-
41 change gear(s)
мeнять, измeнять тeмп, тaктику и т п. [этим. тex. пepeключaть пepeдaчу]The music changed gear and Roberta's partner brought her back to the table (D. Francis). Here in these hours of late afternoon and evening Adam saw his uncle shift gears... the pace quickened, the routine became more complex, the burden heavier (E. O'Connor). Now he deftly shifted gears, switched from threat to flattery (A. Myrer) -
42 aerodrome
abandoned aerodromeнедействующий аэродромaerodrome accumulator plantаэродромная аккумуляторная зарядная станцияaerodrome adverse weatherсложные метеоусловия в районе аэродромаaerodrome air pictureвоздушная обстановка в зоне аэродромаaerodrome alerting procedureпорядок действий по тревоге на аэродромеaerodrome alerting serviceаэродромная служба аварийного оповещенияaerodrome alert measuresдействия по аэродрому при объявлении тревогиaerodrome alert roomпомещение на аэродроме для размещения дежурных экипажейaerodrome alert statusсостояние готовности аэродрома по тревоге, состояние готовности служб аэродрома по тревогеaerodrome alert systemсистема объявления тревоги на аэродромеaerodrome altitudeвысота аэродромаaerodrome approachподход к зоне аэродромаaerodrome approach aidsаэродромные средства захода на посадкуaerodrome approach areaзона подхода к аэродромуaerodrome approach chartкарта подходов к аэродромуaerodrome approach control systemсистема управления подходом к аэродромуaerodrome approach lightsаэродромные огни приближенияaerodrome approach roadподъездная дорога к аэродромуaerodrome authorityадминистрация аэродромаaerodrome beaconаэродромный маякaerodrome boundaryграница аэродромаaerodrome calmотсутствие ветра в районеaerodrome categoryкатегория аэродромаaerodrome chartсхема аэродромаaerodrome check pointконтрольная точка аэродромаaerodrome checkpointконтрольная площадка на аэродромеaerodrome check-point signуказатель контрольного ориентира аэродромаaerodrome circleкруг полета над аэродромомaerodrome circlingполет по кругу над аэродромомaerodrome circuitкруг полета над аэродромомaerodrome circuit-circlingполет по кругу над аэродромомaerodrome climatographical tableаэродромная метеорологическая таблицаaerodrome climatological summaryаэродромная метеосводкаaerodrome complexаэродромный комплексaerodrome conditionsаэродромная обстановкаaerodrome controlуправление в зоне аэродромаaerodrome control communicationаэродромная командная связьaerodrome controlled zoneзона, контролируемая авиадиспетчерской службой аэродромаaerodrome controllerдиспетчер аэродромаaerodrome control pointаэродромный диспетчерский пунктaerodrome control radarдиспетчерский аэродромный радиолокаторaerodrome control radioаэродромная радиостанция командной связиaerodrome control sectorзона контроля аэродрома диспетчерской службойaerodrome control serviceслужба управления движением в зоне аэродромаaerodrome control towerаэродромный диспетчерский пунктaerodrome control tower clearanceразрешение аэродромного диспетчерского пунктаaerodrome control unitаэродромный диспетчерский пунктaerodrome cultureискусственные сооружения в районе аэродромаaerodrome directoryсправочник по аэродромамaerodrome drainageдренаж аэродромаaerodrome drainage systemдренажная система аэродромаaerodrome elevationпревышение аэродромаaerodrome emergencyаварийная обстановка на аэродромеaerodrome emergency exerciseотработка действий на случай аварийной обстановки в аэропортуaerodrome emergency planningразработка мероприятий на случай аварийной обстановки на аэродромеaerodrome emergency serviceаэродромная аварийная службаaerodrome engineeringпроектирование и строительство аэродромовaerodrome engineering instructorсоветник по проектированию и строительству аэродромовaerodrome environmentусловия в районе аэродромаaerodrome environsприаэродромная территорияaerodrome fencingограждение аэродромаaerodrome flight information serviceаэродромная служба полетной информацииaerodrome forecastпрогноз по аэродромуaerodrome forecast materialметеоданные по аэродромуaerodrome graded areaспланированный участок аэродромаaerodrome ground profileпрофиль местности в районе аэродромаaerodrome ground signalназемный аэродромный сигналaerodrome ground visibilityвидимость у земли в зоне аэродромаaerodrome