Electric Braking of Motors There are three types of electric braking as applicable to electric motors. In many cases, provision of an arrangement for stopping a motor and its driven load is as important as starting it. For example, a planing machine must be quickly stopped at the end of its stroke in order to […]
AC Series Motor If an ordinary d.c. series motor were connected to an a.c. supply, it will rotate and exert unidirectional torque because the current flowing both in the armature and field reverses at the same time. But the performance of such a motor will not be satisfactory for the following reasons:- However, by proper
Standard Types of Squirrel Cage Motors Different types of 3-phase squirrel-cage motors have been standardized, according to their electric characteristics, into six types, designated as design A, B, C, D, E and F respectively. The original commercial squirrel-cage induction motors which were of shallow slot type are designated as class A. For this reason, Class
Protection of Transmission Lines The probability of faults occurring on the lines is much more due to their greater length and exposure to atmospheric conditions. This has called for many protective schemes which have no application to the comparatively simple cases of alternators and transformers. The requirements of line protection are:- The protection of lines
3-Phase Transformer Protection Schemes Transformers are static devices, totally enclosed and generally oil immersed. Therefore, chances of faults occurring on them are very rare. However, the consequences of even a rare fault may be very serious unless the transformer is quickly disconnected from the system. This necessitates to provide adequate automatic protection for transformers against
Types of Functional Relays Most of the relays in service on power system today operate on the principle of electromagnetic attraction or electromagnetic induction. Regardless of the principle involved, relays are generally classified according to the function they are called upon to perform in the protection of electric power circuits. For example, a relay which
Types of Protective Relays In a power system consisting of generators, transformers, transmission and distribution circuits, it is inevitable that sooner or later some failure will occur somewhere in the system. When a failure occurs on any part of the system, it must be quickly detected and disconnected from the system. There are two principal
Gas Turbine Power Plant A generating station which employs gas turbine as the prime mover for the generation of electrical energy is known as a gas turbine power plant. In a gas turbine power plant, air is used as the working fluid. The air is compressed by the compressor and is led to the combustion
Generation of Electricity in Thermal Power Plant A generating station which converts heat energy of coal combustion into electrical energy is known as a steam power station. A steam power station basically works on the Rankine cycle. Steam is produced in the boiler by utilising the heat of coal combustion. The steam is then expanded
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Methods of Voltage Control in Power System In a modern power system, electrical energy from the generating station is delivered to the ultimate consumers through a network of transmission and distribution. For satisfactory operation of motors, lamps and other loads, it is desirable that consumers are supplied with substantially constant voltage. Too wide variations of