### DC Generators Objectives part 02

**21 .** If a is the degree of multiplicity and p is the number of poles, the number of parallel paths in a wave winding will be **2a.**

**22 . ** Hysteresis loss in a dc machine depends on **Volume and grade of iron ,Max value of flux density and frequency of magnetic reversals .**

**23 . ** The effect of iron losses on dc machines is **loss of efficiency, excessive heating of core.**

**24 . ** In dc machines the losses which has the highest proportion is **armature copper loss**

**25 . ** In dc machines the losses which has the least proportion is **mechanical losses.**

**26 .** **Armature copper loss **in dc generator significantly varies with the load current.

**27 . ** In dc generator the loss which has a least proportion is** windage loss.**

**28 .** A properly designed dc generator can have an overall efficiency of** 95%.**

**29 . ** Eddy current loss will increase rapidly as compared to others when the number of magnetic reversals is **increased.**

**30 .** For a shunt generator** copper loss **is considered as constant.

**31 . ** For reducing the hysteresis loss in a dc generator armature core material should have** low hysteresis coefficient.**

**32 . ** When B is the maximum flux density then eddy current loss varies as **𝑩𝟐.**

**33 .** The armature voltage control is considered as suitable in case the dc machine is driven **at constant torque.**

**34 . ** Two dc generators have similar characteristics. The essential condition for stable parallel operation of these two generators is that they should have** same drooping voltage characteristics.**

**35 . ** While pole flux remains constant, if the speed of a shunt wound dc generator is doubled its generated **emf will be doubled.**

**36 . ** As a result of armature reaction, the total mutual air gap flux in a dc generator is approximately** 5%.**

**37 . ** Interpoles are usually wound with **heavy guage copper wire.**

**38 . ** **Cool armature by ventilating air** is not the function of the interpoles in dc generators.

**39 . ** In dc generators the change in voltage when the load is reduced from rated value to zero, expressed as a percentage of the rated load voltage, is known as** regulation.**

**40 .** If θm be the mechanical degree θe be the electrical degree and Pbe the numbers of poles on a dc generator, then relation will be **θm=2θe/P.**