Abstract:
The invention relates to a plug-in circuit breaker and has the object of preventing no-load discharges of the closing mechanism when extraction of the circuit breaker is performed. The drive mechanism of the circuit breaker loading and closing mechanism comprises a trip mechanism which is able to move from a closed state wherein actuation of an oscillating lever is designed to move the closing spring to its loaded state, to a tripped state wherein actuation of the oscillating lever is designed to prevent movement of the closing spring to its loaded state. This trip mechanism causes either disengagement of the oscillating lever or neutralization of a free-wheel coupling of the drive mechanism. The circuit breaker is moreover equipped with opening and closing controls causing an opening, closing, opening cycle when extraction is performed.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a circuit breaker of the kind described in the document EP-A-0,222,645, comprising at least one pair of contacts at least one of which is movable and can take with respect to the other contact a closed position corresponding to mechanical and electrical contact and an open position, this circuit breaker being of the type equipped with a closing device provided with an energy storage device. 
     A pole  10  of a known circuit breaker  1  of this type and its opening mechanism  20  have been represented in FIGS. 1 to  3 . FIG. 4 represents a loading and closing mechanism  30  of this circuit breaker, the unloaded position. FIG. 5 represents the circuit breaker&#39;s loading and closing mechanism in the loaded position. 
     The pole  10  comprises in conventional manner a pair of breaking contacts  11 ,  12 . The contact  11  is stationary and the contact  12  is mounted pivotally between an open position which can be seen in FIG. 1, in which it is separated from the stationary contact, and a closed position which can be seen in FIG. 3, in which mechanical and electrical contact between the contacts  11  and  12  is established. The pole  10  also comprises an arc extinguishing chamber  19  and a pair of main terminals  14 ,  15  extending outwards from the rear face of the circuit breaker  1  and designed to engage by means of engagement contacts on connection terminal strips. The circuit breaker  1  comprises a plurality of poles  10  arranged in parallel planes, perpendicular to a pole shaft  16  which is common to these poles. The closing or opening order of the poles is transmitted to each movable contact  12  by means of a connecting rod  13  operating in conjunction with a lever securedly affixed to the pole shaft  16 . 
     The opening mechanism  20  comprises a toggle mechanism  21  with two small rods articulated on one another by a pivoting spindle. One of these rods is mechanically coupled to a crank  23  of the pole shaft common to all the poles, this crank moreover forming one of the levers operating in conjunction with the rods  13 . The other rod is articulated in rotation on a trip hook  22  pivotally mounted on a fixed spindle. An opening spring  24  is secured between the crank  23  and a fixed securing pin and tends to return the crank  23  to its open position shown in FIG. 1, in the counter-clockwise direction in this figure. An opening catch  25  formed by a lever pivoting around a fixed spindle is controlled by an opening latch  26  in the shape of a half-moon. The catch  25  is biased by a spring in a direction in which it is moved away from the half-moon and towards the hook  22 . The opening latch  26  is returned to its latched position. In other words, the half-moon is biased by a spring in a direction opposing rotation of the catch  25  as can be seen in FIGS. 2 and 3. A roller  27  arranged on the opening catch  25  between its ends is designed to operate in conjunction with a V-shaped recess of the trip hook  22 , in the positions of FIGS. 2 and 3. The hook  22  is biased by a spring in a counter-clockwise direction in FIG. 1, tending to shorten the distance between the articulation axis of the toggle mechanism  21  on the hook  22  and the articulation axis of the toggle mechanism  21  on the crank  23 . 
     The loading and closing mechanism  30  is represented in FIG. 4 in its unloaded state. This mechanism comprises a drive lever  31  pivotally mounted around a fixed spindle  32 . A flexible energy storage device comprising at least one closing spring  34  is pivotally mounted on the side of one of its ends on a fixed point and on the side of the other of its ends to a finger of the drive lever  31 . The drive lever bears a roller  33  designed to cooperate with a loading cam  46  keyed onto a shaft  41  of a drive mechanism. The cam  46  comprises a roller  47  designed to operate in conjunction with a closing ratchet  36  which is pivotally mounted around a fixed spindle  37 . A closing latch  38  in the shape of a half-moon is designed to lock the ratchet  36  in the position of FIG.  5 . This latch  38  is flexibly biased by a spring to its closed position. The ratchet  36  is itself biased by a spring to its latched position represented in FIG.  5 . 
     The opening mechanism and the loading and closing mechanism are mounted on one or more flanges constituting a fixed support and the two planes of projection of FIGS. 1 to  3  on the one hand and of FIGS. 4 and 5 on the other hand are disposed approximately parallel to one another. A link between the opening mechanism and the loading and closing mechanism is achieved by a finger  39  securedly united to the drive lever  31  and designed to operate in conjunction with the toggle mechanism  21 , this finger extending according to an axis essentially perpendicular to the sectional planes of FIGS. 1 and 4. The opening mechanism and the loading and closing mechanism are both provided with end of travel stops which can be seen in the figures. 
     The circuit breaker opening and closing sequences can be schematized from FIGS. 1 to  5 . In FIG. 4, the loading and closing mechanism is in its unloaded state: the closing spring  34  is relaxed; the roller  47  is pressing against the closing ratchet  36 ; the closing half-moon is open and also operates in conjunction with the closing ratchet  36 . Movement from the unloaded state of FIG. 4 to the loaded state of FIG. 5 is achieved by clockwise rotation of the shaft  41  and cam  46  in the figures. In a first stage, the roller  47  releases the ratchet  36  which moves due to the force of its return spring to the position represented in FIG.  5 . At the same time, the closing latch  38  recloses due to the action of its return spring and latches the ratchet  36  in position. The cam  46 , continuing its rotation, comes into contact with the roller  33  of the drive lever  31 , driving the latter in clockwise rotation to the position of FIG.  5 . In its rotation, the drive lever loads the spring  34 . In the position reached in FIG. 5, the cam has passed a dead point and has become receiving: the roller  33  has reached a zone of the cam in which it biases the latter clockwise, whereas the ratchet  36  forms a stop for the roller  47  and opposes any movement in the clockwise direction. The mechanism is then loaded. 
