- An electro mechanical energy conversion device is one which convert electrical energy to mechanical energy or vice versa.
- Devices possessing small motion and processing low energy signal such as telephone receiver, loud speaker and mic.
- Force or torque producing devices involving limited range of motion such as electro mechanical instrument.EX:- PMMC, moving iron and relays.
- Devices continuously converting electrical to mechanical energy and vice versa. Ex:- generator ,motor.
Coupling medium:-
Coupling medium is a field that is capable of producing a force or torque because without any field we can not produce force or torque.
Why magnetic field is preferred as coupling medium
Magnetic field has higher energy density so size of machine required is reduced.
In order to used electric field as a coupling medium a high value of electric field required for which high voltage is need which is present in electro static instrument.
Principle of energy conversion
A energy can either be created nor be destroyed but it can only be converted from one form to another.
Motor:- motor convert electrical energy into mechanical energy.
Electrical energy input = mechanical energy output +energy dissipated + energy stored.
Generator:-generator converts mechanical energy into electrical energy.
Mechanical energy input = electrical energy output +energy dissipated+ energy stored.
In power balance we do not consider energy stored because stored energy is assume to be constant and hence it's derivative is zero which means power stored is zero.
Motor:-
In motor coupling field absorb energy in electri in terms of back emf and deliver energy to mechanical in terms of develop torque. In motor develop torque in the direction of motion .
Generator:-
Coupling field produces emf in electrical domain and torque in mechanical domain.
In motor develop torque support ratation while load torque oppose rotation.
Whereas in generator prime mover torque support rotation and developed torque oppose rotation.
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