handing capacityпропускная способность аэродромаaerodrome hazard beaconаэродромный заградительный маякaerodrome identificationопознавание аэродромаaerodrome identification signопознавательный знак аэродромаaerodrome in questionуказанный аэродромaerodrome ladndmarkназемный аэродромный ориентирaerodrome lavatory trackаэродромный ассенизаторaerodrome lavatory truckаэродромный ассенизаторaerodrome layoutсхема аэродромаaerodrome levelвысота аэродромаaerodrome lightingаэродромное светосигнальное оборудованиеaerodrome locating beaconаэродромный приводной маякaerodrome marking systemсистема маркировки аэродромаaerodrome marshallerаэродромный сигнальщикaerodrome master planгенеральный план аэродромаaerodrome meteorological minimaметеорологический минимум аэродромаaerodrome minimaминимум аэродромаaerodrome movement areaзона движения воздушных судовaerodrome networkаэродромная сетьaerodrome observationнаблюдение за аэродромомaerodrome obstruction chartкарта аэродромных препятствийaerodrome of callаэродром выхода на радиосвязьaerodrome of departureаэродром вылетаaerodrome of intended landingаэродром предполагаемой посадкиaerodrome of originаэродром припискиaerodrome operating minimaэксплуатационный минимум аэродромаaerodrome operationэксплуатация аэродромаaerodrome pavementаэродромное покрытиеaerodrome pressureдавление на аэродромеaerodrome reference codeкодовое обозначение аэродромаaerodrome reference pointконтрольный ориентир аэродромаaerodrome reference temperatureрасчетная температура воздухаaerodrome reportсводка по аэродромуaerodrome rulesруководство по производству полетов в зоне аэродромаAerodromes, Air Routes and Ground Aids SectionСекция аэродромов, воздушных трасс и наземных средств(ИКАО) aerodrome security lightingсветосигнальное оборудование аэродрома для обеспечения безопасностиaerodrome serviceаэродромное обслуживание(диспетчерское) aerodrome service roadслужебная дорога на аэродромеaerodrome siteрайон размещения аэродромаaerodrome snow windrowснежные заносы на аэродромеaerodrome stripлетная полоса аэродромаaerodrome strip markerуказатель летной полосы аэродромаaerodrome surveillance radarобзорный аэродромный радиолокаторaerodrome taxi circuitсхема руления по аэродромуaerodrome trafficдвижение в зоне аэродромаaerodrome traffic circuitаэродромный круг полетовaerodrome traffic circuit operationполет по кругу в районе аэродромаaerodrome traffic control zoneзона аэродромного управления воздушным движениемaerodrome traffic patternсхема движения в зоне аэродромаaerodrome traffic zoneзона движения в районе аэродромаaerodrome usabilityстепень загрузки аэродромаaerodrome usability factorкоэффициент использования аэродромаaerodrome utilization factorкоэффициент использования аэродромаaerodrome utilization rateстепень использования аэродромаaerodrome vehicle operationэксплуатация аэродромных транспортных средствaerodrome visual aidsаэродромные визуальные средстваaerodrome warningпредупреждение по аэродромуaerodrome wind distributionроза ветров аэродромаaerodrome wind roseроза ветров аэродромаaerodrome wind shiftизменение направления ветра в районе аэродромаaerodrome wind sockаэродромный ветроуказательall-weather aerodromeвсепогодный аэродромalternate aerodromeзапасный аэродромarrival aerodromeаэродром прилетаarrive over the aerodromeприбывать в зону аэродромаauxiliary aerodromeдополнительный аэродромbase aerodromeаэродром постоянного базированияcarry out a circuit of the aerodromeвыполнять круг полета над аэродромомcategorized aerodromeкатегорированный аэродромcircle the aerodromeлетать по кругу над аэродромомcivil aerodromeгражданский аэродромcoastal aerodromeбереговой аэродромconcrete-surfaced aerodromeаэродром с бетонным покрытиемcontrolled aerodromeаэродром с командно-диспетчерской службойdebarkation aerodromeаэродром выгрузкиdepot aerodromeбазовый аэродромdestination aerodromeаэродром назначенияdomestic aerodromeаэродром местных воздушных линийembarkation aerodromeаэродром погрузкиemergency aerodromeаэродром вынужденной посадкиen-route aerodromeаэродром на трассе полетаentry into the aerodrome zoneвход в зону аэродромаfactory aerodromeзаводской аэродромfamiliar aerodromeоблетанный аэродромfinal aerodromeконечный аэродромfog-plagued