Patent Publication Number: US-2021194222-A1

Title: Multipolar electrical protection system and electrical installation comprising such a system

Description:
TECHNICAL FIELD 
     The present invention relates to a multipolar electrical protection system and to an electrical installation comprising such a system. 
     BACKGROUND 
     Electrical protection systems such as circuit breakers are switching devices which allow the electric arc that may form when an electrical circuit is opened to be channelled and dissipated. When a circuit breaker is able to open a plurality of electrical circuits, corresponding to a plurality of electrical phases, also called poles, together, it is referred to as a multipolar circuit breaker. 
     Circuit breakers are generally designed for a given rating, i.e. for a given current and/or power range. 
     However, the changing requirements for circuit breakers, in particular in conjunction with wind energy production and the increase in the size of wind turbines, nowadays necessitates circuit breakers that are capable of handling currents of very high amperage, ranging up to 10 kA or even 12 kA, and in what is called the “low-voltage” domain, for example between voltages that may reach between 690 V and 1200 V. 
     Conventional approaches for manufacturing modular circuit breakers no longer allow circuit breakers of acceptable performance to be obtained, the increase in the number of elementary switching devices aligned with one another causing problems in terms of bulk and in terms of removing the heat fluxes generated by such very-high-amperage electric currents. 
     SUMMARY 
     It is these problems which the invention more particularly aims to address, by providing a multipolar electrical protection system with a compact and modular structure, which has a high rating per pole and the tripping of which is synchronized regardless of the number of poles. 
     To this end, the invention relates to a multipolar electrical protection system including a plurality of switching devices for switching an electric current. Each switching device has a plurality of compartments, each compartment comprising an extinguishing chamber and a pair of separable electrical contacts that are connected to upstream and downstream connection terminals, the separable electrical contacts being movable between open and closed positions under the action of a tripping device. According to the invention, the switching devices are separate from one another, while the upstream terminals of each device are connected by a first connector in order to keep them at one and the same electrical potential, the downstream terminals of each device are connected by a second connector in order to keep them at one and the same electrical potential and the switching devices are controlled by one and the same common tripping device. 
     By virtue of the invention, the switching devices, the tripping of which is synchronized, may be arranged so as to remove the heat fluxes associated with the high-amperage currents. Each switching device is rated according to the power and current associated with each pole. The common tripping device makes it possible to synchronize the tripping of each switching device with the others. 
     According to some advantageous but non-mandatory aspects of the invention, such an electrical protection system may incorporate one or more of the following features, in any technically permissible combination:
         the first and second connectors of a switching device are located on a rear face of the device, are arranged transversely one above the other and each comprise connection pads, each associated/connected with one of the upstream or downstream terminals, each bar comprising as many connection pads as the switching device comprises extinguishing chambers;   the first and second connectors of a switching device have the same structure and are oriented in two opposite transverse directions, the connection pads of the two connectors of one and the same device each being located in vertical planes that are distinct from one another;   the switching devices include one and the same number of extinguishing chambers;   each switching device comprises two, three or four extinguishing chambers;   each extinguishing chamber of a switching device opens onto an upper face of the switching device via a respective degassing opening, while the devices are spaced apart from one another in a direction orthogonal to the upper face so as to leave the degassing openings free of the other devices;   each switching device includes a switchover mechanism for moving the separable contacts of said device, said switchover mechanisms being coupled to the tripping device;   the tripping device forms part of an electronic control device distinct from the switching devices;   the protection system includes accommodating bases, intended for attachment to an electrical installation, each base comprising electrical connections that are positioned so as to reversibly cooperate together with the connectors of a switching device;   a first switching device includes an actuator and a switchover mechanism, the other switching devices being coupled to the first switching device by a mechanical unit that is arranged on the outside of the devices and connects these devices to one another;   the switching device that includes the actuator also includes the tripping device which drives the actuator;   each switching device includes a common control shaft to which the separable contacts are coupled, the shafts of each device being coupled to the mechanical unit;   the protection system comprises a frame for the attachment of the switching devices, while the frame and the mechanical unit are made of a non-ferromagnetic, preferably metal material.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood and other advantages thereof will become more clearly apparent in the light of the following description of two embodiments of a multipolar electrical protection system and of an electrical installation that are in accordance with its principle, given solely by way of example and with reference to the appended drawings, in which: 
         FIG. 1  is a schematic view of a multipolar electrical protection system according to some embodiments and in particular according to a first embodiment of the invention; 
         FIG. 2  is perspective view of a multipolar electrical protection system according to a second embodiment of the invention; 
         FIG. 3  is an enlarged view of the detail III in  FIG. 2 , some of the parts being hidden for ease of reading; 
         FIG. 4  is a perspective view of the protection system of  FIG. 2 , viewed along the arrow IV in  FIG. 2 , some of the parts being hidden for ease of reading; and 
         FIG. 5  is an enlarged view of the protection system of  FIG. 2 , viewed along the arrow V in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     A multipolar electrical protection system  2  according to a number of embodiments is shown in  FIG. 1 . 
