Description : For routine cleaning of a commutator, you should apply _____________. A. course sandpaper in a slow back and forth motion across the commutator slots B. an emery cloth parallel to the axis of the machine C. a canvas wiper to the machine while running D. cotton swabs between the commutator bars
Last Answer : Answer: C
Description : All of the following items can be used in the maintenance of a D.C. propulsion motor's commutator EXCEPT _______________. A. a canvas wiper B. safety solvent C. abrasive dressing stones D. sandpaper
Last Answer : Answer: B
Description : Which of the following materials is recommended for finishing the slip rings after grinding or turning? A. grade 00 sandpaper B. canvas wiper C. crocus cloth D. smooth file
Description : Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness? A. Fill the motor housing with CO2 to inert the space. B. Strap ... C. Place heat lamps in the motor housings. D. Cover the equipment with a canvas tarpaulin.
Description : In order to decrease the resistance of the 50K pot located at '21Q/R' shown in the illustration, the wiper of the actual component must be moved ____________. EL-0099 A. to the left B. to the right C. clockwise D. counterclockwise
Last Answer : Answer: D
Description : The most practical method used for resurfacing a ship's service motor commutator is to _____________. A. turn it down in the ship's lathe B. use a grinding rig C. use a hand stone D. burnish it with commutator stones
Description : Etched or burned bands on the contact faces of the brushes in a direct current generator can be caused by ____________. A. high mica segments B. copper drag on the commutator C. brushes improperly positioned D. copper embedded in the brushes
Description : Voltage generated by most AC generators is fed from the machine to the bus by means of ____________. A. brushes on a commutator B. brushes on slip rings C. slip rings on a commutator D. direct connections from the stator
Description : A flickering ground detection lamp on a DC system would indicate a _____________. A. multiple-ground condition in the distribution system B. ground in an armature coil of an operating machine C. ground in a motor accompanied with a short D. short between two adjacent bars of the generator commutator
Description : I accidently spilled windshield wiper fluid when trying to refill the windshield wiper reservoir, yesterday. I tried to clean it up as best as I could. I'm a bit leary on starting my car. Do you think that it'll be okay?
Last Answer : It should be ok. Your car’s engine should be weather proof. How old is your car?
Description : In a three-phase electrical system, three ground detecting lamps are provided. One lamp goes dark and the others increase in brightness. When the test button is pushed, all lamps have equal illumination. You ... C. there are grounds on the lines with the bright lamps D. this is a normal condition
Last Answer : Answer: A
Description : In a logic circuit the NOR and NAND gate functions ____________. A. must be accomplished with a common base transistor arrangement B. are available in diode form C. are exact opposites with the ... . have output conditions that are exact opposites to the output condition for OR and AND, respectively
Description : When insulation failure produces a low resistance current path between two conductors, the resulting condition is known as ____________. A. an open B. a short circuit C. a ground D. a surge
Description : One diode of a full-wave rectifier has burned out in a shorted condition. Therefore, the output will be ____________. A. zero B. a rectified half-wave C. a rectified full-wave D. equal to the AC input
Description : Proper storage battery maintenance includes ____________. A. keeping connections tight and casing surfaces clean B. making sure electrolyte level is below the separator plates C. insulating the terminals with naval jelly D. maintaining a high charging rate at all times
Description : You are testing the insulation in an AC generator with a megohmeter. The resistance value of a dry, clean winding will ____________. A. continue to rise as the test potential is maintained, ... fairly steady after 5 to 7 minutes D. stabilize after approximately 2 to 4 minutes of fluctuation
Description : Use complete sentences to explain why AlCl3 is called “aluminum chloride†(no prefix required), but BCl3 is called “boron trichloride.�
Last Answer : Ionic compounds do not have prefixes but covalent compounds have prefixes. “Aluminum chloride†is a ionic compound and "boron tri-chloride†is a covalent compound.
Description : The use and transfer of energy in all cells involves the same compound, ATP. The letters ATP stand for the chemical: a) atrophine trichloride b) aluminum trioxide c) adenosine triphosphate d) none of the above
Last Answer : ANSWER: C -- ADENOSINE TRIPHOSPHATE
Last Answer : : Chemical signal of phosphorus trichloride PCl3
Description : Phosphorus trichloride, `PCl_(3)` undergoes, hydrolysis at room temperature to produce an oxoacid. It has the formula :
Last Answer : Phosphorus trichloride, `PCl_(3)` undergoes, hydrolysis at room temperature to produce an oxoacid. It has the formula : ... 3)PO_(4)` D. `H_(3)PO_(2)`
Description : Which statement regarding iodine trichloride is Incorrect.
Last Answer : Which statement regarding iodine trichloride is Incorrect. A. (A) It forms dimer in gaseous state ... a mixture of iodous acid and hydrochloric acid.
Description : What is the mass of 4.75 moles of arsenic trichloride?
Last Answer : 4,75 moles of arsenic trichloride (AsCl3) is equal to 181,28 g.
Description : The substances that can be used as explosives are 1. phosphorous trichloride 2. mercuric oxide 3. trinitrotoluene 4. nitroglycerine The correct answers are: (a) 1 and 2 (b) 2 and 4 (c) 2 and 3 (d) 3 and 4
Last Answer : Ans:(d)
Description : Give reasons: a) Phosphorous pentachloride is unstable. b) Phosphorous trichloride fumes in moisture.
