Electrical connectors – Including handle or distinct manipulating means – Randomly manipulated implement
Reexamination Certificate
1999-06-24
2001-04-24
Luebke, Renee (Department: 2833)
Electrical connectors
Including handle or distinct manipulating means
Randomly manipulated implement
C439S284000
Reexamination Certificate
active
06220891
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates generally to remote nondestructive sensors and, more particularly, to a connector capable of disconnecting a probe from a probe drive shaft while insulating a data line from a drive line when the probe is connected to the shaft.
2. Prior Art
It is known in the art to have a remote sensor, or probe, traveling in small tubes as small as ½ inch inside diameter such as are found in steam generators and heat exchangers to inspect the integrity of such tubes or to deliver the probe to a remote location. Generally, a testing probe is urged through a tube by means of a positioning, or drive, shaft to which it is attached. During operation, the probe sensor is driven by a drive line voltage and transmits responsive measurement data, both through cables carried within the shaft. An Eddy current probe is one such remote sensor commonly employed in the inspection of tubes.
Cracks and bubbles and other material nonuniformities produce variations in conductivity and permeability. Induction of Eddy currents in the material is a commonly-used technique for nondestructively detecting such defects near the surface of materials by sensing changes in material conductivity or permeability at a material nonuniformity by detecting changes in Eddy currents. Eddy currents are induced in the test material by a drive coil in an Eddy current probe. An oscillating electrical current in the coil generates an alternating primary electromagnetic field that is propagated into the test material. It is this primary field that induces the Eddy currents in the measured material. The Eddy currents in turn generate a secondary electromagnetic field that is propagated back to a sense coil in the probe where an electric current and voltage is induced. The sense coil voltage is therefore a function of the magnitude of Eddy current flow in the test piece. Discontinuities and nonuniformities in the material being tested with inherent change in permeability and conductivity cause a reduction in the magnitude of the Eddy currents and thus a change in the voltage in the sense coil which is analyzed as an indicator of the causing defect in the test material.
The voltage to the drive coil, which might be 400 volts at 4-5 watts, is typically carried in a coaxial drive cable within the drive shaft to the eddy current probe coil. The voltage induced in the sense coil at perhaps 1% of the drive voltage is carried from the probe in a different data cable, well insulated and separated from the drive cable so the drive voltage does not induce a voltage in the data cable that overwhelms the data voltage. When multiple drive coils and multiple sense coils are employed in the probe, a plurality of drive cables are employed, all spaced apart and insulated from multiple data cables.
It is often desirable to disconnect the probe head from the shaft for probe replacement or repair. This requires that the power drive lines and data communication cables be broken. At the break, without other precautions, loss of insulation between the power and communication cables induces cross-talk into the data lines that masks the data signals. Available large coaxial connectors designed to prevent this cross-talk are not suitable because their size prevents their use in small, ½ inch tubes. Thus, previously detachment of an Eddy current probe from the shaft has been ill-advised.
SUMMARY
It is the primary object of the present invention to provide a cable connector useful to connect and disconnect an Eddy current probe from a drive shaft including power and communication cables passing through the shaft to the probe. A second object is to maintain electromagnetic insulation between the power and communication cables at the connector break to avoid electromagnetic leakage from the power cable that might induce a voltage in the communication cable. Another object is that the connector be sufficiently small so that it can be employed in tubes with an inside diameter of about ½ inch.
These objects are achieved in a connector comprising a union with connectable shaft and probe sections of electromagnetically insulative material mating at matching transverse surfaces. The connector includes upper and lower portions with power line connecting pins and matching sockets in the upper portions of the sections and communication line connecting pins and matching sockets in the lower portions of the sections. Each section upper portion transverse surface is separated, or staggered, longitudinally from its lower section transverse surface by a planar ledge surface. The two ledges and the section upper and lower matching surfaces are in face to contact when the union is connected. A trepan may also be provided at inner comers formed between ledge and transverse surfaces. Matching plugs at outer comers formed between ledge and transverse surfaces then slide into and fill the trepans when the connector is closed. Thus, any electromagnetic radiation that may leak from the connection of the matching surfaces at the power line upper portion is effectively prevented from conducting to the connection of the matching surfaces at the communication line lower portion.
REFERENCES:
patent: 3953099 (1976-04-01), Wilson
patent: 4179179 (1979-12-01), Lowden
patent: 5146786 (1992-09-01), Nachbar
Hammond Briggitte R.
Luebke Renee
Tingey David L.
Zetec, Inc.
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