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q. what do you understand by demagnetizing and cross magnetizing effects of armature reaction in a d.c. machine. derive the expression for
q. explain the working principle of a d.c. generator. explain clearly the function of commutator in d.c. machines.sol. working principle of a d.c.
q. series generator having a combined armature and field resistance of 0.4? is running at 1000 r.p.m. and delivering 5.5kw at terminal voltage of 110
q. a shunt generator gives full load output of 30 kw at a terminal voltage of 200v. the armature and field resistance are 0.05? and 50? resp.. the
q. what are the different types of dc generation according to the ways in which fields are excited. show the connection diagram of each type.ans.
q. an 8 - pole dc generator has 500 armature conductors and has a useful flux per pole of 0.065 web. what will be the emf generated if it is lap
q. derive the expression for generated emf in a dc generator.ans.expression for generated emf in a dc
q. in a 110v compound generator the armature shunt and series winding resistance are 0.06? 25? and 0.04? respectively. the load consists of 200
dummy coils these coils are used with wave winding and resorted to when the requirement of the winding are not met by the standard armature punching
q. list and explain the factors involved in the voltage build up of shunt generator.ans.following factors are involved in voltage build up of
q. a 6 - pole dc armature with 36 slots and 2 coil - slidesslot is to be wave wound double layer. calculate the back pitch front - pitch and
q. define and explain the critical field circuit resistance and critical speed of a dc shunt generator. ans. the occ and r - line for a dc
q. state and briefly explain the various phenomena useful for electromechanical energy conversion in rotating machines. sol. in the rotating
q. for an electromagnetic system show that the energy stored in a magnetic field is equal to the area enclosed bw magnetization curves for open
q. in every electromagnetic conversion device both generator and motor action take place simultaneously. explain.the case the output is mechanical
q. what is meant by dynamically induced emf and statically induced emf? on what factors do these depend? derive eq. for these two emfs. sol.
q. describe the principle of energy conversion. show that the reaction of coupling magnetic field on the electrical or mechanical system is
q. derive the expression of torque developed in closely excited magnetic system. clearly explain then assumption made. sol. double - excited
q. two coils with self inductances 1h and 4h have a mutual inductance of 1h. the rms value of current flowing in the two coils is 4a and 1a
q. why are magnetic field system employed in practical electromechanical energy conversion devices rather than electric field systems?ans.in case
q. give the expression for inductance of a ?n? turn coil wound on a core having length i cross - sectional area a and magnetic
q. the area of the hysteresis loop of a given magnetic material is 50cm2 with the two axes scaled as 1cm 20at and 1cm 50mwb for 50hz frequency
leakage flux the flux that links the coil only partially passes through the core does not link the coil as the moving or rotating device is called
requisites of refractory material or essential requirements of good refractorya. it should be able to withstand high temperature.
thermal spelling the breaking or cracking or peeling off the refractory is known as spelling. a good refractory must show a good resistance to