Transmission & distribution voltage is 11KV, 33KV, 66KV, 132KV. Why are they multiples of 11? Why not 10, 30, 80, 120 ??
Let's go Find the explanation.
Many people think that the form factor is 1.11, so the voltage pattern is similar.
10 x 1.11 = 11.1
30 x 1.11 = 33.3
60 x 1.11 = 66.6
120 x 1.11 = 133.2
In reality, this idea is not correct because multiplying 120 volts by 1.11 does not give 132KV.
And the form factor is RMS & Average Value Ratio 1. There is no point in multiplying that. So which one is correct?
Let me give you an analogy before that. Suppose you get a contact for sending 500 mangoes from Rajshahi to Chittagong. Then you have 500 along. Shall I send it? Certainly not. Because there may be snatching on the way, or mango may rot. So you have to keep some backup. You have to pay 50 extra. Similarly, Power transmission/distribution transmits 10% more voltage than the actual voltage to the companies. Because they know that well. There will be system loss along the way.
Now let's calculate,
10 + 10 x 10% = 11 KV
30 + 30 x 10% = 33 KV
60 + 60 x 10% = 66 KV
120 + 120 x 10% = 132 KV
Now the question that comes to the minds of many is who am I doing like 10, 30, 60, 120, but why? Our country mainly generates this voltage at the Generating & Distribution stations. Later in those voltages with backup Transmits. Maybe a little less. However, this calculation is on average.
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