Abstract:
A switch including a plug and a socket for use with high intensity currents includes a power circuit and a pilot circuit for maintaining current flowing through the power circuit. The switch also includes an apparatus for controlling the pilot circuit and preventing insertion of the plug into the socket when the at least one socket pilot contact and the at least one plug pilot contacts are in a closed position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an electric power connection, and more particularly, to those connections adapted for use with high intensity currents. 
     2. Description of Relevant Materials and Background Art 
     The invention relates to an electric power connection, and more particularly, to a connection used with high intensity currents. 
     Electric current power connections are formed, in a known manner, by socket and a plug each provided with power contacts adapted to be electrically connected or disconnected from one another. 
     In high intensity power plugs, there is generally provided a parallel low intensity circuit, hereinafter referenced as a pilot circuit. This pilot circuit is provided with pilot contacts provided in the socket and the plug. As the pilot circuit is closed it controls an energizing apparatus whereby the power contacts are energized, and conversely, as the pilot circuit is opened, it controls a de-energizing apparatus to de-energize the power contacts. 
     Accordingly, the pilot circuit is closed only after the power contacts have made contact, and opened before the power contacts are disconnected. In this manner, the two operations of closing and opening the pilot circuit occur when the electrical power plug is not energized. 
     It is in effect often imperative to bring the power contacts together or to separate them when they are not turned on particulrly so as to avoid electric arcing and so as not to establish power other than when the power contacts are electrically connected. 
     Generally speaking, the power contacts of the plug and of the socket are connected and disconnected by plugging in and unplugging, respectively, the plug and the socket. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the invention, an electric power connection includes a socket and a plug. The socket includes first power contacts and the plug includes second power contacts adapted to be connected to the first power contacts. The switch also includes a pilot circuit comprising first pilot contacts provided in the socket and second pilot contacts provided in the plug. The pilot circuit controls the de-energization and energization of the first power contacts when the circuit is opened and closed, respectively. The switch also includes manipulation means for preventing certain movements of the plug and the socket when the pilot circuit is in a closed position and for allowing the certain movements when the pilot circuit is in an open position. 
     The manipulation means is provided either on the socket to act on the first pilot contacts or on the plug to act on the second pilot contacts. The manipulation means prevents the first power contacts from engaging and disengaging from the second power contacts when the pilot circuit is in its closed position. The pilot circuit is opened and closed by disengaging and engaging, respectively, the first pilot contacts and the second pilot contacts. The first power contacts and the second power contacts are engaged and disengaged from one another by plugging and unplugging, respectively, the plug and the socket. 
     The switch further includes means for preventing activation of the manipulation means while the plug is not inserted into the socket sufficiently to cause the first power contacts to engage the second power contacts, wherein when the manipulation means is activated, the pilot circuit is moved towards a closed position. The means for preventing activation of the manipulation means is provided on the plug, on the socket or on the socket and on the plug. 
     The first and second pilot contacts each include a contact head. The contact heads of the first pilot contacts are movable and the contact heads of the second pilot contacts are fixed. The manipulation means acts on the movable contact heads to move them towards and away from the fixed contact heads for connecting and disconnecting, respectively, the first pilot contacts and the second pilot contacts. The first and second pilot contacts are end contacts and the movable contact heads are adapted to be moved by springs and flexible conductors. The springs and flexible conductors are positioned within a block and the block is axially movably mounted and adapted to be moved by the manipulation means. The manipulation means includes a rotating means comprising a driving spur which cooperates with an opening in the block for translationally moving the block when the driving spur moves along an arcuate path. 
     According to an embodiment of the invention, the contact heads of the second pilot contacts are movable and the contact heads of the first pilot contacts are fixed. The manipulation means acts on the movable contact heads to move them towards and away from the fixed contact heads for connecting and disconnecting, respectively, the first pilot contacts and the second pilot contacts. The first and second pilot contacts are end contacts and the movable contact heads are adapted to be moved by springs and flexible conductors. The springs and flexible conductors are positioned within a block and the block is axially movably mounted and adapted to be moved by the manipulation means. The manipulation means comprises rotating means comprising a driving spur which cooperates with an opening in the block for translationally moving the block when the driving spur moves along an arcute path. 
