In this article we will discuss about:- 1. Meaning of Fuse 2. Metals and Alloys Used for Fuse 3. Types 4. Merits 5. Demerits. Meaning of Fuse: An electric circuit is designed to carry a definite amount of current. If a much greater current passes through the circuit, there may be serious damages. To check it, a length of a [...]
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, [...]
In this article we will discuss about:- 1. Introduction to Insulating Materials 2. Characteristics of a Good Insulating Material 3. Classification of Insulating Materials 4. Air Spaces in Insulation 5. Effect of Moisture on Insulation 6. Protection of Insulation against Moisture. Contents: Introduction to Insulating Materials Characteristics of a Good Insulating Material Classification of Insulating Materials Air Spaces in Insulation [...]
The various high resistivity materials (including alloys) are described below: 1. Tungsten: (i) Hard metal. (ii) Resistivity twice that of aluminium. (iii) Can be drawn into very thin wires (for making filaments). The thinner the tungsten wire, the greater is its tensile strength. (iv) In the atmosphere or inert gas (Nitrogen, Argon etc.) or in vacuum, tungsten can be readily [...]
Here is a list of popular electrical materials. 1. Materials of Low Resistivity and High Conductivity: These materials should have the least possible electrical conductivity. They are employed for making conductors for all kinds of windings required in electrical machines, apparatus and devices, as well as for transmission and distribution of electrical energy. Requirements of Materials of High Conductivity: The [...]
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 [...]
The properties of insulating materials are enumerated and discussed as under: 1. Electrical Properties 2. Thermal Properties 3. Chemical Properties 4. Mechanical Properties. 1. Electrical Properties of Insulating Materials: i. Insulation Resistance: It may be defined as the resistance between two conductors (or systems of conductors) usually separated by insulating materials. It is the total resistance in respect of two [...]
In this article we will discuss about:- 1. Introduction to Ferroelectric Materials 2. Common Ferroelectric Materials 3. Properties of Ferroelectric Materials in Static Fields 4. Spontaneous Polarisation 5. Applications of Ferroelectric Materials 6. Anti-Ferroelectric Materials 7. Permanent Electric Materials. Introduction to Ferroelectric Materials: If the centre of gravity of the positive and negative charges in a body do not coincide [...]
Phase comparison technique is the most widely used technique for all practical directional, distance, differential and carrier relays. In a phase comparator, the operation of the relay takes place when the phase relation between two inputs S1 and S2 varies within certain specified limits. Both inputs must exist for an output to occur; ideally, operation is independent of their amplitudes, [...]
Whenever there is an unbalanced circuit, the unbalanced currents will have a negative phase sequence component. A negative phase sequence (or phase unbalance) relay is essentially provided for the protection of generators and motors against unbalanced loading that may arise due to phase-to-phase faults. Essentially such a relay has a filter circuit which is responsive only to the negative sequence [...]