100% with david beach with the 99.99% of the time with following exception.
I saw some smoke dampers years ago that were gravity operated and held open with fusible links. There was an integral electric heater to melt the link. They were of course "One Time Only Devices" and had to be replaced after every use. We lost a couple during test and commissioning. They would operate on either a high ambient temperature or from a signal from the fire alarm panel. They were powered from the fire alarm system.