     The plug is introduced into the socket and connection of the power contacts is achieved by turning the plug in the socket. 
     The manipulation means includes a rotating activation portion comprising a cam and at least one first abutment having a configuration which cooperates with the cam such that when the plug is introduced into the socket and the pilot circuit is in a closed position, the cam abuts against a first portion of the at least one first abutment and prevents further introduction of the plug into the socket. When the plug is introduced into the socket and the pilot circuit is in an open position, the cam and the abutment do not prevent further introduction of the plug into the socket. The pilot circuit is closed by rotation of the cam after rotation of the plug within the socket and connection of the power contacts. After rotation of the cam, inverse rotation of the plug is blocked by cooperation of the cam and a second portion of the at least one first abutment and by hooking means provided on the plug and the socket. 
     The cam is provided on an exterior portion of either the socket or the plug, and the at least one first abutment is provided either on the plug or on the socket, respectively. 
     The hooking means includes pins provided in the plug and projections provided in the socket. The pins are adapted to hook under the projections in response to rotation of the plug in the socket. The projections include an inclined surface having an orientation which allows the plug to be brought closer to the socket during rotation of the plug in the socket and allows a sealing joint positioned between the plug and the socket to be crushed. 
     The socket includes at least one second abutment adapted to prevent rotation of the plug in an incorrect direction after the plug is introduced into the socket, and at least one third abutment adapted to limit rotation of the plug in the socket. The at least one second and third abutments are adapted to cooperate with the pins. The socket further includes an edge. The edge includes openings adapted to receive the pins. The openings have an angular orientation such that proper introduction of the plug into the socket is imposed. 
     The manipulation means further includes blockage means for the open position and the closed position of the pilot circuit. 
     According to an embodiment of the invention, an electric power connection includes a socket comprising at least one socket power contact and a plug comprising at least one plug power contact. The at least one plug power contact corresponds in number and placement to the at least one socket power contact. The connection also includes a pilot circuit comprising at least one socket pilot contact and at least one plug pilot contact. The at least one plug pilot contact corresponds in number and placement to the at least one socket pilot contact. The pilot circuit is adapted to control the power supplied to the at least one plug power contact and the at least one socket power contact. The connection also includes manipulation means for controlling the pilot circuit and preventing insertion of the plug into the socket when the at least one socket pilot contact and the at least one plug pilot contacts are in a closed position. 
     Each of the at least one socket pilot contacts comprise a contact head located on a free end of the at least one socket pilot contact. Each of the at least one plug pilot contacts comprise a contact head located on a free end of the at least one plug pilot contact. The contact heads of the at least one socket contact are movable and the contact heads of the at least one plug contact are fixed. The manipulation means acts on the contact heads of the at least one socket contact to move them both towards and away from the contact heads of the at least one plug contact, whereby the at least one socket pilot contact is operatively connected to the at least one plug pilot contact when the at least one socket pilot contact comes into contact with the at least one plug pilot contact. 
     The connection also includes an axially movable block mounted in the socket. The block includes a plurality of springs and flexible conductors for moving the contact heads of the at least one socket contact. The manipulation means is operable to move the block from a first position to a second position and from the second position to the first position. The manipulation means includes a driving spur rotatably mounted in the manipulation means for cooperating with a groove in the block for translationally moving the block from a first position to a second position and from the second position to the first position, when the driving spur moves along an arcuate path. 
     The manipulation means further includes a cam connected to an exterior portion of the socket connected to the driving spur and at least one first abutment adapted to cooperate with the cam such that rotation of the cam is prevented until the plug is fully inserted into the socket and complete insertion of the plug into the socket is prevented when the block is in the second position. 
