Patent Publication Number: US-9837771-B2

Title: Electrical connector with short circuit element

Description:
FIELD OF THE INVENTION 
     The present invention relates to an electrical connector provided with a short-circuit element. 
     In particular, the invention relates to a plug-type connector, comprising a female connector element (or insert) or socket and a male connector element or plug, in which the shorting is provided of the output terminals connected to the socket contacts, for example those of the secondary winding of a measuring current transformer (a.k.a. “amperometric transformer” or CT), before the corresponding plug is fully withdrawn from the socket. 
     This measure is imposed to avoid the appearance, at the circuit heads, of a hazardous electric voltage, likely to determine—upon “open circuit”—a disruptive discharge in the circuit of the socket and an hazardous condition for the staff who had inadvertently operated the opening of the secondary circuit with the primary still connected. 
     BACKGROUND OF THE INVENTION 
     Numerous plug connectors and connecting devices are known in prior art which provide, with appropriate means, to automatically achieve the short-circuit upstream of the removable connector element (connector plug) before the complete opening of the contacts of the same, to avoid opening, hence leaving it “unladen”, the electric circuit upstream of the device itself. 
     For example, U.S. Pat. No. 4,988,307 describes a plug connector system that comprises a pair of contacts which are shorted between them until not mated with another pair of contacts, by means of a device operated by a spring. Said spring is however made captive in the insulating body of the plug connector and both its end portions act as spring towards their respective electric contact elements. The insulating body of the connector has a groove (slot) in which the median part of the elastic element is made captive. The spring is largely in the shape of a Z. The contacts of the first plug connector half are one male and one female, those of the corresponding second plug connector half are respectively female and male. The female contacts are surrounded by a tube of insulating material which, interposed between the contact and the spring determines, during the mating of the two plug connector halves, the opening of the short circuit. 
     The patent U.S. Pat. No. 4,988,307 (ITT Corp.) provides contacts equipped of a wrap-around tubule made of insulating material and an actuator pin having a shaped tip with an inclined plane (wedge) that operates the deflection of an arm of an elastic spring element. 
     All the known embodiments are complex, incorporating additional contact elements in series, or elastic elements, like pressure springs, additional to the element that realizes the short-circuit, the assembly resulting in such a way complex, the cost high and the reliability compromised. 
     SUMMARY OF THE INVENTION 
     Object of the invention is to eliminate the drawbacks of prior art. 
     In particular, one object of the invention is to provide an electrical plug connector that ensures the shorting of the output terminals, connected to the socket contacts, before the corresponding plug is fully withdrawn from the socket. 
     Another object of the invention is to provide such an electrical plug connector which is of simple construction and manufactured with a reduced number of components. Yet another object of the invention is to provide such an electrical connector which is of economical construction and highly reliable. 
     These and other objects are achieved by the electrical plug connector according to the invention, which has the characteristics of independent claim  1 . 
     Advantageous embodiments of the invention are apparent from the dependent claims. Basically, the electrical plug connector according to the invention comprises a first connector half configured as a socket connector and a second connector half configured as a plug connector, each of said connector halves comprising an insulating body housing at least a respective pair of electrical contact elements arranged in parallel and each having a front end, on the mating side, shaped in the first connector half in the manner of a bushing or female contact and in the second connector half in the manner of a pin or male contact, and a rear end, on the wiring side, suitable for housing a respective conductor for connection to an electrical circuit, a short-circuit element being provided between said contacts of the socket connector half adapted to hold such contacts shorted upon unmated plug connector, in which said short-circuit element is constituted by a strip of resilient metallic material, shaped so as to constitute a spring and to offer to each of its ends an elastic contact, the first end of said short-circuit element being in stable and substantially integral contact with a respective female electrical contact element, while the second end of said short-circuit element, upon unmated plug connector, goes intimately into contact with the other element of female electrical contact of said at least one pair of contacts of the socket connector, an opening being present on the mating face between the access openings to said at least a pair of female contacts accommodated in said first half of the plug connector, directed towards said other end of said short-circuit element, a plug actuator pin of insulating material being correspondingly formed in said second connector half, between said at least one pair contacts, such that in the mated position of the plug connector, said plug actuator pin is inserted in said opening of the socket connector half and is interposed between said second end of said short-circuit element and said contact, opening the short-circuit previously operated by said short-circuit element. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional features of the invention will be appear more clear by the detailed description that follows, referring to a merely exemplary, and therefore non-limiting embodiment thereof, illustrated in the appended drawings, in which: 
         FIG. 1  shows a perspective view of a plug connector according to the invention, with the two elements of the plug connector, respectively socket and plug unmated and both sectioned with a vertical plane in order to highlight the internal elements of the same. 
         FIG. 2  shows the plug connector of  FIG. 1  in the fully mated position. 
