Heat may have

Heat may have a dramatic effect on the rate of reaction.

The amount of water present on the surface has a profound effect on activity.

Heat may have a dramatic effect on the rate of reaction.

The amount of water present on the surface has a profound effect on activity.

(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 I_Z
[ 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

• длительно допустимый ток
• допустимый ток

EN

• ampacity (US)
• continuous current
• continuous current-carrying capacity
• current-carrying capacity

DE

• Dauerstrombelastbarkeit, f
• Strombelastbarkeit, f

FR

• courant admissible, m
• courant permanent admissible, m

We will show how these numbers can be put to use.

Advantage is taken of this fact in some turbojet engines.

Unique processes and equipment have been successfully applied in the mining and refining of potash salts.

The great majority of amplifiers are electronic and depend (or rely) upon transistors and chips for their operation.

These projects can draw on the data from five tests.

The new relay employs three sets of contacts.

We shall follow this method.

To harness atomic energy for peaceful uses,...

This reaction may be harnessed to perform work.

The power unit makes use of a standard electric starter.

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This offers the possibility of putting hydrides to work in heat pumps.

These techniques take advantage of the laser's high spectral intensity.

Lasers are exploited to heat plasmas with short pulses of light.

Double-break or multibreak devices can exploit this effect even at higher voltages.

We make use of the generalized invariants.

The author's suggestions were picked up by the Japanese who ran some preliminary tests on eleven pure elements.

The steam from a dry field can be put to use() other than power production.

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The newest accelerators exploit the same fundamental principles as the first ones.

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This prevents defective parts from being put into service.

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The total number of asteroids is estimated to be as high as 100,000.

As many as 50 individual reaction steps might be necessary for complete synthesis.

If the region of accumulation is extended as far as the emitter...

These losses may be as much as 1.5% of the silver present.

Barretters can measure powers as small as 10^-8 watt.

We have made wire in sizes down to 0.005 in diameter.

The heater will heat the gas to the desired temperature.

This will heat the thermistor enough to lower the resistance to 200 ohms.

Pieces weighing up to (or not over) three kilograms may be used for the test.

The group I tRNAs arose prior to the others (биол.).

Prior to the seventeenth century...

Until the Three Mile Island accident the most widely discussed type of reactor malfunction was...

Prior to testing, all specimens were dried.

This decreases time to rupture.

Paste adhesives are knife-coated to uniform thickness.

A globe valve is installed in the supply air line, upstream from (or of) the reducer, so that the air may be shut off by hand.

The lake is up to 600 m deep.

The total number of asteroids is estimated to be as high as 100,000.

As many as 50 individual reaction steps might be necessary for complete synthesis.

If the region of accumulation is extended as far as the emitter...

These losses may be as much as 1.5% of the silver present.

Barretters can measure powers as small as 10^-8 watt.

We have made wire in sizes down to 0.005 in diameter.

The heater will heat the gas to the desired temperature.

This will heat the thermistor enough to lower the resistance to 200 ohms.

Pieces weighing up to (or not over) three kilograms may be used for the test.

The group I tRNAs arose prior to the others (биол.).

Prior to the seventeenth century...

Until the Three Mile Island accident the most widely discussed type of reactor malfunction was...

Prior to testing, all specimens were dried.

This decreases time to rupture.

Paste adhesives are knife-coated to uniform thickness.

A globe valve is installed in the supply air line, upstream from (or of) the reducer, so that the air may be shut off by hand.

We will show how these numbers can be put to use.

Advantage is taken of this fact in some turbojet engines.

Unique processes and equipment have been successfully applied in the mining and refining of potash salts.

The great majority of amplifiers are electronic and depend (or rely) upon transistors and chips for their operation.

These projects can draw on the data from five tests.

The new relay employs three sets of contacts.

We shall follow this method.

To harness atomic energy for peaceful uses,...

This reaction may be harnessed to perform work.

The power unit makes use of a standard electric starter.

These vehicles rely on ambient air as a source of oxygen.