     The pilot circuit is closed by rotation of the cam after the plug is fully inserted into the socket and the plug is rotated within the socket. The rotation of the cam causes the driving spur to move along the arcuate path and thereby move the block to the second position causing the contact heads of the at least one socket contact to come into contact with the contact heads of the at least one plug contact. After rotation of the cam, inverse rotation of the plug within the socket is prevented by cooperation of the cam and a portion of the at least one first abutment and by hooking means provided on the plug and the socket. 
     The hooking means includes a plurality of pins located on the plug, and a plurality of corresponding projections located on the socket. The plurality of pins are adapted to hook under the plurality of projections in response to rotation of the plug in the socket. The plurality of projections each includes an inclined surface having an orientation such that the plug is brought closer to the socket during rotation of the plug in the socket and a sealing joint positioned between the plug and the socket is crushed. 
     The socket includes at least one second abutment adapted to prevent rotation of the plug in an incorrect direction after the plug is introduced into the socket, and at least one third abutment adapted to limit rotation of the plug in the socket. The at least one second and third abutments are adapted to cooperate with the pins. kThe socket also includes an edge. The edge includes openings adapted to receive the pins. The openings have an angular orientation such that proper introduction of the plug into the socket is assured. 
     The manipulation means further includes blockage means for locking the pilot circuit in the open position and the closed position. 
     According to an embodiment of the invention, a switch includes a plug and a socket for use with high intensity currents. The switch includes a power circuit, a pilot circuit for maintaining current flowing through the power circuit, and means for controlling the pilot circuit and preventing insertion of the plug into the socket when the at least one socket pilot contact and the at least one plug pilot contacts are in a closed position. 
     The power circuit includes at least one socket power contact poisitioned in the socket, and at least one plug power contact positioned in the plug. Current flows through the power circuit when the at least one socket power contact comes into contact with the at least one plug power contact and the pilot circuit is closed. 
     The pilot circuit includes at least one socket pilot contact positioned in the socket and at least one plug pilot contact positioned in the plug. Current flows through the power circuit only when the at least one socket pilot contact comes into contact with the at least one plug pilot contact. The means for controlling the pilot circuit includes a block in which the at least one socket pilot contact is located. The block is axially movable between a first and second position. When the block is in the second position, the at least one socket pilot contact is in contact with the at least one plug pilot contact. 
     The means for controlling the pilot circuit further includes a driving spur rotatably mounted in the means for controlling the pilot circuit for cooperating with a groove in the block for axially moving the block between the first and second positions as the driving spur moves along an arcuate path. The means for controlling also includes a cam connected to the driving spur and at least one abutment adapted to cooperate with the cam to prevent rotation of the cam unless the plug is fully inserted in the socket and to prevent complete insertion of the plug into the socket unless the block is in the first position. The pilot circuit is closed by rotation of the cam after the plug is fully inserted into the socket and the plug is rotated within the socket. The driving spur moves along the arcuate path in response to rotation of the cam, the block axially moves from the first position to the second position in response to the driving spur, and the at least one socket pilot contact engages the at least one plug pilot contact in response to the block movement. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The invention will now be described with reference to the drawings, given by way of non-limiting example, in which: 
     FIG. 1 is an elevational view of the socket and of a portion of the plug according to one embodiment of the invention; 
     FIG. 2 is a top view of the socket; 
     FIGS. 3 and 4 are partial cross-sectional views from an upright position of a pair of power contacts in the two different positions; 
     FIG. 5 is an axial cross-sectional view of the plug and the socket with the power contacts connected and the pilot circuit open; 
     FIG. 6 is an axial cross-sectional view of the plug and the socket with the power contacts open; and 
     FIGS. 7a, 7b, 7c and 7d schematically show a plurality of relative positions of a portion of the body of the plug with respect to the apparatus for manipulating the pilot contacts along with the corresponding positions of a pilot contact, facing each other. 
