铁道供电专业英语教学课件unit6.pptx

《铁道供电英语》Introduction to Railway Power Supply Systems项目六 高电压绝缘技术High-voltage Insulation TechnologyHigh-voltage Insulation TechnologyLearning ObjectivesAfter learning this unit, youll be able to: master the main technical terms related to high-voltage insulation technology learn about the insulation properties of different dielectrics learn about the types and functions of insulation tests for electrical equipment talk about high-voltage insulation technology in EnglishHigh-voltage Insulation Technology一Part One Lead-inDirections: Have you ever seen the situations shown in the following pictures? Read the descriptions and discuss the relationship between safety and insulation of electrical equipment.High-voltage Insulation Technology The picture on the left shows a transformer fire accident. When a short circuit occurs due to insulation damage inside a transformer, the strong electric current caused by the short circuit can set the transformer on fire, cut the power supply and burn out the equipment.High-voltage Insulation Technology The picture on the left shows the electric arc generated when a disconnector switch is opened. When electrical equipment is in a heavily polluted area, pollutants can accumulate on the surface of the equipment and a surface flashover (i.e. electric arc) is highly likely to occur in wet weather, which may cause a blackout.High-voltage Insulation Technology The picture on the left shows the high-voltage power transmission lines. The performance of insulators will be greatly weakened when they are covered in dirt，which is a common cause of the surface flashover on the insulators.High-voltage Insulation Technology The picture on the left shows workers wiping dirt off the surface of an insulator on outdoor electrical equipment to keep the surface clean and maintain good insulation performance.High-voltage Insulation Technology The picture on the left shows the silicone-rubber insulator umbrella skirt on an outdoor high-voltage disconnector,