The various electrical conducting materials are discussed as follows: 1. Copper 2. Aluminium 3. Tungsten 4. Iron and Steel 5. Nickel 6. Tin 7. Lead 8. Alloys 9. Carbon and Graphite 10. Molybdenum 11. Platinum 12. Mercury 13. Non-Linear Conductors. 1. Copper: Properties: (i) Its colour is reddish. (ii) It is highly malleable and ductile. (iii) It can be cast, [...]
Semiconductors are solid materials, either non-metallic elements or compounds, which allow electrons to pass through them so that they conduct electricity in much the same way as a metal. Characteristics of Semiconductors: Semiconductors possess the following characteristics: 1. The resistivity is usually high. 2. The temperature co-efficient of resistance is always negative. 3. The contact between semiconductor and a metal [...]
In this article we will discuss about:- 1. Introduction to Carrier-Current Protection 2. Methods of Carrier-Current Protection 3. Advantages. Introduction to Carrier-Current Protection: In modern high-power electrical systems it is necessary to have quick-acting protections on long transmission lines. The requirements to be met by such protections are fully satisfied by the circulating current differential protection with its high sensitivity, [...]
The application of time-graded protection to radial feeders, parallel feeders, and ring main system will be discussed here: Application # 1. Protection of Radial Feeders: The main characteristic of a radial system is that power can flow in one direction only, from generator or supply end to the load end. It has the drawback that continuity of supply cannot be [...]
The following points highlight the seven main types of conductors used in transmission and distribution of electric power. The types are: 1. Stranded Hard Drawn Copper 2. Aluminium 3. Steel-Cored Aluminium 4. Galvanised Steel 5. Cadmium Copper 6. Copper-Clad Steel 7. Phosphor Bronze. Type # 1. Stranded Hard Drawn Copper: Hard drawn copper conductor is the best conductor owing to [...]
The demand of electric power is increasing throughout the world and in many countries it is doubling every five to eight years. The power stations (hydro, thermal or nuclear) are usually located far away from the load centres. Thus transmission of large amounts of power over long distances, which can be accomplished most economically only by using extra high voltages [...]
There are numerous factors such as system frequency, system voltage, air conductivity, air density, conductor radius, surface of conductor, load current and atmospheric conditions, on which the corona loss depends. Factor # 1. Effect of System Frequency: From Eqs. (7.8), (7.9) and (7.10) it is obvious that corona loss varies directly as the system frequency. Factor # 2. Effect of [...]
Depending upon which quantities have been specified, the buses are classified into three categories viz.: 1. Generation Bus 2. Load Bus and 3. Slack Bus. Category # 1. Generation Bus or Voltage-Controlled Bus: This is also called the P-V bus, and on this bus the voltage magnitude corresponding to generation voltage and true or active power P corresponding to its [...]
A power system may comprise several buses interconnected through transmission lines. Power is injected into a bus from generators, while the loads are tapped from it. Of course, there may be buses with only generators, and there may be others with only loads. Some buses may have both generators and loads while some others may have static capacitors (or synchronous [...]
The following points highlight the two main types of arrangement of resistance for conductors. The arrangements are: 1. Resistances in Series 2. Resistances in Parallel. Type # 1. Resistances in Series: When two or more conductors or coils or electrical appliances or resistors are joined together one after another to form a single circuit, they are said to be in [...]