Problems of energy loss when electricty is transmitted through cables?

Question

Problems of energy loss when electricty is transmitted through cables?

Answer 1

how refreshing, a question and all answers so far make sense and are more or less correct.

Three kinds of losses, most important is ohmic resistance as has been said and formulars given to work out how much, and what to do about reducing it.

next is corona discharge and as this is higher for small diametre wires than large ones, the metal of the wire is separated into several smaller thinner wires and arranged in a roughly cylindrical shape, this has the efect of reducing the discharge to that expected for the diameter of the 'cylinder' (does not usually even look like a cylinder, most often just 4 wires on the corners of an imaginary square, but for the purpose that is enough to work.)

finally there is electromagnetic radiation, as the current in the wires is AC, it creates radio waves (very low frequency), and these are energy lost to the grid as they radiate away. The energy radiated in this way is a function of frequency, power grids operate at 50 or 60 Hz, do not a lot of energy, but over the whole grid it is a considerable amount. If y6ou were sending higher frequency signals, it would be a problem. Coaxial shielded cable is used to send microvave frequency power.

now outside of this but related to it are losses in converting the generated power at the power station into a high voltage low current (Transformer is used) and then converting it back into low voltage for distribution again. Transformers are about 98% efficient, and great care is taken to make them as efficient as possible. A typical power train has at least 1 low voltage to high voltage transformer and usually 2 some times 3 down converting transformers, from say 400,000 volts to local city grid of 66,000V then suburb 11,000 or 22,000V and finally neighbourhood lines down to 415/220/240/110 depending what your standard is.

the above sequence results in (.98 x .98 x .98 x.98)= roughly 8% loss overall just on the transformers! So even small increases in efficiency in these is worth following up.

Answer 2

yes you are correct

Answer 3

resistance

Answer 4

yes some energy is lost as heat when the high current is passed through a wire .that is why u send high voltage current and then the transmitters turn it back into high current

Answer 5

The principal loss is ohmic; the cables have a finite resistance, and there is an I^2R loss from the current flow.  High voltage transmission lines have additional loss from corona discharge; this is controlled by use of multiple conductors per phase so as to increase the effective diameter of the conductors.

Answer 6

Not all cables are created equal. My husband swears by Monster Cables. It's kinda a joke with us. This man has more cables and wires than any one person needs. My mom affectionately refers to him as "techno boy".

Answer 7

Energy loss depends on 2 things - current in the wire and the resistance of the wire. The longer the wire the more energy loss there is because the resitance is increasing with the length.

Energy loss in joules = Current squared x resistance.

So to transmit electricity over long distances you need very thick wires made of a light low resistance metal ( aluminium is the most suitable material to use on the national grid wires).

The voltage has to be stepped up to the very high voltages - 400,00volts for the main power cables - this reduces the current down from several thousand amps down to perhaps 20 - power loss is then kept down to just a few % .