| 摘要 |
The present invention describes a valve actuator having a first motor (30) for moving a valve element and a second motor (30') for energizing a failsafe spring (130). The second motor is operated independently from the first, thus allowing the valve element to be moved between its open and closed positions while the spring is energized. In an emergency, the spring will be de-energized and move the valve element to its failsafe position no matter the position of the valve element. |
