What is Electrical machines: Definition and 15 Discussions

In electrical engineering, electric machine is a general term for machines using electromagnetic forces, such as electric motors, electric generators, and others. They are electromechanical energy converters: an electric motor converts electricity to mechanical power while an electric generator converts mechanical power to electricity. The moving parts in a machine can be rotating (rotating machines) or linear (linear machines). Besides motors and generators, a third category often included is transformers, which although they do not have any moving parts are also energy converters, changing the voltage level of an alternating current.Electric machines, in the form of generators, produce virtually all electric power on Earth, and in the form of electric motors consume approximately 60% of all electric power produced. Electric machines were developed beginning in the mid 19th century and since that time have been a ubiquitous component of the infrastructure. Developing more efficient electric machine technology is crucial to any global conservation, green energy, or alternative energy strategy.

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  1. L

    Electrical Machines and Power Flow

    I have been studying the representation of generators in power flow studies and I would appreciate your comments in this thread. From the book Fitzgerald & Kingsley's Electric Machinery, I understand that there are unsaturated and saturated reactances. In section 5.3.2 of the book it is said...
  2. S

    Engineering Electrical Machine - Shunt DC Motor Problem

    Hi guys, can someone please have a look at the following problem that I am struggling with; An 8.25 kW shunt DC motor is supplied with a terminal DC voltage of 300 V. The armature resistance of the motor Ra is 0.25 ohms, and the field resistance Rf is 40 ohms. The field winding consists of 1500...
  3. J

    Prerequisite Required for a Course in Electrical Machines

    I want to study "Electrical Machines" Course. I looked for online courses but they all had different prerequisites to study "Electrical Machines" course. Can anyone guide me about what prerequisites are needed to study "Electrical Machines" or any specific contents that i should study (e-book or...
  4. Manoj Sahu

    Which is the best book for getting in-depth knowledge of Electrical Machines?

    Hi. I am preparing for IES (Indian Engineering Services ) exam. I have basic knowledge of electrical machines both ac and dc. For the examination point of view I need to have in depth knowledge of each and every topic in electrical machines (both ac and dc). Can you suggest me some really good...
  5. srinaath

    What are the effects of changing the speed of alternator?

    Homework Statement What are the effects of changing the speed of alternator? (elctrical synchronus generator) Homework Equations Ns=120*f/p; p-poles f-frequency Ns-synch speed E=4.44*f*phi*T phi-max flux linkage T-turns f-freq E- generated voltage The Attempt at a Solution from the above...
  6. E

    Engineering Electrical Machines DC Shunt Motor

    An 8.25 kW shunt DC motor is supplied with a terminal DC voltage of 300 V. The armature resistance of the motor Ra is 0.25 , and the field resistance Rf is 40 . The field winding consists of 1500 turns. An adjustable resistance Radj is connected in series to the field winding. Radj may be...
  7. H

    Iron loss curve estimation

    Hi all, I am recently calculating the iron loss in a permanent magnet synchronous machine with a speed of 24000 rpm (electrical frequency 800 Hz). However, the iron loss data from the data sheet is not sufficient since only frequency of 50 Hz, 100 Hz, 200 Hz, 400 Hz, 1000 Hz and 2500 Hz are...
  8. srinaath

    Why slip is more in low HP induction motor?

    am doing a comparative study of induction motors (both single and three phase) based on cost, size, efficiency,etc... while analyzing 1/4Hp and 5 HP motors, i read that 1/4HP motor has high slip than 5HP motor because 1/4HP motor has greater rotor winding resistance than 5HP...so efficiency is...
  9. G

    Distribution Factor in Electrical Machines

    Homework Statement demonstrate that the distribution factor is equal to 1 in concentric windings. Homework EquationsThe Attempt at a Solution i have tried to solve it doing the equations shown in this page, http://www.electrical4u.com/winding-factor-pitch-factor-distribution-factor/ but i...
  10. V

    Good book on electrical machines

    hello, i am an undergraduate student pursuing engineering. kindly suggest me a good book on electrical machines (induction motors, dc motors ,etc) so that they can be understood very easily . please suggest as fast as possible :cool:
  11. B

    Need a software for working on electrical machines

    hi! i want to couple the 2 A.C. machines mechanically so i need a software to work out on this can anyone help me please...
  12. V

    Engineering Electrical Machines and Power Electronics - 3 phase, 6 pole induction motor

    Homework Statement A three phase, 6-pole, \Delta connected induction motor is rated 208V, 60Hz. It has R_R\,=\,5.2\,\Omega, R_S\,=\,2.2\,\Omega, X_m\,=\,220\,\Omega, X_{lr}\,=\,7.5\,\Omega, X_{ls}\,=\,2.3\,\Omega. Calculate the starting torque and both phase and line currents when the motor...
  13. R

    Calculate Number of Turns Per Phase: Electrical Machines Exam

    Hi there [I] am presently studying for my electrical machines exam and i have a few examples to tackle. A 50hz, 3 phase, core-type transformer is connected star-delta and has a line voltage ratio of 11000/400V. The cross-section of the core is square with a circumscribing circle of 0.6m...
  14. B

    Electrical Machines: Find a Book on Magnetic Field Behavior

    I am looking for a book on electrical machines. I am particularly interested in one which would described the behaviour of the magnetic field inside the machine during various operating conditions like no load short circuit etc. can you recommend a book or a website which would describe it I...
  15. I

    Understanding Electrical Machines: Queries & Answers

    Hello Guys, I am a beginner in the field of Electrical well i have certain queries to ask from u genius guys 1):WHY THERE IS NO BACK EMF in 3-phase INDUCTION MOTOR 2):WHY WE REMOVE RHEOSTAT after 3-5 seconds of STATRTING OF 3-pahse INDUCTION MOTOR. 3):IF WE APPLY SINGLE PHASE ,THEN HOW...