aerodromeаэродром, имеющий частые туманыget into the aerodromeприземляться на аэродромеgiven aerodromeуказанный аэродромgrass aerodromeаэродром с травяным покрытиемhard surface aerodromeаэродром с твердым покрытиемhelicopter aerodromeвертодромhigh-level aerodromeгорный аэродромhome aerodromeаэродром припискиidentify the aerodrome from the airопознавать аэродром с воздухаintermediate aerodromeпромежуточный аэродромjet aerodromeаэродром для реактивных воздушных судовjoint civil and military aerodromeаэродром совместного базирования гражданского и военных воздушных судовkey aerodromeузловой аэродромland aerodromeсухопутный аэродромlanding aerodromeаэродром посадкиlanding off the aerodromeпосадка вне аэродромаlayout of aerodrome markingsмаркировка аэродромаlocal aerodromeаэродром местного значенияlogistics aerodromeаэродром материально-технического обеспеченияmain aerodromeглавный аэродромmilitary aerodromeвоенный аэродромmunicipal commercial aerodromeмуниципальный аэродром для коммерческой авиацииnonradar aerodromeаэродром без радиолокационных средствoperate from the aerodromeвыполнять полеты с аэродромаoperational aerodromeоперативный аэродромparticipating aerodromeзадействованный аэродромpermanent aerodromeстационарный аэродромprincipal aerodromeосновной аэродромprovisional aerodromeвременный аэродромreceiving aerodromeаэродром прилетаrefuelling aerodromeаэродром, обеспечивающий заправку топливомregular aerodromeрегулярный аэродромreserve aerodromeрезервный аэродромrigid pavement aerodromeаэродром с жестким покрытиемsatellite aerodromeвспомогательный аэродромsupplementary aerodromeдополнительный аэродромtakeoff aerodromeаэродром вылетаtemporary aerodromeвременный аэродромterminal aerodromeконечный аэродромtest aerodromeиспытательный аэродромtraining aerodromeучебный аэродромuncontrolled aerodromeаэродром без командно-диспетчерской службыunfamiliar aerodromeнеоблетанный аэродромunmarked aerodrome obstructionsнемаркируемые аэродромные препятствияunpaved aerodromeгрунтовой аэродромX-type aerodromeаэродром с перекрещивающимися ВПП -
43 Cayley numbers
The English-Russian dictionary general scientific > Cayley numbers
-
44 generation of random numbers
The English-Russian dictionary general scientific > generation of random numbers
-
45 signed numbers
The English-Russian dictionary general scientific > signed numbers
-
46 salt
salt 1. соль; 2. растущий на засоленных почвахto salt out высаливать(ся)complex salt комплексная сольdomestic salt пищевая сольtable salt пищевая сольEnglish-Russian dictionary of biology and biotechnology > salt
-
47 continuous current-carrying capacity
длительная пропускная способность по току
—
[Я.Н.Лугинский, М.С.Фези-Жилинская, Ю.С.Кабиров. Англо-русский словарь по электротехнике и электроэнергетике, Москва, 1999 г.]Тематики
- электротехника, основные понятия
EN
(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
Англо-русский словарь нормативно-технической терминологии > continuous current-carrying capacity
-
48 ampacity (US)
(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
Англо-русский словарь нормативно-технической терминологии > ampacity (US)
-
49 continuous current
(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
непрерывный ток
—
[Я.Н.Лугинский, М.С.Фези-Жилинская, Ю.С.Кабиров. Англо-русский словарь по электротехнике и электроэнергетике, Москва, 1999]Тематики
- электротехника, основные понятия
EN
Англо-русский словарь нормативно-технической терминологии > continuous current
-
50 current-carrying capacity
(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
предельно допустимый ток
—
[Я.Н.Лугинский, М.С.Фези-Жилинская, Ю.С.Кабиров. Англо-русский словарь по электротехнике и электроэнергетике, Москва, 1999 г.]Тематики
- электротехника, основные понятия
EN
прочность печатной платы к токовой нагрузке
Свойство печатной платы сохранять электрические и механические характеристики после воздействия максимально допустимой токовой нагрузки на печатный проводник или металлизированное отверстие печатной платы.
[ ГОСТ Р 53386-2009]Тематики
EN
Англо-русский словарь нормативно-технической терминологии > current-carrying capacity
См. также в других словарях:
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