     Impulse relaxation of the closing spring  34  is obtained by unlocking the latch  38 . This unlocking in fact releases the ratchet  36  biased by the roller  47  of the cam  46 . The cam  46 , itself biased by the roller  33  of the drive lever  31 , rotates clockwise and totally releases the roller  33 , resulting in counter-clockwise impulse rotation of the drive lever due to the impulse of the relaxing spring  33 . At the end of the closing spring relaxation phase the mechanism is in the position shown in FIG.  4 . 
     The closing spring loading phase and relaxation phase can be performed whatever the state of the opening mechanism. During the loading phase, the finger  39  pivots clockwise around the spindle  32 . In the opposite manner, during the relaxation phase, the finger  39  pivots counter-clockwise and returns to its previous position. 
     These pivotings of the finger  39  have different effects on the opening mechanism depending on whether the latter is initially open or closed. 
     The unloaded open switchgear apparatus is represented in FIG.  1 . The finger  39  is then pressing against a recess of one of the rods of the toggle mechanism  21  and opposes counter-clockwise rotation of the hook  22  due to the biasing effect of its return spring. Rotation of the finger  39  during the loading phase releases the toggle mechanism  21  and the hook  22  which progressively move to the position represented in FIG. 2 due to the biasing effect of the return spring of the hook: the hook  22  has rotated counter-clockwise and the distance between the ends of the toggle mechanism has decreased. The hook, by operating in conjunction with the stop  27  of the catch  25 , allows counter-clockwise rotation of the catch  25  due to the biasing effect of its return spring until the catch passes beyond the half-moon of the opening latch  26 . The latch then recloses due to the biasing effect of its own return spring and prevents the opening catch  25  from returning in the clockwise direction. The hook  22 , when it has completed its rotation, places itself in such a way that its V-shaped recess operates in conjunction with the stop  27  of the catch  25  and is blocked in position by the latter, as represented in FIG.  2 . The opening mechanism is then in the loaded open position. 
     Relaxation of the closing spring causes, as has already been said, rotation of the finger  39  which follows a reverse trajectory to the previous one. In doing this, the finger  39  drives one of the small rods of the toggle mechanism  21 . The hook  22  is blocked in position by the stop  27  of the opening catch  25 . The articulation axis of the toggle mechanism  21  on the hook  22  therefore remains fixed and it is the articulation axis of the toggle mechanism on the crank  23  which is forced to move, thus moving the crank  23 , pole shaft  16 , levers, rods  13  and movable contacts  12  of the different poles to their closed position. The opening spring  24  is for its part automatically loaded when closing of the poles takes place due to the movement of its point of attachment to the crank  23 . At the end of this phase, the switchgear apparatus is closed and unloaded. The opening mechanism is in the position represented in FIG. 3, with the finger  39  in its position shown by a broken line. The toggle mechanism  21  has moved slightly past its dead point, which means that the articulation axis between the toggle mechanism rods has passed from one side to the other of a plane containing the other two articulation axes of the toggle mechanism, that one of the rods is pressing against an end of travel stop  28  securedly affixed to the hook  22  and that there is no longer any cooperation between the finger  39  and the toggle mechanism  21 . 
     If, from the unloaded closed position, the opening latch  26  is unlatched, the position is of FIG. 1 is reached in the following manner: opening of the half-moon of the latch  26  releases the opening catch  25  and consequently the hook  22 . Due to the biasing of the opening spring  24 , the toggle mechanism  21  biases the hook  22  both at the level of its common articulation with the hook  22  and at the level of the end of travel stop  28 . This biasing results globally in a torque causing clockwise rotation of the hook  22 , which lowers the articulation axis of the toggle mechanism on the hook, makes the toggle mechanism pass via its dead point again and enables it to fold back to the position of FIG. 1, the toggle mechanism  21  coming up against the stop formed by the finger  39  in the unloaded position. 
     Starting again from the unloaded closed position, the loading mechanism can also be reset whereas the poles remain closed, which moves the mechanism to its loaded closed position and the finger  39  to the position indicated by an unbroken line in FIG.  3 . Following this resetting operation, opening of the opening latch moves the opening mechanism to the loaded open position of FIG. 2 by a sequence similar to the previously described opening sequence, except for the fact that the folding movement of the toggle mechanism is not stopped by the stop and can be pursued, driving with it the hook  22 , which again enables counter-clockwise rotation of the catch  25  due to the biasing of its return spring, until the catch has passed the half-moon of the opening latch  26 . The latch  26  then recloses due to the biasing of its return spring and the hook, on completing its rotation, replaces itself in the position represented in FIG.  2 . The opening mechanism is then in the loaded open position. 
     It can therefore be seen that, from the loaded closed position of FIG. 3, it is possible to consecutively perform an opening which leads to the position of FIG. 2, a closing which leads to the position of FIG. 3, in broken lines, and an opening which leads to the position of FIG. 1, without resetting the loading device. This opening, closing, opening (OCO) sequence is characteristic of this type of circuit breaker. 
