Final answer:
Approximately 80% of the energy expanded in lifting a traction elevator car is returned to the system by regeneration when the car is lowered.
Step-by-step explanation:
Approximately 80% of the energy expanded in lifting a traction elevator car is returned to the system by regeneration when the car is lowered.
During the lowering process, the motor acts as a generator, converting the potential energy of the car back into electrical energy that can be stored or used to power other systems in the building. This process helps to improve the overall efficiency of elevator systems.
For example, if a traction elevator car is lifted using 1000 Joules of energy, approximately 800 Joules would be regenerated back into the system when the car is lowered.