When is it impossible to start a motor across the line?
What will be an ideal response?
There are conditions where it is not possible to start a motor across the line due to excessive starting current or excessive torque. Some power systems are not capable of providing the high initial currents produced by starting large horsepower motors. When this is the case, some means must be employed to reduce the amount of starting current. Two of the most common methods are resistor starting and reactor starting. Although these two methods are very similar, they differ in the means used to reduce the amount of starting current.
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When preparing a job site for excavation or construction, the removal of objects below the original ground level is called _____.
a. clearing b. stripping c. grubbing d. scalping
Which of these devices can retain a high-voltage charge after power has been removed?
a. Capacitors used in motor circuits b. Control relays c. Compressor contactor d. Compressor terminals
All of the following statements are true EXCEPT:
A. aluminum oxide is very abrasive; it is what sand paper is made of. B. if there is aluminum oxide in the cooling system, it looks like black sand beads. C. when flushing a cooling system with aluminum oxide contamination, heat the engine to operating temperature and reflush the system at least three times, heating to full temperature each time. D. using a commercial chemical cleaner, the radiator can be flushed but it must be removed from the car.
Which of the following transmits power between shafts whose axes intersect, not necessarily at 90°?
a. Worm gear b. Friction wheel c. Bevel gear d. Spur gear e. Herringbone gear