Soft and Hard Magnetic Materials

Soft Magnetic Materials These materials are easy to magnetise and demagnetise. These materials favour rapid switching (it means high frequency) of magnetism to applied ac field. These materials have low retentivity. Low coercivity. High permeability High magnetic saturation Low hysteresis losses because of the lesser area of the hysteresis loop. These materials are used for […]

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Electrical Engineering Materials: Assertion/Reason Questions

Each of the following questions consists of two statements, one labelled ‘Assertion (A)’ and the other labelled the ‘Reason (R)’. Examine the two statements carefully and decide if the Assertion (A) and Reason (R) are individually true and if so whether the Reason (R) is the correct explanation of the Assertion (A). Select your answers […]

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Insulating Materials for Cables & Electronic Equipments

Insulating Materials for Cables The insulating materials (dielectrics) used for cables must have low discharge current, low dissipation factor (low loss tangent), and should be chemically stable. The materials generally used are impregnated paper, bituminous compounds, rubber, compressed air, mineral oil etc. In the present days, cross-linked polyethylene cables (XLPE) are manufactured for 11 kV, […]

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Electrical Machine Insulation

In electrical machines, the insulation system must withstand the high electrical stresses and severe mechanical stresses induced by the magnetic field of the moving rotor. In machines, multi-turn windings are put in narrow armature slots, which are usually grounded. Rotating machine stator insulation construction is divided into principal types: Random wound conductor machines with small […]

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Insulating Materials for Power & Distribution Transformers

The insulating materials used in power and distribution transformers must possess the following properties: Good electrical properties to withstand the power frequency (50 Hz) voltages and impulse overvoltages. Good mechanical properties to withstand fabrication and handling during manufacture and electromagnetic forces during overload, short circuit, and normal operating conditions. Good thermal stability and low ageing […]

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Solid Insulating Materials

Solid insulating materials may be natural organic substances like paper, cloth, rubber, etc. or inorganic materials like Mica, Glass, or synthetic materials like plastics. The different solid insulating materials are: Paper and Pressboards Fibrous materials (unimpregnated and impregnated) Impregnated coating, filling, and bonding materials Resins (Polymers) Natural and synthetic rubbers Inorganic Insulating Materials: a) Glass b) […]

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Liquid Insulating Materials

An ideal insulating liquid must have following properties: High electric strength, impulse strength, and volume resistivity. Low dielectric dissipation factor. High or low dielectric constant (depending on application). High specific heat and thermal conductivity. Excellent chemical stability and gas-absorbing properties. Low viscosity, low-density, low volatility, low solvent power and high flash point. Good arc quenching […]

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Types of Superconductor Material

There are two types of superconductor materials Type-1 superconductor Type-2 superconductor Type-1 superconductor They are also called as Soft Superconductor. Their critical field and transition temperature are low. They exhibit complete Meissner’s and Silsbee rule. The change of state from normal to superconductivity and vice-versa is abrupt. Examples: Zn, Pb, Hg, Al, In, etc. Type-2 superconductor They are also called as Hard Superconductor […]

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