| 摘要 |
<p>Movement of a movable barrier (10) such as, for example, a vertically-dropping fire door, can be controlled in an informed manner and with greater flexibility regarding the manner of movement via, in one embodiment, use of a motor 20 as a generator to resist the downward movement of the barrier. One or more dummy electrical loads 22 can be used in combination with the generator mode of operation to influence the degree of braking proffered by the motor. In various embodiments, one or more sensors (25, 26, 27) can be used to detect local and remote conditions of interest to thereby at least partially inform the barrier movement decision process. A display (90 fig 9) (or displays) can serve to provide various kinds of information to authorized personnel and an operator control (120 figure 12) can serve, at least under some operating circumstances, to permit a person to locally cause a closed barrier to move to at least a partially opened position.</p> |
