Electricity: Generation, Transmission & Distribution

• Electrical power system consist of 4 major categories:
  a. Generation System
  b. Transmission System
  c. Distribution System
  d. Utility System
• Majority of electricity (65-70%) is produced by steam turbine plants and fuel is Coal or Nuclear.
• Hydro electric generation (25-30%) forms the 2nd largest means of generating electricity.
• Renewable sources of energy fall in a very small range (2-5%).
• Renewable sources of energy – solar, wind, ocean, bio gas, geothermal, etc.
• Gas Turbines are used during short periods of high demand for Peaking.
• Large generators voltage rating or generation is @ 13.8kV to 24kV voltage levels.
• Generator voltage is stepped up to transmission voltage level using transformers.
  Because a. Generation and Distribution stations are far away, b. There will be huge I²R losses (transmission losses or copper losses) if the voltage level is low, c. Transformers can transform this energy to higher voltage levels, without much loss.
• Transmission voltage levels in the range from 115kV to 765kV.
• Standard transmission voltages are 115kV, 138kV, 230kV, 345kV, 500kV and 765kV.
• At distribution station, the transformer steps down the voltages.
• Low voltage ranges from 34.5kV to 138kV at distribution station.
• Distribution standard voltages are 4.16kV, 12.47kV, 13.2kV, 13.8kV and 34.5kV i.e. range is from 5kV to 34.5kV.
• Why we cannot use higher voltages directly?
  a. Difficult to have equipments with such a high insulation rating.
  b. Not economical.
• Distribution transformers are used to further step down to utilization voltage levels, usually at 600V.
• Standard utilization voltages are 480Y/277V, 460V, 208Y/120V, 240V, and 120V.
• Higher utilization voltages – 6.9kV and 4.16kV are standard voltages for supplying large industrial motor loads.

Electrical Engineering - Overview

           Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical power supply. It now covers a range of subtopics including power, electronics, control systems, signal processing and telecommunications.

           Electrical engineering may include electronic engineering. Where a distinction is made, usually outside of the United States, electrical engineering is considered to deal with the problems associated with large-scale electrical systems such as power transmission and motor control, whereas electronic engineering deals with the study of small-scale electronic systems including computers and integrated circuits.Alternatively, electrical engineers are usually concerned with using electricity to transmit energy, while electronic engineers are concerned with using electricity to process information. More recently, the distinction has become blurred by the growth of power electronics.

Sub-disciplines:

1. Power

2. Control

3. Electronics

4. Microelectronics

5. Signal processing

6. Telecommunications

7. Instrumentation

8. Computers

Electricity:-

          Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire. In addition, electricity encompasses less familiar concepts such as the electromagnetic field and electromagnetic induction.

          In general usage, the word "electricity" adequately refers to a number of physical effects. In a scientific context, however, the term is vague, and these related, but distinct, concepts are better identified by more precise terms:

1. Electric charge: a property of some subatomic particles, which determines their electromagnetic interactions. Electrically charged matter is influenced by, and produces, electromagnetic fields.
2. Electric current: a movement or flow of electrically charged particles, typically measured in amperes.
3. Electric field: an influence produced by an electric charge on other charges in its vicinity.
4. Electric potential: the capacity of an electric field to do work on an electric charge, typically measured in volts.
5. Electromagnetism: a fundamental interaction between the magnetic field and the presence and motion of an electric charge.

          Electric power provided commercially by the electrical power industry. In a loose but common use of the term, "electricity" may be used to mean "wired for electricity" which means a working connection to an electric power station. Such a connection grants the user of "electricity" access to the electric field present in electrical wiring, and thus to electric power.