     The protection system  2  comprises a plurality of switching devices, for example three, here referenced  4 ,  6  and  8 . 
     Each of the switching devices  4  to  8  is an electrical switchover device which is able to interrupt an electric current flowing across separable contacts and which can be switched over between an open state and a closed state. 
     Advantageously, the switching devices  4  to  8  are for example existing circuit breaker sub-assemblies, and/or comprise existing low-voltage circuit breaker components. 
     For example, the protection system  2  is intended for use in an electrical installation, such as an electricity distribution or production installation. According to some examples, an electrical installation includes an electric generator, at least one electrical load, and a switching device  2  connected between the generator and said electrical load. For example, the generator may be an aerogenerator, in particular a wind turbine. 
     The switching devices  4  to  8  are separated from one another. 
     Preferably, the switching devices of the system  2  are substantially identical to one another and perform a similar function such that, for simplicity, only one of these switching devices is described in detail in what follows. 
     Each of the devices  4  to  8  is associated with an electrical pole or electrical phase, referenced P 4 , P 6  and P 8 , respectively. 
     In alternative embodiments, the system  2  may include a different number of switching devices. According to some examples, the system  2  comprises two switching devices. According to other examples, the system  2  comprises four switching devices. In this sense, the protection system  2  is referred to as multipolar. 
     Each of the poles P 4  to P 8  is associated with an upstream terminal  10  and with a downstream terminal  12 . In the present description, the concepts of “upstream” and “downstream” are used to distinguish between the various elements of the protection system  2 , and do not presuppose any particular direction of connection of the various elements of the protection system  2 . 
     For each of the devices  4  to  8 , the upstream terminal  10  is connected to an upstream connector  14 , which is mounted on the corresponding device  4  to  8 . Analogously, each downstream terminal  12  is connected to a respective downstream connector  16 . 
     Each of the devices  4  to  8  comprises a plurality of compartments  18 . Advantageously, the devices  4  to  8  have the same number of compartments  18 . In the example illustrated, each of the devices  4  to  8  comprises three compartments  18 . 
     Each of the compartments  18  comprises an extinguishing chamber and a pair of separable electrical contacts, these adjoining the extinguishing chamber. By extension, the reference  18  relating to each of the compartments also includes the extinguishing chamber housed in said compartment. 
     The separable contacts of each of the pairs are connected, respectively, to an upstream terminal or to a downstream terminal, which are not shown. The separable contacts are reversibly moveable between open and closed positions. 
     For example, the separable contacts of each switching device  4  to  8  are coupled to a control shaft common to the whole device. This shaft may be set in motion by a switchover mechanism, such as an energy accumulation mechanism. This mechanism may be activated by means of an actuator, such as an electromechanical actuator, in particular an electromagnetic actuator. In practice, this actuator may be driven by a tripping device  20 . 
     When all of the separable contacts of one of the switching devices  4  to  8  are in the open/closed state, it is said by extension that the corresponding device  4  to  8  is also in the open/closed state. 
