IC Voltage Regulator Circuits Due to low-cost fabrication technique, many commercial integrated-circuit (IC) regulators are available since the past two decades. These include fairly simple, fixed-voltage types of high-quality precision regulators. These IC regulators have much improved performance as compared to those made from discrete components. They have a number of unique build-in features such […]
Electronic Control of AC Motors Efficient control of motors becomes critical where high precision, accuracy, reliability and faster response are of paramount importance. Electronic and digital controls are employed in such conditions. Classes of Electronic A.C. Drives AC motors, particularly, the squirrel-cage and wound-rotor induction motors as well as synchronous motors lend themselves well to
Construction, Working & Types of Synchros and Resolver It is a general name for self-synchronizing machines which, when electrically energized and electrically interconnected, exert torques which cause two mechanically independent shafts either to run in synchronism or to make the rotor of one unit follow the rotor position of the other. They are also known
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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