| 摘要 |
An operator for operating a fire door, the fire door having a drive shaft, comprising: (1) A motor having an output shaft coupled to the drive shaft; (2) A brake for holding the fire door in an open or a closed position; (3) An electronically controlled descent device comprising; (i) A DC solenoid for engaging and disengaging the brake; (ii) A speed sensor for detecting a descent speed of the fire door; and (iii) An electronic controller, responsive to the speed sensor, selectively enabling the DC solenoid when the descent speed reaches a predetermined minimum speed and disabling the DC solenoid when the descent speed reaches a predetermined maximum speed; (4) A limit shaft coupled to the output shaft for selling open limit and closed limit positions; and (5) A DC power source for providing power to the electronically controlled descent device.
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