     For each device  4 ,  6  and  8 , the upstream terminals are connected to the same upstream connector  14  and are thus brought to one and the same electrical potential. 
     Analogously, for each device  4  to  8 , the downstream terminals are connected to the same downstream connector  16  and are thus brought to one and the same electrical potential. 
     The switching devices  4  to  8  are connected to one and the same tripping device  20 . The tripping device  20  is configured to receive and process the information from each of the devices  4  to  8 . 
     According to some examples, the tripping device  20  may be an electronic tripping device including an electronic circuit and/or a processor, in particular programmed to detect potential electrical faults on the basis of information from each switching device  4  to  8 , such as electric current and/or voltage measurements. 
     For example, the tripping device  20  is connected by data links  22  to measurement devices  26  associated with the switching devices  4  to  8 . The tripping device  20  is further connected by data links  24  to one or more actuators associated with the switching devices  4  to  8  in order to switch over their separable electrical contacts between their open and closed states. 
     For example, the measurement devices  26  may comprise one or more current sensors and/or voltage sensors and/or sensors configured to measure any relevant electrical quantity. 
     According to some examples, the tripping device  20  forms part of an electronic control unit, which is also configured to transmit switchover orders, for example open, close and reset orders, to each of the devices  4  to  8 . 
     In particular, the trip orders sent by the tripping device  20  are sent together to all of the switching devices  4 ,  6  and  8  of the protection system  2 . In other words, the switching devices  4  to  8  are controlled by the same tripping device  20 . 
     According to some examples, a single tripping device  20  is associated with the various devices  4 ,  6  and  8 . 
     In a first embodiment, and as illustrated in  FIG. 1 , the tripping device  20  is distinct from the devices  4  to  8 . The tripping device  20  forms for example part of an electronic control unit that is distinct from the devices  4  to  8 . 
     In other words, the slaving of the switching devices  4  to  8  to the common tripping device  20  is achieved electronically. 
     According to other examples, the tripping device  20  may be integrated into one of the switching devices  4  to  8 , the one of the switching devices  4  to  8  which includes the tripping device  20  then being called the “master” switching device, while the other switching devices which do not include the tripping device  20  are called “slave” switching devices. 
     Optionally, but nevertheless advantageously, the switching devices  4  to  8  are detachable, i.e. each of the switching devices  4  to  8  cooperates reversibly with a respective accommodating base. More precisely, each accommodating base comprises electrical connections which are reversibly electrically connected together with the upstream and downstream connectors  14  and  16  of the corresponding device  4  to  8  via a simple translational movement of the devices  4  to  8  with respect to the respective accommodating base in a direction of mounting. 
     The devices  4  to  8  are thus easily removable and replaceable, for example when performing maintenance. 
     In such a case, the data links  22  and  24  are themselves also detachable, i.e. the connecting and/or disconnecting of the links  22  et  24  take place together with the connecting and/or disconnecting of the connectors  14  and  16  when mounting/dismounting the switching device  4  to  8  on/from a respective accommodating base. 
       FIGS. 2 to 5  illustrate a second embodiment of the protection system  2 . 
     In the second embodiment, those elements which are analogous to those of the first embodiment bear the same references plus 100, and work in the same way. For example, in  FIGS. 2 to 5 , the protection system is referenced  102 . The system  102  includes three switching devices, referenced  104 ,  106  and  108 , which correspond to the switching devices  4 ,  6  and  8  of the first embodiment shown in  FIG. 1 . However, here again, the number of switching devices is not limiting and could differ. 
     In what follows, mainly the differences between the first and second embodiments are described. 
     The protection system  102  differs in particular from the protection system  2  in that the switching devices  104  to  108  are mechanically coupled to one another so as to be controlled by one and the same tripping device  120 , this latter performing a similar or identical role to that of the tripping device  20  described above. 
     In other words, the slaving of the switching devices  104  to  108  to the common tripping device  120  is achieved mechanically, for example by virtue of a mechanical connecting unit  124 , which is described in greater detail below. 
