جهد عال
جهد عال مصطلح جهد عال يميز الدوائر الكهربائية ، التي تستخدم الجهد هو سبب وخاصة المخاوف المتعلقة بالسلامه ومتطلبات العزل. جهد عال تستخدم في توزيع الطاقة الكهربائية، وأنابيب اشعه القطب السالب ، لتوليد الاشعه السينيه والجسيمات الحزمه ، لاثبات الإنحناء ، لالاشتعال ، في photomultiplier الانابيب ، ومكبر للصوت عالية فراغ السلطة الأنابيب وغيرها من التطبيقات العلميه والصناعية.
تعريف
قالب:IEC 61140 voltage bands The numerical definition of high voltage depends on context. Two factors considered in classifying a voltage as high voltage are the possibility of causing a spark in air, and the danger of electric shock by contact or proximity.
The International Electrotechnical Commission and its national counterparts (IET, IEEE, VDE, etc.) define high voltage as above 1000 V for alternating current, and at least 1500 V for direct current.[1] in IEC 61140.
In the United States, the American National Standards Institute (ANSI) establishes nominal voltage ratings for 60 Hz electric power systems over 100 V. Specifically, ANSI C84.1-2020 defines high voltage as 115 kV to 230 kV, extra-high voltage as 345 kV to 765 kV, and ultra-high voltage as 1,100 kV.[2] British Standard BS 7671:2008 defines high voltage as any voltage difference between conductors that is higher than 1000 VAC or 1500 V ripple-free DC, or any voltage difference between a conductor and Earth that is higher than 600 VAC or 900 V ripple-free DC.[3]
Electricians may only be licensed for particular voltage classes in some jurisdictions.[4] For example, an electrical license for a specialized sub-trade such as installation of HVAC systems, fire alarm systems, closed-circuit-television systems may be authorized to install systems energized up to only 30 volts between conductors, and may not be permitted to work on mains-voltage circuits. The general public may consider household mains circuits (100 to 250 VAC), which carry the highest voltages they normally encounter, to be high voltage.
Voltages over approximately 50 volts can usually cause dangerous amounts of current to flow through a human being who touches two points of a circuit, so safety standards are more restrictive around such circuits.
In automotive engineering, high voltage is defined as voltage in range 30 to 1000 VAC or 60 to 1500 VDC.[5]
The definition of extra-high voltage (EHV) again depends on context. In electric power transmission engineering, EHV is classified as voltages in the range of 345,000– 765,000 V.[6] In electronics systems, a power supply that provides greater than 275,000 volts is called an EHV Power Supply, and is often used in experiments in physics. The accelerating voltage for a television cathode ray tube may be described as extra-high voltage or extra-high tension (EHT), compared to other voltage supplies within the equipment. This type of supply ranges from 5 kV to about 30 kV.
The Unicode text character representing "high voltage" is U+26A1, the symbol "⚡︎".
وصلات خارجية
- Prevention of High Voltage Accidents
- NFPA 70E: Electrical Safety in the Workplace, USA
- Mike Holt NEC in the USA
- USA Department of Energy electrical safety handbook
- High voltage glossary
- [1] Vladimir Gurevich "Protection Devices and Systems for High Voltage Applications", CRC Press, London - New York, 2003, 292 p.
- ^ "Electrical installation rules, standards". 22 أغسطس 2010. Archived from the original on 22 أغسطس 2010. Retrieved 18 يوليو 2020.
- ^ "ANSI C84.1 - Electric Power Systems and Equipment - Voltage Ratings (60 Hertz) | Engineering360". standards.globalspec.com. Retrieved 18 يوليو 2020.
- ^ "Electrical safety".
- ^ One such jurisdiction is Manitoba, where the Electrician's Licence Act, CCSM E50 establishes classes of electrician's licences by voltage.
- ^ UNECE regulation No 100 (revision 2, 12 August 2013), paragraph 2.17 http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R100r2e.pdf
- ^ Gönen, T. (2014). Electrical Power Transmission System Engineering: Analysis and Design (3 ed.). CRC Press. p. 3,36. ISBN 9781482232233.