Cable condition analyzing system for electric arc furnace conductors

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.

Claim 7

The system of claims 1, 2, or 3, said transducer comprising a toroid current transformer.

Claim 8

The system of claims 1, 2, or 3, said input means comprising an integrator and an R.M.S. network.

Claim 14

The system of claims 1, 2, 3 or 10, said read-out means comprising a current measuring meter and selector means for selecting a respective one of said stored signals for delivery to said meter.

Claim 16

The system of claims 1, 2, 3, or 8, said read-out means comprising comparison means for comparing the largest of said stored signals selectively with each of said stored signals.

Claim 17

The system of claims 1, 2, 3, or 10, said read-out means comprising comparison means for comparing each of said stored signals with the sum of said stored signals.

Claim 18

The system of claims 1, 2, 3 or 8, further comprising means for generating a reference signal representative of a known condition of an electrical cable, and said read-out means comprising comparison means for comparing each of said stored signals with said reference signal.

Claim 22

The system of claims 1, 2, or 3, said read-out means comprising a single read-out means for producing selectively said output information representative of each of said stored signals.

Claim 26

The system of claims 1, 2, or 3 wherein said system is portable.

Claim 27

The system of claims 1, 2, or 3 wherein said system is permanently located proximate an electric furnace.

Claim 28

The system of claims 1, 2, or 3 further comprising means for connecting at least one of said input means, timed means and memory means to external electrical equipment.