Mechanism by which the blade of the damper gets remotely unlatched by a current impulse to a magnet or a current breaking, or automatically by the melting down of a thermic fuse at a temperature of + 72°C (for higher temperatures fusible links of 100°C or 140°C are also possible) in the duct. The internal torsion spring thus unlatches and the blade closes.
With an end or begin or range switch the position of the blade can be verified.
The re-arming of the damper needs to be done manually.