     The three switching devices  104  to  108  are mounted on an attachment frame  128 . In the example illustrated, the frame  128  is formed of metal profiles joined to one another, for example by welding. Other embodiments of the frame  128  are however possible. In the views of  FIGS. 2 to 5 , the frame  128  is shown placed on a horizontal surface. 
     In the rest of the description, the terms “up”, “down”, “in front of”, “behind”, “lateral”, “right”, “left”, etc., are given with reference to the orientation of the elements of the protection system  2  in the drawings but do not presuppose, unless specifically stated, a particular working of the system  2 . 
     In  FIGS. 3 to 5 , the frame  128  is partially shown for ease of reading. The frame  128  comprises three receiving spaces  130 ,  132  and  134  which are distinct from one another, and which are configured to accommodate a respective switching device  104 ,  106  and  108 , the devices  104  to  108  thus being separated. Each of the receiving spaces  130  to  134  here includes a rectangle-shaped horizontal plate, the spaces  130  to  134  extending lengthwise parallel to one another. 
     The switching devices  104  to  108  are each attached to a respective receiving space  130  to  134  by means of flanges  136  and attachment members which are not shown. 
     Each of the switching devices  104  to  108  is overall parallelepipedal in shape, with a front face  138 . In the example illustrated, the front faces  138  are located in a vertical plane, are parallel to one another and are oriented in the same direction, in order to facilitate the use of the protection system  102 . The front face  138  of the device  104  includes various control and/or monitoring members which are accessible to an operator in order to use the protection system  102 . 
     For convenience, a transverse plane P 1  of the protection system  2  is defined as being a plane parallel to the front faces  138  of the switching devices  104  to  108 . 
     Additionally, a longitudinal plane P 2  is defined as being a vertical plane orthogonal to the transverse plane P 1 . 
     The switching device  104  is shown enlarged in  FIG. 3 , a cover for the front face  138  being hidden for ease of reading. The switching device  104  includes a plurality of compartments  118  which correspond to the compartments  18  described above with reference to  FIG. 1 . In the example illustrated, the switching device  104  includes three compartments  118 . Each compartment  118  comprises an extinguishing chamber, not shown, adjoining the separable contacts. Each extinguishing chamber opens onto an upper face  140  of the device  104  via a degassing opening  142  which serves to allow the breaking gases to escape from the extinguishing chambers. 
     The openings  142  are advantageously oriented upwards in order to facilitate the escape of the breaking gases. Advantageously, the switching devices  104  to  108  are spaced apart from one another in a direction orthogonal to the upper face  140  of each of the devices  104  to  108  so as to leave the degassing openings  142  of each of the switching devices  104  to  108  free and thus prevent a switching device  104  to  108  from being able to obstruct an opening  142  of another switching device  104  to  108 . In the example illustrated, the switching devices  104  to  108  are spaced apart from one another in a horizontal direction. 
     Each switching device  104  to  106  comprises a control shaft  144 , which is arranged transversely to the corresponding device  104  to  106  and which protrudes from a lateral face  146  of the devices  104  to  108  by an end  148  of the shaft  144 . The end  148  is therefore located outside of the corresponding device  104  to  108 . The separable contacts of one and the same switching device  104  to  108  are thus coupled to a common shaft  144  and are switched over together between the open and closed states under the action of the corresponding shaft  144 . 
     More precisely, the shafts  144  are each in the shape of a cylinder centred on an axis, about which the shafts  144  are rotatably mobile with respect to the corresponding device  104  to  108 , and the separable contacts of one of the switching devices  104  to  108  are moved between an open state and a closed state when the corresponding shaft  144  is rotated. When all of the separable contacts of one of the switching devices  104  to  108  are in the open/closed state, it is said by extension that the corresponding switching device  104  to  108  is also in the open/closed state. 
