Thomas Edison thought we should use DC. Nikola Tesla thought we should use AC. There was a great competition between the two, and Tesla won.
Why do we use AC supply in our homes?
The value of AC is that the voltage can be changed easily with a transformer. High voltage suffers much less loss in long transmission lines, and then the voltage can be reduced for safe introduction into the home. Ridiculous reason, thought Edison; we don’t need long transmission lines, he argued—just place a coal burning generator every few blocks in the city.
Thanks to Tesla, most of our power generation is done at distant places, and I am thankful for that! The right reason won.
Here’s the math: the power lost in a wire is given by L = (I^2)R, where L is the power lost to heat, I is the current and R is the resistance. The power transmitted is given by P = VI, where P is the power delivered to the customer, V is the voltage. So if you make V big and I small, you can transmit the same power but reduce the power lost to heat. So high voltage gives the best performance.
Of course, high voltage could be delivered by DC also, but at the time there was no convenient way to reduce the voltage for use in the home. These days, with advanced DC converters, the DC voltage can be reduced, so many long-distance transmission lines are now DC. They have several advantages, including the fact that they use a lower peak voltage (since the signal doesn’t oscillate) and they do not induce eddy-current losses in the ground from their fluctuating magnetic fields.
Thanks to Tesla, most of our power generation is done at distant places, and I am thankful for that! The right reason won.
Here’s the math: the power lost in a wire is given by L = (I^2)R, where L is the power lost to heat, I is the current and R is the resistance. The power transmitted is given by P = VI, where P is the power delivered to the customer, V is the voltage. So if you make V big and I small, you can transmit the same power but reduce the power lost to heat. So high voltage gives the best performance.
Of course, high voltage could be delivered by DC also, but at the time there was no convenient way to reduce the voltage for use in the home. These days, with advanced DC converters, the DC voltage can be reduced, so many long-distance transmission lines are now DC. They have several advantages, including the fact that they use a lower peak voltage (since the signal doesn’t oscillate) and they do not induce eddy-current losses in the ground from their fluctuating magnetic fields.
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