable branch box conforms to ieee386 standard.

China Southern Power Grid Guangdong company announced recently that its intelligent inspection robot has been put into use, which is expected to realize 24-hour monitoring of substation, which will improve the intelligent level of power system. The first robot to be put into use started working in Yunfu 500kV Wolong substation of Guangdong power grid on November 4.

Jinan, November 11 (people's daily) in the early morning of November 11, with the success of the impact power transmission of the newly expanded 1000 kV transformer substation, the expansion project of quanzheng 1000 kV substation, the first UHV substation in Shandong Province, operated smoothly.

"110kV one two bus and all outgoing lines, 10kV all outgoing lines and 9012 switch for cold standby." At 21:59 on November 10, with the last power transmission instruction issued by the dispatching office of Baotou Power Supply Bureau, the 220kV Dongliang substation was successfully started. The Bureau has taken a solid step in assisting Baotou photovoltaic "leader" project and promoting local economic development.