Cable condition analyzing system for electric arc furnace conductors
First Claim
1. For use with electric arc furnaces or the like usually provided with multiple phase electrical power and having for each phase plural electrical cables that ordinarily conduct relatively large electrical currents and encounter current fluctuations during operation, a system for sensing current flow for use in analyzing the condition of all of such electrical cables serving a respective phase, comprising input means for simultaneously producing a plurality of representative electrical signals indicative, respectively, of the electrical currents carried by such plurality of cables, said input means comprising a separate input means for each of the cables being monitored by the system and each input means including a respective transducer that produces an output voltage representative of the change of current flowing through a monitored cable with respect to time and means for producing such representative electrical signals from such output voltages, timed means including a plurality of timed integrator means for respectively integrating simultaneously each of said representative electrical signals for a period of time to produce respective integrated signals, said timed integrator means comprising a separate one of the same for each of the cables analyzed by the system, each including an integrator circuit and timer means for delivering to said integrator circuit for a selected period of time said representative electrical signal for integration by said integrator circuit, means for coupling each integrator circuit to said input means, memory means for storing a plurality of stored signals, each being indicative of a respective integrated signal, means for coupling said memory means to said integrator circuits, and means for making a comparison between at least one of said stored signals representing the electrical signal carried by at least one such cable at a given time and at least another one of said stored signals representing the electrical signal carried by at least another such cable at the same time, said means for making a comparison including read-out means selectively operable for producing output information respresentative of said stored signals, and display means for displaying the output from said read-out means.
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Abstract
The present invention provides for measuring and analyzing AC currents and preferably relatively large AC currents, such as those that are conventionally delivered to an electric arc furnace, as an indication of the current carrying capability or condition of one or, preferably, several cables, e.g. electric arc furnace conductors, carrying such AC currents. The invention monitors such AC currents for a period of time, stores the monitored information, and permits subsequent read-out of the stored information.
32 Citations
28 Claims
- 1. For use with electric arc furnaces or the like usually provided with multiple phase electrical power and having for each phase plural electrical cables that ordinarily conduct relatively large electrical currents and encounter current fluctuations during operation, a system for sensing current flow for use in analyzing the condition of all of such electrical cables serving a respective phase, comprising input means for simultaneously producing a plurality of representative electrical signals indicative, respectively, of the electrical currents carried by such plurality of cables, said input means comprising a separate input means for each of the cables being monitored by the system and each input means including a respective transducer that produces an output voltage representative of the change of current flowing through a monitored cable with respect to time and means for producing such representative electrical signals from such output voltages, timed means including a plurality of timed integrator means for respectively integrating simultaneously each of said representative electrical signals for a period of time to produce respective integrated signals, said timed integrator means comprising a separate one of the same for each of the cables analyzed by the system, each including an integrator circuit and timer means for delivering to said integrator circuit for a selected period of time said representative electrical signal for integration by said integrator circuit, means for coupling each integrator circuit to said input means, memory means for storing a plurality of stored signals, each being indicative of a respective integrated signal, means for coupling said memory means to said integrator circuits, and means for making a comparison between at least one of said stored signals representing the electrical signal carried by at least one such cable at a given time and at least another one of said stored signals representing the electrical signal carried by at least another such cable at the same time, said means for making a comparison including read-out means selectively operable for producing output information respresentative of said stored signals, and display means for displaying the output from said read-out means.
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2. For use with electric arc furnaces or the like usually provided with multiple phase electrical power and having for each phase plural electrical cables that ordinarily conduct relatively large electrical currents and encounter current fluctuations during operation, a system for sensing current flow for use in analyzing the condition of all of such electrical cables serving a respective phase, comprising input means for simultaneously producing a plurality of representative electrical signals indicative, respectively, of the electrical currents carried by such plurality of cables, said input means comprising a separate input means for each of the cables being monitored by the system, each including a transducer that produces an output voltage representative of the change of current flowing through a monitored cable with respect to time and a voltage controlled oscillator means for producing a frequency signal having a frequency proportionally representative of the magnitude of such transducer output voltage, a separate timed means for each of the cables analyzed by the system, each of said timed means comprising counter means for counting for a period of time the number of frequency pulses produced by said respective voltage controlled oscillator means and timing means for establishing such period for said timed means, memory means for storing a plurality of stored signals representative of respective outputs of said timed means, and read-out means selectively operable for producing output information representative of said stored signals, and display means for displaying the output from said read-out means, whereby a comparison can be made between at least one of said stored signals representing the electrical signal carried by at least one such cable at a given time and at least another one of said stored signals representing the electrical signal carried by at least another such cable at the same time.
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3. For use with electric arc furnaces or the like usually provided with multiple phase electrical power and having for each phase plural electrical cables that ordinarily conduct relatively large electrical currents and encounter current fluctuations during operation, a system for sensing current flow for use in analyzing the condition of all of such electrical cables serving a respective phase, comprising input means for simultaneously producing a plurality of representative electrical signals indicative, respectively, of the electrical currents carried by such plurality of cables, said input means comprising a separate input means for each of the cables being monitored by the system and including a transducer that produces an output voltage representative of the change of current flowing through a monitored cable with respect to time, and voltage controlled oscillator means for producing a frequency signal having a frequency proportionally representative of the magnitude of such transducer output voltage timed means including a plurality of timed integrator means for respectively integrating simultaneously each of said representative electrical signals for a period of time to produce respective integrated signals, and said timed integrator means comprising divider means for normalizing such integrated signals with respect to the period of time of operation of said timed means and counter means for counting for a period of time the number of frequency pulses produced by said voltage controlled oscillator means, memory means for storing a plurality of stored signals, each being indicative of a respective integrated signal, and read-out means selectively operable for producing output information representative of said stored signals, and display means for displaying the output from said read-out means, whereby a comparison can be made between at least one of said stored signals representing the electrical signal carried by at least one such cable at a given time and at least another one of said stored signals representing the electrical signal carried by at least another such cable at the same time.
Specification