Lecture_10_AC_Machinery_Fundamentals

Lecture_10_AC_Machinery_Fundamentals - AC MACHINERY...

This preview shows pages 1–9. Sign up to view the full content.

04/11/17 1 Electrical Machines Aamir Hasan Khan AC MACHINERY FUNDAMENETALS

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
The Rotating Magnetic Field 04/11/17 2 Electrical Machines Aamir Hasan Khan If two magnetic fields are present in a machine, then a torque will be created which will tend to line up the two magnetic fields. If one magnetic field is produced by the stator of an ac machine and the other by the rotor, then a torque will be induced in the rotor which will cause the rotor to turn and align itself with the stator magnetic field. If there were some way to make the stator magnetic field rotate, then the induced torque in the rotor would cause it to ‘chase’ the stator magnetic field. a 3-phase set of currents, each of equal magnitude and differing in phase by 120º, flows in a 3-phase winding, then it will produce a rotating magnetic field of constant magnitude.
04/11/17 3 Electrical Machines Aamir Hasan Khan (a) A simple three phase stator. Currents in this stator are assumed positive if they flow into the unprimed end and out the primed end of the coils. The H produced by each coil are also shown. (b) The magnetizing intensity vector H aa’ (t) produced by a current flowing in coil aa’. The Rotating Magnetic Field

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
04/11/17 4 Electrical Machines Aamir Hasan Khan Assume currents in the 3 coils are: A t I t i M aa sin ) ( ' A t I t i M bb ) 120 sin( ) ( ' A t I t i M cc ) 240 sin( ) ( ' The current in coil aa’ flows into the a end of the coil and out the a’ end of the coil. It produces the magnetic field intensity: m turns A t H t H M aa / 0 sin ) ( ' m turns A t H t H M bb / 120 ) 120 sin( ) ( ' m turns A t H t H M cc / 240 ) 240 sin( ) ( ' The Rotating Magnetic Field
04/11/17 5 Electrical Machines Aamir Hasan Khan The flux densities equations are T t B t B M aa 0 sin ) ( ' T t B t B M bb 120 ) 120 sin( ) ( ' T t B t B M cc 240 ) 240 sin( ) ( ' Where B M = µ H M . The Rotating Magnetic Field

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
04/11/17 6 Electrical Machines Aamir Hasan Khan At time 0 t T B B M bb 120 ) 120 sin( ' T B B M cc 240 ) 240 sin( ' 0 ' aa B B net = B aa’ + B bb’ +B cc’ 240 2 3 120 2 3 0 M M B B 90 5 . 1 M B The Rotating Magnetic Field
04/11/17 7 Electrical Machines Aamir Hasan Khan The Rotating Magnetic Field

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
04/11/17 8 Electrical Machines Aamir Hasan Khan 90 t At time T B B M bb 120 5 . 0 ' T B B M cc 240 5 . 0
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern