| 摘要 |
In order to prevent dangerous operation of machinery, for example excessive speeds in internal combustion engines upon electrical failure in the fuel management system or associated sensors, the current passing through the electromagnetic final control element which engages the fuel control rod is monitored. In normal operation of the final control element, when the armature is displaced, a back EMF opposes the applied voltage, thereby reducing the effective current. Accordingly, a jammed armature and similar malfunctions will produce increased current through the final control element. The threshold of a threshold response switch is set to lie between these two values of the current, whereby, when the armature is jammed or short circuits occur, the current will rise above the threshold and permit fuel shut-off or a switchover to mechanical fuel control. Another embodiment of the invention monitors the output voltage of a position transducer associated, for example, with the fuel control rod of the engine and initiates emergency procedures when the signal departs from its nominal range in one direction.
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