| 摘要 |
<p>Apparatus for the rapid monitoring of an alternating (a-c) variable with respect to amplitude, frequency and phase which includes a generator circuit for forming, from an actual a-c voltage imaging the monitored a-c variable, a reference a-c voltage of predetermined amplitude and frequency which is linked to the former in rigid phase relationship, and comparators for comparing individual signals of the generator circuit with the instantanious values of the actual value a-c voltage, permitting recognition of disturbances in a time which is substantially shorter than one period of the a-c variable monitored.</p> |
