LEC # 02
SUBTRANSMISSION
SUBTRANSMISSION
IT is that part of the electric utility system which delivers powerfrom bulk power sources, such as large transmission substation tothe distribution substations.
maximum voltage that can be generated economically is 25 KV(16.7 KV in Pak)
the biggest generator in the world today is rated 1500 MVA.
The voltage of these circuits varies form 12.47 to 245 kV, with majority at 69,115 & 138 KV voltage levels (In Pakistan the voltages are 66 and 132 kV and in rare cases 33 kV ). Types of subtransmission system:
1. RADIAL SYSTEM (simplest, cheapest)
2. Loop system
3. Grid or network type system
It radiates from bulk powerstations to the distributionsubstations.
It is simple & cheap but haslow service continuity (notgenerally used)
Radial Type Subtransmission
Improved Form of Radial – Type Subtransmission
Loop Type Subtransmission
Grid or Network Type Subtransmission
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