     FIG. 8 is an axial cross-sectional view of a second embodiment of the invention wherein the movable pilot contacts are located in the plug. 
     FIG. 9 is a schematic diagram showing a current cutting apparatus controled by pilot circuit. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention relates to a connection of the type provided with a pilot circuit. The connection is notable in that the pilot contacts of the socket and of the plug are connected or disconnected from one another so as to close or open the pilot circuit by means of a manipulation apparatus which acts on the pilot contacts of the socket or of the plug. The manipulation apparatus is provided on the socket or on the plug, respectively, in a manner such that the apparatus prevents at least certain manipulations of plugging in or separating the plug and the socket when the contacts of pilot circuit are in the closed position. Thus when the pilot contacts of the pilot circuit are in the closed position, the manipulation apparatus prevents the power contacts from being connected or disconnected. Thus, when the plug is not inserted in the socket, but the block is in an upper position whereby if the plug was there the pilot circuit would be closed, the insertion of the plug is prevented. The apparatus, to the contrary, allows the manipulations when the pilot circuit is in the open position. 
     Such an apparatus offers a large measure of safety because it prevents the power contacts of the plug and of the socket from being, on the one hand, connected and, on the other hand, disconnected, when these power contacts of the plug and socket are energized. 
     Preferably, and this further improves safety, the plug and/or respectively the socket is provided with means which prevents the manipulation apparatus from being activated to drive the pilot circuit towards its closed position while the insertion of the plug is not sufficient to cause the connection of the power contacts. 
     According to a preferred embodiment, the contact heads of the pilot contacts of either the socket or of the plug are movable and those of the plug or of the socket, respectively, are fixed. The manipulation apparatus acts on the mobile contact heads to bring them towards and away from the fixed contact heads so as to cause the pilot contacts to be connected and disconnected. 
     Preferably, in this case, the pilot contacts are end contacts. The mobile contact heads of the socket or of the plug are positioned, with the assistance of springs and flexible conductors or braided cables, in a block which is axially movably mounted and which is moved by the manipulation apparatus. 
     Preferably, the manipulation apparatus is a rotating apparatus provided with a motor or driving spur which cooperates with an opening in the block in which the contact heads are located. The block is translationally moved as the spur is moved along an arcuate path. 
     The invention relates more particularly, but not exclusively, to a power connection whose activation consists of first introducing the plug into the socket and then turning the plug in the socket, to obtain connection of the power contacts. 
     One embodiment according to the invention, is notable in that the manipulation apparatus of the pilot contacts has a rotatable activation portion in the form of a cam provided on the exterior of the socket or of the plug on which the cam is mounted. The plug or the socket, whichever does not include the cam, has at least one abutment whose configuration cooperates with the configuration of the cam. In the relative introduction position of the plug into the socket, that is, as the plug is being introduced into the socket, the cam, when the pilot circuit is in the closed position, makes contact with at least one portion of the abutment and prevents the introduction. The cam does not affect the introduction of the plug into the socket when the pilot circuit is in the open position. The manipulation for closing the pilot circuit by rotation of the cam is possible after the rotation of the plug and thus after the power contacts have been connected. In this position, the cam blocks rotation of the plug in the opposite direction by cooperating with a corresponding portion of the abutment and by virtue of hooking means provided on the plug and the socket. 
     The hooking means is, for example, formed by pins provided in the plug and projections provided on the socket. The pins are adapted to be moved into position under the projections by rotation of the plug in the socket. 
     Preferably, the projections of the socket thus have an inclined section whose orientation allows the plug to be brought together into the socket in the course of the rotation of the plug in the socket. This orientation also allows a sealing joint positioned between the plug and the socket to be crushed. 
     Furthermore, and preferably, the socket has at least one abutment adapted to prevent rotation of the plug in the wrong direction after its introduction into the socket. The socket also includes at least one abutment adapted to limit the abutment which cooperate with the pins of the plug at the end of the rotational course of the plug in the socket. 
