# Comment on efficiency of the transmission line as the supppy voltage changes ?

### 2 Answers

- billrussell42Lv 78 months ago
The higher the voltage the better, as that means less resistive losses in the wires, or you can use thinner wire, which weigh less, which means less mechanical issues with supporting the weight.

but there can be problems. Higher voltage means better insulators, and wires must be higher off the ground. Increased losses due to capacitive loading. Higher risk of electrocution. Capacitive losses can be reduced by transmitting DC, which has other problems.

example: use number 0 wire, which is 0.1 Ω per 1000 ft.

distance is 10 miles, say 50000 ft, which is 5 Ω

if you want to transmit 1 MW single phase

at 5000 volts, that is 200 amps, which at 5 Ω is 1000 volts drop, losing

1000•200 = 200000 watts or 20% of the total

at 10000 volts, that is 100 amps, which at 5 Ω is 500 volts drop, losing

100•500 = 50000 watts or 5% of the total

so just doubling the voltage reduced the losses to 1/4

at 20000 volts, that is 50 amps, which at 5 Ω is 250 volts drop, losing

250•50 = 12500 watts or 1.25% of the total

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- 異域秦後人Lv 78 months ago
THE HIGHEST SUPPLY VOLTAGE, MORE EFFICIENCY TO OVERCOME LONG TRANSMISSION WIRE RESISTANCE COPPER LOSS.

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