Higher voltage = lower energy loss
[From: ] [author: ] [Date: 11-06-13] [Hit: ]
Two cases. One, low voltage (100 volts) all the way, and wire resistance over the distance is 10 ohms. Load is 10 ohms. No transformers.......
It's cheaper to have thinner cables at high voltage and use air as an insulator. So that's what they do for long-distance transmission. Around people it's too dangerous so they user lower voltage like 240V or 110V.
-
That is the resistance of the load which is irrelevant here.
Two cases.
One, low voltage (100 volts) all the way, and wire resistance over the distance is 10 ohms. Load is 10 ohms. No transformers. total R is 20 ohms, and voltage at the load is 50 volts, Current is 5 amps, so half the voltage is lost, and the power to the load is only 250 watts.
Case 2, use of transformers.
Lets start out with 100 volts, and step it up to 1000 volts for the wire over a distance, then to another transformer to reduce it to 100 volts. The load is 10 ohms. Wire resistance is still 10 ohms.
In this case, in the HV section, the current (assuming 1000 watt load) is 1000/1000 = 1 amp, and the voltage drop is 1 volt out of 1000, or 999. After the transformer, that is 99.9 volts. So the load gets almost all the power, 998 watt.
So in case 1, half the power is lost in the wire, in case 2, 0.2% is lost.
.
