Module 1 : Electric Field Intensity (Electric Stress)
Lecture 1:  An introductory lecture
VOLTAGE LEVELS
Consumer
  • ac power frequency :
                  110 V, 220 V- single phase
                  440 V, 3.3 kV ,6.6 kV, 11 kV-three phase (3.3 & 6.6 kV are being phased out)
  • Besides these levels ,the Railway Traction at 25 kV , single phase is one of the biggest consumer of power spread at any particular stretch to 40 km of track length .
Generation : Three phase synchronous generators
                         440 V, 3.3 kV, 6.6 kV (small generators) , 11 kV (110 & 220 MW)             
                         21.5 kV ( 500 MW), 33 kV (1000 MW)
                         [limitation due to machine insulation requirement]

Distribution :

Three phase
440 V, 3.3 kV, 6.6 kV, 11 kV, 33 kV, 66 kV
With the increase in power consumption density, the power distribution voltage levels are at rise because the     power handling capacity is proportional to the square of the voltage level.
(In Germany 440 V , 3.0 kV 6.0 kV, 10 kV, 30 kV, 60 kV)

ac Transmission : 110 kV, 132 kV, 220 kV, 380 - 400 kV, 500 kV, 765 - 800 kV, 1000 kV and 1150 kV exist.
                                   Work on 1500 kV is complete.
In three phase power system, the rated voltage is always given as line to line, rms voltage .
d.c. transmission : dc single pole and bipolar lines :
                                    ± 100 kV to ± 500 kV
 
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