Transmission Voltage ...

Discussion in 'General Electronics Chat' started by myvision_2525, Jun 13, 2008.

  1. myvision_2525

    Thread Starter New Member

    Jun 4, 2008
    Hello Guys,

    I am bit confuse about one transmission voltage query...

    Transmission voltage is alway like this value "11 kV or 33 kV or 66 kV or 220 kV ... "
    so why in all country they alway use this kind of value ?
    can we use different voltage notation ?

    thanks in advance .
  2. recca02

    Senior Member

    Apr 2, 2007
    Standardization, I guess.

    In engineering mostly all equipments/devices/etc are standardized so that they can be easily replaced or can be maintained/operated according to usual practice.

    The transformers are quite critical for plant operation and have to be made according to some predetermined standards. Perhaps all companies follow some set of rules. Again a transformer may be made by some other company and alternator by other and C&I + protection by some other. It would thus be quite a problem to put these together for the plant to operate properly without set standards. The general trend is to adopt a scheme in practice which has proved itself over time. A failed part must be replaced immediately or it costs the power company millions for outage.

    All generated power at different plants is send to a grid and must be at same voltage thus they will have to be stepped up or down to the same level at some stage or other.

    AFAIK, the higher the voltage the lesser the transmission losses, but then there are design limitations such as insulation.
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    Recca02 is correct. If there were a difference between one voltage source and another, tremendous current would overheat and melt the conductors between them.

    Imagine an 11KV source a few kilometers from a 33KV source. Imagine both somehow connected to the same grid. Imagine the 22KV difference in potential across a scant few ohms would result in a current of thousands of Amps and millions of Watts of heat dissipated! :eek:

    In addition to matching voltage, the various generating stations must also match frequency.