An electric power system is a network of electrical components deployed to supply, transfer, and use electric power. An example of a power system is the electrical grid that provides power to homes and industries within an extended area. The electrical grid can be broadly divided into the generators that supply the power, the transmission system that carries the power from the generating centers to the load centers, and the distribution system that feeds the power to nearby homes and industries. Smaller power systems are also found in industry, hospitals, commercial buildings, and homes. A single line diagram helps to represent this whole system. The majority of these systems rely upon three-phase AC power—the standard for large-scale power transmission and distribution across the modern world. Specialized power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners, submarines, and automobiles.

1. Power Supply Systems
(MEPCO)

2. Power Supply Systems
• The conveyance of electric power from a power station to consumers’
premises is known as electric supply system.
• Three Components
Power Stations
Transmission Lines
Distribution Systems

3. Power Supply Systems
• Classification of Electric Supply System
DC or AC System
Overhead and Underground System
• Universal Adoption of 3 phase 3 wire System for generation and
transmission

4. 500/220
KV
132 KV
11 KV
400/230 V
11 KV
AC Power Supply Scheme

5. DC Transmission System
Advantages
Less Conductor material requirement
No inductance, capacitance, phase displacement and surge problems in d.c.
transmission
Less Voltage Drop
No Skin Effect

6. DC Transmission System
Less insulation required
No Stability Problems and synchronizing difficulties
Absence of Corona effect
Free from dielectric losses

7. DC Transmission System
Disadvantages
Electric power cannot be generated at high DC voltage due to commutation
problems.
The DC voltage cannot be stepped up for transmission of power at high
voltages.
The DC switches and circuit breakers have their own limitations

8. AC Transmission System
Advantages
 The power can be generated at high voltages.
The maintenance of AC sub-stations is easy and cheaper.
The AC voltage can be stepped up or stepped down by transformers with
ease and efficiency. This permits to transmit power at high voltages and
distribute it at safe potentials

9. AC Transmission System
Disadvantages
An AC line requires more copper than a DC line.
 The construction of AC transmission line is more complicated than a DC
transmission line.
 Due to skin effect in the AC system, the effective resistance of the line is increased.
An AC line has capacitance. Therefore, there is a continuous loss of power due to
charging current even when the line is open.

10. Advantages of High Transmission Voltage
Reduces volume of conductor
material

11. Advantages of High Transmission Voltage
Increase in Transmission Efficiency

12. Advantages of High Transmission Voltage
Decrease in percentage voltage
drop

13. Limitations of High Voltage Transmission
 The increased cost of insulating the conductors
The increased cost of transformers, switchgear and other
terminal apparatus

14. THANKS