Barber Colman Company

Hung-Sun Oh

Peter C Hightower

Gary B Burwell

A method and apparatus for controlling a ventilation damper unit utilizing a direct coupled two-position rotary damper actuator with a DC solenoid is disclosed. The actuator acts to rotate the output coupling, and in turn, the damper shaft to open the damper. After approximately 95 degrees &plus;/&minus;3 degrees of output coupling rotation, a limit switch is activated and a DC solenoid equipped with a full way bridge rectifier extends to a brake rotor to lock the damper into position. Simultaneously power is shut-off to the actuator motor assembly to reduce electrical consumption. Upon complete power failure to the actuator unit, such as during a fire and smoke emergency, the DC solenoid is spring returned allowing the damper to be spring returned to a closed position, thus preventing flow of air and smoke through a building and starving a fire of oxygen.

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Rockford, IL, United States of America

Hung-Sun Oh