1. The maximum voltage value between commutator bars considered safe for a compensated armature with a diameter of 6 in is A. 21 B. 15 C. 19 D. 17 2. The most likely cause oi short circuits in armatures is A embedded metal particles. B. absorbed moisture. C. insulation break down at bends D. incorrect tooth alignment 3. If the metal band on a large armature is loose and shows signs of shifting, it should be replaced by a A. steel band. B. glass-fiber cond C. glass-tape band. D. copper band. 4. The insulation placed on the coil supports of a machine with Class B insulation consists of A cotton upe B. varnished cloth C. impregnated glass cloth D. fallerboard. 5. If an armature has a core length of 32 in, the length of each of the wedges used should be A. 12 in B. 32 in C. 8 in. D. 16 in 6. Which one of the following instruments is used to measure insulation resistance? A. Ammer B. Millivoltmeter C. Megohmmeter D. Growler 7. If the armature of a d-e motor becomes too hot during motor operation, the most probable cause is A brushes with insufficient pressure. B. a low supply voltage. C. a rough commutator surface. D. a short circuit in the armature col 8. If the brushes are too abrasive, the commutator will show Ag A grooves Bridges C. bars out of line D. high mica. 9. During the process of removing the commutator from the armature, the varnish on the commutator leads should be softened by Adipping in epoxy. B. applying rosin flux C. using pulverized in D. heating the armature 10. If a 240-volt lap-wound machine with four-tum coils is to be changed to operate on 120 volts, the modification should include Awave-windings B. a lower wattage resistor. C. two-tum coils. D. smaller brushes. 11. Soldered clips on the end of the armature opposite the commutator indicate that the armature uses A. frog-leg coils. B. half coils C. U-bend coils. D. involute coils. 12. If an armature has 15 slots and 60 commutator bars, each coil bundle will have A. eight loads. B. four leads. C. six leads. D. two leads. 13. A disadvantage of mica-folium insulated form-wound coils is that they A may develop open spots in the mica. B. must be well coated with varnish. C. make the coils too flexible. D. tend to be damaged by abrasion 14. Coils with a pitch of 6 are to be inserted into a 17-slot armature. Before the first coil is inserted, insulation should be placed in A. slots 1 and 7. B. slots through 17. C. slot 7. D. slot 1. 15. If an armature for a four-pole machine has 49 slots and 49 commutator bars, which one of the following pitches is correct? A. A progressive bar pitch of 24 B. A retrogressive bar pitch of 25 C. A short coil pitch of 12 D. A fall cell pitch of 13 16. The armature defect which can be located only when the armature is hot is A. a short circuit B. carbonized mica C. an intermittent ground D. shorted bars. 17. Which one of the following causes of pitted bearings may require one bearing on the machine to be insulated? A. Circulating currents B. Oil rings C. Lubrication shortage D. Dityll 18. Carbonizing between commutator bars is caused by Astuck brushes B. overload. C. water glass D. oil. 19. If a wave wound armature develops a defective coil, a temporary repair can be made by disconnecting A. the defective coil and one set of brush arms. B. the equalizer and commutator poles. C. the defective coil and inserting a jumper in the commutator D. coils in a symmetrical arrangement. 20. Which one of the following voltage values should the repairman use as the maximum test voltage for a 120-volt 7 hp machine? A 250 volts B. 750 volts C.675 volts D. 500 volts