Thyristor convertor failure detection device
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorToshiaki Ishii
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Abstract
A failure detection device for a convertor which converts alternating current into a direct current through a plurality of rectifying thyristors. The waveform of the output direct current of the convertor is detected and is supplied to a band-pass filter which selectively passes the harmonic component which has a frequency corresponding to that of the AC voltage source for the convertor. The existence of the component of this frequency is characteristic of an occurrence of a failure within convertor. The amplitude of the component passing through the filter is then detected by a zener diode, and a failure signal is generated when the amplitude exceeds a predetermined level.
Claims4
A failure detection device for a convertor circuit which converts alternating current into an output direct current through a plurality of rectifying elements connected between an alternating current voltage source and a direct current load, said failure detection device comprising:
- waveform detector means for detecting the waveform of said output direct current of said convertor, and for producing a waveform signal corresponding to said waveform;
- harmonic component detector means connected to said waveform detector means and responsive to said waveform signal for detecting a harmonic component of said waveform, and for producing a harmonic component signal corresponding to said harmonic component, said harmonic component being a harmonic component having a frequency which is characteristic of an occurrence of a failure within said convertor;
- and
- amplitude detector means connected to said detector means and responsive to said harmonic component signal for detecting the amplitude of said harmonic component and for producing a failure signal when said amplitude of said harmonic component exceeds a predetermined level.
Dependencies are inferred from the claim text.