Electric motors

Collection T echnique ..........................................................................

Cahier technique no. 207
Electric motors
... and how to improve their control and protection

E. Gaucheron

Building a New Electric World

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no. 207
Electric motors
... and how to improve their control and protection

Etienne Gaucheron Graduate electronics engineer by training. After ashort period with Thomson he joined the VsD (Variable speed drives and starters) division of Telemecanique in 1970. He then completed his training at ENSAM (the national college for arts and vocational training) in Paris during his position with Telemecanique's after sales service. As a specialist in motor control, he was involved in the development of variable speed control for AC motors. He hasgained a wide range of experience in various positions: systems platform engineer, product manager for machine tool drive products, product manager for drives for asynchronous motors (Altivar products) and manager of the VSD project marketing team. He is currently a motor control "applications" specialist within the advance development team for the Schneider Electric PCP (Power Control and Protection)division.

ECT 207 first issue, October 2004

Cahier Technique Schneider Electric no. 207 / p.2

Electric motors
... and how to improve their control and protection

Nowadays, apart from lighting devices, electric motors represent the largest loads in industry and commercial installations. Their function, to convert electrical energy into mechanical energy, means they are particularlysignificant in economic terms, and hence, they cannot be ignored by installation or machinery designers, installers or users. There are many types of motor in existence, but 3-phase asynchronous motors, and in particular squirrel cage motors, are the most commonly used in industry and in commercial buildings applications above a certain power level. Moreover, although they are ideal for manyapplications when controlled by contactor devices, the increasing use of electronic equipment is widening their field of application. This is the case for start/stop control with soft start/soft stop units, and when precise speed adjustment is also necessary with variable speed drives/regulators. However, slip-ring asynchronous motors are used for certain high power applications in industry, and...