What is the voltage level of LT and HT line

full form of LT and HT

 LT - Low tension ( Low voltage )

• voltage range - Below 1000 Voltage
• Used in secondary distribution system

HT - High Tension ( High Voltage )

Voltage range - 1000 V to 33 kv

Used in primary distribution system

EHT - Extra High Tension ( Extra High Voltage )

Voltage range - Above 33 kV

Used in transmission system 

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Why we use HT motors

 HT Motors - High Tension Motors

 HT motors take high voltage the increase in voltage leads to decrease in current which thereby leads to decreases in size of conductor. Thus the size of the cables and distribution line reduces. The protection equipment size and cost also reduced and also the size of the machine reduces as compared to that LT motor size.

Power losses = I^2 R

Here 

I - current flow through the winding 

R- Resistance of the winding 

Resistance R = R = ρ L / A

1. Low power losses

2. High efficiency

3. Smaller construction 

4. Cable cost is low