     The invention relates more precisely to this type of circuit breaker, when it is mounted in its plug-in version, that is to say integrated in a switchgear unit comprising a frame called the fixed frame, and a circuit breaker movable with respect to the fixed frame between an extracted position and a plugged-in position. The frame is generally box-shaped and comprises an opening on the front panel enabling the circuit breaker to be inserted, as well as slides for support and guiding thereof between the extracted position and the plugged-in position. The extracted position is that in which the circuit breaker can be removed from the frame slides. The plugged-in position is that in which the circuit breaker terminals are secured to the corresponding terminals of the frame, themselves connected to the electrical circuit, for example by an external busbar. Intermediate positions between the extracted position and the plugged-in position are generally distinguished, in particular, starting from the extracted position, a position called the plugged-out position in which no electrical contact exists between the circuit breaker and frame, but from which a kinematic transmission system becomes active for subsequent movement of the circuit breaker to the plugged-in position, and a position called the test position in which the main circuits of the circuit breaker, i.e. the terminals referred to above, are disconnected, but auxiliary electrical circuits are connected to the frame. Certain intermediate positions may be identical to one another or to the extreme positions: for example, the extracted position may be the same as the plugged-out position, or the plugged-out position be the same as the test position. The kinematic transmission system serving the purpose of moving the movable part of the circuit breaker between the plugged-out position and the plugged-in position is generally driven by a removable crank operated by the operator. It may also be motor-driven. 
     For this type of switchgear in its plug-in version, usage imposes that the handling operations enabling the circuit breaker to be extracted from its frame give rise to automatic sequences so that the circuit breaker at the end of the extraction phase is open and unloaded. This usage corresponds to a concern for preventing any risk of accident for the operator who may have to handle or reomve the circuit breaker. 
     Traditionally, to achieve this result, manufacturers ensure that the opening latch and closing latch are both placed in their unlatched position so long as the switchgear apparatus is not between the plugged-out position and the plugged-in position. A switchgear apparatus of this type is described for example in the document EP-A-0,227,586. This solution is not entirely satisfactory either from the accident risk prevention point of view or from the equipment reliability point of view. 
     From the equipment reliability point of view, it should be emphasized that the extraction sequence according to the state of the technique comprises two stages: the first is unlatching of the opening latch, the second unlatching of the closing latch whereas the opening latch is kept open. This second stage gives rise to an operating sequence, called no-load discharge or discharge on open poles, which differs from the sequences described hitherto. If the circuit breaker is previously in its loaded closed state, the opening order in fact moves it first of all to a loaded open state, which differs from that of FIG. 2 by the fact that the opening latch is kept in the unlatched position. The pole closing order, i.e. the closing latch unlatching order, then releases the roller  33  causing impulse rotation of the drive lever  31  and of its finger  39 . Due to the absence of latching of the opening catch  25 , the hook  22  is free in rotation and is moved directly to the position of FIG.  1 . The excess kinetic energy is absorbed by the end of travel stops of the hook, whereas in a normal cycle, this stop only absorbs a small amount of energy. This no-load discharge therefore implies either that the switchgear unit be over-dimensioned or that its endurance be sacrificed. 
     In state of the technique equipment in the extracted position, the opening and closing latches are kept open. It is however always possible to operate the resetting lever which acts on the reloading cam. At the end of loading travel, when the roller  47  of the cam  46  comes into contact with the closing ratchet  36 , no blocking of the cam occurs due to the fact that the ratchet is not blocked in rotation. Rotation of the cam is therefore pursued and a no-load discharge is obtained. 
     SUMMARY OF THE INVENTION 
     One of the objects of the present invention is therefore to limit the no-load discharge cycles or to avoid them completely, by means of a simple and economical device. 
     According to a first feature of the invention, this problem is solved with a plug-in switchgear apparatus comprising a fixed frame and a circuit breaker movable in the fixed frame between a plugged-out position and a plugged-in position. The circuit breaker comprising at least one pair of contacts, at least one of which is movable and can take with respect to the other contact a closed position also referred to as an intermediate closing position, and an open position, a loading and closing mechanism comprising a spring, called the closing spring, designed to move from a loaded state to a released state; a latch, called the closing latch, designed to latch the closing spring in its loaded state, the closing spring being associated to the movable contact in such a way that relaxation of the closing spring drives the movable contact to its closed position. A drive mechanism comprising a driving part, a switchgear apparatus whose drive mechanism comprises a trip mechanism which is designed to move from a closed, or coupling state wherein actuation of the drive part is designed to move the closing spring to its loaded state, to a tripped state wherein actuation of the drive part is designed not to move the closing spring to its loaded state. When the trip mechanism is in its tripped, or uncoupling state the closing spring can no longer be loaded. The risk of no-load discharge by operation of the drive part of the drive mechanism is consequently eliminated, both on extraction of the circuit breaker and when the circuit breaker has been extracted. In addition to preserving the equipment, this trip mechanism moreover provides a decisive advantage for safety of persons. State of the art equipment in the extracted position, with the opening and closing latches open, is not in fact hazard-free. It is in particular possible to operate the drive part of the circuit breaker loading device, i.e. the oscillating loading lever, so as to partially load the closing spring, before the dead point of the loading cam  46  is reached. The state of the partially reloaded loading mechanism is stable, since the free-wheel coupling opposes the force exerted by the spring. The operator in charge of performing maintenance of the switchgear unit can therefore, without being aware of it, find himself confronted with a circuit breaker whose closing spring is partially loaded. Opening of the switchgear unit in this state is potentially dangerous, as is handing thereof, all the more so as the slightest action on the reloading lever can result in the dead point being passed and lead to high-speed discharge of the closing spring. From this point of view, the trip mechanism, in its tripped position, prevents any action on the loading cam and any reloading, even partial, of the closing spring. 
