Patent Publication Number: US-11651877-B2

Title: Support arrangement for an electrical protection assembly

Description:
FIELD OF THE INVENTION 
     THIS invention relates to safety equipment in an electric power distribution system, and in particular to a support arrangement for an electrical protection assembly. 
     BACKGROUND TO THE INVENTION 
     ARIPO patent no. 2675 provides an electrical protection assembly for connection between an electrical power supply line and electrical equipment. There are several components that are common to the assembly in the prior art ARIPO patent and the assembly  10  of the present invention, as shown in  FIG.  1   . Thus, for the sake of clarity, similar reference numerals will be used for similar components. The prior art assembly comprises a central support arrangement  12  comprising a first, substantially straight, insulator support arm  14 , which carries a plurality of circular sheds or skirts  15  (as is well known in the art). A fuse cutout assembly  16  comprising a fuse tube  18  extends on one side of the support arrangement  12 , and on the other side there is a surge protection assembly  20  comprising a drop out voltage surge protection unit  22 . 
     The fuse tube  18  is held between the end of a first upper, displaceable arm  24  and a second lower support arm  26  that is spaced from the upper arm  24 . The lower support arm  26  also carries a plurality of circular sheds or skirts  27 . The lower support arm  26  has a first bracket  28  at its free end, fitted with a connector  30 , with the lower end of the fuse tube  18  being connected thereto, in use, in a pivotal manner, as is known in the art. A hood assembly  32  is attached to a first free end of the upper arm  24  to be displaceable relative thereto. The hood assembly  32  is connectable to the upper end of the fuse tube  18 , and is movable away from the connector  30  upon fusing of the fuse tube  18 , to ultimately allow the fuse tube  18  to detach, by pivoting away, from the fuse cutout assembly  16  (and thus the larger assembly  10  itself). 
     Significantly, in the prior art, the first insulator support arm  14  and the lower support arm  26  are separately fitted to a rectangular bracket. This generally works reasonably well but it does have a number of shortcomings that the present invention aims to address, namely it requires a number of separate parts and it also requires that these parts are correctly fitted together. 
     In addition, when the voltage surge protection unit  22  pivotally drops out (which it is designed to do in a well-known manner), this action is uncontrolled and may sometimes cause damage to the assembly  10 . It is thus a further advantage of the present invention to provide a buffer plate to soften the impact of the surge protection unit  22  as it drops out. 
     SUMMARY OF THE INVENTION 
     According to a first aspect of the invention there is provided a support arrangement for an electrical protection assembly for connection between an electrical power supply line and electrical equipment, the support arrangement comprising:
         a first, substantially straight, insulator body; and   a second, substantially straight, insulator body extending transversely to, and thus away from, the first insulator body,
 
wherein the first and second insulator bodies are integrally formed into a unitary body.
       

     In an embodiment, the second insulator body extends from a lower end of the first insulator body, at right angles thereto, so as to define a unitary L-shaped support arrangement. 
     In an embodiment, a displaceable upper arm extends across the top of the support arrangement, with a fuse cutout assembly comprising a fuse tube extending on the side of the support arrangement with the second insulator body, and on the other side of the support arrangement there is a surge protection assembly comprising a drop out voltage surge protection unit. 
     A fuse cutout assembly is typically used to protect distribution transformers from current surges and overloads. When an overcurrent is caused by a fault in the transformer, for example, a fuse within a fuse tube melts. The melting results in the fuse tube detaching from the fuse cutout assembly, which in turn disconnects the transformer from the line. 
     In an embodiment, the upper end of the fuse tube is releasably fitted to a first end of the displaceable upper arm, with the distal end of the second insulator body including a first bracket with a connector at its free end to accommodate the lower end of the fuse tube, in use, in a pivotal manner, as is known in the art. 
     In one version, an elongate, flexible, resilient fuse buffer plate is fitted to, so as to extend below, the first bracket to buffer, in a controlled manner, the fuse tube as it pivotally drops out. 
     In an embodiment, the upper end of the drop out voltage surge protection unit is releasably fitted to a second end of the displaceable upper arm, with the lower end of the support arrangement, opposite the second insulator body, including a second bracket with a connector at its free end to accommodate the lower end of the drop out voltage surge protection unit, in use, in a pivotal manner, as is known in the art. 
     In one version, an elongate, flexible, resilient surge buffer plate is fitted to the second bracket to buffer, in a controlled manner, the voltage surge protection unit as it pivotally drops out. 
     In an embodiment, the second insulator body includes first mounting holes for receiving bolts for securing the first bracket. 
     In an embodiment, the first insulator body includes second mounting holes for receiving bolts for securing the second bracket. 
     In an embodiment, the first insulator body includes a third mounting hole at its lower end for receiving a bolt for securing a third bracket. 
     In an embodiment, the first insulator body includes fourth mounting holes for receiving bolts for securing a support arm strut to an upper end of the first insulator body. 
     In an embodiment, the support arrangement comprises an L-shaped inner support frame around which the first and second insulator bodies are (injection) molded. 
     The L-shaped inner support frame comprises a T-shaped metal connector having a first end from which a first fibre glass support arm (or rod) extends, around which the first insulator body can be molded, and a second end from which a second fibre glass support arm or rod) extends, around which the second insulator body can be molded. A third end of the T-shaped metal connector defines the bottom of the support arrangement, with the third mounting hole being defined within the third end of the T-shaped metal connector. 
     In an embodiment, the T-shaped metal connector includes a mounting formation, opposite the second end of the T-shaped metal connector, in which the second mounting holes for receiving bolts for securing the second bracket are defined. 
     In an embodiment, the end of the second fibre glass support arm is fitted with a first metal connector, in which the first mounting holes for receiving bolts for securing the first bracket are defined. The first metal connector is slightly enlarged relative to the second fibre glass support arm. 
     In an embodiment, the end of the first fibre glass support arm is fitted with a second metal connector, in which the fourth mounting holes for receiving bolts for securing the support arm strut are defined. The second metal connector is slightly enlarged relative to the first fibre glass support arm. 
     In an embodiment, the first and second insulator bodies each carry a plurality of sheds or skirts. In one version, a shed on the first insulator body, typically a shed proximate a lower region of the first insulator body, is joined to a proximate shed on the second insulator body (to provide support and for aesthetic purposes). 
     According to a second aspect of the invention, there is provided a method of manufacturing a support arrangement for an electrical protection assembly, the method comprising:
         providing an L-shaped inner support frame, and   injection molding, under pressure using a suitable polymer, an insulator body along and around the L-shaped support frame, so as to ultimately define a support arrangement comprising a first, substantially straight, insulator body and a second, substantially straight, insulator body extending transversely to, and thus away from, the first insulator body, wherein the first and second insulator bodies are integrally formed into a unitary L-shaped support arrangement.       

