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1 трекинг
трекинг
Последовательное образование токопроводящих мостиков, которые формируются на поверхности твердого электроизоляционного материала вследствие совместного действия электрического напряжения и наличия загрязнений на его поверхности.
[ ГОСТ Р 51330.20-99]
трекинг
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[IEV number 442-01-41]EN
tracking
the progressive degradation of the surface of a solid insulating material by local discharges to form conducting or partially conducting paths
NOTE – Tracking usually occurs due to surface contamination.
[IEV number 212-01-42]
[IEV number 442-01-41]FR
cheminement
dégradation progressive de la surface d'un matériau isolant solide par des décharges locales formant des chemins conducteurs ou partiellement conducteurs
NOTE – Le cheminement est causé habituellement par une contamination superficielle
[IEV number 212-01-42]
[IEV number 442-01-41]Тематики
- электробезопасность
- электротехника, основные понятия
EN
DE
FR
Русско-немецкий словарь нормативно-технической терминологии > трекинг
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2 постепенный отказ
постепенный отказ
Отказ, возникающий в результате постепенного изменения значений одного или нескольких параметров объекта.
[ ГОСТ 27.002-89]
постепенный отказ
Отказ, вызванный постепенным изменением со временем заданных характеристик объекта.
Примечание - Постепенный отказ можно предвидеть на основании результатов предшествующего наблюдения или технического обслуживания и иногда его можно избежать с помощью технического обслуживания [1].
[1] Международный стандарт МЭК 50 (191). Международный Электротехнический Словарь. Глава 191: Надежность и качество услуг.
[ОСТ 45.153-99]EN
gradual failure
drift failure
a failure due to a gradual change with time of given characteristics of an item
NOTE – A gradual failure may be anticipated by prior examination of monitoring and can sometimes be avoided by preventive maintenance.
[IEV number 191-04-11]FR
défaillance progressive
défaillance par dérive
défaillance due à une évolution dans le temps des caractéristiques d'une entité
NOTE – En général, une défaillance progressive peut être prévue par un examen ou un contrôle antérieur et elle peut quelquefois être évitée par l'entretien de l'entité.
[IEV number 191-04-11]Тематики
- надежность средств электросвязи
- надежность, основные понятия
Обобщающие термины
EN
DE
FR
Русско-немецкий словарь нормативно-технической терминологии > постепенный отказ
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3 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
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