Basics of Electrical Machines

by / Thursday, 15 June 2017 / Published in Blog


Real Life Application
In this topic, Basics of Electrical Machines, the Principles of Electromechanical Energy Conversion Devices and the Relations between Electric field and Magnetic field are explained whose real life applications are immense. For example, all the DC Machines and the AC Machines are derived from these theories and are being used in possibly every field of technology.

To understand all the Electrical Machines with clarity it’s important to have basic idea of Electric Field, Magnetic Field, and the Relation between Electric Current and Magnetic Field and a very brief idea of Electromechanical Energy Conversion Principles.
Electromechanical Energy Conversion Principles in layman terms is nothing but the interaction between Electrical System and Mechanical System. Electrical Energy cannot be directly converted to Mechanical Energy and vice-versa. A medium is needed in between these two systems which is known as Coupling Field. Now, this Coupling Field can be either Electric Field or Magnetic Field. The function of this field is to convert energy, for example electrical energy to mechanical energy in case of Motors and vice-versa in Generators. In Electrical machines, the coupling field which is preferred is the Magnetic Field because it can store more energy and produce more force compared to Electric Field. A classic example of Electromechanical Energy Conversion Device with Magnetic Field is a Relay.
Electric Field is said to be present around a body which is positively or negatively charged, while Magnetic Field is said to be produced due to moving charges like electrons moving in a conductor in one direction (Electric Current).
Relations between Electric Current and Magnetic Field:
1. A steady current produces a steady magnetic field.(Given by Hans Orsted in 1819)
2. A steady magnetic field cannot produce a current. (Failed experiment of Michael Faraday).
3. A steady magnetic field can produce current in a moving conductor loop. (Michael Faraday).
4. A changing magnetic field can produce current in a steady conductor loop. (Michael Faraday).
5. A current carrying conductor will experience force when it is present in a steady magnetic field. (Michael Faraday).
The above relationships led to establishment of the most important laws of Electrical Engineering namely Ampere’s Law, Biot-Savart’s law, Faraday’s Law.

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