Why all voltages are multiple of 11? Like 11kv,22kv,33kv,66kv,132kv etc.?

Question

Why all voltages are multiple of 11? Like 11kv,22kv,33kv,66kv,132kv etc.?

Answer 1

This gets asked about once a week.

goes back to Edison, who was trying to pick a voltage for his new incandescent lamps. Too high and they were too difficult to make. Too low meant high currents that were difficult to distribute. He picked 100 volts (DC), and set the generators at 110 volts to compensate for wiring drops.

Everything else evolved from that 110 voltage number.

But nominal voltage in the US is 117 or 118 volts actually.

Answer 2

Just as an aside, the term "nominal voltage" is typically used to describe the voltage classification, 120Vac in the references above.  The actual observed voltage may vary from that number, as the poster above mentioned.

Answer 3

I would add to the good answer above:

>>>But nominal voltage in the US is 117 or 118 volts actually<<<

I have seen voltages from 110V to 125V in different cities.

Answer 4

These voltages are all transmission line related. KV as in 1000Volt etc.

Based on the Transformer of the Substation the High Tension Line of kV to transformed into the 2400V - 3200V range. It's based on the configuration of the Transformer windings.

The voltage is then Transformed down to a more conventional value such as 2400V on the Utility pole along a city street. Then the Xfmr on these utility poles converts it to Household value of 220- 240V which when split provide 110-120V to ground.