What are the requirements of composite insulators for sheaths and umbrella skirts?
The sheath and umbrella skirt of composite insulators are very important. So today, let's talk about the requirements of composite insulators for sheaths and umbrella skirts. Sheath and umbrella skirt are the external insulation parts of composite insulators. Their main functions are to protect the mandrel from the effects of climate and electric erosion, and to provide the required creepage distance. Sheaths and umbrella skirts are made of silicone rubber. The sheath and umbrella skirt of composite insulator should be manufactured by integrated moulding 10KV wall-piercing bushing quotation (injection or hot-pressing moulding) process, and 500KV umbrella-piercing by extrusion is permitted. The interface between sheath and mandrel of composite insulator and between umbrella skirt and sheath should be permanent bonding. The bonding part should be firm and compact, without bubbles and cracks, in order to prevent dirt and water from entering, and the bonding strength should be greater than the tearing strength of the silicone rubber material itself.
The requirements for composite insulator sheaths and umbrella skirts are as follows:
(1) Weather resistance to prevent rapid deterioration caused by ozone, ultraviolet light, humidity, high and low temperatures of high-voltage circuit breakers.
(2) Leakage mark resistance and electrical erosion resistance shall meet the requirements of Article 5.6 of GB/T 19519-2004 in order to prevent the formation of conductive channels and the breakdown of sheaths and umbrella skirts.
(3) The flame retardancy and AC dielectric strength test of sheath and umbrella skirt materials shall meet the requirements of GB/T 19519-2004, Article 5.5 and DL/T 864-2004, Article 4.3.3b, respectively.
(4) The hydrophobicity of sheath and umbrella skirt materials should meet the requirements of DL/T 864-2004.
(5) The sheaths and umbrella skirts of high voltage insulators have high tear strength to prevent damage during handling and installation. Their mechanical tensile and tear strength should meet the requirements of DL/T 864-2004 Article 4.3.3 d, e, F and G.
(6) High hydrolysis resistance to prevent the increase of electrical conductivity. The volume resistivity of the umbrella sleeve material of high voltage disconnector should meet the requirements of DL/T 864-2004 Article 4.3.3a).
(7) High flexibility should be maintained within the temperature range of the service environment in order to prevent cracks or cracks from occurring when the temperature changes sharply at low temperatures and temperatures. In order to ensure the effectiveness and durability of mandrel protection, the connecting interface (mandrel? Sheath, sheath? Fittings) must be of high quality.
(8) Silicone rubber with high temperature setting must be used for end seal. (9) The umbrella group of composite insulators must adopt the size umbrella structure designed to prevent icing.