THE WORD Power generation seems familiar to us but as a matter of fact most of us didnt have any sound knowledge regarding it. Most of the people know that power is generated at Tarballa or Mangla dam with the help of turbines and transmitted to consumers through cables while in cities it is distributed from power houses. Its the basic structure but there are a lot of things involved in it which are beyond the thinking of a normal person.
At Tarballa or Mangla hydel power is generated with the pressure flow of water. Water enters a turbine with pressure which makes the motor of turbine to rotate. Rotating motor converts mechanical energy of flowing water to electrical energy. This water flow to the turbine is controlled in such a way that the power is generated at 50 hertz, which is our major requirement. This whole process is called power generation. At power generation site couples of generators work in parallel and high voltage (in hundreds of kilo volt) is generated. This method of power generation is known as hydel power generation.
Power generated by other methods is a bit different but all have the same mechanism. Power generated through fossils or atomic powers has similar methods. Burning of fossils produces intense heat that is used to convert water into steam. This steam has low velocity, which is then increased by making it pass through nozzles, which are relatively bigger in size. This high speed steam hits the blade of motor and causes it to rotate and hence electrical power is the result from mechanical source. Similar procedure is adopted for the power generation through atomic plants.
After generation the problem that arises is the transmission of power to the distant areas. But a huge amount of power is wasted. To overcome this headache, transformers are used installed at generation site. These transformers raise the generated high voltage further higher and the current is lowered. This exercise reduces the power transmission losses. Another amazing fact is that it is proven both mathematically and practically that for higher currents, thicker wires especially copper wires had to be used. While low currents relatively requires thinner wires which reduces the cost of wires. Although high voltages and low currents save the power loss during transmission, yet 25-30 per cent of power is still wasted during the transmission process. That is still a major problem. Furthermore, we have no solution to overcome this loss right now.
These high voltages are hazardous for human health. Due to this hazard, transmission lines are taken at some height outside the cities. At the receiving end outside the urban areas, it is again fed to a transformer, which lowers the high voltage into the safe limits. From this station it is sent to different sub-power stations within the cities that distribute it to the domestic or industrial users. This voltage is still much high than 220 volts. So far in every small area a transformer is installed that lowers the high voltage to 220 volts and then we are able to consume this power.
Local consumers use it in different electrical devices and lighten their homes. But our appliances use more than half of the power, while the rest is wasted as heat. This heat can normally damages our equipment. Now to overcome this heat, heat sink is installed in almost every equipment and special ventilation systems are designed that does not allow the equipment temperature above the safety level. If the ventilation system is not functioning properly, the system overheats and as a result components installed in the system get damaged. So ventilation system is necessary in every appliance. Thats why the devices that have high power rating are relatively more heated. While in industrial sector power is used to run different plants and machineries.
Power is usually rated in watts. The domestic meters installed outside our homes show the reading by calculating watts consumed.
One can notice that three or sometimes four pair of lines are delivering power to residences? These are actually the three phases. These three lines have the same voltage i.e. 220 volts but are mathematically 120 degrees apart, means they have voltage with the angle difference of 120 degrees. The other fourth cable is the neutral wire, which is necessary for the circuit to complete. This wire serves us as ground. These four pairs of wire start from the generation site, carrying the generated power and then as a transmission line, transmitting high voltages reaching us and delivering the power for our requirement.
The generation, transmission systems and consumption devices are not a work of a single brain as this involves a hectic work on the part of different departments.