     The trip mechanism can be set to its tripped state by a manual control. However, it is preferable to equip the switchgear apparatus with a control means of the trip mechanism able to detect the fact that the circuit breaker passes via an intermediate position called the tripped, or intermediate uncoupling position between the plugged-out position and the extracted position, in the extraction direction, and in this case to move the trip mechanism to its tripped state, as well as with a control means of the closing latch able to detect the fact that the circuit breaker passes via an intermediate position called the closed position between the plugged-out position and the extracted position, in the extraction direction, and in this case to drive the closing latch to its unlatched position, the intermediate tripped position being situated between the plugged-out position and the intermediate closed position, or being appreciably the same as the latter position. The sequencing obtained enables any involuntary reloading operation of the closing spring to be prevented after the closing latch has been unlatched. 
     In preferred manner, the intermediate closed position and the intermediate tripped position are appreciably identical and, furthermore, the closing latch control means and the trip mechanism control means have in common a movable element supported by the circuit breaker between a passive position and a tripping command position, and at least one cam supported by the fixed frame, the movable element operating in conjunction with a tripping command surface of the cam so as to move from its passive position to its tripping command position when the circuit breaker passes via the common intermediate closed and tripped position, in the extraction direction. This arrangement enables a particularly economical device to be achieved which is moreover simple to assemble. 
     In preferred manner, the switchgear apparatus in addition comprises on the one hand an opening mechanism comprising a spring called the opening spring able to move from a loaded state to a released state and from the released state to the loaded state, and a latch called the opening latch designed to latch the opening spring in its loaded state, the opening spring being associated to the movable contact in such a way that relaxation of the opening spring drives the movable contact to an open position and that movement of the movable contact to its closed position results in loading of the opening spring, and on the other hand a control means of the opening latch able to detect the fact that the circuit breaker passes via an intermediate position called the first open position between the plugged-out position and the tripped position, in the extraction direction, and in this case to drive the opening latch to its unlatched position, the opening latch control means and the trip mechanism control means having in common a movable element supported by the circuit breaker between a passive position and a tripping command position, passing via a first opening control position situated between the other two positions and at least one cam supported by the fixed frame, the movable element operating in conjunction with a first opening command surface of the cam in such a way as to move from its passive position to its first opening control position when the circuit breaker passes via the intermediate open position, in the extraction direction, the movable element operating in conjunction with a tripping, or uncoupling command surface of the cam so as to move from its first open position to its tripping, or uncoupling command position when the circuit breaker passes via the intermediate tripped position, in the extraction direction. This arrangement enables the simplicity to be further increased by limiting the number of parts and making assembly and adjustment setting operations easier. Depending on whether the opening latch is able to revert to its closed position or not after passing via the first open position, the closing order when the circuit breaker passes via the intermediate closed position excludes or does not exclude the possibility of no-load discharge. The movable element may moreover be common to the opening control, the tripping control and the closing control, which enables the number of parts to be limited even further and adjustment settings to be made even easier. 
     Preferably, the drive part is rotary, the drive mechanism comprises at least one free-wheel clutch designed to transmit the movement of the drive part in one direction of rotation of the latter and not to transmit it in the other direction of rotation, and the trip, or uncoupling mechanism in its tripped, or uncoupling state is designed to neutralize said free-wheel clutch so that rotation of the drive part is not transmitted in either of the two rotation directions. This embodiment enables the drive part, generally formed by an oscillating lever, to be totally disengaged. More precisely, the free-wheel clutch comprises at least one movable part movable between a closed, or engaged position in which it enables transmission of the movement of the drive part and a tripped, or disengaged position in which it does not enable transmission of the movement of the drive part and the trip mechanism comprises a blocking plate for blocking said movable part of the free-wheel clutch in the tripped position. 
     According to another alternative embodiment, the drive mechanism comprises a rotary driven part and at least one free-wheel coupling designed to prevent rotation of the driven part in one direction, and the trip mechanism in its tripped state is designed to neutralize said free-wheel coupling so that rotation of the driven part is possible in both directions. This alternative embodiment enables the closing spring to be relaxed when the latter is in a partially loaded state between its released state and its loaded state. In this intermediate state, unlatching of the closing latch does not in fact have any effect on the closing spring. Neutralizing the free-wheel coupling enables the cam to rotate in the opposite direction to the loading direction and thus enables relaxation of the closing spring. This alternative embodiment can usefully be combined with the previous embodiment. By disengaging the drive part of the drive mechanism before neutralizing the free-wheel coupling, relaxation of the partially loaded closing spring is in fact enabled, while preventing its energy from being transmitted to the drive part. 
