|
所在平台: Udemy |
课程主页: https://www.udemy.com/course/electrical-hazards/
课程评论：没有评论
课程名称：电气危害（印地语） 课程概述： 本课程旨在介绍电气实用知识，包括导体、绝缘体和接地等基础概念。导体是指电阻较小的物质，如金属；绝缘体是电阻较大的物质，如干木、橡胶、玻璃和酚醛树脂。接地是指与大地的电导连接，作为一种保护措施。课程强调了常见的电气危害，如烧伤、电击、电弧闪光、火灾和爆炸等。 电气能量的危害： 当电流流经人体时，会对身体产生影响。电流的基本单位是安培，流经1欧姆电阻的电流在1伏特的电压下产生。即使是几毫安的电流也可能对身体产生不良影响。 电气保护方法： 维护与高压电线的安全距离是至关重要的，课程中提供了不同电压下电线的安全间距表。同时，接地标准也被讨论，包括系统接地和设备接地的定义与重要性。接地的目的在于确保系统的安全和保护设备及人员避免因漏电而引发的危险。 危险区域的分类： - 区域0：此类区域持续存在危险气氛，任何火花都可能导致火灾或爆炸，因此必须保证电气设备具有绝对保护。 - 区域1：此类区域随时可能存在危险气氛，需要采取最大的实践措施来防止电气条件的危险。 - 区域2：此类区域只有在异常操作条件下才可能出现危险气氛，通常情况下不易引发火灾或爆炸。 课程旨在提高学员对电气安全的认识，并了解必要的保护措施和标准，以预防电气事故的发生。
Introduction•Conductors - substances, such as metals, that have little resistance to electricity•Insulators - substances, such as dry wood, rubber, glass and Bakelite, that have high resistance to electricity•Grounding - a conductive connection to the earth which acts as a protective measureBE SAFE:•Burns•Electrocution•Shock•Arc flash/arc blast•FireExplosionsHazards of Electrical Energy•Electric current affects the body when it flow through.•The basic unit of current is the amp.•This is applied across the current which flow through a resistance of 1 ohm, When a voltage of 1 volt is applied across it.•However, current as low as thousands of maps (milliamps) can have an adverse effect on the body.•The given table an illustration of the type of effects various of currents can have on the body.Electrical Protection MethodsMaintain safe distance from overhead power lines:•Staying away•Following table shows the safe power line clearance distance for various line voltages.Earthing Standard•Earthing means a low impedance return path of fualth current. Actually the earth now rarely serves as a part of the return path of the return Circuit but is being used mainly for fixing the Voltages of system neutrals.•Earthing of current carrying conductor is known as a system earthing, while that of non-current carrying conductor or metal work is known as Equipment Earthing.•The farmer is essential to the security of the system and the latter to the safety of persons, property, and animals•IS:3043, code of practice for Earthing and SP 30 National Elective Code must be referred for details of Earthing.Following is the synopsis of Earthing standards mentioned is Section 12, Part I of our National Electric Code:The purpose of system earthing is to preserve the security of the system.1. There should be two separate and distinct connections with earth through an earth electrode.2. The earth system resistance should be such that the fault should operate the protective gear(fuses or circuit breaker) to isolate the faulty portion.3.The purpose of equipment earthing is to protect the equipment from danger to life or risk ofFire due to leakage of current through the metal work and through the person in contact. TheLeaking current operates the protective gear due to earthing.4. In case of high and extra high voltages, the neutral points shall be earthed by two or moreSeparate electrodes.5. Earth electrodes shall be provided at generating stations, substations and consumer premisesas per requirements.Classification of Hazardous Areas•Zone 0 Areas: Here hazardous atmosphere exists continuously viz., the vapour space of closed. process vessels, storage tanks or closed containers. Any spark will certainly lead to fire or explosion. Therefore, any electrical apparatus in this zone must afford an absolute protection.•Zone 1 Areas: Here hazardous atmosphere is likely to exist at any time. Therefore the fullest. practicable measures should be applied to prevent a hazardous electrical condition at any time and in any circumstances•Zone 2 Areas: Here hazardous atmosphere is likely to occur only under abnormal operating conditions. This classification is applicable only where a fire or explosion hazard is unlikely and may be caused only by the simultaneous and improbable occurrence of an arc or spark resulting from an electrical failure and a hazardous atmosphere arising through failure of the conditions of control.
