Basic Characteristic of electrical power system :
- 3-phase AC system at constant voltage .
- Generation and Transmission facilities use 3-phase equipment .
- Industrial loads are invariably three phase , single phase commercial and
residential loads are distributed equal among so it balanced three phase system
- use synchronous machine for generation of electricity , prime mover transfers
the prime source of energy to mechanical energy that converts to electric
energy by generator .
- transmit power over signification distance consumer .
The Transmission system :
Transmission System .
Sub-transmission System .
Distribution System .
Transmission System :
interconnect all main generation station and main loads , operates at highest voltage
level (230 KV and above) , the generator voltage are usually in the range of 11 to 35
KV these are stepped up to the transmission voltage level , power transmitted to the
transmission substation where the voltage are stopped down to the sub-transmission
level (69 kV to 138 KV) .
Sub-Transmission System :
Transmit power in small quantities from the transmission substation to distribution
substation , large industrial customer supplied directly from the sub-transmission
system .
Distribution System :
The final stage in the transfer of power to customer , it at low voltage connected to
load (220V) .
- The voltage from sub-transmission system (69 to 138 KV) come to ring main
unit which in it step down transformer to come out in low value to residential
and commercial loads .
- we step up the voltage from generator (11 to 35 KV) by step up transformer to
(220 KV -380 KV .....) to reduce the losses in transmission line , hence we can use
cable not large .
To continue our Course about Power System :
[ The second lecture of Power System ]
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