It depends on the surround material, temperature, type of cable, and what you mean by "maximum current rating". Typically a maximum load current rating will be specified, such as 15A; this means you can push 15A through that cable nonstop without damaging it (it won't overheat). You might have a short time rating as well, such as a 4 hour rating, where the cable can handle runing 22A for 4 hours if the surrounding temperature is kept to some value, though this may slightly degrade the insulation. There's also a fusing current rating for many cables. At this current, the cable will eventually melt (like a fuse).
The supply won't have to work as hard. It is perfectly acceptable, for example, to use a 1A, 12v supply to supply a 12v, .5A load. The current rating indicates the ability of the supply to dissipate heat caused by the current flowing. If the load current is above the power supply current rating, the power supply will overheat.
With a constant voltage and increase in wire length will increase the end to end resistance and therefore the current will decrease.
making current is a peak value attain at first cycle when the circuit breaker is close.the making current rating is expressed in "peak" value of the maximum ac current it can safely close on that's why it is always have higher value than breaking current. Making current is limited by the withstand capability of the contacts. Breaking current is based on the ability of the contacts to interrupt the current. If the contacts are not able to interrupt the current when they open, the heat energy in the resulting arc will often destroy the device. the breaking current rating is expressed in RMS value of the current.
A single-core cable generally has a higher current rating because it can be separated from neighbouring cables to allow any heat generated to escape. However if power cables continuously run warm it is a sign that they are being run uneconomically and the use of a thicker wire gauge is indicated, because the extra capital costs of a thicker cable would be more than offset by the saving on the cost of the energy wasted in heating the cable.
Resistors are not usually given 'current ratings' but, rather, 'power ratings' expressed in submultiples of the watt. It is then up to the user to calculate the safe maximum operating current for a particular resistor, by manipulating the equation: P = I2 R.Since a power rating is dependent upon the resistor's ability to dissipate energy by heat transfer, the actual power rating is dependent upon the surface area and, hence, the physical size of the resistor. So you will find that resistors come in a variety of physical sizes for any given resistance value.Unfortunately, power ratings are not indicated through colour codes, etc., so you will have to either specify its power rating when you purchase a resistor, or match your existing resistor against a scale-drawing to determine its power rating.
The supply won't have to work as hard. It is perfectly acceptable, for example, to use a 1A, 12v supply to supply a 12v, .5A load. The current rating indicates the ability of the supply to dissipate heat caused by the current flowing. If the load current is above the power supply current rating, the power supply will overheat.
With a constant voltage and increase in wire length will increase the end to end resistance and therefore the current will decrease.
Because if the rated current is lower than the actual current, it causes resistance to the electrical flow which in turn is dispelled as heat.
If you want to operate the conductors maximum capacity, the conductor needs the heat, that the amperage produces, to be dissipated. This is why in the electrical code book there are two amperage ratings. The first one is for a free air rating which allows for a high ampacity of the wire. The other rating is for three conductors in a conduit which confines the cooling capacity and so the ampacity rating of these wires is lowered. The same procedure is used in cable spacings in ladder tray networks.
If this cable is very thin, then it can not withstand the current that go through it. Too high current make cable go hot. A car battery can give out 100 ampere easily for a short period of time. If you attach "heavy" equipment, then cables will heat up. Another source of heat is a bad connection.
making current is a peak value attain at first cycle when the circuit breaker is close.the making current rating is expressed in "peak" value of the maximum ac current it can safely close on that's why it is always have higher value than breaking current. Making current is limited by the withstand capability of the contacts. Breaking current is based on the ability of the contacts to interrupt the current. If the contacts are not able to interrupt the current when they open, the heat energy in the resulting arc will often destroy the device. the breaking current rating is expressed in RMS value of the current.
Heat cannot escape the duct as easily as in open air. This results in the same amount of current causing the cable to heat to a higher temperature.
Dead Heat - 2002 is rated/received certificates of: Argentina:16 Australia:MA (cable rating) Finland:K-15 Germany:12 South Korea:15 UK:15 USA:R
Current in the single core cable would induce a magnetic current in the steel cable, though a transformer effect. This would heat the steel armored strands, and the circuit would increase more electrical power from the load supply point. The earthing of the cable glands would complete the circuit and the return current would flow in the earth bonding cable between the two points. This is called Eddy currents generated in the cable by the twist of the steel armored around the central core, current flowing in one direction
A single-core cable generally has a higher current rating because it can be separated from neighbouring cables to allow any heat generated to escape. However if power cables continuously run warm it is a sign that they are being run uneconomically and the use of a thicker wire gauge is indicated, because the extra capital costs of a thicker cable would be more than offset by the saving on the cost of the energy wasted in heating the cable.
1. We consider cable de-rating factor, because the method of laying of cable either in air, duct or trench, affect the current carrying capacity as dissipation of heat in air is more than in duct or trench. Now the factors that causes derating are 1. ambient temperature (this is the average temperature of the plant). If surrounding temperature is higher than cable temperature at which it is designed then that increase the resistance of cable conductor which decreases the current 2. Number of cables in cable tray either they are touching each other or at a distance. If cables are touching each other, they created dielectric field around them which in case of touching causes interference with one another that causes resistance to increase. 3. No. of cable trays in a tier.
That depend on the current rating of the cor in amps. The watt rating is equal to the voltage (300) times the current rating, which might be marked on the cord but anyway it depends on how thick the wire is. A rolled-up power cord must ways be completely unrolled if more than one-tenth of the rated current is to be drawn. That is to allow the heat generated in the wire's resistance to escape.