     Thus, the socket preferably is provided with an edge which is provided with reserves or openings adapted for passage of the pins of the plug. The angular position of the openings is such that the openings provide for the proper introduction and positioning of the plug in the socket. 
     Likewise, to further compliment the safety provided by the apparatus, the manipulation apparatus of the pilot contacts is provided with blockage means in the closed and/or the opened position of the pilot circuit. The blockage means serve to lock the pilot circuit in the open or closed position. 
     Other details and advantages are likewise provided in the invention. 
     FIGS. 1, 5 and 6 illustrate a connection comprising socket 1 and plug 2. The plug is formed of plug body 3, grip body 4 and grip casing 5 (clearly shown in FIGS. 5 and 6). 
     Plug grip body 4, and grip casing 5 are angled to facilitate the manipulations which will be discussed below. 
     The plug comprises power contacts 6 and pilot contacts 7a, 7b, which are in the form of pins (shown in FIGS. 5 and 6). 
     The socket is likewise provided with power contacts 8 and pilot contacts 9a, 9b. 
     The term power contacts is used to refer to phase contacts, neutral, and possibly a ground-plate. The term pilot contacts designates the contacts adapted to form a pilot circuit to control, as has already been stated, a current cutting apparatus such as for example 34 (FIG. 9) positioned up circuit of the socket, the wire 38 being connected to ground, wires 39 connected to phase contacts and wires 40 connected to pilot contacts. 
     Furthermore, it is clear that the pilot contacts can likewise serve as auxiliary contacts to control other apparatus or, for example, to light control lamps. 
     In the example shown, the socket and the plug are provided with five power contacts (three phases, one neutral and one ground contact) and four pilot contacts (not shown in their entirety in the drawings). 
     As with many high intensity plugs, the socket is provided with safety disc 10 (shown in FIGS. 2, 5, 6 and 7a-7b). Safety disc 10 is provided with openings 11a-11e and 12a-12d (shown in FIG. 2) for the passage of the power contacts and, respectively, the pilot contacts of the plug respectively. 
     However, while at rest, openings 11a-11e and 12a-12d are not directly aligned with the contacts of the socket so as to avoid touching the latter by accident. 
     Power contacts 8 of the socket are formed by contact heads 8a biased towards the exterior by springs 13 which are supported on an insulating portion of the socket. Contact heads 8a are electrically connected in a fixed manner to the socket by flexible blades 14 made of copper (shown in FIGS. 5 and 6). 
     Pilot contacts 9a, 9b of the socket are formed in a known manner, as shown in FIGS. 5 and 6, by contact heads 36a, 36b biased towards the exterior by springs 15a, 15b. Contact heads 36a, 36b are electrically connected in a fixed fashion to the socket by conductive braided cables 16a, 16b. These braided cables can be full braided cables which are arranged in an undulatory configuration. They may also be hollow braided cables which may be compressed. Additionally, other flexible conductors may be used. 
     According to the invention, contact heads 36a, 36b of pilot contacts 9a, 9b of the socket are mounted in insulating block 17. Insulating block 17 is formed in two portions (in order assemble of the contacts). Contact heads 36a, 36b are movable within the block, and are biased towards the upper portion of the block by springs 15a, 15b. Springs 15a, 15b are wedged between the contact heads and a portion of the block. 
     Block 17 is axially movably mounted in the socket and includes groove into which is introduced driving spur or projection 18. Projection 18 is integrally connected to manipulation apparatus 19 (shown in FIGS. 5 and 6). Manipulation apparatus 19 is rotatably mounted in a sealed fashion in the socket by means of toroidal joint 20. 
     Manipulation apparatus 29 extends through the socket and has an exterior portion in the form of cam 21 (shown in FIGS. 1, 5, 6, and 7a-7d). 
