114 SECTION 3 Electric Motors 12. In an operating DC motor, the armature current depends on the applied voltage. a. minus the CEMF c. both a and b b. and the armature resistance 13. In a DC motor, an increasing mechanical load, a. increases armature current b. decreases armature current c. has no effect on armature current 14. T/F A shunt motor's field winding has more resistance than the armature. 15. A DC shunt motor has, a. a high starting torque c. zero speed at no load b. a constant speed rating d. all of the above 16. To change direction of a DC shunt motor with compensat- ing windings, you must interchange leads, a. A and F1 b. S, and S₂ c. C₁ and C2 d. Fl and F2 e. F₁ and C₁ f. A, and A₂ ог 17. When the load on a DC shunt motor is increased, its speed will and the amount of torque developed will. a. increase, increase b. decrease, decrease c. increase, decrease d. decrease, increase 18. A DC shunt motor operating at 240 V draws 4.5 A. It has an output of 1 horsepower. Its efficiency is. a. 69 b. 73 c. 58 d. 43 19. T/F A series DC motor should never be connected to a load by a belt or chain drive. 20. The series field winding of a DC series motor has (low, high) resistance. a. low starting torque 21. A DC series motor has, c. high starting torque d. zero speed at no-load b. low no-load speed 22. In a DC series motor, if the armature current is reduced to one-half of its full-load rating, the torque is, a. constant b. doubled 23. A compound motor has c. reduced d. increased a. higher starting torque than a DC motor b. a better constant speed rating than a shunt motor c. a higher starting torque than a shunt motor d. no interpoles 24. When connecting a compound motor for operation, which leads are wired in parallel with the power supply?. a. A₁-A₂ b. C₁-C₂ c. S₁-S₂ d. F₁-F2 than a 25. A differential compound motor has cumulative compound motor. a. higher starting torque b. higher RPM at no load c. more constant speed 26. A cumulative compound motor has differential compound motor. than a a. higher starting torque b. better speed regulation 27. T/F Neither a series nor a compound motor can be re- versed simply by changing the input power leads. 28. The magnetic fields of the series and shunt motors of a cummulative compound motor b. cancel a. are additive