Welcome to the test on DC Machines I (Designed by Aditya Chorghade) 1) Working principle of DC machine is based on _____ a) Faradays First Law of Electrolysis b) Electromagnetic Induction c) (a) or (b) d) None of the above2) In a DC machine the function of interpoles is to _____ a) Reduce field winding heating b) Improve commutation c) Compensate for air gap variation d) Reduce losses3) The nature of EMF in DC armature circuit is _____ a) AC b) DC4) The DC generator that has poorest voltage regulation is _____ a) Shunt generator b) Over compounded generator c) Series generator d) Flat compounded generator5) Carbon brushes are preferred in DC machines because a) It has –ve RTC b) It has +ve RTC c) It allows more current d) It allows less current6) Fleming’s Left Hand Rule is applicable to _____ a) DC Generator b) DC Motor c) Both (a) &( b) d) Alternator7) The LAP winding in DC machine is used for _____ a) Low current b) High voltage c) Zero voltage d) High current 8) In the separately excited DC generator the value of armature resistance is approximately _____ a) 1 Ω b) < 1 Ω c) ≤ 1 Ω d) > 1 Ω 9) In the armature reaction of DC generator the induced EMF is _____ a) Increased b) Reduced c) Remains constant d) Increased then decreased 10) As the load increases ,speed of the DC shunt motor _____ a) Increases b) Remain unchanged c) Decreases d) None11) The magnetization characteristic of DC machine is the relation between _____ a) Armature EMF and armature current b) No load voltage and field current c) Line voltage and line current d) None 12) If there is fault occur in the winding or number of turns of DC generator then the voltage at the output is _____ a) Reduced b) Increased c) Constant d) None13) In the series generator the value of resistance of series field winding is approximately _____ a) 0.1 Ω b) > 0.1 Ω c) < 0.1 Ω d) 1 Ω14) The value of current flowing through shunt field winding in shunt generator is _____ a) = series field winding b) > series field winding c) < series field winding d) Both (a) & (c) 15) Shunt generator is also known as _____ a) Voltage booster b) Constant voltage generator c) Voltage divider d) Voltage converter 16) If the terminal voltage of DC series motor is increased, what will be the effect on the armature current under full load condition _____ a) Increases b) Decreases c) No change d) None 17) Is there any induction takes place in long shunt DC motor under steady state _____ a) Yes b) No c) Can’t say d) None18) In the electric welding what type of DC generator is suitable _____ a) DC shunt generator b) Flat - compounded DC generator c) Differential compounded DC generator d) Cumulative compounded DC generator 19) The compensating winding in DC machine is _____ a) Located in armature slots for compensation of armature reaction b) Located on commutating poles for improving commutation c) Located on pole shoes for avoiding flashover at commutator surface d) Located on pole shoes to avoid sparking at brushes 20) A 4 – point starter is used to start and control the speed of a _____ a) DC shunt motor with armature resistance control b) DC shunt motor with field weakening control c) DC series motor d) DC compound motor (59) Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Google+ (Opens in new window) DC machines I test Gaurav J | Test | April 12, 2017 8:27 pm
