NEIEP Mechanics Practice Exam

At what percentage of mechanical tripping speed must electrical safeties trip for cars traveling above 150 to 500 fpm?

1. 70%

2. 80%

3. 90%

4. 95%

The correct answer is: 90%

The correct percentage of mechanical tripping speed for electrical safeties, when cars are traveling above 150 to 500 feet per minute, is essential for ensuring safety and compliance with codes and standards in vertical transportation systems like elevators. At 90% of the mechanical tripping speed, electrical safeties are designed to engage. This threshold is crucial as it provides a timely response to prevent accidents or malfunctions caused by excessive speed. When cars operate at high speeds, prompt activation of safeties is vital to protect passengers and equipment. By setting the tripping speed at 90%, there is a sufficient margin to account for variations in performance and operational conditions while ensuring that any critical issue, such as overspeed, is swiftly addressed. In comparison, lower percentages such as 70% or 80% may not effectively capture all necessary scenarios where overspeed could pose a risk, while higher percentages like 95% may leave even less margin for safety, potentially resulting in unsafe conditions. Thus, 90% strikes the right balance for mechanical tripping in high-speed elevator systems.