Which of these applications always operates under some load upon startup?
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Answer: C. Pistol drills
Explanation
Pistol drills and similar hand-held power tools always encounter mechanical resistance and load immediately upon startup. The drill bit engaging with a workpiece creates immediate friction and rotational resistance the moment the trigger is pulled. This initial mechanical load requires the motor to develop adequate starting torque right from the very first rotation. Pistol drills typically use high speed universal motors capable of delivering strong initial torque for drilling applications. Unlike ceiling fans that start in free air, tools like drills start against the physical resistance of the material. Motor performance curves indicate that series wound motors excel at delivering high torque under heavy starting loads.
Vacuum cleaners start with restricted airflow, but fan motors generally start with very minimal initial aerodynamic load. Fan motors typically start in open air with negligible initial mechanical resistance compared to drills and compressors. Since fan motors and vacuum cleaners do not always encounter heavy startup loads, the option encompassing all of them is false.
- Subject
- Engineering
- Category
- Electrical Engineering
- Topic
- —
- Difficulty
- medium
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