Why are electricity in forms of 11kV, 22kV, 33kV, 66kV, and 132kV transmitted in India?

Why are electricity in forms of 11kV, 22kV, 33kV, 66kV, and 132kV transmitted in India

 Electric supply system: definition

The transmission of electric power from a power station to consumers premises is known as electric supply system . 

An electric supply system consists of three major  components viz. , the power station ,the transmission lines and the distribution system . Electric power is produced at the power stations which are located at favourable places , generally quite away from the consumers. It is then transmitted over large distances  from substation to load with the help of conductors known as transmission lines. Finally , power is distributed to large number of consumers through a distribution system . 

    People cite  Form Factor a reason for so. Form Factor is defined as RMS (root mean square) Value to Average value of a given AC voltage and it is different for different waveforms.

 Now the commonly used AC waveform in transmission. A sine wave AC waveform has form factor of 1.11. So, the reason given is that the transmitted voltage of 10kV, 20kV, 60kV etc. is multiplied to this form factor to obtain such results which you described in the question like

For 10kV → 10 x 1.11 kV = 11.1 kV (It is approximately correct)

For 20kV → 20 x 1.11kV = 22.2 kV (It is approximately 22kV)

For 60kV → 60 x 1.11 kV= 66.6 kV (Error! it is 66kV)

Like that

120 x 1.11 kV = 133.2kV (A big error of about +1.2kV because it is 132kV as used)

As,there is huge difference (1kv) for 132 kv ,the form factor is not correct answer for the question.

(2)The generation companies tends to generate round figure high voltages like 10kV, 20kV, 60kV, 120kV etc. But this huge voltage need to be transmitted over huge distance. There is some voltage drop. This drop is 10%. That’s why generation companies add 10% more in their actual target which neutralizes the line losses and the receiving end gets the targeted result. 

Net voltage = Target Voltage + 10% of Target Voltage

→ 132kV = 120kV + 12kV (10% of 120kV)

→ 66kV = 60kV + 6kv (10 %of 60 kV)

But power loss depends on different factors :

• load type(resistive , inductive or capacitive. Losses of inductive and capacitive loads are greater than losses of resistive load)

•Load value (how much load we have)

•Length and number of lines (as length of line increases the voltage drop across the line because of increased resistance.For R phase we use one wire /two wires /three wires.)

•Location of load ( as length affects the voltage drop. )

•voltage level (losses deceases with increase in voltage and vice-versa.)

    From above factor ,our losses are dependent. So,we can't give accurate idea about losses ( they may be less than or greater than 10% because power loss depends on changing factors). Hence,the voltage drop is also not accurate answer .

More accurate and correct answer is : 

     *Technology available: which technology we are using 

     *Facilities available:which facilities are available 

     *Requirement: which type of load one wants to use (resistive, inductive or capacitive)

     *Components available. 

     From these points , engineers and developers stated the

       11kV, 22kV, 33kV, 66kV, and 132kV 

Voltage rating.