     According to another feature of the invention, the problem is solved with an electrical switchgear apparatus comprising a fixed frame and a circuit breaker movable in the fixed frame between a plugged-out position and a plugged-in position, the circuit breaker comprising at least one pair of contacts at least one of which is movable and can take with respect to the other contact a closed position and an open position, a loading and closing mechanism comprising a spring called the closing spring designed to move from a loaded state to a released state, a latch called the closing latch designed to latch the closing spring in its loaded state, the closing spring being associated to the movable contact in such a way that relaxation of the closing spring drives the movable contact to its closed position, an opening mechanism comprising a spring called the opening spring designed to move from a loaded state to a released state and from the released state to the loaded state, and a latch called the opening latch designed to latch the opening spring in its loaded state, the opening spring being associated to the movable contact in such a way that relaxation of the opening spring drives the movable contact to an open position and that movement of the movable contact to its closed position results in loading of the opening spring, said switchgear apparatus comprising a control means of the opening latch able to detect the fact that the circuit breaker passes via an intermediate position called the first open, or first intermediate opening position between the plugged-out position and the extracted position, in the extraction direction, and in this case to drive the opening latch to its unlatched position, and a control means of the closing latch able to detect the fact that the circuit breaker passes via an intermediate position called the closed position between the first open position and the extracted position, in the extraction direction, and in this case to drive the closing latch to its unlatched position, a switchgear apparatus whose opening latch is designed to revert to its latching position before the circuit breaker passes via its intermediate closed position, in the extraction direction, said opening latch control means being moreover designed to detect the fact that the circuit breaker passes via an intermediate position called the second open, an intermediate position between the closed position and the extracted position, in the extraction direction, and in this case to drive the opening latch to its unlatched position. By modifying the sequencing of the closing and opening commands on extraction in this way, the no-load discharge cycle of the state of the technique is prevented, since it is replaced by a full OCO cycle. The fact that the OCO discharge cycle is controlled by the positioning of the circuit breaker in the switchgear apparatus frame makes implementation of the device very flexible. In particular, if for certain uses the OCO discharge cycle is not desired, it is possible by very simple modifications of the control means to choose another discharge sequence. Preferably, the opening latch control means is able to detect the fact that the circuit breaker passes via the intermediate second open position in the plug-in direction, and in this case to drive the opening latch to its unlatched position, the opening latch being designed to revert to its latched position before the circuit breaker passes via its intermediate closed position, in the plug-in direction, the closing latch control means being able to detect the fact that the circuit breaker passes via the intermediate position called the closed position in the plug-in direction, and in this case to drive the closing latch to its unlatched position, and the opening latch control means being able to detect the fact that the circuit breaker passes via the intermediate first open position in the plug-in direction and in this case to drive the opening latch to its unlatched position. This enables no-load discharges to be prevented also when plug-in is performed. 
     Preferably, this OCO sequence when extraction is performed is combined with a trip mechanism of the previously described type. This combination enables no-load discharges to be prevented both during extraction and on the extracted circuit breaker. 
     In practice, the control means of the opening and closing latches and of the trip mechanism comprise one or more cams or contact surfaces securedly affixed to the frame of the switchgear apparatus, operating in conjunction with movable follower elements, for example levers or slides, transmitting the information directly or via a connecting rod system to the mechanisms concerned, i.e. the opening latch, the closing latch and the trip mechanism. It is therefore possible, by modifying the contact surfaces of the cams or by limiting the travel of the movable follower elements by end of travel stops, to defer the choice between operation according to the invention and conventional operation till the stage when the apparatus is put into operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages and features of the invention will become more clearly apparent from the following description of different embodiments of the invention, given as non-restrictive examples only and represented in the accompanying drawings in which: 
     FIG. 1, which has already been commented, represents an open pole and its opening mechanism in the open and unloaded position, in an embodiment common to the state of the technique and to the set of embodiments of the invention; 
     FIG. 2 represents the pole of FIG. 1 in the open position and its opening mechanism in the loaded open position; 
     FIG. 3 represents the pole of FIG. 1 in the closed position and its opening mechanism in the closed position; 
     FIG. 4, which has already been commented, represents a loading and closing mechanism in the unloaded position in an embodiment common to the state of the technique and to the invention; 
     FIG. 5 represents the loading and closing mechanism of FIG. 4, in the loaded position; 
     FIG. 6 represents in perspective a frame for a plug-in circuit breaker according to a first embodiment of the invention; 
     FIG. 7 represents in perspective the plug-in circuit breaker according to the first embodiment of the invention, withdrawn from its frame, and shows in particular a left side flange; 
     FIG. 8 represents, in another perspective, the circuit breaker according to the first embodiment of the invention, withdrawn from its frame, showing in particular a right side flange supporting a coupling part; 
     FIG. 9 is a sectional view in a plane parallel to the right side flange of the movable part of the circuit breaker according to the first embodiment of the invention, showing the control part of the coupling part in an inactive state; 
     FIG. 10 is a sectional view in a plane parallel to the right side flange of the movable part of the circuit breaker according to the first embodiment of the invention, showing the control part of the coupling part in an active state; 
     FIGS. 11 to  14  are schematic views showing operation of opening control and closing control levers in conjunction with a cam supported by the circuit breaker frame according to the first embodiment of the invention; 
     FIG. 15 is a view of a second embodiment of the invention, corresponding to FIG. 8 of the first embodiment; 
     FIG. 16 is a schematic view of a third embodiment of the invention, with a single control lever in the inoperative position; 
     FIG. 17 is a schematic view of the third embodiment of the invention, with the single control lever in the opening control position; 
     FIG. 18 is a schematic view of the third embodiment of the invention, with the single control lever in the closing control position; 
     FIG. 19 is a perspective view of the third embodiment of the invention, showing more particularly a control mechanism comprising the single control lever; 
     FIG. 20 is a perspective view of the third embodiment of the invention, showing more particularly a trip mechanism; 
     FIG. 21 is a detailed view of a single control latch of a fourth embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The fixed external frame  50  of a plug-in circuit breaker has been represented in FIG.  6 . This frame comprises on its rear face terminal strips  51  for electrical connection to a busbar of the electrical power distribution system. On the side walls  53  and  54  of the frame there are arranged slides  55  designed to support and guide the circuit breaker in its translation movement between its extracted position and its plugged-in position. The wall  53  has affixed thereon a cam  56 . The frame also comprises in its lower part a draw-in mechanism comprising a longitudinal primary shaft  57  whose free end is designed to operate in conjunction with an operating crank and a transverse countergear shaft  58  linked to the primary shaft  57  by a countergear transmission (not represented), the transverse shaft  58  bearing two sectors of cog-wheels  59  each engaging with a draw-in cam. Rotation of the primary shaft  57  brings about rotation of the cams in conventional manner which both drive a roller of the circuit breaker in reversible manner between the plugged-out position and the plugged-in position. 
