Why AC current is used for transmission of electricity over long distance.
The reason we use AC is that the AC voltage is easily changed using a transformer. To change DC voltage requires complex and inefficient circuitry.
Suppose you are sending some powerPPfrom the power station to the end user. The power lines have some resistanceRRso they dissipate some of the original power as heat. Specifically the power dissipated is given by:
Plost=I2R whereIIis the current running through your power lines. If our supply voltage isVVthen the power, voltage and current are related by:
P=IV
And if we use this to substitute forIIin the power loss equation we get:
Plost=P2RV2 The key result is that:
Plost∝1÷V2 So if we increase the supply voltageVVwe decrease the power lost. This is why the electricity transmission lines use very high voltages. The electricity produced by the power station is passed through a transformer to raise its voltage to the100,000100,000V or so used in the tranmission lines. Then when it reaches your town the electricity is passed through several more transformers to reduce it to the domestic voltage.
But changing the voltage this way only works for AC because transformers don't work for DC. And that's why mains electricity is AC. Reason for difficulty for conversion of dc to ac :DC voltages require change to AC via oscillators - high powered, high frequency ones. Then a variety of techniques can be used to transform the AC, and then it must be filtered effectively to get back to DC. For many years the electronics to do so were impossible, now they are possible but still quite expensive compared to low voltage stuff. Read carefully and understand and like if satisfied
The reason we use AC is that the AC voltage is easily changed using a transformer. To change DC voltage requires complex and inefficient circuitry.
Suppose you are sending some powerPPfrom the power station to the end user. The power lines have some resistanceRRso they dissipate some of the original power as heat. Specifically the power dissipated is given by:
Plost=I2RwhereIIis the current running through your power lines. If our supply voltage isVVthen the power, voltage and current are related by:
P=IV
And if we use this to substitute forIIin the power loss equation we get:
Plost=P2RV2The key result is that:
Plost∝1÷V2So if we increase the supply voltageVVwe decrease the power lost. This is why the electricity transmission lines use very high voltages. The electricity produced by the power station is passed through a transformer to raise its voltage to the100,000100,000V or so used in the tranmission lines. Then when it reaches your town the electricity is passed through several more transformers to reduce it to the domestic voltage.
But changing the voltage this way only works for AC because transformers don't work for DC. And that's why mains electricity is AC. Reason for difficulty for conversion of dc to ac :DC voltages require change to AC via oscillators - high powered, high frequency ones. Then a variety of techniques can be used to transform the AC, and then it must be filtered effectively to get back to DC. For many years the electronics to do so were impossible, now they are possible but still quite expensive compared to low voltage stuff. Read carefully and understand and like if satisfied
