Electric Power Distribution

Electrical energy is one form of energy which is generated, transported and utilized most in modern days. Unlike other forms of energy it is not available naturally. The easiest form of conversion is form mechanical energy to electrical energy and vice-versa. The other forms of conversion like solar to electrical, chemical energy to electrical etc, is less efficient and more tedious. Most of the electrical energy is generated where the fuel or resources are available, i.e., near coal mines or water falls and reservoirs. Modern power stations are of large sizes ranging from 500 MW to 2000 MW or more, each generator size being 100 to 500 MW. The present generation in our country is more than 100 GW.

The power generated is to be transported from the generating stations through transmission lines over long distances. Typical transmission voltages range from 220 kV to 765 kV or more (1100 kV in USA, Russia etc) and is distributed to various utilities through sub-transmission and distribution network, usually the transmission network, Inter-connected and forms a GRID through the substations each local or bulk load is connected to a substation and the power is transmitted. Most of transmission systems used are 3-phase ac 50 or 60 Hz. D.C Transmission.

The electrical distribution network or system will be the supply system to the electrical power consumers of the following:

• Smaller requirement typically less than about 25 kVA (20 kW} through single phase 230 V or 3-phase 400 V. These loads may be domestic agricultural, commercial etc
• Larger power requirement more then 20 kW (25 kVA) supplied through 3ph systems. Example-. Industrial loads, commercial loads, special loads like electric traction, chemical plants, etc.

Electrical utilities or loads may be in general, grouped as

• Mechanical loads: Motor loads and drives
• Chemical utilities: metal extraction through electrolysis process, electroplating, etc,
• Heating loads: furnaces etc,
• Lighting and illumination
• Power converters and electronics.

Questionnaire:

• Explain about the electric power distribution.