| 摘要 |
A reducing station has a safety function in a negative direction of action for metering energy flows in the form of gases, steam or water, in particular in thermal or industrial power plants. An operating leg of a servo valve is supplemented by at least one further safety leg of displacing a first spindle section carrying a restrictor body at one end, into a closed position. The displacement is effected as a function of an applied pressure-monitor tripping signal. A second spindle section is coupled to the other end of the first spindle section through preloadable springs and non-self-locking, securely brakeable safety-spindle thread stages. The second spindle section has a spindle drive which transmits an axial thrust or pull to the first spindle section through the securely braked safety-spindle thread stages, in a regulating mode. In a tripping mode, the second spindle section forms an abutment for the movement of the first spindle section with the restrictor body into a desired, closed position. The movement is released by the safety spindles. At least two safety legs each have one non-self-locking safety-spindle drive. Both safety legs can act on a rocker-like, two-armed safety lever. The safety legs can be tested as to their function.
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