TITLE: CABLE CONNECTION APPARATUS AND METHOD

FIELD OF THE INVENTION

[0001] The invention relates to connecting cables, and in particular, to an apparatus for joining electrical cables.

BACKGROUND OF THE INVENTION [0002] Many types of electrical cables are known in the art. One such type of cable is a mineral-insulated (Ml) cable. Ml cables are typically used in electricity transportation and electric heat tracing applications. Ml cables typically include at least one inner conductor surrounded by a mineral-based insulation layer, such as magnesium oxide (MgO) powder insulation. The insulation layer is surrounded by an outer sheath composed of a metal material, such as copper.

[0003] The above components of the Ml cable are all produced together by series drawing, as is well known in the art. Due to the nature of the production process, the length of the Ml cable which may be produced is limited. Accordingly, lengths of Ml cable frequently require connection to each other in the field. As Ml cables are used in environments where high temperature or an aggressive medium may be present, it is desirable for Ml cables to be fire-resistant. Consequently, it is preferred that any connections between two lengths of Ml cable also be fire-resistant. [0004] Prior art field connections for Ml cables include a crimp-on splice connector to connect the two ends of the conductors. The exposed conductors are then covered by a plastic material, such as a tape and/or a PVC sleeve as a sealing insulation. The disadvantage of this prior art field connection is that it is not fire resistant due to the of the plastic tape and/or sleeve. [0005] Another type of prior art Ml cable connection may be made in a plant by welding the two ends of the Ml cable. Such cable connections may be fire resistant, but have the disadvantage significant labor time and cost.

[0006] Accordingly, there is a need for a cable connection apparatus which may facilitate the joining of two lengths of cable in the field and provides a fire resistant connection.

SUMMARY OF THE INVENTION [0007] According to a first aspect of the invention, an apparatus for connecting a first cable to a second cable is provided. Each of the first and second cables has at least one conductor, an insulating layer surrounding the conductor, and an outer sheath surrounding the insulating layer. The conductor of each cable has an exposed end portion. The apparatus comprises: a) a barrel defining a first open end and a second open end, the barrel defining a channel therethrough, the channel communicating with the first and second ends, wherein the channel is adapted to receive a portion of the first cable and a portion of the second cable; b) a connector adapted to electrically connect the conductor of the first cable to the conductor of the second cable; c) a fire-resistant insulation located in the channel, the insulation substantially surrounding at least the connector and the exposed end portion of the conductors of the first and second cables; and d) a sealing means for sealing the first cable to the first end of the barrel. [0008] According to a second aspect of the invention, an apparatus for connecting a first cable to a second cable is provided. Each of the first and second cables has at least one conductor, an insulating layer surrounding the conductor, and an outer sheath surrounding the insulating layer. The conductor of each cable has an exposed end portion. The apparatus comprises: a) a barrel defining a first open end and a second open end, the barrel defining a channel therethrough, the channel communicating with the first and second ends, wherein the channel is adapted to receive a portion of the first cable and a portion of the second cable;

b) a connector adapted to electrically connect the conductor of the first cable to the conductor of the second cable; c) a fire-resistant insulation located in the channel, the insulation substantially surrounding at least the connector and the exposed end portion of the conductors of the first and second cables; d) a first sealing means for sealing the first cable to the first end of the barrel; and e) a second sealing means for sealing the second cable to the second end of the barrel. [0009] According to a third aspect of the invention, a method of connecting a first cable to a second cable is provided. Each of the first and second cables has at least one conductor, an insulating layer surrounding the conductor, and an outer sheath surrounding the insulating layer. The method comprises: a) sliding a barrel on to the first cable; b) sliding an insulating spacer on to the end portion of the conductor and securing the spacer to the insulating layer; c) repeating step (b) for the second cable; d) electrically connecting the conductors of the first and second cable; e) placing a fire-resistant insulation over exposed end portions of the conductors of the first and second cables and over the ceramic spacers connected to the first and second cable; f) sliding the barrel over the end portions of the conductors and the insulating spacers of the first and second cables; and g) sealing the barrel to the first and second cables.

BRIEF DESCRiPTION OF THE DRAWINGS [0010] In the accompanying drawings:

Figure 1 is a cross-sectional view showing two lengths of Ml cable joined by a preferred embodiment of the cable connection apparatus according to the present invention; and

Figure 2 is an exploded perspective view of one half of the embodiment shown in Fig. 1 , with the other half being identical.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT [0011] Figures 1 and 2 show a cable connection apparatus 10 according to a preferred embodiment of the present invention, which may be used to connect a first cable 12a to a second cable 12b. Preferably, the first and second cables 12a, 12b are two lengths of the same type of cable.

