d.c motor bits 30-40

31) As the load is increased , the speed of a d.c shunt motor
     a) increases proportionately
     b) remains constant
     c) increases slightly
     d) reduces slightly

ans d

32) Which of the following load would be best driven by d.c compound motor
     a) reciprocating pump
     b) centrifugal pump
     c) electric locomotive
     d) fan

ans a

33) If load on a d.c shunt motor is increased, its speed is decreased due due primarily to
    a) increase in its flux
    b) decrease in back e.m.f
    c) increase in armature current
    d) increase in brush drop

ans b

34) In a d.c. motor , the mechanical output power actually comes from
    a) field system
    b) air gap flux
    c) back e.m.f
    d) electrical input power

ans d

35) The normal value of the armature resistance of a d.c motor is
     a) 0.005
     b) 0.5
     c) 10
     d) 100

ans b

36) One of the main advantages of swinburne's test
     a) is applicable both shunt and compound motors
     b) needs one running test
     c) is very economical and convenient
     d) ignores any charge in iron loss

ans c

37) Retardation test is used for finding which losses on d.c shunt motor
     a) stray
     b) friction
     c) iron
     d) magnetic losses

ans a

38) Practically which method is mostly adopted for reversing the direction of d.c motor
     a) by reversing field current
     b) by reversing armature current
     c) by reversing supply terminals
     d) by reversing both b and c

ans b

39) Which of the following connection is used for connecting the interpole winding to armature
     a) parallel
     b) series
     c) both parallel and series
     d) any of above

ans b

40) What happens when d.c motor is accidentally connected to a.c supply
    a) it will run
    b) run slowly
    c) burn out
    d) run very fast

ans c