Energy Flow in Electromechanical Energy Conversion Device

Energy Flow in Electromechanical Energy Conversion Device

AU : May-03, 08, 10, 11, 15, Dec.-09, 06

• For any electromechanical energy conversion, there are two systems, electrical system and mechanical system. These systems are coupled through a coupling field which is mostly a magnetic one.

• Now for a generator, input is mechanical energy but entire input cannot reach to the coupling field for the conversion. Part of it gets lost in the form of friction and windage losses. The available mechanical input is converted to electrical by the device via coupling field. But net output cannot be equal to converted electrical energy as some part of it gets lost in the form of electrical losses such as copper (I²R) losses and core or iron losses. The Fig. 2.4.1 shows the energy flow diagram of electromechanical energy conversion device working as a generator.

Key Point : The heat loss due to coupling field is practically neglected and conversion process is assumed to be ideal.  

• The conversion process is reversible. For an electromechanical energy conversion device working as a motor, the net input is electrical energy. But part of this gets lost in electrical losses such as copper and iron losses. The remaining part is available to the coupling field for the conversion called net electrical input. The coupling field converts this to gross mechanical output. But entire gross mechanical output cannot be available to the load due to mechanical losses like friction and windage. Thus net mechanical output is less than the gross mechanical output. Practically conversion process is not ideal as there are coupling field losses. But from analysis point of view these losses are neglected as small and the conversion process is assumed to be ideal. The Fig. 2.4.2 shows the energy flow diagram of electromechanical energy conversion device working as a motor. 

• This energy flow is according to the energy balance equation.

Review Questions

1. Give a brief note on flow of energy in electromechanical devices. AU : May-03, Marks 8

2. Draw and explain the general block diagram of an electromechanical energy conversion device. AU : Dec.-06, Marks 8        

3. Represent pictorially the flow of energy in electromechanical devices for both generating and motoring action.   AU : May-08, 10, 11, Dec.-09, Marks 8   

4.Explain the methods of energy conversion via electric field, with examples of electrical machines.    AU : May-15, Marks 16