Data processing: measuring – calibrating – or testing – Measurement system – Performance or efficiency evaluation
Reexamination Certificate
2000-12-27
2004-02-17
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Performance or efficiency evaluation
C700S029000
Reexamination Certificate
active
06694286
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and a system for monitoring the condition of an individual machine belonging to a selected class of machines, as defined by the preamble of independent patent claim 1, as well as to a system for executing the method.
The industrial economy is a complex system of people, objects, machines, and processes interacting with each other, to create, produce, distribute and consume products. All elements of this system are expected to work according to certain values, to keep it alive. As regards the technical side of the system, the status of processes and machines has to be monitored, to be able to decide whether they can deliver the output they have been designed for. Status monitoring in general comprises a repeated or continued consideration of critical values like temperature, pressure, speed, etc. that are known to have a major influence on process or machine behaviour, or that are known to indicate a malfunction.
Status monitoring of machines, such as electrical machines, is known to be done by comparing data that has been gathered by means of sensors or equivalent measures, for the same machine at different points in time. The problem with doing so, notwithstanding the fact that valuable data can be gathered for this single machine, is that it takes a lot of time to build a data pool for the machine to be monitored, so that certain behaviours, and trends as regards the status of this machine can only be predicted on the basis of such data, after the machine has been running for a long time. Similar monitoring has also been carried out for industrial processes. This is not only ineffective but also costly, and thus economically disadvantageous.
BACKGROUND ART
Several methods and devices for monitoring the status of a machine are known from the state of the art.
Document U.S. Pat. No. 5,251,151 discloses a method and apparatus for diagnosing the mechanical condition of a machine. The method includes the steps of sensing a reference vibration signal of the machine; creating a reference set of events from the reference vibrational signal of the machine; saving the reference set of events; sensing a test vibrational signal of the machine; creating a test set of events from the test vibrational signal of the machine; and, comparing the test set of events with the reference set of events to determine the mechanical condition of the machine.
Furthermore, document WO 97/20224 discloses a process and a device for testing a plurality of electric devices, whereby measurement values are simultaneously collected for the plurality of electric devices and the signals that describe said values are provided with device specific identification-codes. The thus identified signals are then uninterruptedly supplied on-line to a data processing system where they are compared to nominal values. When a signal deviates from a nominal value, the device from which the signal originated is indicated as defective.
Finally, document EP 0 775 335 B1 discloses a method for monitoring multivariate processes, in which the course of the process is dependent on a multiple of variables relevant to the process. The method involves a description of the relevant variables as a multidimensional room, wherein each variable represents an independent component in the room, that the observations of the variable values at a certain time represent a point in the multidimensional room, that the observations from a number of times form a point swarm in the room, that at least one first and one second principal direction of the point swarm are calculated, that the projections of the observations on these first and second principal directions are determined, that the observations are illustrated graphically in the plane which is formed by the first and second principal directions in the point swarm, further that the principal directions are continuously up-dated during the course of the process, whereby the graphic information becomes dynamic, and, finally, that the operator or the monitoring member of the process, based on the presented information, adapts members which influence variable quantities in the process such that the process is controlled to optimum operating conditions. Information about the course of the process is obtained by projecting measured data onto a plane which is comprised in the variable space which describes the process. The plane to which measured data are projected, according to the PCA and PLS methods, dynamically follows the flow of new series of measured process data, the projection plane being able to rotate in the multivariate room which describes the process. This provides a constant monitoring of the process in relation to the present stage and not in relation to a process historical stage.
However, although the above mentioned methods provide a number of advantageous features, a substantial problem remains, namely a shortage of reference data when a new machine, method, or process is developed. More specifically, there is a shortage of data on faults, and problems with new machines/processes, etc.
Thus the object of the present invention is, to provide a method and a system for monitoring the condition of an individual machine of a certain type, which method and system provides status data for comparison quickly and reliably, makes reference data rapidly available to a new machine/process, so that faults or problems with a new machine or process can be rapidly detected.
This object is solved by the features of independent patent claim 1, whereby advantageous embodiments of the invention are described by the features as contained in the dependent claims.
SUMMARY OF THE INVENTION
The basic idea of the present invention is that instead of gathering a data pool for a single object, e.g. one machine only, that object or machine is compared with similar machines by means of a common, possibly global data bank, obtaining a much greater statistical basis, resuiting in many more possibilities to anticipate needs or demands for corrective measures, as regards the monitored machine. By comparing data for a machine with data from many others of the same type, with help of a global data bank and an analysis function, one can determine the absolute and actual condition for the machine and in such a way more quickly capture a deterioration. Thus, a method for the determination of the absolute/actual status for a machine, electrical or not, via a global data bank is provided. This is carried out by comparing data from individual machines with a compilation of data from many other machines. The benefit is more certain information, determinations, much earlier detection of change or deterioration for a newly developed machine or process, of operating condition and through that better maintenance planning and thereby lower costs for customers.
There are different types of data that may be used to compare an object, a machine, or aggregate, with all other objects, or machines of the same type. One way is to compare the rate of change of e.g. a bearing temperature with the mean values of the rate of change for all other machines, as contained in the data base. Another way could be to compare the machine data measured at specified loads, e.g. 100%, with the other machines as contained in the data base at 100% load. Although every machine is individual, the mean value of many machines should be essentially constant, while the individual machine can vary. For example, electrical generators of the Powerformer™ type may be considered as a specific type of machine or as a selected class of machines. Even somewhat different machines may have certain selections of parameters that behave in a common way. For example, Powerformer™ generators of a broadly similar output for both hydro-generation and for turbo-generation may together form a selected class of machines, especially in respect of a selection of parameters of interest considered to act in a common or similar way.
The method according to the present invention for monitoring the condition of an individual ma
ABB AB
Hoff Marc S.
Jenkens & Gilchrist
Raymond Edward
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