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1 длительный допустимый ток
- courant permanent admissible, m
- courant admissible, m
(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-французский словарь нормативно-технической терминологии > длительный допустимый ток
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2 stretch
stretch [stretʃ]1 noun(a) (expanse → of land, water) étendue f;∎ this stretch of the road is particularly dangerous in the winter cette partie de la route est très dangereuse en hiver;∎ a new stretch of road/motorway un nouveau tronçon de route/d'autoroute;∎ a long straight stretch une longue route en ligne droite;∎ it's a lovely stretch of river/scenery cette partie de la rivière/du paysage est magnifique;∎ Horseracing & figurative to go into the final or finishing or home stretch entamer la dernière ligne droite(b) (period of time) période f;∎ for a long stretch of time pendant longtemps;∎ for long stretches at a time there was nothing to do il n'y avait rien à faire pendant de longues périodes;∎ to do a stretch of ten years in the army passer dix ans dans l'armée;∎ familiar he did a stretch in Dartmoor il a fait de la taule à Dartmoor;∎ familiar he was given a five-year stretch (in prison) il a écopé de cinq ans(c) (act of stretching) étirement m;∎ he stood up, yawned and had a stretch il se leva, bâilla et s'étira;∎ to give one's legs a stretch se dégourdir les jambes;∎ do a couple of stretches before breakfast faites quelques étirements avant le petit déjeuner;∎ Music stretch of the fingers (at the piano) écart m des doigts;∎ by no stretch of the imagination même en faisant un gros effort d'imagination;∎ he's the better writer by a long stretch c'est de loin le meilleur écrivain;∎ not by a long stretch! loin de là!(d) (elasticity) élasticité f;∎ there isn't much stretch in these gloves ces gants ne sont pas très souples;∎ there's a lot of stretch in these stockings ces bas sont très élastiques ou s'étirent facilement;∎ with two-way stretch (of elastic fabric) extensible dans les deux sens(a) (pull tight) tendre;∎ stretch the rope tight tendez bien la corde;∎ a cable was stretched across the ravine on avait tendu un câble à travers le ravin;∎ they stretched a net over the pit ils ont tendu un filet au-dessus de la fosse;∎ Art to stretch the canvas on the frame tendre la toile sur le châssis∎ to stretch sth out of shape déformer qch;∎ don't pull your socks like that, you'll stretch them ne tire pas sur tes chaussettes comme ça, tu vas les déformer(c) (extend, reach to full length) étendre;∎ stretch your arms upwards tendez les bras vers le haut;∎ he stretched his arm through the broken window il allongea le bras à travers le carreau cassé;∎ if I stretch up my hand I can reach the ceiling si je tends la main je peux toucher le plafond;∎ to stretch one's neck to see sth tendre le cou pour voir qch;∎ to stretch oneself s'étirer;∎ the bird stretched its wings l'oiseau déploya ses ailes;∎ figurative to stretch one's wings (become more independent) voler de ses propres ailes; (seek out new challenges) aller de l'avant(d) (force, bend → meaning) forcer; (→ rules) tourner, contourner, faire une entorse à; (→ principle) faire une entorse à; (→ imagination) faire un gros effort de;∎ you're really stretching my patience ma patience a des limites;∎ to stretch the truth exagérer;∎ they have stretched their authority a bit too far ils ont un peu abusé de leur autorité;∎ that's stretching it a bit! il ne faut pas exagérer!;∎ it would be stretching a point to call him a diplomat dire qu'il est diplomate serait exagérer ou aller un peu loin;∎ I suppose we could stretch a point and let him stay je suppose qu'on pourrait faire une entorse au règlement et lui permettre de rester(e) (budget, income, resources, supplies → get the most from) tirer le maximum de; (→ overload) surcharger, mettre à rude épreuve;∎ our resources are stretched to the limit nos ressources sont exploitées ou utilisées au maximum;∎ I can't stretch my income that far