Category: Induction Machine

High Efficiency Induction Motors

High Efficiency Induction Motors: With ever-increasing energy cost the life-time operating cost of an induction motor can be traded against a high efficiency and high capital cost induction motors. With rising demand for high efficiency or energy efficient induction motors, designers and manufacturers are stepping up their production of such motors. Some of the important […]

Inverted Induction Machine

Inverted Induction Machine: In a wound-rotor induction machine the three-phase supply can be given to the rotor windings through the slip rings and the stator terminals can be shorted (see Fig. 9.68). Such a rotor-fed induction machine is also called an inverted induction machine. The three-phase rotor current will generate a rotating field in the […]

Induction machine Dynamics

Induction machine Dynamics: Induction machine Dynamics – In general, the mechanical time-constant for any machine is much larger than the electrical time constant. Therefore, the dynamic analysis can be simplified by neglecting the electrical transient without any loss of accuracy of results. The circuit model of Induction machine Dynamics of Fig. 9.8(b) holds for constant […]

Isolated Induction Generator Working Principle

Isolated Induction Generator Working Principle: An Isolated Induction Generator Working Principle feeding a load is shown in Fig. 9.61. The delta-connected capacitors across the generator terminals provide the magnetizing current necessary to excite the isolated generator. The voltage build-up will be explained later in this section. As the generator is loaded, the operating frequency depends […]

Induction Generator

Induction Generator: It has been observed from Fig. 9.14 and Example 9.7 that an induction machine is in generating mode for s < 0 (negative slip). An induction generator is asynchronous in nature because of which it is commonly used as windmill generator as a windmill runs at non-fixed speed. These are used in remote […]

Classes of Squirrel cage motors

Classes of Squirrel cage motors: Classes of Squirrel cage motors – To cater to the different starting and running requirements of a various industrial applications, several standard designs of squirrel-cage motors are available in the market. The torque-speed characteristics of the most common designs are shown in Fig. 9.58. The effective resistance of the rotor […]

Double Cage Rotor

Double Cage Rotor: Double Cage Rotor – A rotor design, which though more expensive gives still better starting, and running performances than the deep-bar design, is the double-cage rotor. The squirrel-cage winding in this design consists of two layers of bars short-circuited by end rings. The upper bars have a smaller cross-sectional area than the […]

Deep Bar Rotor

Deep Bar Rotor: Deep Bar Rotor –┬áThe chief advantage of the slip-ring induction motor compared to the squirrel-cage one lies in the fact that while its rotor is designed with low resistance to give good running performance (high efficiency, low slip, etc.), excellent starting characteristic (low starting current, high starting torque, etc.) is simply achieved […]

Speed Control in Induction Machine

Speed Control in Induction Machine: Speed Control in Induction Machine – Stepless control of speed of induction motors cannot be carried out as efficiently and inexpensively as for dc motors. Various methods of controlling the speed of the induction motor can be visualized by consideration of the speed equation It is seen from this equation […]

Cogging and Crawling

Cogging and Crawling: Cogging and Crawling – A squirrel-cage rotor may exhibit a peculiar behaviour in starting for certain relationships between the number of poles and the stator and rotor slots. With the number of stator slots S1 equal to or an integral multiple of rotor slots S2, the variation of reluctance as a function […]