Abstract: An abnormal vibration monitor is used for a monitor by detecting the abnormal vibration of a rotary device placed in an explosive atmosphere by using a plurality of piezo-pick-ups. In the monitor, many signal wires and power source wires for devices are placed in an explosive atmosphere whereby there is a possibility of an explosion. In order to prevent the explosion, pre-amplifiers for detection which are respectively connected to the piezo-pick-ups and scanners for scanning the pre-amplifiers and power sources are contained in one antiexplosion casing and the casing is placed in the explosive atmosphere and the parts in the casing are connected by only small number of cables to the monitor placed in an nonexplosive atmosphere. The piezo-pick-ups are respectively fixed to parts for vibration out of the casing to give high detection accuracy.

Abstract: A bearing failure judging apparatus correctly judges the type of the cause of a failure of a bearing by synthetically judging many factors found in a vibrating waveform of a vibration produced when a failure takes place in the bearing i.e. various features of the time-waveform; a localization of the amplitudes of the time-waveform, the periods of pulsating waves, a degree of the acuteness of the waveform depicted by its envelope, the presence or absence of the proper peak value in the frequency spectra, and a change of the waveform after a given time.

Abstract: A system for detecting whether a machine is in the normal or abnormal state by comparing detected values of waveforms of signals such as vibration generated from the machine with a set value a plurality of times to indicate failure of the machine when the detected values reach the set value a predetermined number of times.

Abstract: An apparatus for monitoring torsional vibrations of a rotating shaft system such as for a turbine generator in which torsional vibrations at certain positions of the rotating shaft system are detected by detectors and the detected vibrations are converted into torsional vibration at an arbitrary position of the rotating shaft system by using an operation device having desired transfer characteristics, said arbitrary position is monitored on torsional vibration on the basis of the converted torsional vibration.

Abstract: The disclosed torsional vibration monitoring apparatus estimates torsional vibration at arbitrary positions in a shaft system, such as in a turbine generator. Detectors detect torsional vibrations produced at fixed positions of the rotating shaft system and the detected vibrations are separated into modal vibrations so that subtractors and matrix operators can obtain up to n vibration mode components from the modal vibrations and the torsional vibrations detected. First modal vibration operators obtain modal vibrations higher than the (n+1)th modal vibrations at the arbitrary positions of the rotating shaft system from the detected torsional vibrations, second modal operators obtain up to the n-th modal vibrations at the arbitrary positions from the vibration mode components and adders add the respective modal vibrations obtained by the first and second modal operators.

Abstract: The disclosed torsional vibration monitoring method measures torsional vibrations produced in a rotating shaft system, for apparatuses such as a turbine generator, at a small number of measurable points on the system and the measured torsional vibrations are linearly separated to estimate torsional vibrations at arbitrary positions of the system are estimated. According to one high precision torsional vibration monitoring method, up to 2n torsional vibrations at the arbitrary positions are obtained from the torsional vibrations detected at n selected positions of the rotating shaft system.

Abstract: The present invention is a torsional vibration monitoring method and an apparatus for performing the same, in which torsional vibrations produced in a rotating shaft system for use in such as a turbine generator are measured at a small number of certain positions therealong at which the measurements are possible, the torsional vibrations are linearly decomposed and torsional vibrations at arbitrary positions on the rotating shaft system are estimated from the linear decompositions.

Abstract: The present invention relates to a torsional vibration monitoring apparatus for a rotating shaft system which is characterized by comprising a detector disposed at a certain position of the rotating shaft system for detecting torsional vibration of the shaft system, a memory device for storing the torsional vibration having a constant time duration which is detected by the detector as a time series data obtained by sampling the torsional vibration with minute unit times, a Fourier transforming device for Fourier-transforming the time series data to obtain a frequency series data, multiplier each for multiplying the frequency series data with a relation which is previously obtained between the vibration of the shaft system at the certain position of the shaft system and that at an arbitrary position thereof at respective frequencies to obtain a frequency series data for the arbitrary position, and reverse Fourier transformer for reverse-Fourier-transforming the frequency series data to obtain a time series dat

Abstract: A torsional vibration monitoring system for monitoring torsional vibration occurring in a rotating shaft system such as in a power generator turbine is disclosed. Torsional vibrations are measured at a small number of measurable positions on the rotating shaft system, and stresses at other arbitrary positions are estimated by linearly decomposing the torsional vibrations. The fatigue life expenditure on the rotating shaft system is obtained and monitored on the basis of the estimation obtained by the linear decomposition of the torsional vibration. For a huge vibration such as caused by thunder which may produce stresses on the rotating shaft system and which can not be estimated by the linear decomposition thereof, the torsional vibration monitoring apparatus may be provided with means to produce data which may be used in other analysis, by recording real torsional vibrations caused thereby.