-
1 для ... условий
Для (наиболее тяжёлых) условий-- For the most severe conditions studied in the present experiments, the maximum temperature was only a few degrees below the saturation temperature.Русско-английский научно-технический словарь переводчика > для ... условий
-
2 длительный допустимый ток
(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-английский словарь нормативно-технической терминологии > длительный допустимый ток
См. также в других словарях:
The Institutes for the Achievement of Human Potential — is a non profit organization providing teaching programs and literature which it promotes as improving the health and neurological development of normal children and of children who have sustained a brain injury. Although the institute s programs … Wikipedia
The Ship Who Sang — (1961) is a short story by science fiction author Anne McCaffrey about the brainship Helva. The Ship Who Sang (1969) book is a collection of Helva short stories. Readers also use the phrase to refer to the entire Brain Brawn Ship series. Plot… … Wikipedia
American Foundation for the Blind — The American Foundation for the Blind is an American nonprofit that expands possibilities for people with vision loss. AFB s priorities include broadening access to technology; elevating the quality of information and tools for the professionals… … Wikipedia
The Carmelite Order — The Carmelite Order † Catholic Encyclopedia ► The Carmelite Order One of the mendicant orders. Origin The date of the foundation of the Order of Our Lady of Mount Carmel has been under discussion from the fourteenth century to … Catholic encyclopedia
The United States of America — The United States of America † Catholic Encyclopedia ► The United States of America BOUNDARIES AND AREA On the east the boundary is formed by the St. Croix River and an arbitrary line to the St. John, and on the north by the… … Catholic encyclopedia
The Irish (in Countries Other Than Ireland) — The Irish (in countries other than Ireland) † Catholic Encyclopedia ► The Irish (in countries other than Ireland) I. IN THE UNITED STATES Who were the first Irish to land on the American continent and the time of their arrival are … Catholic encyclopedia
The Sacrament of Penance — The Sacrament of Penance † Catholic Encyclopedia ► The Sacrament of Penance Penance is a sacrament of the New Law instituted by Christ in which forgiveness of sins committed after baptism is granted through the priest s absolution to… … Catholic encyclopedia
Severe weather — is any destructive weather phenomenon. The term is usually used to refer to severe thunderstorms and related phenomena, such as tornados, hail, and downbursts. [ [http://amsglossary.allenpress.com/glossary/search?p=1 query=severe+weather… … Wikipedia
The Byzantine Empire — The Byzantine Empire † Catholic Encyclopedia ► The Byzantine Empire The ancient Roman Empire having been divided into two parts, an Eastern and a Western, the Eastern remained subject to successors of Constantine, whose capital was at … Catholic encyclopedia
The Benedictine Order — The Benedictine Order † Catholic Encyclopedia ► The Benedictine Order The Benedictine Order comprises monks living under the Rule of St. Benedict, and commonly known as black monks . The order will be considered in this article under… … Catholic encyclopedia
The Gothenburg Study of Children with DAMP — was a study of six year old children in Gothenburg, Sweden that began in 1977. The purpose was to find out what proportion of the children had DAMP (initially called MBD) and to follow the development of that group over the years. The results and … Wikipedia
