Electrical & Control Systems Flashcards
6 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Electrical & Control Systems flashcards as text
What is the main function of a relay in elevator control systems?
Answer: Switch circuits using control signals
Relays act as electrically operated switches that control circuits using low voltage signals.
Which type of motor is commonly used in modern traction elevator systems?
Answer: AC gearless permanent magnet motor
AC gearless permanent magnet motors are widely used for their energy efficiency and smooth operation.
What is the purpose of a limit switch in elevator systems?
Answer: Prevent over-travel of the elevator car
Limit switches prevent the elevator from moving beyond safe boundaries by cutting off power when limits are reached.
Which component converts AC to DC for elevator control circuits?
Answer: Rectifier
Rectifiers are used to convert alternating current (AC) to direct current (DC) for elevator control components.
What safety component cuts off power during an elevator malfunction?
Answer: Circuit breaker
A circuit breaker or main disconnect switch is designed to interrupt power during overload or faults to protect the system.
Which device is used in elevator systems for variable speed control of motors?
Answer: Variable Frequency Drive (VFD)
A variable frequency drive (VFD) regulates the speed and torque of elevator motors for efficient operation.