-
1 длительный допустимый ток
- Strombelastbarkeit, f
- Dauerstrombelastbarkeit, f
(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-немецкий словарь нормативно-технической терминологии > длительный допустимый ток
-
2 классификация землепользования
классификация землепользования
—
[ http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]EN
land use classification
The arrangement of land units into a variety of categories based on the properties of the land or its suitability for a particular purpose. It has become an important tool in rural land-resource planning. (Source: WHIT)
[http://www.eionet.europa.eu/gemet/alphabetic?langcode=en]Тематики
EN
DE
FR
Русско-немецкий словарь нормативно-технической терминологии > классификация землепользования
См. также в других словарях:
Use of Free and Open Source Software (FOSS) in the U.S. Department of Defense — is a 2003 report by The MITRE Corporation that documented widespread use of and reliance on free software (termed FOSS ) within the United States Department of Defense (DoD). The report helped end a debate about whether FOSS should be banned from … Wikipedia
Properties of water — H2O and HOH redirect here. For other uses, see H2O (disambiguation) and HOH (disambiguation). This article is about the physical and chemical properties of pure water. For general discussion and its distribution and importance in life, see Water … Wikipedia
Properties of concrete — Concrete has relatively high compressive strength, but significantly lower tensile strength, and as such is usually reinforced with materials that are strong in tension (often steel). The elasticity of concrete is relatively constant at low… … Wikipedia
.properties — Infobox file format name = Properties extension = .properties mime = owner = creatorcode = genre = ASCII containerfor = containedby = extendedfrom = extendedto = .properties is a file extension for files mainly used in Java related technologies… … Wikipedia
use up — verb 1. use up (resources or materials) (Freq. 3) this car consumes a lot of gas We exhausted our savings They run through 20 bottles of wine a week • Syn: ↑consume, ↑eat up, ↑eat, ↑ … Useful english dictionary
Properties of musical modes — The modern musical modes consist of seven different scales related to the familiar major and minor keys, each with different properties and characteristics which distinguish them from one another. Called the Ionian mode, Dorian mode, Phrygian… … Wikipedia
Use of biotechnology in pharmaceutical manufacturing — Escherichia coli bacteria, which are often utilized in production of pharmaceutical products. Modern pharmaceutical manufacturing techniques frequently rely upon biotechnology. Contents 1 … Wikipedia
use up — transitive verb Date: 1816 to exhaust of strength or useful properties < land that has been used up > … New Collegiate Dictionary
Emaar Properties — Infobox Company company company name = Emaar Properties company type = Real Estate (dfm|EMAAR) foundation = 1997 location = Dubai, flagicon|UAE United Arab Emirates industry = Holding company revenue = homepage = [http://www.emaar.com/… … Wikipedia
Century Properties, Inc. — Century Properties, Inc. Website http://www.century properties.com References [1] … Wikipedia
Material properties of diamond — This article addresses the material properties of diamond. For a broader discussion of diamonds, see diamond. For other uses of the word diamond, see diamond (disambiguation). Diamond An octahedral diamond crystal in matrix Gener … Wikipedia
