Flood Lighting

Flood Lighting Q. State any four specific requirements of flood lighting. Meaning of Flood Lighting Its meaning is, copious artificial light projected many directions, eliminating all the shadows on the surface illuminated. Applications of Flood Lighting Flood lighting is used to illuminate various surfaces of various categories like    (a) Aestetic    (b) Industrial and … Read more

Primary lonization, Avalanche, Secondary lonization

Q. Important Definitions Define Townsend’s first and second ionization constant. How the condition for breakdown is obtained in a Townsend’s discharge? Primary Ionization It is the process of liberation of free electrons from gas molecules with simultaneous production of positive ions due to collision with free electrons. Townsend’s Primary Ionization Coefficient (α) It is number … Read more

Practical Considerations in using Gases for Insulation Purpose

Practical Considerations in using Gases for Insulation Purpose Air has great advantage of being low in cost, therefore it found some application at increased pressure in condensers, cables and other insulation constructions. But it does not satisfy the second requirement, since ionization of air is accompanied by emission of ozone, nitrous and nitric oxides causing … Read more

Control of Over Voltages due to Switching and Power Frequency

Control of Over Voltages due to Switching and Power Frequency (a) Energization of TL in or more steps by inserting resistances and withdrawing them afterwards It is normal practice to have a series resistance with the circuit breaker contacts during switching ON and then but short circuiting this resistance after a few cycles. (b) Eliminating … Read more

Distribution of Switching Surges (EHV and UHV Systems)

Distribution of Switching Surges (EHV and UHV Systems) Switching surges originate when there is sudden release of internal energy stored in the electrostatic form (in the capacitance) or in the electromagnetic form (in the inductance). This can happen in following situations :     (i) Current chopping phenomenon : Interruption of magnetizing currents (transformers/reactors re switched … Read more

Methods of Calculation of Electric Field

Methods of Calculation of Electric Field There are different graphical, experimental and numerical field calculation methods. Special methods like method of images, conformal mapping, co-ordinate transformation are applied to simple geometrical configuration. The experimental measurement of field strength in small air gaps stressed by high voltages is a very difficult process and not quite accurate. … Read more

Fields in Multidielectric, Isotropic Materials

Fields in Multidielectric, Isotropic Materials Many insulating materials used in high voltage insulation system are formed with different layers of various insulating materials. Different materials have different permittivities. e.g. Bakelite sheets or mica sheets or materials used in transformers. The necessity of using such a material is Different layers are used to control electric stresses. … Read more

DC Generator Principle

Working Principle of DC Generator An electrical generator is a machine which converts mechanical energy (or power) into electrical energy (or power). The energy conversion is based on the principle of the production of dynamically (or motionally) induced e.m.f. As seen from Figure, whenever a conductor cuts magnetic flux, dynamically induced e.m.f. is produced in … Read more