     In an embodiment, the step of providing an L-shaped inner support frame comprises the steps of:
         providing a T-shaped metal connector having a first end and a second end at right angles to the first end;   inserting a first end of a first fibre glass support arm (or rod) into the first end of the T-shaped metal connector, around which the first insulator body can be molded;   inserting a second end of a second fibre glass support arm (or rod) into the second end of the T-shaped metal connector, around which the second insulator body can be molded;   fitting a first metal connector to a second end of the second fibre glass support arm, in which first mounting holes are defined for receiving bolts for securing a first bracket; and   fitting a second metal connector to a second end of the first fibre glass support arm, in which mounting holes are defined for receiving bolts for securing a support arm strut.       

     In an embodiment, a third end of the T-shaped metal connector defines the bottom of the support arrangement, with a mounting hole being defined within the third end of the T-shaped metal connector. 
     In an embodiment, the method comprises fitting or providing a mounting formation to the T-shaped metal connector, opposite the second end of the T-shaped metal connector, in which mounting holes are defined for receiving bolts for securing a second bracket. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a side view of an electrical protection assembly with an L-shaped support arrangement according to a first aspect of the invention; 
         FIG.  2    shows a side view of the L-shaped support arrangement of the present invention, the L-shaped support arrangement comprising a first, vertically extending, insulator body, and a second, horizontally extending, second insulator body extending from a lower end of the first insulator body; 
         FIG.  3    shows a side view similar to  FIG.  2   , and related views, but with an L-shaped inner support frame being shown in dotted outline relative to the L-shaped support arrangement (and with the sheds on the first and second insulator bodies being removed for clarity); and 
         FIG.  4    shows a side view of the L-shaped inner support frame by itself as a separate component. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The bulk of the assembly has already been described above. In addition to the components described above, a mounting bracket  34  is fitted to the central portion of the upper arm  24 . The bracket  34  is pivotally mounted to the upper end of the central support arrangement  12  by a pivot pin  36 . 
     The upper arm  24  extends beyond the mounting bracket  34  and the central support arrangement  12  to have a portion  38  on the opposite side of the central support arrangement  12  to the hood assembly  32 , by means of which the voltage surge protection unit  22  is mounted. The portion  38  is urged in an anticlockwise direction by means of a first urging element, in the form of a compression spring  40 , acting against a stop washer  42  secured to an underlying support arm strut  44  by means of a bolt  46 . The spring  40  is positioned on the voltage surge protection unit side and acts on the portion  38  of the upper arm  24 . 
     The support arm strut  44  extends to the fusible device side of the central support arrangement  12  and carries a second spring  48  that also acts on the upper arm  24  to displace it in an anticlockwise direction together with the spring  40 . It will be appreciated that, in use, when the voltage surge protection unit  22  drops out (with the upper end of the unit  22  dislodging from a holder  49  at the end of the upper arm portion  38 , in a known manner), the upper arm  24  is caused to pivot to release the fuse tube  18  to allow it to drop out as well. 
     It will be appreciated further that when the voltage surge protection unit  22  is engaged with the portion  38  the upper arm  24  is effectively fixed in position and an auxiliary arm  50  of the hood assembly  32  then moves independently relative thereto. However, when the voltage surge protection unit  22  drops out, the auxiliary arm  50  and the upper arm  24  then move together under the action of the springs  40  and  48 . 
     A further urging element, in the form of a compression spring  52 , is provided for urging the hood assembly  32  towards the connector  30 . The spring  52  acts on a stop washer  54  secured to the upper arm  24  by a bolt  56 . It will be seen that the spring  52  urges the auxiliary arm  50  in a clockwise direction. 
