I have seen the regenerative capabilities of a elevator in freefall. At no STAGE in the free fall episode did regenerative energy come even close to nullifying the free fall.
The speed drive was set at manufacturing stage to use the regenerative braking in a freefall situation. However the outcome was that when it was required it did sweet fa. AND I WAS IN THE LIFT WHEN IT FAILED. The centrifugal "gravity switch" was engaged after 2 levels of freefall. It was a tongue cutting experience.
Experiencing the free fall firsthand I was engaged to investigate the motors and speed drives.
I can tell you that the regenerative braking feature. Big ass resistors were engaged during the freefall but the thermal overload feature for the regenerative controllers using the resistors tripped. It could not keep up. In fact as I experience two of these episodes I can say I noticed no slowing down at all during the free-fall situation.
The multiple faults identified was the following;
A programming issue with the speed drive. The speed drive was designed to go into a "coast to a stop" mode if the speed drive went into a fault status.
Not a good idea on a elevator.
The primary cause however was a intermittent fault with the internal fan of the speed drive. The speed drive was overheating and cutting out on overtemp. Then setting the incorrectly programmed safeties into action.
Regenerative braking and then the last stop measure was the centrifugal switch. Or the gravity switch.
Not a nice experience for the few that had their knees drive through their jaw.
I guess you did qualify yourself in saying that it COULD help. I guess your right.
