Question

Why did the utility industry decide to use alternating current instead of direct current for power transmission?

Answer 1

AC is widely used because of properties of AC which DC doesn’t have.

• AC is relatively much easier to transmit over long distances then DC. As AC allows for it to be stepped up or stepped down to higher voltages by the use of the Transformers. This property allows for transmitting of power over power lines over long distances without much loss of energy.
• On the other hand, DC doesn’t allow to be stepped up or down using transformers as it is constant ( When compared to AC). Hence it doesn’t result in an alternating magnetic field thus , no transformers. Therefore it is not feasible to transmit it over long distances. If we were to use DC instead of AC in power lines.
• Also AC can easily be converted to DC. AC can be converted to DC using Rectifiers which can easily be made .Easiest example being Bridge Rectifier which only uses 4 registers to convert AC to DC ( although it is not very efficient method, there are more efficient methods). But to convert DC to AC is relatively much harder. That’s another point in favor of AC.

• In power application, the efficiency is determined by the efficiency of the unit being driven, such as an AC motor or a DC motor.In power transmission, the power lines act to some degree like a resistor; very low resistance per foot, but when multiplied by hundreds of miles, the total resistance to a DC current adds up to quite a bit. Therefore, a DC power system will have a considerable voltage drop at the point of application; and the current through those wires will dissipate energy, in proportion to the P=I²R product of the transmission lines. This is known as Line Loss.AC power involves elections moving back and forth, instead of one-way over long distances. So line losses are much lower. Also, AC can be (and is) stepped up to very high voltages for transmission, which is much more efficient.

there are many reason behind the utility use of AC