-
1 длительный допустимый ток
- courant permanent admissible, m
- courant admissible, m
(длительный) допустимый ток
Максимальное значение электрического тока, который может протекать длительно по проводнику, устройству или аппарату при определенных условиях без превышения определенного значения их температуры в установившемся режиме
[ ГОСТ Р МЭК 60050-826-2009]
Этот ток обозначают IZ
[ ГОСТ Р 50571. 1-2009 ( МЭК 60364-1: 2005)]EN
(continuous) current-carrying capacity
ampacity (US)
maximum value of electric current which can be carried continuously by a conductor, a device or an apparatus, under specified conditions without its steady-state temperature exceeding a specified value
[IEV number 826-11-13]
ampacity
The current in amperes that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
[National Electrical Cod]FR
courant (permanent) admissible, m
valeur maximale du courant électrique qui peut parcourir en permanence, un conducteur, un dispositif ou un appareil, sans que sa température de régime permanent, dans des conditions données, soit supérieure à la valeur spécifiée
[IEV number 826-11-13]Ampacity, the term is defined as the maximum amount of current a cable can carry before sustaining immediate or progressive deterioration. Also described as current rating or current-carrying capacity, is the RMS electric current which a device can continuously carry while remaining within its temperature rating. The ampacity of a cable depends on:
- its insulation temperature rating;
- conductor electrical properties for current;
- frequency, in the case of alternating currents;
- ability to dissipate heat, which depends on cable geometry and its surroundings;
- ambient temperature.
Electric wires have some resistance, and electric current flowing through them causes voltage drop and power dissipation, which heats the cable. Copper or aluminum can conduct a large amount of current before melting, but long before the conductors melt, their insulation would be damaged by the heat.
The ampacity for a power cable is thus based on physical and electrical properties of the material & construction of the conductor and of its insulation, ambient temperature, and environmental conditions adjacent to the cable. Having a large overall surface area may dissipate heat well if the environment can absorb the heat.
In a long run of cable, different conditions govern, and installation regulations normally specify that the most severe condition along the run governs the cable's rating. Cables run in wet or oily locations may carry a lower temperature rating than in a dry installation. Derating is necessary for multiple circuits in close proximity. When multiple cables are near, each contributes heat to the others and diminishes the amount of cooling air that can flow past the individual cables. The overall ampacity of the insulated conductors in a bundle of more than 3 must be derated, whether in a raceway or cable. Usually the de-rating factor is tabulated in a nation's wiring regulations.
Depending on the type of insulating material, common maximum allowable temperatures at the surface of the conductor are 60, 75 and 90 degrees Celsius, often with an ambient air temperature of 30°C. In the U.S., 105°C is allowed with ambient of 40°C, for larger power cables, especially those operating at more than 2 kV. Likewise, specific insulations are rated 150, 200 or 250°C.
The allowed current in cables generally needs to be decreased (derated) when the cable is covered with fireproofing material.
For example, the United States National Electric Code, Table 310-16, specifies that up to three 8 AWG copper wires having a common insulating material (THWN) in a raceway, cable, or direct burial has an ampacity of 50 A when the ambient air is 30°C, the conductor surface temperature allowed to be 75°C. A single insulated conductor in air has 70 A rating.
Ampacity rating is normally for continuous current, and short periods of overcurrent occur without harm in most cabling systems. The acceptable magnitude and duration of overcurrent is a more complex topic than ampacity.
When designing an electrical system, one will normally need to know the current rating for the following:- Wires
- Printed Circuit Board traces, where included
- Fuses
- Circuit breakers
- All or nearly all components used
Some devices are limited by power rating, and when this power rating occurs below their current limit, it is not necessary to know the current limit to design a system. A common example of this is lightbulb holders.
[http://en.wikipedia.org/wiki/Ampacity]
Тематики
- электротехника, основные понятия
Синонимы
EN
DE
- Dauerstrombelastbarkeit, f
- Strombelastbarkeit, f
FR
- courant admissible, m
- courant permanent admissible, m
Русско-французский словарь нормативно-технической терминологии > длительный допустимый ток
См. также в других словарях:
Need for Speed: Most Wanted — North American cover art for Windows version Developer(s) EA Black Box, EA Redwood Shores, Ideaworks Game Studio (Mobile Version) Publi … Wikipedia
Physical dependence — refers to a state resulting from chronic use of a drug that has produced tolerance and where negative physical symptoms[1] of withdrawal result from abrupt discontinuation or dosage reduction.[2] Physical dependence can develop from low dose… … Wikipedia
physical science — physical scientist. 1. any of the natural sciences dealing with inanimate matter or with energy, as physics, chemistry, and astronomy. 2. these sciences collectively. [1835 45] * * * Introduction the systematic study of the inorganic world … Universalium
Physical fitness — can be achieved through physical exercise. Physical fitness comprises two related concepts: general fitness(a state of health and well being), and specific fitness (a task oriented definition based on the ability to perform specific aspects of… … Wikipedia
Need for Speed: High Stakes — Developer(s) EA Canada Publisher(s) Elec … Wikipedia
Physical access — is a term in computer security that refers to the ability of people to physically gain access to a computer system. According to Gregory White, Given physical access to an office, the knowledgeable attacker will quickly be able to find the… … Wikipedia
Physical Effects of Abstinence — Physical Effects of Abstinence † Catholic Encyclopedia ► Physical Effects of Abstinence The effects on the human system of abstinence from flesh meats divide themselves naturally and logically into two parts: ♦ Effects due to… … Catholic encyclopedia
Physical information security — is concerned with physically protecting data and means to access that data (apart from protecting it electronically). Many individuals and companies place importance in protecting their information from a software and/or network perspective, but… … Wikipedia
Physical inventory — is a process where a business physically counts its entire inventory. A physical inventory may be mandated by financial accounting rules or the tax regulations to place an accurate value on the inventory, or the business may need to count… … Wikipedia
Physical timing closure — is the process by which an FPGA or a VLSI design with a physical representation is modified to meet its timing requirements. Most of the modifications are handled by EDA tools based on directives given by a designer. The term is also sometimes… … Wikipedia
Need to Know (The Twilight Zone) — Need to Know The Twilight Zone (1985 series) episode Episode no. Season 1 Episode 21a Directed by Paul Lynch Written by … Wikipedia
