Electrical engineering

you can download catalog from ABB, Schnieder or Siemens

It all depends on what document or reference you are using. Really in the USA, the National Electrical Code (NFPA 70) does not really use the terms low voltage, medium voltage and high voltage. It referes to three voltage ranges, below 50 volts, below 600 volts and over 600 volts. In the IEEE Red Book, it refers to low voltage is anything under 600 volts, 601 to 25,000 volts is medium voltage and over 25,000 volts to 43KV is High Voltage, then you have Ultra High Voltage after that. I would suggest you find the nearest Engineering Library and take a look at the IEEE Red Book - Recommended Practices for Industrial Power Distribution. What I have found is that some of the new and young EEs coming out of school do not understand the terminology/definitions and end up in trouble due to it. For example, a three phase voltage system is not defined by it's phase to neutral or ground voltage but instead by it's phase to phase voltage. But one young gentleman did not understand it and applied 4.16 KV to a 2.3KV motor. I ain't seen that much smoke outside of a cigar shop. I hope this helps.

Dear Friend,

LV - Low Voltage upto 600 Volts

MV - Medium Voltage upto 6600 Volts

HV - High Voltage 11 KV to 33 KV

EHV - Extra High Voltage above 33 KV in steps of 66 KV, 110 KV, 230 KV, 400 KV, 600 KV, 735 KV, (In some countries it is 800 KV) 1200 KV.

DHAYANANDHAN.S