maximum+duration

(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

максимальная концентрация иммиссии
—
[ http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]

EN

maximum immission concentration
The maximum concentration of air polluting substances in the free environment whose impact when of specified duration and frequency is not objectionable to man, fauna and flora. (Source: ECHO2)
[http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]

Тематики

• охрана окружающей среды

EN

• maximum immission concentration

DE

• MIK-Wert

FR

• concentration maximale d'immission

время считывания
-
[IEV number 314-02-08]

EN

readout time
duration during which the output signal is available for reading when the instrument is in continuous operation
NOTE – Generally, the readout time is specified at the maximum conversion rate.
[IEV number 314-02-08]

FR

temps de lecture
durée pendant laquelle le signal de sortie est disponible pour la lecture lorsque l'appareil est en fonctionnement continu
NOTE – Généralement, le temps de lecture est spécifié à la vitesse de conversion maximale.
[IEV number 314-02-08]

Тематики

• измерение электр. величин в целом

EN

• readout time

DE

• Auslesezeit

FR

• temps de lecture

неотпускание
Максимальное или близкое к максимальному мышечное сокращение, вызванное электрическим воздействием.
Примечание - Длительность неотпускания при повторяющемся электрическом воздействии может быть меньше, чем при единичном воздействии.
[ ГОСТ Р МЭК 60050-195-2005]

EN

(electrical) tetanization
maximal or nearly maximal muscular contraction caused by electrical stimulation
NOTE – A continuous tetanization may be produced by electric stimuli repeated at intervals shorter than the duration of the tetanization produced by a single stimulus.
Source: 891-01-12
[IEV number 195-03-02]

FR

tétanisation (électrique)
contraction musculaire maximale ou proche du maximum provoquée par stimulation électrique
NOTE – Une tétanisation soutenue peut être provoquée par des stimuli électriques répétés à des intervalles inférieurs à la durée de la tétanisation produite par un seul stimulus
Source: 891-01-12
[IEV number 195-03-02]

Тематики

• электробезопасность

Синонимы

• электрическое неотпускание

EN

• (electrical) tetanization

DE

• elektrische Tetanisierung

FR

• tétanisation (électrique)

номинальное напряжение
Uн
Действующее значение напряжения промышленной частоты, которое ограничитель может выдерживать в течение 10 с в процессе рабочих испытаний. Номинальное напряжение должно быть не менее 1,25 наибольшего длительно допустимого рабочего напряжения.
[ ГОСТ Р 52725-2007]

EN

rated voltage of an arrester
Ur
maximum permissible r.m.s. value of power-frequency voltage between its terminals at which it is designed to operate correctly under temporary overvoltage conditions as established in the operating duty tests
NOTE 1 The rated voltage is used as a reference parameter for the specification of operating characteristics.
NOTE 2 The rated voltage as defined in this standard is the 10 s power-frequency voltage used in the operating duty test after high-current or long-duration impulses. Tests used to establish the voltage rating in IEC 60099-1, as well as some national standards, involve the application of repetitive impulses at nominal current with power-frequency voltage applied. Attention is drawn to the fact that these two methods used to established rating do not necessarily produce equivalent values (a resolution to this discrepancy is under consideration).
[IEC 60099-4, ed. 2.0 (2004-05)]

FR

tension assignée d'un parafoudre
Ur
valeur maximale de la tension efficace à fréquence industrielle admissible entre ses bornes pour laquelle le parafoudre est prévu pour fonctionner correctement dans des conditions de surtension temporaires comme il est défini dans les essais de fonctionnement
NOTE 1 La tension assignée est utilisée comme paramètre de référence pour la spécification des caractéristiques de fonctionnement.
NOTE 2 La tension assignée comme définie dans la présente norme est la tension à fréquence industrielle de 10 s, utilisée pour vérifier la stabilité après application des chocs de courant de grande amplitude ou de longue durée lors de l'essai de fonctionnement. Les essais utilisés pour définir la tension assignée dans la CEI 60099-1, ainsi que dans certaines normes nationales, impliquent l'application de chocs répétés au courant nominal pendant que la tension à fréquence industrielle est appliquée. On attire l'attention sur le fait que ces deux méthodes utilisées pour définir les valeurs assignées ne produisent pas nécessairement des valeurs équivalentes (une résolution de cette différence est à l'étude).
[IEC 60099-4, ed. 2.0 (2004-05)]

Тематики

• высоковольтный аппарат, оборудование...

EN

• rated voltage of an arrester

FR

• tension assignée d'un parafoudre