         FIGS. 3, 4, and 5  show in cross-section the plug connector wired and respectively unmated ( FIG. 3 ), in the initial mating position but with short-circuit element still active ( FIG. 4 ) and in the position of full mating with short-circuit element fully open by means of the plug actuator pin ( FIG. 5 ). 
         FIGS. 6 a   ),  b ) show respectively a side view and a perspective view of the short-circuit element. 
         FIGS. 7 and 8  are front views respectively of the socket element and plug element of a plug connector according to the invention. 
         FIG. 9  shows in perspective the two halves, respectively socket and plug of a plug connector according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to these figures, a plug connector according to the invention, globally indicated by the reference number  1 , comprises a first element or connector half socket-type  10  having an insulating body  2  provided with at least a pair of facing contacts of the female type  3 ,  4  each having a front end  3   a ,  4   a  shaped in the manner of a bushing and a rear end  3   b ,  4   b  for housing a respective conductor  40  for connection to an electric circuit, and an element or connector half plug-type  20  having an insulating body  2 ′ provided with at least a corresponding pair of male contacts,  3 ′,  4 ′, each having a front end  3 ′ a ,  4 ′ a  shaped in the manner of a pin and a rear end  3 ′ b ,  4 ′ b  adapted to house a respective conductor  40 ′. 
     In the appended figures, the female contact  3 ,  4  and male contacts  3 ′,  4 ′ are provided with spring-clamp terminals  43 ,  43 ′, as foreseen for example in the multipole plug connector of the patent application MI2012A 001974 in the name of the same applicant ILME S.P.A., and are adapted to lock the respective conductors  40 ,  40 ′ by means of the respective actuator pins  41 ,  41 ′ which, in this case, are provided with longitudinally extended opening  42 ,  42 ′, for the access of the probe to a test device to allow electrical measurements. 
     However, it is evident that the plug connector  1  can be of any other type and the locking of the conductors  40 ,  40 ′ can be, for example, of the screw type, of the insulation piercing type or of the insulation displacement type, or the like. 
     Between contacts  3 ,  4  of the socket connector half  10  a short-circuit element  5  is provided, best seen in  FIGS. 3-6 , in the form of a strip of resilient conductive material with a spring function and shaped so as to offer to both its ends  5   a ,  5   b  an elastic contact. The first end  5   a  is a substantially integral contact with a respective female contact  3 , while the other end  5   b , upon unmated plug connector  1 , goes intimately into contact with the other socket contact  4  of said at least one pair of contacts of the socket connector  10 . 
     As best seen in  FIG. 9 , on the mating face of the first socket connector half  10 , between the two access openings  8 ,  9  of the corresponding male contacts  3 ′,  4 ′ of the second plug connector half  20  to the respective aforementioned female contacts  3 ,  4 , an opening  11  suitably shaped (in this case with a profile substantially T) is also present, adapted to receive a corresponding actuator pin  6  arranged on the mating face of the second plug connector half  20 , between the two front portions  3 ′ a  and  4 ′ a  of the respective pin contacts. 
     Upon plug connector  1  unmated—i.e. socket connector  10  and plug connector  20  completely separate—said short-circuit element  5  therefore operates a bridge between the two female contacts  3 ,  4  of the socket connector  10 . 
     In the second connector plug connector half  20  fitted with male contacts a corresponding actuator pin  6  is present, between each pair of facing male contacts  3 ′,  4 ′, integral with the insulating body of said second plug connector half  20 , having a substantially prismatic development, reproducing the T-shape of said opening  11 , and with upper end  6 ′ wedge-shaped. The actuator pin  6  can be made in a single piece with the body  2 ′ of the plug connector half  20 , or be reported on it. 
     With reference to  FIGS. 3, 4 and 5 , during mating (closing) of the two connector halves respectively socket  10  and plug  20 , said pin  6 , with a suitable delay compared with the electrical coupling between the corresponding male contacts  3 ′,  4 ′ and female contacts  3 ,  4 , operates the progressive opening of the short-circuit element  5  placed between the two female contact elements  3 ,  4  in the first socket half  10  of plug connector  1  (socket connector), operating a eversion of the respective spring arm and the opening of the contact between the end  5   b  and the corresponding female contact  4 . Contextually, said actuator pin  6 , made of insulating material, restores, upon plug connector half  20  mated to the corresponding socket connector half  10 , the necessary electrical insulation between the two facing parts of female contact  3 ,  4 . 
     Coding pins  13  are also visible in the appended figures, normally colour-coded, mounted in corresponding seats  12  for a correct coupling of the connectors. 
     Naturally the invention is not limited to the particular embodiment previously described and illustrated in the appended drawings, but it can be subject to numerous modifications of detail within the reach of the skilled in the art, without departing from the scope of the invention itself, as defined in the following claims.