In terms of speed control, how does a four-terminal starter differ from a three-terminal starter?
What will be an ideal response?
A four-terminal starter provides for variable speed control using a field rheostat. As the arm is raised to the first position, the shunt field receives full voltage, yet there is still resistance in the armature circuit. As the arm is moved to the right, resistance is added to the shunt field circuit but removed from the armature circuit. Because adding resistance to the shunt field circuit reduces the current to the field, the holding electromagnet is not in series with the shunt field but is connected across the line, hence the fourth terminal.
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A 100,000 ft2 office building might have 500 occupants. A 1% improvement in occupant productivity would have approximately what economic value, assuming an average occupant compensation of $75,000 per year?
A) $375,000 per year. B) $175,000 per year. C) $75,000 per year. D) $275,000 per year.
What three environmental conditions have the most effect on comfort?
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The lowest evaporator coil temperature that traditional mechanical compression systems can attain is approximately:
A) 0°F. B) -00°F. C) -40°F. D) -250°F.