frequency+surface

(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

обработка питьевой воды
—
[ http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]

EN

drinking water treatment
The Directive on the Quality of Surface Water Intended for Drinking Water defines three categories of water treatment (A1, A2, A3) from simple physical treatment and disinfection to intensive physical and chemical treatment. The treatment to be used depends on the quality of the water abstracted. The Directive uses imperative values for parameters known to have an adverse effect on health and also guide values for those which are less adverse. There is also a directive which complements the "surface water abstraction" Directive by indicating the methods of measurement and the frequency of sampling and analysis required. (Source: PORT)
[http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]

Тематики

• охрана окружающей среды

EN

• drinking water treatment

DE

• Trinkwasserbehandlung

FR

• traitement de l'eau potable

классификационный ток ОПН
Iкл
Амплитудное значение (более высокое амплитудное значение из двух полярностей, если ток асимметричен) активной составляющей тока промышленной частоты, которое используется для определения классификационного напряжения ОПН и нормируется изготовителем.
[ ГОСТ Р 52725-2007]

EN

reference current of an arrester
peak value (the higher peak value of the two polarities if the current is asymmetrical) of the resistive component of a power-frequency current used to determine the reference voltage of the arrester
NOTE 1 The reference current will be high enough to make the effects of stray capacitances at the measured reference voltage of the arrester units (with designed grading system) negligible and is to be specified by the manufacturer.
NOTE 2 Depending on the nominal discharge current and/or line discharge class of the arrester, the reference current will be typically in the range of 0,05 mA to 1,0 mA per square centimetre of disc area for single column arresters.
[IEC 60099-4, ed. 2.0 (2004-05)]

FR

courant de référence d'un parafoudre
valeur de crête (la plus grande des deux polarités si le courant est dissymétrique) de la composante résistive du courant à fréquence industrielle utilisée pour déterminer la tension de référence d'un parafoudre.
NOTE 1 Il convient que le courant de référence soit suffisamment élevé pour rendre négligeables les effets des capacités parasites aux tensions de référence mesurées sur les éléments de parafoudre (avec leur système de répartition) et qu’il soit spécifié par le constructeur.
NOTE 2 Fonction du courant de décharge nominal et/ou de la classe de décharge de ligne du parafoudre, il convient que le courant de référence soit typiquement dans la gamme de 0,05 mA à 1,0 mA par centimètre carré de surface de disque pour les parafoudres à colonne unique
[IEC 60099-4, ed. 2.0 (2004-05)]

Тематики

• высоковольтный аппарат, оборудование...

EN

• reference current of an arrester

FR

• courant de référence d'un parafoudre