Elevator Mechanic Practice Exam

If an elevator travels at 1760rpm @ 60hz, how many Hz are needed to run at 600fpm?

1. 10Hz

2. 20Hz

3. 30Hz

4. 40Hz

The correct answer is: 10Hz

To understand how to determine the frequency needed for an elevator to travel at a specific speed, it's crucial to connect the rotation speed of the motor (in RPM) and the desired travel speed (in FPM). The relationship between RPM, feet per minute (FPM), and frequency (in hertz or Hz) is governed by the specifics of the elevator hoist system, including the rope and pulley mechanics. In this scenario, if the elevator is currently operating at 1760 RPM at 60 Hz, we first need to establish the relationship between the frequency and the motor speed. Generally, as frequency increases, the RPM of the motor increases proportionally because the speed of the motor is directly related to the frequency of the supply power. Knowing that the elevator is traveling at 600 FPM, you can use the proportion of the current speed (1760 RPM) to the current frequency (60 Hz) to find the new frequency necessary to achieve this new travel speed. If we assume that the lift travels linearly with changes in RPM and frequency, we can set up a ratio based on achievable speeds: If 1760 RPM corresponds to 60 Hz, we can set up the following equation to find out how many Hz would correspond to