     The auxiliary arm  50  is configured such that the hood assembly  32  is disposed substantially transversely to the fuse tube  18 , such that, when the fuse tube  18  fuses, in use, a perpendicular thrust is exerted on the hood assembly  32 . As shown, the hood assembly  32  is further from the first insulator support arm  14  than the connector  30 . Thus, if the first insulator support arm  14  is vertically mounted, as shown, which is normally the case, the fuse tube  18  is outwardly angled. Thus, in use, upon fusing of the fuse tube  18 , it pivots in a clockwise direction, in a known manner, about the connector  30 . 
     In addition, an elongate, flexible, resilient fuse buffer plate  29 , typically extending vertically downwardly, is fitted to the first bracket  28  to buffer, in a controlled manner, the fuse tube  18  as it pivotally drops out. 
     The lower end of the central support arrangement  12 , on the surge protection side  20  of the assembly  10 , has a second bracket  58  fitted with a connector  80 , with the lower end of the surge protection unit  22  being connected thereto, in use, in a pivotal manner, as is known in the art. 
     In addition, an elongate, flexible, resilient surge buffer plate  62 , typically extending vertically downwardly, is fitted to the second bracket  58  to buffer, in a controlled manner, the voltage surge protection unit  22  as it pivotally drops out. 
     Horns  57  are fitted to the hood assembly  32 , which can either be lifted up, which would in turn cause the fuse tube  18  to pivot away, or pushed down, which would in turn cause the surge protection unit  22  to pivot away, as described in more detail further below. 
     Turning now specifically to the present invention, with reference to  FIG.  2    as well, the support arrangement  12  of the present invention comprises a first, substantially straight, insulator body  14  and a second, substantially straight, insulator body  26  extending transversely to, and thus away from, the first insulator body  14 , substantially at right angles. Significantly, the first and second insulator bodies  14 ,  26  are integrally formed into a unitary body, to address the disadvantages set out above. 
     Turning now to  FIG.  2    in particular, the second insulator body  26  includes first mounting holes  70  for receiving bolts for securing the first bracket  28 . The central support arrangement  12  further includes second mounting holes  72  for receiving bolts for securing the second bracket  58 . The central support arrangement  12  further includes a third mounting hole  74  for receiving a bolt for securing the bracket  76 . The central support arrangement  12  further includes fourth mounting holes  78  for receiving bolts for securing the support arm strut  44  to the first insulator body  14 . 
     Turning now to  FIGS.  3  and  4   , the support arrangement  12  comprises an L-shaped inner support frame  100  around which the first and second insulator bodies  14 ,  26  are (injection) molded. 
     The L-shaped inner support frame  100  comprises a T-shaped metal connector  102  having a first end  104  from which a first fibre glass support arm (or rod)  106  extends, around which the first insulator body  14  can be molded. The T-shaped metal connector  102  further includes a second end  106  from which a second fibre glass support arm (or rod)  108  extends, around which the second insulator body  26  can be molded. 
     A third end  110  of the T-shaped metal connector  102  defines the bottom of the support arrangement  12 , with the third mounting hole  74  being defined within the third end of the T-shaped metal connector  102 . 
     In an embodiment, the T-shaped metal connector  102  includes a mounting formation  112 , opposite the second end  106  of the T-shaped metal connector  102 , in which the second mounting holes  72  for receiving bolts for securing the second bracket  58  are defined. 
     In an embodiment, the end of the second fibre glass support arm  108  is fitted with a first metal connector  114 , in which the first mounting holes  70  for receiving bolts for securing the first bracket  28  are defined. The first metal connector  114  is slightly enlarged relative to the second fibre glass support arm  108 . 
     In an embodiment, the end of the first fibre glass support arm  106  is fitted with a second metal connector  116 , in which the fourth mounting holes  78  for receiving bolts for securing the support arm strut  44  are defined. The second metal connector  116  is slightly enlarged relative to the first fibre glass support arm  106 . 
     In an embodiment, the first and second insulator bodies  14 ,  26  each carry a plurality of sheds or skirts  15 ,  27 , respectively. In one version, a shed  15 . 1  on the first insulator body  14 , typically a shed proximate a lower region of the first insulator body  14 , is joined to a proximate shed  27 . 1  on the second insulator body  27 , to provide support and for aesthetic purposes. 
     Although the invention has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention.