JPS6485518A - Bus line service interruption detector - Google Patents

Abstract

PURPOSE:To enable service interruption to be quickly detected, by comparing the waveform of bus line residual-voltage after the service interruption of a bus line, with a reference frequency waveform, and by judging the waveforms as from the service interruption of the bus line when the waveforms are positionally shifted from each other continuously at specified intervals only. CONSTITUTION:A bus line service interruption detector has a combining circuit 1 for putting the waveform of bus line residual-voltage together with a reference frequency waveform, a pulse generating circuit 2 for generating positionally shifted intervals between the combined waveforms, as pulse, and a judging circuit 3, as a comparison stabilizing circuit. To the combining circuit 1, a phase detecting circuit 5 and a reference frequency generator 6 are connected, and when the waveforms of input from the combining circuit 1 are positionally shifted from each other, then by the pulse generating circuit 2, pulse for the positionally shifted intervals is generated. Then, the judging circuit 3 judges that the service interruption of a bus line 8 is generated when the input of two pulses or more of its pulse width at least is continuously provided, thereby outputting bus line service interruption command signal (a).