     FIG. 7 represents the circuit breaker  1  withdrawn from its external frame  50 . The circuit breaker pole partitioning walls  2  can be seen at the rear part. The poles are similar in their construction to the state of the technique of FIGS. 1 to  5 . The front part comprises a left flange  3  and a right flange  4  acting as supports for the various elements of the opening mechanism  20  and of the loading and closing mechanism  30 . 
     FIG. 7 also shows an oscillating operating lever  45  constituting the driving part of a drive mechanism  40  of the loading cam  47 , the driven part being the shaft  41  (FIG.  4 ). The lever  45  oscillates around its geometric pivoting axis which is identical to the shaft  41 , between the raised position represented in FIG. 7 and a lowered position located 90° from the former. The pole shaft  16  on which the crank  17  is fixed, which is articulated on the one hand with one end of the toggle mechanism  21  and on the other hand with the rod  13  of one of the circuit breaker poles, can in addition be seen in FIG.  7 . For the other poles, the rods  13  are articulated on levers  18  fixed to the pole shaft  16 . 
     The intermediate elements of the drive mechanism  40  of the shaft  41  and of the loading cam  47  can be seen in FIGS. 8 to  10 . In FIG. 8, the oscillating lever  45  has been removed to show a rack wheel  42  keyed onto the shaft  41 . The rack wheel  42  operates in conjunction with an anti-return catch  43  whose spindle is supported by the flange  4 . This catch  43  prevents rotation of the rack wheel in the clockwise direction in FIG.  8 . The rack wheel  42  and catch  43  therefore form together a free-wheel coupling between the shaft  41  or loading cam  47  and the support flange  4  secured to the circuit breaker  1 . The oscillating lever  45  is secured to a dish whose cylindrical edges can be seen in cross section in FIG.  9  and whose base, which is not visible, extends in the plane of FIG.  9  and supports the spindle of a drive ratchet  4 . The ratchet  44  operates in conjunction with the rack wheel  42  in such a way as to oppose rotary movement of the rack wheel  42  with respect to the ratchet  44  and oscillating lever  45  in the clockwise direction. The rack wheel  42  therefore forms with the ratchet  44  a free-wheel clutch between on the one hand the drive part  45  and on the other hand the shaft  41  or cam  47  constituting a driven part. 
     The circuit breaker also comprises a trip mechanism  60  comprising a ratchet cache lever  61  pivotally mounted with respect to the axis of the shaft  41 . This ratchet cache  61  bears a plate  62  extending in a direction appreciably parallel to the axis of the shaft  41 . According to the position of the ratchet cache lever  61 , this plate  62  is movable between a withdrawn position which can be seen in FIG.  9  and an active position which can be seen in FIG.  10 . 
     The circuit breaker further comprises a common control  80  of the trip mechanism  60  and of the closing latch  38 . A part of the control  80  is supported by the fixed external frame  50  of the circuit breaker and is formed by a first surface  81  of the cam  56  (FIG.  11 ). Another part of the control  80  is arranged on the circuit breaker and comprises a lever  82  which can be seen in FIG. 8 with a drive arm  83  designed to operate in conjunction with the surface  81  and a driven arm  84  articulated on an intermediate lever  85  by a sliding articulation, the articulation comprising a slide securedly affixed to the arm  84  and sliding in an oblong hole of the intermediate lever  85 . This intermediate lever is moreover articulated on the arm of the ratchet cache lever  61  by a sliding articulation. The intermediate lever  85  also comprises an arm designed to operate in conjunction with a finger of the closing latch  38 . It is clear that the control  80  does not constitute the sole closing control of the circuit breaker. It is naturally superposed on other closing controls which are not included in the scope of the present invention, among which control by a pushbutton on the circuit breaker front panel. 
     The circuit breaker also comprises an operating mechanism  90  of the opening latch  26 . It will be clearly apparent to the man of the trade that this operating mechanism  90  is superposed on one or more other controls commanding the opening latch which are not included in the scope of the present invention and which serve the purpose among other things of commanding opening of the circuit breaker in the plugged-in position (by pushbutton or by electrical control) or between the plugged-in position and the plugged-out position (by a set of levers and cams). A part of the operating mechanism  90  is arranged on the fixed frame and is formed by a second surface  91  of the cam  56 . Another part of the operating mechanism is arranged as a mobile part and comprises a control lever  92  designed to operate in conjunction with the surface  91 . This lever is biased by a spring to a rest position. It cooperates directly on the opening latch in such a way that the movement of the latch against the return force of its spring drives the opening latch  26  to its open position and that in the opposite manner the lever  92  in its rest position does not interact with the opening latch  26 , whatever the position of the latter. 
     Operation of the device is as follows: 
     Between the plugged-in position and the plugged-out position represented in FIG. 11, the first surface  81  keeps the drive arm  83  of the lever  82  in the raised position, the intermediate lever  85  thereby being held in the position of FIG. 9 against the force of its return spring. In this position, the plate  62  of the ratchet cache  61  does not interact with the drive ratchet  44 . Likewise, the intermediate lever  85  does not interact with the closing latch  38 , whatever the position of the latter. Furthermore, the second surface  91  does not interact with the lever  92 , the latter therefore remaining in its rest position in which it does not interact with the opening latch  26 , whatever the position of the latter. 