     The control shafts  144  of each device  104  to  108  are coupled to the mechanical connecting unit  124 . The mechanical unit  124  comprises a control rod  125  which is connected to each of the control shafts  144  via levers  150 . The connection between a shaft  144 , a lever  150  and the rod  125  is more clearly visible in  FIG. 3 . 
     The lever  150  is secured, at a first end, to the shaft  144  in the vicinity of the end  148  of the shaft  144 , while a second end of the lever  150 , opposite the first end, is joined to the rod  125  in such a way as to pivot about an axis that is parallel to the axis of the corresponding shaft  144 . The mechanical connecting unit  124  is therefore located outside of each of the devices  104  to  108 . 
     The translational movements of the rod  125  are thus transformed into rotary movements of the shaft  144 . Since the shafts  144  of all of the switching devices  104  to  108  are coupled by the mechanical unit  124 , the rotary movements of one of the shafts  144  are copied by the other shafts  144  such that the separable contacts located within each of the devices  104  to  108  are moved together between the open or closed states. In other words, by virtue of the mechanical unit  124 , the switchover of the switching devices  104  to  108  between the open and closed states is simultaneous. 
     Advantageously, the frame  128  and the mechanical unit  124  are made of a non-ferromagnetic, preferably metal material in order to avoid the generation of induction phenomena under the effect of the electric currents flowing through the protection system  2 . 
     Preferably, a centring rod  152  and a guide  154  are provided in order to help the mechanical unit  124  to operate correctly, in particular to keep the shafts  144  parallel and the ends  148  aligned, in order to decrease friction within the mechanical unit  124  and to decrease the force required to rotate the shafts  144 . 
     The centring rod  152  includes bores, in which bearings accommodating the ends  148  of the shafts  144  are housed. The shafts  144  are thus guided in rotation with respect to the rod  152  about their respective axis. 
     The guide  154  is connected to a flange  136  of each of the switching devices  104  to  108  on the side opposite the lateral face  146 . It is understood that the control rod  125 , the centring rod  152  and the guide  154  extend lengthwise in directions that are parallel to one another, the switching devices  104  to  108  thus being aligned in one and the same direction. More specifically, the shafts  144  of the devices  104  to  108  are parallel to one another, are coplanar, and the connections between the levers  150  and the corresponding shafts  144  are aligned. 
     One of the switching devices  104  to  108  further includes a tripping device. 
     In the example illustrated, the tripping device  120  is mounted on the switching device  104 , which is the switching device located at the bottom of  FIGS. 2 to 4 . The tripping device  120  is preferably housed in a receiving housing provided for this purpose in the façade of one of the switching devices  104  to  108 . 
     As a variant (not shown), the tripping device  120  is mounted on another of the switching devices  106  or  108 , or even placed elsewhere such as on one of the switching devices  104  to  108 . 
     In the example illustrated, the switching device  104  also comprises an actuator  156 , shown in  FIG. 2 , the actuator  156  being driven by the tripping device  120 . 
     The actuator  156  is designed to receive the trip order from the tripping device  120  and to actuate an energy accumulation mechanism, which is not shown, this mechanism pivoting the shaft  144  of the device  104  so as to switch over the separable contacts of the device  104 . 
     The rotary motion of the shaft  144  of the device  104  is transmitted, via the mechanical unit  124 , to the shafts  144  of the other switching devices  106  and  108 , separating the separable contacts of the devices  106  and  108 . 
     In other words, the switching devices  104  to  108  are controlled by one and the same common tripping device  120 , which is here placed on or in the switching device  104 . 
     The separable contacts of an extinguishing chamber are connected to an upstream connector  114  and to a downstream connector  116 , which can be seen in  FIGS. 4 and 5 . 
     In the example illustrated, the connectors  114  and  116  are located on a rear face  158  of each of the devices  104  to  108 , the rear face  158  being opposite the front face  138 . 
     The upstream  114  and downstream  116  connectors each comprise a beam  160 , of rectangular cross section, and connection pads  162  which may be attached to or integrated into said beam  160 . In the example illustrated, two beams  160  are shown transversely on the rear face  158  of each of the devices  104  to  108 , one above the other, the beams  160  being attached to the switching devices  104  to  108  by means of attachment members, such as screws. 
