Switchable load coil case

Details Switchable load coil case Switchable load coil case

1999-06-21

2001-08-28

Scott, J. R. (Department: 2832)

Electricity: circuit makers and breakers

Multiple circuit control

Pivoted contact

C200S0110TC, C200S302100

Reexamination Certificate

active

06281454

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to a load coil case for terminating loads and, more particularly, to a switchable load coil case.
BACKGROUND OF THE INVENTION
In data and voice transmission lines typically used in the telephone industry, the cable consists of a plurality of wire pairs, typically segregated into groups of 50, 100, 200, 400, 600, 1200 or 1800 pairs, which are covered by a pressurized and airtight metallic sheath and a plastic outer protective sheath. Wire pairs extending between a central source and a subscriber have substantial capacitance, resulting in a change in impedance with length. The capacitance effect of the cable conductors has a direct relation on the voice band (300 Hz to 3000 Hz) from any given point—the higher the frequency, the greater the loss or attenuation. Thus, it is conventional to connect inductance or load coils in the conductors to maintain a predetermined impedance to balance and improve the voice frequency characteristics of the cable conductors and to assure maximum signal power transfer between the central source and the subscriber. The load coils are typically connected to wire pairs at predetermined intervals so that the known capacitance of the resulting predetermined wire pairs will be balanced by the inductance of the load coil.
Load coil cases are typically used for housing the plurality of load coils associated with each of the 50, 100, 200, 400, 600, 1200 or 1800 wire pairs. After the individual wire pairs are connected to a corresponding load coil, they are typically assembled in a compact configuration in the load coil case and the load coil case is filled with an appropriate encapsulating or potting compound to keep moisture from affecting the load coils, such as by oxidizing the metallic inductor cores, damaging the insulation of the wires in the load coil, or forming conductive paths between wire pairs which would result in degraded compensation and cross linking and cross talk between wire pairs The load coil may then be stored in pedestal cabinets, in underground manholes, and the like.
In many applications, however, when the subscriber wants high frequency service, each and every load coil located between the source and subscriber must be “unloaded” or bypassed from the wire pair servicing the particular subscriber. In order to bypass the load coil, each load coil case must first be located in the dirt, water, and other debris typically found in the outside plant telephone environment. After the outer and metallic sheaths are removed and the specific wire pair servicing the subscriber is located from the potentially hundreds of wire pairs typically found in telecommunications cables, the load coil is unloaded or bypassed by splicing the wire pair around the load coil. The cable must be recovered with the metallic and plastic sheaths, pressurized and tested for leaks It will be appreciated that a subscriber may alternatively require that a disconnected load coil be reloaded or re-connected to the wire pair in a similar manner. In either case, it may typically take two technicians eight hours or more to complete the splicing operation for each load coil in the subscriber's wire pair.
SUMMARY AND OBJECTS OF THE INVENTION
Accordingly, it is an object of the present invention to provide a novel load coil case which permits a load coil to be easily and selectively loaded into the circuit and unloaded or bypassed from the circuit.
A related object of the present invention is to provide a load coil case having a switch assembly which may be adapted to accommodate any number of wire pairs and load coils.
A further object of the present invention is to provide a switch assembly which may be easily and quickly assembled. A related object is to provide a switch assembly to which a load coil and wire pairs may be easily and quickly assembled.
It is another object of the present invention to provide a novel actuator which permits contacts to be electrically separated in a small package.
Yet another object of the present invention is to provide a switchable load coil case which is adapted for use in hostile environments such as, for example, underground, under water or other wet conditions.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of a preferred exemplified embodiment of the invention and upon reference to the accompanying drawings.


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Brochure of Coil Sales & Manufacturing Company, a Charles Industries company, on Load Coil “Highest Performance Load Coil for Uninterrupted Reliability”; Aug. -1996.
Brochure of Coil Sales & Manufacturing Company, a Charles Industries company, on Universal Case for Universal load coil cases; Jan. 1993.

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