     When the circuit breaker is progressively removed from its frame from the plugged-out position to the extracted position in the direction D, the control levers  82  and  92  successively take the positions represented in FIGS. 12 to  14  with respect to the cam  56 . In a first phase, schematically illustrated in FIG. 12, the movement of the circuit breaker  1  out of the frame  50  in the direction D causes a cooperation between the opening control lever  92  and a ramp of the second surface  91  of the cam  56 , moving the opening control lever  92  to the lowered position and thus bringing about opening of the opening latch  26 . At the end of this first phase, the opening mechanism is either in its unloaded open state of FIG. 1 or in its loaded open state of FIG. 2, depending on its initial state. In a second phase, between the positions of FIGS. 12 and 13, the opening control lever  92  is released and due to the bias exerted by its return spring reverts to its rest position releasing the opening latch which is biased to its rest position by its own return spring. The opening latch is then in the latched position. In a third phase, schematically represented in FIG. 13, the control lever  82  of the common control  80  of the trip mechanism  60  and of the closing latch  38  is released by the first surface  81  and, biased by its return spring, moves to its lowered position. The intermediate lever  85  then pivots to the position of FIG.  10 . When this pivoting has been completed, the closing latch  38 , whatever its previous position, is blocked in its unlatched position, whereas the plate  62  of the ratchet cache  61  has inserted itself between the rack wheel  42  and the drive ratchet  44 . Due to the unlatching of the closing latch  38 , the loading and closing mechanism  30 , if it was previously loaded, is therefore necessarily in its unloaded position at the end of this phase whereas the opening mechanism  20  moves to its closed state: in this case, the poles  10  in fact close and the circuit breaker  1  is in the state of FIGS. 3 and 4. From this moment on, the loading cam  47  can no longer be driven due to the fact that the drive mechanism  40  is neutralized by the trip mechanism  60 . The next phase of extraction is schematically represented in FIG.  14 : the opening latch control lever  92  is again biased by a ramp of the second surface  91  of the cam  56  and pivots to the lowered position again causing opening of the opening latch  26 . At the end of this phase, the switchgear apparatus is therefore necessarily in the unloaded open position, whether it was initially in the open or closed, loaded or unloaded position. Finally, in a last phase of extraction, not represented, the opening control lever  92  is released and, due to the biasing of its return spring, reverts to its rest position releasing the opening latch which also reverts to its rest position due to the biasing of its own return spring. 
     The extracted circuit breaker is therefore open, and an action on the oscillating lever has no effect on the loading mechanism. The mechanism can no longer be reset, even partially, and therefore no longer constitutes a potential danger for the maintenance operator. However, when the circuit breaker is extracted from its frame, the control levers  82  and  92  are accessible. An operator who is aware of this can therefore purposely fraud the trip mechanism by lowering the control lever  82  manually and blocking it with a tool. A system is thus obtained which prevents dangerous operating errors by an unskilled operator, without penalizing the specialist. 
     The sequences described above for extraction are reversible when the circuit breaker is pushed from its extracted position to its plugged-out position. 
     The first embodiment described comprises a common control for the closing latch and trip mechanism, notably using the intermediate lever  85  with three arms, enabling the closing latch and ratchet cache lever to be driven simultaneously or almost simultaneously. It can however be envisaged to replace this common control by two independent controls, each operated by a control lever and a surface of the cam fixed to the frame. Such a solution is shown schematically in FIG. 15 representing a second embodiment of the invention. A control  170  of the closing latch  138  comprises a control lever  172  operated by a ramp of a cam fixed to the frame of the switchgear apparatus and an intermediate countergear lever  175  biased by a return spring. The arm driving the countergear lever  175  is articulated on the control lever  172  whereas its driven arm is designed to operate in conjunction with a finger of the closing latch  138 . Likewise, the control of the trip mechanism  180  comprises a control lever  182  activated by a cam fixed to the frame and by an intermediate countergear lever  185  biased by a return spring. 
     This solution is interesting in particular if a clear sequencing of the trip control and closing control is to be obtained. 
     Furthermore, the second embodiment of the invention differs from the first by its trip mechanism  160 , which acts both on the drive ratchet  144  and on the anti-return catch  143  of the drive mechanism  140 . When the intermediate lever  185  is driven by its return spring in the clockwise direction of FIG. 15, it drives the arm of the ratchet cache  161  which pivots in the counter-clockwise direction. In a first part of its travel, a plate  162  of the ratchet cache clears the drive ratchet  144 , then in a second part of its travel, a second plate  163  of the ratchet cache clears the anti-return catch  143 . Clearing the drive ratchet  144  has the same function of disengaging the oscillating lever  145  as in the first embodiment. Clearing the anti-return catch  143  also enables the shaft  141  to be released, and therefore relaxes the closing spring  134  if the latter was previously partially loaded. Due to the sequencing of the actions of the two ratchet cache plates, the relaxation of the closing spring is not transmitted to the oscillating lever  145 , which eliminates any risk of accident. The cam acting on the control lever  182  of the trip mechanism  160  comprises a first ramp enabling the ratchet cache  161  to perform the first part of its travel and a second ramp enabling the ratchet cache to perform the second part of its travel. The cams of the switchgear apparatus frame act on the control levers of the closing latch and of the trip mechanism in such a way that unlatching of the closing latch takes place between clearing of the drive ratchet and clearing of the anti-return catch. 
     Naturally, it is also possible to command a trip mechanism of the type described with respect to the second embodiment by a common control of the type described with respect to the first embodiment, in particular by using an intermediate lever with three arms. 
     It can moreover be envisaged to use a single ratchet cache plate only, interposed between the anti-return catch and the rack wheel. In this case, an oscillation of the oscillating lever does in fact drive the loading cam, but the cam returns to its unloaded position when the lever moves to its raised position, which results in the closing spring never reaching its loaded state. 