[0012] Continuing to refer to Figures 1 and 2, each of the cables 12a,

12b, includes a corresponding conductor 14a, 14b which is surrounded by an insulating layer 16a, 16b, respectively. The insulating layers 16a, 16b of each cable 12a, 12b are surrounded by an outer sheath 18a, 18b, which is preferably made of a metal material, such as copper. The insulating layers 16a, 16b are preferably composed of a mineral insulation, such as magnesium oxide.

[0013] Continuing to refer to Figures 1 and 2, the connection apparatus

10 includes first and second sealing means 19a, 19b for sealing the first and second cables 12a, 12b to a barrel 34 which is fitted over the cable joint. Preferably, the first and second sealing means 19a, 19b comprise first and second nuts 20a, 20b, first and second sliding ferrules 22a, 22b, and first and second glands 24a, 24b, respectively. The first and second nuts 20a, 20b, first and second sliding ferrules 22a, 22b, and the first and second glands 24a, 24b fit onto the first and second cables 12a, 12b, respectively. [0014] The apparatus 10 may also include first and second insulating spacers 26a, 26b which fit over corresponding exposed portions 28a, 28b of

conductors 14a, 14b. Preferably, the insulating spacers 26a, 26b are made from a ceramic material.

[0015] A connector 30 is provided to electrically connect the conductors

14a, 14b. Preferably, the connector 30 is a crimp-on splice connector. [0016] Fire-resistant insulation 32 is wrapped around the joined exposed portions 28a, 28b of conductors 14a, 14b, the connector 30, as well as adjacent portions of first and second cables 12a, 12b. Preferably, the fire-resistant insulation 32 is a ceramic filling or a fire-rated fiber.

[0017] The cable joint surrounded by the fire-resistant insulation 32 is received in a channel 37 in the barrel 34. The channel 37 extends between opposing first and second open ends 36a, 36b of the barrel 34. The first gland 24a is connected to the first open end 36a and the second gland 24b is connected to the second open end 36b of the barrel 34. The first and second glands 24a, 24b are connected to the barrel 34 by screwing first and second outer threaded portions 38a, 38b of the glands 24a, 24b, respectively, to corresponding inner threaded portions 40a, 40b of the barrel 34. Preferably the outer threaded portions 38a, 38b and the inner threaded portions 40a, 40b of the barrel 34 are dry seal threaded connections.

[0018] Preferably, the nuts 20a, 20b, sealing ferrules 22a, 22b, glands 24a, 24b and the barrel 34 are all made from a metal material which is suitable for meeting the performance requirements for the connection. In one example, the foregoing components may be made of copper.

[0019] The operation of the apparatus 10 and the method according to a preferred embodiment of the present invention will now be described with reference to Figures 1 and 2.

[0020] The outer sheath 18a, 18b and insulating layer 16a, 16b are peeled from the end of cables 12a, 12b, respectively, to create the exposed end

portions 28a, 28b of the conductors 14a, 14b. Nuts 20a, 20b, sealing ferrules 22a, 22b, and glands 24a, 24b are then slid on to corresponding first and second cables 12a, 12b. Insulating spacers 26a, 26b are then fitted on to the exposed portions 28a, 28b of conductors 14a, 14b and secured to the insulating layer 16a, 16b of corresponding cables 12a, 12b. The barrel 34 is then fitted on to one of the cables 12a or 12b. The connector 30 is crimped-on to the exposed portions 28a, 28b of the conductors 14a, 14b using hydraulic tool. The tool has crimp dies which deform the crimp-on connector 30 to crimp and hold the conductors. The fire-resistant insulation 32 is wrapped around portions of the first and second cable 12a, 12b, and all other components located in the channel 37 of the barrel 34, such as the exposed portions of the conductor 28a, 28b, connector 30, and insulating spacers 26a, 26b. In this manner, the fire-resistant insulation 32 secures the insulating spacers in position. The barrel 34 is then moved into position and substantially centered over the connector 30 to cover the fire-resistant insulation 32. The first gland 24a is then screwed into the inner threaded portion 40a of the first end 36a of the barrel 34 to seal the first gland to the barrel. The first nut 22a is then tightened by screwing it to the other end of gland 24a thereby pushing the first sealing ferrule 22a into engagement with the first gland 24a to seal the first gland 24a to first cable 12a. The second gland 24b and second nut 22b are then tightened in the same manner to seal the second gland 24b against the barrel 34 and the second cable 12b.

[0021] The method and apparatus of the present invention provides the advantage of a fire resistant cable joint which can be assembled in the field and which is sealed to keep out aggressive media which may be present in places where the cable is installed.

[0022] While the present invention as herein shown and described in detail is fully capable of attaining the above-described objects of the invention, it

is to be understood that it is the presently preferred embodiment of the present invention and thus, is representative of the subject matter which is broadly contemplated by the present invention, that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." All structural and functional equivalents to the elements of the above-described preferred embodiment that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims.