**9. References**

[1] Muşuroi, S.; Vătău, D.; Andea, P.; Şurianu, F.D.; Frigură, F. & Bărbulescu, C. (2007). Analysis of the Magnetic Losses from the Induction Machines Supplied by Inverters**,** *Proceedings of EUROCON 2007 International Conference on Computer as a Tool*, pp. 1800-1809, ISBN 978-1-4244-0812-2, Warsaw, Poland, September 9-12, 2007

**Chapter 3** 

© 2012 Mirošević, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Mirošević, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**The Dynamics of Induction Motor Fed** 

Additional information is available at the end of the chapter

Marija Mirošević

**1. Introduction** 

intermittently.

http://dx.doi.org/10.5772/49973

**Directly from the Isolated Electrical Grid** 

An induction motor is the most common machine used for industrial drives. It is used in variety of drives due to its robust construction, relatively low cost and reliability. In isolated electrical network, such as marine and offshore power systems and emergency generation plant, induction motors are the most power consuming loads and are used for winches, water pumps, compressors, fans and for other on-board applications, in continuous mode or

In many applications induction motors are direct-on-line switch-started. Their dynamic characteristics have an obvious influence on the transient process of power system; however, they cause a significant disturbance in transients (significant impacts loads) that can produce disturbances in the isolated electrical network, which in turn affects the quality

Direct-on-line starting represents the simplest and the most economical system to start squirrel-cage induction motor. During starting induction motors draw high starting currents which are several times the normal full load current of the motor. This current causes a significant voltage dip on the isolated electrical grid until the induction motors reach nearly full speed. This voltage drop will cause disturbances in the torque of any other motor running on the isolated electrical grid. Significant disturbances in transients are caused by direct-on-line switch-started induction motors, especially if the load torque on the motor shaft is increased and beside that, also by the sudden change load, such as the impact load on the motor shaft (McElveen, et al., 2001; Cohen, 1995). This situation is particularly difficult because of relatively strong electrical coupling between electrical grid and loads. Besides the voltage dips, an interruption can also appear, which further affects on the fatigue of induction motors connected to the grid. When an interruption of the supply lasts longer than one voltage period, many AC contactors will switch off the motor. In some

of electric power system and thus, on the dynamic behavior of induction motors.