mon salaire ne me permet pas de faire de telles dépenses;∎ we should be able to stretch the food until the weekend nous devrions pouvoir faire durer les provisions jusqu'au week-end;∎ our staff are really stretched today le personnel travaille à la limite de ses possibilités aujourd'hui;∎ to be fully stretched (machine, engine) tourner à plein régime; (factory, economy) fonctionner à plein régime; (resources, services) être sollicité à fond; (person, staff) faire son maximum;∎ the job won't stretch you enough le travail ne sera pas assez stimulant pour vous;∎ she believes young people need to be stretched elle pense qu'il faut être exigeant avec les jeunes pour qu'ils donnent le meilleur d'eux-mêmes(f) (ligament, muscle) étirer∎ this fabric tends to stretch ce tissu a tendance à s'étirer;∎ the shoes will stretch with wear vos chaussures vont se faire ou s'élargir à l'usage;∎ my pullover has stretched out of shape mon pull s'est déformé(b) (person, animal → from tiredness) s'étirer; (→ on ground, bed) s'étendre, s'allonger; (→ to reach something) tendre la main;∎ she stretched lazily elle s'étira nonchalamment;∎ he had to stretch to reach it (reach out) il a dû tendre le bras pour l'atteindre; (stand on tiptoe) il a dû se mettre sur la pointe des pieds pour l'atteindre;∎ she stretched across me to get the salt elle a passé le bras devant moi pour attraper le sel;∎ can you stretch over and get me the paper? pouvez-vous tendre le bras et me passer le journal?;∎ he stretched up to touch the cupboard il s'est mis sur la pointe des pieds pour atteindre le placard(c) (spread, extend → in space, time) s'étendre;∎ the forest stretches as far as the eye can see la forêt s'étend à perte de vue;∎ the road stretches away into the distance la route s'étend au lointain;∎ the road stretched across 500 miles of desert la route parcourait 800 km de désert;∎ the rope stretched across the ravine le corde allait d'un côté à l'autre du ravin;∎ minutes stretched into hours les minutes devenaient des heures;∎ our powers don't stretch as far as you imagine nos pouvoirs ne sont pas aussi étendus que vous l'imaginez(d) (money, resources)∎ my salary won't stretch to a new car mon salaire ne me permet pas d'acheter une nouvelle voiture;∎ my resources won't stretch to that mes moyens (pécuniaires) ne vont pas jusque-là(a) (in a row) d'affilée;∎ we worked for five hours at a stretch nous avons travaillé cinq heures d'affilée(b) (with much effort) à la limite, à la rigueur;∎ we could finish by Monday at a stretch à la limite ou à la rigueur, on pourrait finir pour lundi;∎ we could fit six people in the car at a stretch à la rigueur, on pourrait tenir à six dans la voiture∎ to be at full stretch (factory, machine) fonctionner à plein régime ou à plein rendement; (person) se donner à fond, faire son maximum;∎ we were working at full stretch nous travaillions d'arrache-pied;∎ even at full stretch, we can't meet the delivery date même en tournant à plein régime, nous ne pouvons pas respecter les délais de livraison►► stretch class cours m de stretching;stretch fabric Stretch ® m;stretch limo limousine f à la carrosserie allongée(a) (pull tight) tendre;∎ the sheets had been stretched out on the line to dry on avait étendu les draps sur le fil à linge pour qu'ils sèchent;∎ the plastic sheet was stretched out on the lawn la bâche en plastique était étalée sur la pelouse∎ she stretched out her hand towards him/for the cup elle tendit la main vers lui/pour prendre la tasse;∎ she lay stretched out in front of the television elle était allongée par terre devant la télévision∎ she has to stretch her thesis out a bit for publication il faut qu'elle étoffe un peu sa thèse pour la publier(d) (make last → supplies, income) faire durer(a) (person, animal) s'étendre, s'allonger;∎ they stretched out on the lawn in the sun ils se sont allongés au soleil sur la pelouse∎ a nice long holiday stretched out before them ils avaient de longues vacances devant eux
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