why high voltage is necessary to transmit the electricity
High voltage is used for the transmission of electricity over long distances primarily for two reasons: efficiency and safety.
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Efficiency: The main reason for using high voltage in electricity transmission is to minimize energy loss during the transmission process. When electricity flows through a conductor (such as a power line), it encounters resistance. This resistance generates heat, which is a form of energy loss. The amount of energy loss is determined by the formula P = I^2R, where P is the power loss, I is the current, and R is the resistance of the conductor.
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By increasing the voltage (V), the power (P) remains the same (since power is equal to voltage multiplied by current, P = VI). Therefore, to transmit the same amount of power, you can use higher voltage and lower current.
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Lowering the current reduces the I^2R losses in the transmission lines. This means that a higher percentage of the electricity generated at the power station reaches its destination without being wasted as heat.
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Reduced Energy Losses: When electricity is transmitted at high voltage, the energy losses as heat are significantly reduced. This is especially crucial for long-distance transmission lines that may span hundreds or thousands of miles. Lower energy losses mean that more electricity reaches consumers, and less electricity is wasted.
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Economical Conductors: High-voltage transmission lines can use thinner conductors (wires) for the same power transmission compared to lower-voltage lines. Thinner conductors are lighter and less expensive, making the infrastructure more economical.
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Voltage Regulation: High voltage also allows for better voltage regulation throughout the transmission network. Voltage drop can occur as electricity travels long distances. By starting with high voltage, utilities can ensure that the voltage at the end of the line remains within an acceptable range for consumer use.
However, it's important to note that the electricity that arrives at homes and businesses is typically delivered at a lower voltage. Substations near populated areas step down the voltage before distribution to ensure safety for consumers and to match the requirements of household appliances and devices. This step-down transformation occurs in local distribution networks.