     A third embodiment of the invention can be seen in FIGS. 16 to  20 . This embodiment differs from the previous one essentially by the fact that a single control lever  292  is used for a common control  290  of the opening latch  226 , the trip mechanism  260  and the closing latch  238 . 
     An opening latch  226 , a closing latch  238  and a trip mechanism  260  can be seen in FIGS. 16 and 19. A single control lever  292  is able to take an inoperative position, an opening control position and a closing control position, represented respectively in FIGS. 16 to  18 . It is biased to the closing control position by a return spring. An intermediate lever  285  with three bearing surfaces is designed to operate in conjunction with the single control lever  292 , the trip mechanism  260  and the closing to latch  238 . FIG. 20 shows a part of the drive mechanism  240  and of the trip mechanism  260  which are similar to those of the first embodiment. The plate  262  of the ratchet cache  261  can in particular be seen between the rack wheel  242  and the drive ratchet  244 . For the sake of clarity, certain elements have not been represented, in particular the ratchet return springs. It can be noted that the intermediate lever  285  is not provided with its own return spring, the return springs of the closing latch on the one hand and of the ratchet cache on the other hand proving sufficient. 
     In the neutral position (FIG.  16 ), the single control lever  292  does not interfere either with the opening latch  226  or with the intermediate lever  285 . When moving to its opening control position, by pivoting in the counter-clockwise direction in FIG. 17, the single control lever cooperates via a spigot with the opening latch  226  and drives the latter to its unlatched position. When moving to its closing control position in the counter clockwise direction in FIG. 18, the single control lever  292  cooperates with the intermediate lever  285  and makes the latter pivot in the clockwise direction in the figure. The intermediate lever  285  thus almost simultaneously drives on the one hand the closing latch  238  to its unlatched position and on the other hand the plate  262  of the ratchet cache  261  to a position such that it is interposed between the drive ratchet  244  and the rack wheel  242 . 
     Operation of the device is as follows. In the plugged-out position, the single control lever  292  operates in conjunction with a cam of the frame which holds it in an inoperative position against the biasing of its return spring. When the extraction sequence takes place from the plugged-out position, the single control lever  292  comes into contact with a first ramp of a cam securedly united to the frame and pivots to its opening control position due to the biasing of its return spring. At the end of this first sequence, the circuit breaker is open, whatever its previous state may have been. When extraction is pursued, the single control lever  292  is released and is driven by its return spring to its closing control position. No-load closing of the circuit breaker then takes place and the plate  262  of the ratchet cache  261  is interposed between the drive ratchet  244  and the rack wheel  242 . It is then impossible to reset the device. 
     This solution is sub-optimal compared to the previous one, as it does not prevent no-load discharge when extraction is performed. It does on the other hand prevent any reloading of the extracted switchgear apparatus, and therefore any risk of no-load discharge of the extracted switchgear apparatus. It also meets the requirements of protection of maintenance operators. 
     It is also possible on the basis of a device with a single control lever to perform an OCO sequence when extraction takes place, as in the device of the first embodiment. The modifications to be made to the device of FIGS. 16 to  20  to obtain this result have been illustrated schematically in FIG.  21 . According to this embodiment, a single control means  390  comprises a single control lever  392  which can by pivoting counter-clockwise around its axis take four positions: an inoperative position, a first opening control position, a closing control position and a second opening control position. It is biased by a return spring to its second opening control position. A cam  393  in the form of a disk comprising two asperities  394 ,  395  each constituting two ramps at 45° is secured to the single control lever  392 . These asperities are designed to operate in conjunction with a spigot  396  of the opening latch  326 . For the rest, this embodiment is identical to the embodiment of FIGS. 16 to  20 . 
     When the circuit breaker is in the plugged-out position, the single control lever  392  operates in conjunction with a surface of a cam fixed to the frame of the switchgear apparatus. When extraction takes place, the lever encounters a first ramp of this cam of the frame, which enables it to pivot to its first opening control position due to the biasing of its return spring. During this pivoting, the first asperity  394  of the cam  393  operates in conjunction with the spigot  396  of the opening latch  326  and makes the latch pivot to its unlatched position. At the end of this pivoting phase of the single control lever  392 , the first asperity  394  is no longer in contact with the spigot  396  of the opening latch  326 . The opening latch  326  is designed to reclose due to the biasing of its own return spring. When extraction of the circuit breaker is pursued, the single control lever  392  encounters a second ramp which enables it to pivot to its closing control position due to the biasing of its return spring. As in the third embodiment, this pivoting causes pivoting of an intermediate lever which almost simultaneously drives the closing latch and the ratchet cache. When extraction of the circuit breaker is pursued, the single control lever  392  is released enabling the second asperity  395  of the cam  393  to operate in conjunction with the spigot  396  of the opening latch in the same way as the first asperity, again causing unlatching and latching of the opening latch. 
     When the switchgear apparatus is moved from the extracted position to the plugged-out position, the sequence is reversed, each stage being in itself reversible. 
     Certain national usages do not prescribe an unloading sequence when extraction is performed. With the single lever devices of the second and fourth embodiments, it is still possible to comply with these usages. To do this a stop simply has to be provided on the circuit breaker restraining pivoting of the single control lever and preventing it from reaching the closing control position. It is thus possible to comply with different usages with an almost identical switchgear apparatus. The device according to the invention has a great flexibility of use and makes it possible to defer differentiation between the products intended for different markets. 
     Finally, certain alternative embodiments will be immediately apparent to the man of the trade. For example, it is clear that the control levers  82  and  92  can be replaced by any other mobile part supported by the circuit breaker  1 , for example by pull-rods movable in translation.