     This exterior portion or cam 21 has the shape of a disc from which a segment has been removed (shown in FIGS. 1, and 7a-7d). 
     As is seen more particularly in FIG. 1, plug 2 comprises hooking abutments in the form of pins 22a and 22b The socket includes edge 23 and projections 24a, 24b as well as at least one abutment 25, which will be discussed below. 
     The edge of the socket is provided with reserves or openings 26a-26c for the passage of pins 22a, 22b of the plug (plus a pin which is not visible in FIG. 1). 
     Projection 24a, 24b (plus one which is not visible in FIG. 1) of the socket includes inclined surfaces 35a, 35b and right angle portion 27 (shown in FIG. 1). 
     The plug is furthermore provided with an abutment in the shape of an opening or abutment 28 (shown in FIGS. 1, 5, 6) of the shape and of dimensions which corresponds to the shape of the cam 21, having flat portion 28a and rounded portion 28b. 
     The operation of the plug according to the invention described with reference to the figures previously described as well as FIGS. 3 and 4, the schematic diagrams 7a-7d showing, for the sake of simplicity, only a single pilot contact 7a of the plug and only one head of a pilot contact 9a of the socket, is as follows. 
     Plug 2 is brought by its handle above socket 1, as shown in FIGS. 1 and 7a and cam 21 is in the position shown in FIG. 1. 
     Contacts 7a, 7b and 6 of the plug are introduced into openings 11a-11e and 12a-12c of safety disc 10 of the socket. 
     Pins 22a, 22b of the plug pass, during the course of the introduction of contacts 7a, 7b and 6 into the respective openings, into the corresponding openings 26a,  26b of the socket. 
     It is clear that the angular arrangement of the pins and of the openings appropriately position the plug with respect to the socket. 
     Once introduced, the plug is in the position shown in FIGS. 3 and 7b, i.e. that power contacts 6 and 8 and pilot contacts 7a, 7b and 9a, 9b are not connected. Contact heads 6a and 8a of power contacts 6 and 8 are, however, substantially in a single plane but angularly offset from one another. 
     As is seen more particularly in FIG. 7b, this introduction can occur only if cam 21 is in the position shown particularly in FIGS. 1 and 7b. 
     In effect, if cam 21 was in the position shown in FIG. 7d, its upper circular portion would strike the flat portion 28a of opening 28 of the plug, preventing the plug from being further introduced into the socket. 
     The position of cam 21 for the introduction is shown in FIG. 5. FIG. 5 also shows that when cam 21 is in this position, mobile block 17 is in its lowest position. 
     After introduction of the plug, the plug is rotated in the socket. 
     The rotation of the plug can occur only in a single direction by virtue of abutment 25 which cooperates with pin 22b. The angular value of the rotation is limited by right angle portions 27 of projections 24a, 24b of the socket. Right angle portions 27 serve as abutments which limit the course of pins 22a, 22b, pins 22a, 22b hooking under the projections. Inclined surfaces 35a, 35b of projections 24a, 24b are oriented downwardly with respect to the direction of rotation of the plug such that the plug will further tighten on the socket. As the plug tightens on the socket, sealing joint 29 (shown in FIGS. 5 and 6 between the socket and the plug) is crushed between the plug and the socket. 
     During the course of the rotation, the contacts of the plug move safety disc 10. 
     Power contacts 6 of the plug make electrical contact with the power contacts 8 of the socket by rotation, as seen in FIG. 4. Springs 13 assure a pressurized contact. 
     Pilot contacts 7a, 7b of the plug face pilot contacts 9a, 9b of the socket as is seen in FIGS. 5 and 7c, but without touching each other (block 17 being in the lower position previously described). 
     In the position shown in FIGS. 5 and 7c, it is clear that the connection of the power contacts is achieved but the pilot contacts are not connected. 
     Furthermore, it is clear that it is not possible during this manipulation (passage from FIGS. 7b to 7c) to activate cam 21 because of flattened portion 28a of opening 28. 