Last Answer : Ans: a) Because of two longer axial bonds. b) Because it reacts with water and forms hydrochloric acid.
Description : The tip of the match-stick contains (1) phosphorus pentoxide (2) white phosphorus (3) red phosphorus (4) phosphorus trichloride
Last Answer : red phosphorus
Description : Which of the following precautions should you take when securing propulsion generators and motors for an extended period of time? A. Disconnect the brush pigtails from their contacts and circulate air ... Lift the brushes from commutator collector rings and circulate cool dry air through the units.
Description : Due to which of the following factors the brush wear rate is altered ? (a) Speed of the machine (b) Contact pressure (c) Surface conditions of brush and commutator (d) Excessive sparking (e) All of the above
Last Answer : Ans: E
Description : As shown in the illustration, part 'X' of the diagram is known as a/an _____________. EL-0052 A. commutator B. interpole C. starting pole D. auxiliary pole
Description : If only one brush on a commutator is sparking excessively, you should look for _____________. A. a high commutator bar B. copper imbedded in the brush C. a loose commutator bar D. flux in the commutating zone
Description : Which of the diagrams shown in the illustration depicts the proper method of aligning brushes on a commutator? EL-0057 A. A B. B C. C D. D
Description : Uneven wear of the commutator surface on a direct current propulsion motor can be caused by _____________. A. rapid change in load B. excessive operation at light load C. incorrect brush staggering D. unequal pole spacing
Description : Brushes in a generator must be positioned in the neutral plane to avoid sparking between the brushes and the _____________. A. yoke B. armature windings C. field pole windings D. commutator
Description : Which of the listed colors properly describes a DC motor commutator when correct commutation is taking place? A. Shiny blue B. Burnished green C. Brick red D. Chocolate brown
Description : Which of the following is a characteristic of fractional horsepower repulsion start motors? A. They start with a rotating stator field. B. The short circuiting ring is removed from the commutator while ... brushes are removed from the commutator while starting. D. They have a low starting torque.
Description : Sparking at the brushes of a running motor could be an indication of _____________. A. normal operation B. a dirty commutator C. increased brush capacity D. water vapor absorption
Description : Which of the listed conditions might contribute to very rapid wearing of a DC machine's commutator bars? A. A grounded commutator bar B. Using improper carbon brushes C. Aligning the front and rear mica V-rings improperly D. An open circuit in the armature
Description : A short in the shunt field of a DC motor is best located by _____________. A. visual inspection of the commutator B. applying AC voltage to each field coil and measuring the voltage drop across ... using a growler and hacksaw blade D. isolating each coil from the others and using a megohmmeter
Description : An open in the armature of a DC motor is suspected, but is not found by visual inspection of the commutator. The next step in troubleshooting this problem is to ________________. A. conduct a ... windings C. conduct an insulation resistance test of the armature D. test the commutator for a ground
Description : If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist? A. Incorrect lead connections B. Incorrect brush setting C. A dirty commutator D. All of the above are correct.
Description : The most effective method of locating a loose commutator bar in a D.C. motor is by _____________. A. visual inspection B. jiggling each by hand C. sounding each bar with a light weight hammer D. checking with a calibrated torque wrench
Description : Which of the listed conditions will occur if dirt and grease are allowed to accumulate between the commutator segments of a motor? A. A partial short circuit. B. A dead short circuit. C. Misalignment of the motor shaft. D. Overspeeding of the motor.
Description : In the illustrated test, if the lamp fails to light on any of the three windings then _________. EL-0027 A. all three windings are grounded and the motor should be sent out for repair B. ... the motor controller and the controller should be checked D. the test should be redone at a higher voltage
Description : D.C. motor brush adjustment includes attention to _________. A. angle with the commutator and clearance within the holder B. brush length and pigtail tightness C. grade of material and surface dirt conditions D. all of the above
Description : In addition to undercutting the mica, proper maintenance of a D.C. motor's commutator includes _______________. A. side-cutting the copper segments and insulating the slots B. coating the copper surface with light machine ... in an oven at a maximum of 95°C for not over 8 hours D. all of the above
Description : Which of the listed faults cannot be eliminated, EXCEPT by turning or grinding a commutator with a rigidly supported tool? A. Sparking brushes B. Eccentricity C. High mica D. Blackened commutator
Description : Temporary repairs to an open DC propulsion armature coil can be made by _____________. A. connecting the coil ends directly to a pair of negative brushes B. disconnecting coil ends, insulating ... C. grounding the coil ends and short circuiting the commutator bar D. removing the sparking brushes
Description : In general, D.C. propulsion motor brush sparking can be caused by _______________. A. incorrect brush grade, pressure or position B. a concentric commutator C. a dark chocolate colored commutator D. all of the above
Description : In D.C. motor construction, the armature coils' ends are _______________. A. soldered to the commutator bar risers B. imbedded into core slots C. crimped together with brush pigtails D. spliced with the field windings
Description : An important factor in reducing D.C. motor commutator wear is _______________. A. keeping the ambient humidity as low as possible B. ensuring a very low brush current density C. establishing the copper oxide surface film D. all of the above