temperature+environment

(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 I_Z
[ 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

• длительно допустимый ток
• допустимый ток

EN

• ampacity (US)
• continuous current
• continuous current-carrying capacity
• current-carrying capacity

DE

• Dauerstrombelastbarkeit, f
• Strombelastbarkeit, f

FR

• courant admissible, m
• courant permanent admissible, m

условия окружающей среды
-
[IEV number 151-16-03]

EN

ambient conditions
environmental conditions
characteristics of the environment which may affect performance of a device or system
NOTE – Examples of ambient conditions are pressure, temperature, humidity, radiation, vibration.
[IEV number 151-16-03]

FR

conditions ambiantes, f, pl
caractéristiques du milieu ambiant qui peuvent influer sur le fonctionnement d'un dispositif ou d'un système
NOTE – Des exemples de conditions ambiantes sont la pression, la température, l'humidité, les rayonnements, les vibrations.
[IEV number 151-16-03]

Тематики

• электротехника, основные понятия

EN

• ambient conditions
• environment
• environmental conditions

DE

• Umgebungsbedingungen

FR

• conditions ambiantes

тепловое равновесие
-
[IEV number 151-16-33]

EN

thermal equilibrium
state reached when the temperature of the parts of a component or equipment operating in a given environment no longer varies faster than a specified limit
[IEV number 151-16-33]

FR

équilibre thermique, m
état atteint lorsque la température des parties d’un composant ou d’un matériel fonctionnant dans un environnement déterminé a cessé de varier plus vite qu’une limite spécifiée
[IEV number 151-16-33]

EN

• thermal equilibrium

DE

• thermisches Gleichgewicht

FR

• équilibre thermique

сжигание в факеле газов
—
[ http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]

EN

flaring
1) Flares use open flames during normal and/or emergency operations to combust hazardous gaseous. The system has no special features to control temperature or time of combustion; however, supplemental fuel may be required to sustain the combustion. Historically, flares have been used to dispose of waste gases in the oil and gas industry and at wastewater treatment plants having anaerobic digestors. Regulation for thermal destruction of hazardous wastes limit the practical use of flaring to combustion of relatively simple hydrocarbons, such as methane from digesters or landfill gas collection systems.
2) A control device that burns hazardous materials to prevent their release into the environment; may operate continuously or intermittently, usually on top a stack.
(Source: CORBIT / EPAGLO)
[http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]

Тематики

• охрана окружающей среды

EN

• flaring

DE

• Abfackelung

FR

• brűlage ŕ la torche