     The latter operation consists of connecting the pilot contacts and to do this, cam 21 is turned 180° by means of a key introduced into hexagonal impression 30 provided at the center of cam 21. Opening 28 is provided with notch 31 (shown in FIG. 1) for the passage of the key. 
     After rotation of cam 21 as has just been described, cam 21 assumes the position shown in FIGS. 6 and 7d, i.e., a circular portion of the cam is positioned in rounded portion 28b of opening 28. Thus opening 28 functions to prevent activation of cam 21 because cam 21 cannot be rotated unless it is directly under opening 28. As shown in FIGS. 1-7, the opening 28 can be placed on the plug. Aditionally, the opening 28, along with cam 21 can be placed on the base, as shown in FIG. 8. To the extent that the combination of cam 21 and opening 28 acting together in concert prevents activation of cam 21, means are provided for preventing manipulation of cam 21 both on the socket and on the plug. 
     In the course of rotation of cam 21, projection 18 of apparatus 19 (FIGS. 5 and 6) moves along a half circle, thus translationally axially moving insulating block 17. In this way contact heads 36a, 36b of pilot contacts 9a, 9b of the socket touch contact heads 37a, 37b of pilot contacts 7a, 7b of the plug, as shown in FIGS. 6 and 7d. In FIG. 7d, the anterior position of contact head 9a is indicated in draft lines at 9&#39;a. 
     Pilot contacts 9a, 9b are also in electrical pressurized contact with pilot contacts 7a, 7b by virtue of springs 15a, 15b. 
     During the translational movement of block 17, the contact heads of contacts 9a, 9b follow the movement of block 17 in response to conductive braided cables 16a, 16b.  Braided cables 16a, 16b stretch while losing at least a portion of their initial undulation or by expanding to pass from the position of FIG. 5 to that of FIG. 6. As shown in FIG. 6, springs 15a, 15b are slightly compressed under the force of contacts 7a, 7b. The reverse movement of block 17 by the opposite rotation of cam 21 quite obviously causes a relaxation of springs 15a, 15b then an undulation or a compression of braided cables 16a, 16b. 
     Cam 21 can furthermore be latched in the position shown in FIGS. 6 and 7d by means for example of an attached screw activated by a key introduced into impression 32 provided for this purpose. The key passes through notch 33 of opening 28 (shown in FIG. 1). This latching can likewise be provided for the opened position of the pilot circuits of FIGS. 1, 5 and 7a-7c. 
     The connection of the pilot contacts causes the energizing of power contacts 8 of the socket, these being already connected to power contacts 6 of the plug. 
     It is clear that in this final connection position (shown in FIGS. 6 and 7d), it is impossible to turn the plug in the reverse direction because it is retained not only in rottion by cam 21 and the rounded portion 28b of opening 28, but also in translation by pins 22a, 22b and projections 24a, 24b. 
     To separate the plug from the socket, it is thus necessary first to unlatch cam 21 and to again manipulate it by 180° to bring it from the position of FIGS. 6 and 7d to the position of FIGS. 5 and 7c. In this way, the pilot contacts are separated by axial reversed translation of block 17, thus removing the voltage from power contacts 8. The complete separation of the plug from the socket thus occurs by reverse manipulations from those of insertion (reverse rotation, translational separation). After the reverse movements, the power connection is found in the position of FIGS. 1 and 7a. 
     The embodiment described can undergo numerous modifications, particularly as it concerns the number and configurations of the power and pilot contacts, as well as the number and configurations of the abutments and projections. 
     The above described drawings show apparatus 19 and block 17 located within the socket. A second embodiment of the invention includes apparatus 19 and block 17 located in the plug as shown in FIG. 8. In this second embodiment, manipulation apparatus 19, block 17 and the movable pilot contacts are located within the plug and the fixed contacts are located within the socket. 
     Although the invention has been described with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to the particulars disclosed and extends all equivalents within the scope of the claims.