Hi Bill, > Can someone tell me what is the differences between Synchronous and > Asynchronous motor ? A regular motor used in a factory is Synchronous or > Asynchronous ?
Here a more in depth explanation: Electric motors can roughly be devided in 2 types: In one type the stator field has a fixed direction in space, allthough it need not neccessairely be constant in strength. Motors of this type are the DC motor and the universal motor. The rotor of this motor type is wire wound and has a mechanism which causes the rotor current switched in such a way that there is allways a torque on the rotor. The switching can be mechanical (collector) or electronical based on e.g. Hall sensors. The second type has a field that rotates in space. It can either be a 3 phase or a 1 phase motor. This type appears as induction motor (1 phase), asynchronous motor (3 phase) and synchronous motor (3 phase). In the synchronous motor the rotor has a field that is fixed in direction with respect to the rotor itself. That can be realised by a DC current through the rotor (2 collector rings) or by a permanent magnet. In this motor the rotor must turn at the same speed as the stator field. Only the angle between both can vary a bit. Synchronous motors need allways a provision to startup, for, during startup this motor does not work synchronously. In the asynchronous motor there is a rotor provided with a short circuited winding which is in most cases not connected to the outside. In order to have a current through this winding there must be a magnetic field in it that varies in direction with respect to the rotor. This is achieved by a difference in speed between the turning stator field and the turning of the rotor. This difference in speed is called 'slip'. So the rotor is turning asynchronously with respect to the stator field. The varying magnetic field in the rotor causes an induction current in the stator and in turn this induction current causes a magnetic field. The interaction of the induced rotor field and the stator field is the driving fenomenon for the asynchrous motor. In industry the farmost used type is the asynchronous motor. By the modern static converters, which produce a voltage which can be varied in frequency and strength, the speed of this motor (and also of the synchronous one) can be varied between very low and about twice the mains frequency. Regards, Harry -- Author: H.C. Croon INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