This nonreciprocity has as yet not been turned to useful account in antennas.

At present, these laboratories are being utilized to test timbers.

Such high precision makes it possible to employ (or use, or utilize) laser radiation as a primary standard of length and time.

With electricity farmers could run useful devices of all kinds.

This offers the possibility of putting hydrides to work in heat pumps.

These techniques take advantage of the laser's high spectral intensity.

Lasers are exploited to heat plasmas with short pulses of light.

Double-break or multibreak devices can exploit this effect even at higher voltages.

We make use of the generalized invariants.

The author's suggestions were picked up by the Japanese who ran some preliminary tests on eleven pure elements.

The steam from a dry field can be put to use() other than power production.

We can draw on the equation of general relativity to calculate...

The newest accelerators exploit the same fundamental principles as the first ones.

Simplifying assumptions have been invoked to separate the two processes for individual study.

If this natural gas can be tapped, there would be a tremendous source of fuel.

This prevents defective parts from being put into service.

When all the even (or odd) integers are used up, there will still be half the series...

This mechanism is presumed to be adequately represented by...

You may anticipate that the stream discharge will increase with increasing basin area.

It was originally conceived (or conjectured) that the hydrogen bonds were responsible for...

These forms can be surmised.

He speculated that the lower mantle was inhomogeneous.

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The existence of superclusters has long been conjectured (астрон.).

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One can infer that craters have been erased.

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In such cases covalent bonding may be inferred.

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We shall consider the repercussions of short slugs on the final stage of an extrusion operation.

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Comets frequently show (or have) a tail.

Sulphur can accommodate more than eight electrons in its outer quantum shell.

This material is of high heat resistance.

The capacitor features (or exhibits, or shows, or possesses, or displays, or has) extraordinary stability.

Calcite may exhibit a wide variety of forms.

The instrument features eight data channels.

The cycloidal curve exhibits a higher pressure angle.

Many grains show slightly abraded edges.

The forklift truck is today sporting (жарг.) such accessories as barrel handling devices, belt conveyors,...

The reamer is provided with helical flutes.

If you are given a line of a fixed length,...

The coil is rectangular in shape (or in form).

The top rim of the trough is formed into a flange.

The conduit is shaped like (or has the shape of) a star in cross section.

The electro-pneumatic sewage unit takes the form of small receivers.

The variation may take the form of amplitude modulation.

Empirical correlations of heat-transfer data are frequently of the form (or frequently have the form) Nu=f(R,Pr).

The ionized streams take on a treelike form.

This object possesses (or has) a symmetry axis.

Comets frequently show (or have) a tail.

Sulphur can accommodate more than eight electrons in its outer quantum shell.

This material is of high heat resistance.

The capacitor features (or exhibits, or shows, or possesses, or displays, or has) extraordinary stability.

Calcite may exhibit a wide variety of forms.

The instrument features eight data channels.

The cycloidal curve exhibits a higher pressure angle.

Many grains show slightly abraded edges.

The forklift truck is today sporting (жарг.) such accessories as barrel handling devices, belt conveyors,...

The reamer is provided with helical flutes.

If you are given a line of a fixed length,...

The coil is rectangular in shape (or in form).

The top rim of the trough is formed into a flange.

The conduit is shaped like (or has the shape of) a star in cross section.

The electro-pneumatic sewage unit takes the form of small receivers.

The variation may take the form of amplitude modulation.

Empirical correlations of heat-transfer data are frequently of the form (or frequently have the form) Nu=f(R,Pr).

The ionized streams take on a treelike form.

Among other things, the paper stated that...

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Michelangelo, for one, protested against...

This Group was previously known as the Inert Gases or Rare Gases. As will be seen, argon for one is certainly not rare, and xenon and krypton are not inert.

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To illustrate,...

To take an illustration,...

To take one (or an) example,...

After capturing one type of carrier, say, an electron, the centre would become negatively charged.

These materials include some of the rare earth elements, such as caesium.