     Each connection pad  162  comprises a base  164 , which is attached to a respective beam  160  by means of attachment members, and an attachment bar  166 . The bar  166  here takes the form of an elongate block, arranged vertically lengthwise and protruding from the base  164 . Each bar  166  includes through-bores which are designed to cooperate with other attachment members of an electrical installation, these attachment members not being shown. 
     Advantageously, the upstream  114  and downstream  116  connectors have the same structure, the upstream  114  and downstream  116  connectors being mounted in opposite directions on the rear face  158  of the switching devices  104  to  108 . 
     For convenience, a direction D 1  is defined as being a horizontal direction, located in the transverse plane P 1  and oriented in the same direction as the lateral face  146 , i.e. to the right of  FIG. 5 . Analogously, a direction D 2  is defined as being a direction parallel to D 1  and oriented in the opposite direction, i.e. to the left of  FIG. 5 . 
     Thus, in the example illustrated in  FIG. 5 , the connectors  114  are oriented in the direction D 1  while the connectors  116  are oriented in the direction D 2 . 
     For example, the downstream connector  116  is upside down with respect to the upstream connector  114 , such that the connection pads  162  of the upstream connector  114  are unaligned with respect to the connection pads  162  of the downstream connector  116 . 
     In this way, the attachment bars  166  of the pads  162  do not hinder the circulation of the air flows at the rear of the device. This facilitates, by way of natural convection, the removal of the heat generated by the electric current flowing at the level of each pad  162 . 
     Of course, a fan-forced convection system may be provided in order to assist in cooling the switching devices  104  to  108 . 
     For example, the attachment bars  166  of one and the same device  104  to  108  are thus located in vertical planes parallel to the planes P 2  which are distinct from one another. 
     Advantageously, each upstream  114  and downstream  116  connector of a device  104  to  108  comprises as many pads  162  as the corresponding device  104  to  108  comprises extinguishing chambers, each pad  162  being aligned with a respective extinguishing chamber along a plane parallel to the longitudinal plane P 2 . 
     In the example illustrated, each device  104  to  108  comprises three extinguishing chambers, while each of the connectors  114  and  116  comprises three connection pads  162 , which are aligned with the three extinguishing chambers of the corresponding device  104  to  108 . 
     Having pads  162  which are associated with each of the extinguishing chambers, these pads  162  being connected to one another by a beam  160 , makes it possible to decrease the heating of the middle pad  162 , i.e. that pad  162  which is located between the two other pads  162  of the same connector  114  or  116 , which is thus decreased with respect to a situation in which the connection pads  162  were not connected to one another by a beam  160 . 
     It is understood that, in the second embodiment of the protection system  102 , the use of switching devices  104  to  108  which are distinct from one another but controlled by one and the same common tripping device  120  makes it possible to handle, in a relatively small volume, currents of high amperage by virtue of effective removal of heat and breaking gases. 
     Numerous aspects of the second embodiment may be implemented independently of the first embodiment. Likewise, the second embodiment may be implemented independently of the first embodiment. 
     In particular, the mechanical slaving of the switching devices to the tripping device may be implemented independently of the electronic slaving. 
     Additionally, the frame  128  may be used in the protection system  2  described above and is not exclusive to the second embodiment. 
     Furthermore, the connectors  114  and  116 , both in terms of their structure and their arrangement, are not exclusive to the second embodiment and may be applied to the protection system  2  of the first embodiment. 
     In general, in the different embodiments described above, just one tripping device  20  or  120  is required to slave the switching devices  4  to  8  or  104  to  108 . It is thus possible to manufacture protection systems  2  or  102  which exhibit higher switching performance while using switching devices comprising existing low-voltage circuit breaker components without having to design specific new components, which is economically and industrially advantageous. 
     The embodiments and the variants mentioned above may be combined with one another so as to create new embodiments of the invention.