CET Door Operators & Interlocks 3 — Questions and Answers
Question 1: According to ASME A17.1, what must happen if the door reopening device fails on a power-operated door?
- The door must remain open until repaired
- The door must still be able to close at reduced speed (Correct answer)
- The elevator must be taken out of service immediately
- The door may close at normal speed with a warning buzzer
Correct answer: The door must still be able to close at reduced speed
If the reopening device (such as a safety edge or light curtain) fails, the door must still be capable of closing but must do so at reduced kinetic energy.
Question 2: Which of the following BEST describes the function of a bi-parting center-opening door system?
- Both door panels move toward the same side wall
- Each door panel moves in opposite directions away from center (Correct answer)
- One panel opens while the other remains stationary
- The doors open vertically rather than horizontally
Correct answer: Each door panel moves in opposite directions away from center
In a bi-parting center-opening door system, two panels simultaneously move away from each other toward opposite sides of the opening.
Question 3: A light curtain used as a door reopening device operates on which principle?
- Measures resistance when a passenger pushes on the door edge
- Projects infrared beams across the door opening and reverses on beam interruption (Correct answer)
- Uses ultrasonic sound waves to detect obstructions
- Monitors motor current draw to detect contact with an obstruction
Correct answer: Projects infrared beams across the door opening and reverses on beam interruption
A light curtain emits a matrix of infrared beams across the door opening and triggers door reversal when any beam is broken by a passenger or object.
Question 4: What is the minimum landing sill-to-car sill gap allowed before it becomes a safety hazard for passengers stepping over it?
- 1/2 inch
- 1 inch
- 1-1/4 inches (Correct answer)
- 2 inches
Correct answer: 1-1/4 inches
ASME A17.1 allows a maximum gap of 1-1/4 inches between the car sill and hoistway (landing) sill to prevent tripping or entrapment hazards.
Question 5: On an elevator with automatic power-operated doors, what must be verified before the car is permitted to leave a landing?
- Only the car gate switch must be closed
- Both the car door contact and the hoistway door interlock contacts must be in the closed position (Correct answer)
- Only the hoistway door interlock must confirm door closure
- The floor selector must confirm the correct floor position
Correct answer: Both the car door contact and the hoistway door interlock contacts must be in the closed position
Both the car door contact and every hoistway door interlock in the travel path must be confirmed closed in series before the car is allowed to leave a landing.
Question 6: During a door interlock test, a technician bypasses the hoistway door interlock and the car moves. This result indicates:
- The interlock circuit is correctly wired in series
- The interlock is NOT in the safety circuit and must be corrected (Correct answer)
- The door operator speed is too high and must be adjusted
- The retiring cam needs realignment
Correct answer: The interlock is NOT in the safety circuit and must be corrected
If bypassing the interlock allows car movement, the interlock is not properly in series with the safety circuit, which is a code violation requiring immediate correction.
Question 7: What is the role of the door dwell time setting on an automatic elevator door operator?
- Controls how long the door pauses at the fully open position before closing (Correct answer)
- Sets the maximum door closing speed
- Limits how long the door will attempt to close before reversing
- Determines the motor acceleration rate during opening
Correct answer: Controls how long the door pauses at the fully open position before closing
Door dwell time is the adjustable period the door remains fully open at a landing, giving passengers adequate time to enter or exit before automatic closing begins.
CET Door Operators & Interlocks 3
According to ASME A17.1, what must happen if the door reopening device fails on a power-operated door?