Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Patent
1990-11-09
1993-03-30
Harvey, Jack B.
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
364482, 324551, G01N 2700
Patent
active
051987759
DESCRIPTION:
BRIEF SUMMARY
The object of the present invention is a device for verifying the water-tightness of networks of cables having a sheathing of metal or metal wires and, in particular, of optical-fiber cables, used in telecommunication systems.
It is known that the use of optical fibers in telecommunication networks has expanded greatly during the last few years due to the substantial advantages which this material offers over the existing materials and, in particular, over coaxial cables. Optical fibers, in particular, constitute the three-directional wide band support to which leading-edge technologies have recourse and the applications of which are increasing, in particular for transmission, telebraodcasting, teleremote measurements, etc.
Optical fibers are generally contained within polyethylene cables having a metal sheathing between the cable core and the polyethylene covering. Optical-fiber cables are most frequently sheathed with aluminum or steel and referred to by the expressions "ALUPE" and "ACIEPE" respectively, these cables having a tubed or grooved-rod structure.
The proper operation of a telecommunication system is, of course, dependent on the water-tightness of the cables used, the infiltration of water resulting in the short or longer term in degradation of the cables.
In the case of optical-fiber cables, this degradation may cause extensive damage due to the slowness with which the initial degradation of the carrier cable is propagated up to the optical transmission support. It is therefore important to be able to act rapidly on a line which presents a lack of tightness, which presupposes continuous and effective verification of the system of cables so as to permit rapid detection of such a defect before the optical fibers are reached. However at present, the breakdown of a cable can be detected only when the optical fiber is damaged.
The object of the present invention is to remedy this drawback of telecommunication systems by proposing a device which permits an effective, continuous verification of the water-tightness of cables having a metallic or metal-wire sheathing, as well as supervision of the aging of these networks by verification of the condition of the metallic sheathing of said cables.
Another object of the present invention is a device which permits the rapid systematic detection of a lack of tightness in a network of telecommunication cables, this device being intended to be installed in the telecommunication center and comprising in combination:
a) means for selecting one by one the cable assemblies to be verified;
b) means for effecting the disconnecting of ground from the cable assembly which is selected;
c) means, on the one hand, for measuring the insulation resistance with respect to ground of the cables selected and comparing this resistance with a standard resistance and, on the other hand, for measuring the electrochemical couple generated by a lack of tightness;
d) alarm means which go off when a lack of tightness is detected;
e) means which make it possible, based on a computer controlled by specific software, to record, process and supply all information concerning these assemblies;
f) means which make it possible to interrogate the system from a supervisory center or in-situ.
In practice, the assemblies of cables checked can be formed by racks of the network, which are selected one by one periodically from a central measurement unit installed in the distribution center, each rack of the network being connected to a rack unit which, in its turn, is connected to the central measurement unit and contains the electrical device necessary in order to effect, upon control by the latter, the disconnecting of the corresponding rack from ground and the connecting thereof to the point of measurement.
The device in accordance with the invention thus comprises two complementary parts:
a central measurement unit which includes a system for the triggering of the measurement, a system for acquisition of the measurement information, for the processing of this information and for the giving of an
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Seisakusho, "Patent Abstracts of Japan", vol. 5, No. 126, Aug. 14, 1981, p. 75.
Bussinger Jean
Jacquelin Yvon
Harvey Jack B.
Regan Maura K.
Societe Socrat & Belec Sarl
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