Перевод: со всех языков на французский

с французского на все языки

surface-area+factor

  • 1 длительный допустимый ток

    1. courant permanent admissible, m
    2. 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:

    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:

  • Surface area to volume ratio — In chemical reactions involving a solid material, the surface area to volume ratio is an important factor for the reactivity, that is, the rate at which the chemical reaction will proceed. In some industries it is abbreviated sa/vol.Physical… …   Wikipedia

  • Accessible surface area — Illustration of the solvent accessible surface in comparison to the van der Waals surface. The van der Waals surface as given by the atomic radii is shown in red. The accessible surface is drawn with dashed lines and is created by tracing the… …   Wikipedia

  • Area of a disk — Part of a series of articles on the mathematical constant π …   Wikipedia

  • Surface enhanced Raman spectroscopy — Surface Enhanced Raman Spectroscopy, or Surface Enhanced Raman Scattering, often abbreviated SERS, is a surface sensitive technique that results in the enhancement of Raman scattering by molecules adsorbed on rough metal surfaces. The enhancement …   Wikipedia

  • Surface diffusion — [ adatom diffusing across a square surface lattice. Note the frequency of vibration of the adatom is greater than the jump rate to nearby sites. Also, the model displays examples of both nearest neighbor jumps (straight) and next nearest neighbor …   Wikipedia

  • Surface runoff — Runoff flowing into a stormwater drain Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water… …   Wikipedia

  • surface coating — ▪ chemistry Introduction       any mixture of film forming materials plus pigments, solvents, and other additives, which, when applied to a surface and cured or dried, yields a thin film that is functional and often decorative. Surface coatings… …   Universalium

  • Surface-conduction electron-emitter display — A surface conduction electron emitter display (SED) is a flat panel display technology that uses surface conduction electron emitters for every individual display pixel. The surface conduction emitter emits electrons that excite a phosphor… …   Wikipedia

  • factor — 1. One of the contributing causes in any action. 2. One of the components that by multiplication makes up a number or expression. 3. SYN: gene. 4. A vitamin or other essential element. 5. An event, characteristic, or other definable entity that …   Medical dictionary

  • Orders of magnitude (area) — An area of one square kilometre consists of 100 hectares each containing 10000 square metres. This page is a progressive and labeled list of the SI area orders of magnitude, with certain examples appended to some list objects. List of orders of… …   Wikipedia

  • Form factor (radiative transfer) — In physics, form factor (usually written e ) of a material, sometimes called emissivity, relates the proportion of energy transmitted by that object which can be transferred to another object.For instance, an object with surface area A transmits… …   Wikipedia

Поделиться ссылкой на выделенное

Прямая ссылка:
Нажмите правой клавишей мыши и выберите «Копировать ссылку»