BEE
ASSIGNMENT-5(UNIT-5:D.C.GENERATORS)
1. (A)
Explain in detail, the principle of a single loop DC generator.
(OR)
Explain the principle of operation
of DC generator.
(B). the
armature of a 6-pole D.C. generator has a wave winding containing 664
conductors. Calculate the generated emf when the flux per pole is 0.06 weber
And
the speed is 250 rpm. At what speed must the armature be driven to
Generate
an emf of 250 V if the flux per pole is reduced to 0.058 weber?
2. (A).
Explain briefly various types of generators.
(Or)
Explain
different types of excitations in D.C. Generators
(Or)
Explain
how will you classify DC generators in detail and also explain the types of DC
generators
(or)
(B) Write the applications of D.C generators.
(C). A 6 – pole, Lap wound
armature has 840 conductors and flux per pole of 0.018 Wb.
Calculate the emf generated when the
machine is running at 600 rpm.
3. (A) Draw a detail sketch of a DC
machine and identify the different parts. Briefly explain the function of each
major part.
(Or)
List out the main parts of a DC
machine and explain with help of neat sketch.
(B) A 4 – pole DC shunt
generator with lap connected armature supplies a load of 100 A at 200 V. The
armature resistance 0.1 ohms and the shunt field resistance is 80 ohms find the
i) Total armature current ii) Current per armature path iii) Emf generated.
4. (A). Explain the losses that occur in
a DC machine.(or) explain the total losses in D.C. Generator (or)Explain the
total losses in D.C. Motor and explain how to reduce them
(B) A lap
wound DC generator having 80 slots with 10 conductors per slot generates at no
load emf of 400 V, when running at 1000 rpm. At what speed should it be rotated
to generate a voltage of 220 V on open circuit.
5. (A). Derive
from first principle an expression for the induced EMF in the armature of the
dc Machine. (Or) Derive the emf equation of D.C. Generator.
(B) A dynamo has a rated armature current
at 250A.what is the current per path of the armature if the armature winding is
lap or wave connected? The machine has 12 poles.
6. (A) Discuss in detail the process of voltage build up in a
dc generator and explain about causes for failure of voltage build up process
in d.c generator.
(B) A separately exicted D.C generator ,when
running at 1000RPM supplied 200A at 125V.what will be the load current when the
speed drops to 800RPM if “If” is unchanged? Given that the armature
resistance=Ra=0.04Ω and brush drop=2V