Patent Publication Number: US-7915982-B2

Title: Device for detecting the three states of a circuit breaker

Description:
The present invention relates to a device for detecting the three states, “On”, “Off” and “Trip” of an electric circuit breaker. 
     Through document U.S. Pat. No. 4,969,063, a device for detecting and signalling the three states “On”, “Off” and “Trip” of an electric circuit breaker is known. This device comprises a three-position switch mechanically coupled with the member for actuating the circuit breaker. The three-position switch is materialized by three electric tracks each allocated to one of the positions of the actuation member and interacting with a moveable electric contact secured to the actuation member. Depending on the position of the actuation member, the switch switches on a first LED of a first colour, a second LED of a second colour or both LEDs at the same time to mix their colours. 
     This type of device operates by mechanical contact between the actuation member and the electric tracks. These tracks may become worn gradually with the switchings of the actuation member, eventually affecting the quality of the electric connections. Also, if, in one of its positions, the actuation member has some clearance, the electric connection between the moveable contact and the corresponding magnetic track may be deficient. 
     The object of the invention is to propose a device for detecting the three states of a circuit breaker that is reliable, precise, requires little space and whose electric connections do not risk wear that is too premature. 
     This object is achieved by a device for detecting the three states of an electric circuit breaker, characterized in that it comprises:
         a moveable magnetic device, that can be moved between three positions corresponding to the three states of the circuit breaker and comprising at least one permanent magnet,   two microswitches that can be controlled by magnetic effect by the permanent magnet, and in that:   each microswitch has a moveable element capable of being aligned in an orientation of the magnetic field lines in order to take an open position or a closed position,   in each position of the magnetic device, the two microswitches are controlled in the open position or in the closed position in order to form a particular combination representative of one of the three states of the circuit breaker.       

     According to a particular feature, the magnetic device is mechanically coupled to an actuation member of the circuit breaker capable of taking three positions corresponding to the three states of the circuit breaker. 
     According to a first variant embodiment of the invention, the magnetic device is actuated in translation. 
     According to one particular feature, the magnetic device comprises a symmetrical part made of ferromagnetic material. In a first configuration, the ferromagnetic part has for example two U-shaped branches and the permanent magnet is mounted symmetrically on the ferromagnetic part, between the two branches. In a second configuration, the ferromagnetic part may also have three branches in order to form an E, a permanent magnet occupying each one of the two hollows formed by the three branches of the ferromagnetic part. 
     According to a second variant embodiment, the magnetic device is actuated in rotation. The permanent magnet of the magnetic device is for example mounted on a frame actuated pivotingly by a rail mechanically coupled to the actuation member. 
     According to the invention, the moveable element is for example a ferromagnetic membrane capable of pivoting under the magnetic effect. 
     According to the invention, the detection device comprises a signalling device responsible for indicating each of the three states of the circuit breaker depending on the position of the microswitches. The signalling device is for example mounted on the casing of the circuit breaker or is remote relative to the circuit breaker. 
     The invention also relates to an electric circuit breaker comprising a detection device as defined above and a system for monitoring a plurality of circuit breakers of this type. The monitoring system comprises for example a communication bus to which the circuit breaker detection devices are connected. This communication bus is connected to a central terminal responsible for processing and centralizing the signals received and displaying the state of each of the circuit breakers connected to the bus according to these signals. The display may be produced on an illuminated board or on a screen of the terminal. 
    
    
     
       Other features and advantages will appear in the following detailed description with reference to an embodiment given as an example and represented by the appended drawings in which: 
         FIGS. 1A to 1C  represent, in side view, an electric circuit breaker with three positions, respectively in the “Off”, “On” and “Trip” state and furnished with a detection device according to the invention. 
         FIG. 2  represents in perspective a first embodiment of a moveable plate of the detection device of the invention. 
         FIG. 3  represents, in perspective, a magnetic device according to a first embodiment. 
         FIG. 4  shows the field lines of the magnetic field generated by the magnets of the magnetic device of  FIG. 3 . This figure also shows two microswitches at rest. 
         FIGS. 5A to 5C  represent, in a side view, in three different positions, the magnetic device of  FIG. 3  and show the influence of the magnetic fields generated by its permanent magnets on the state of the two microswitches. 
         FIG. 6  shows, in a top view, a second embodiment of the moveable plate of the detection device of the invention. 
         FIG. 7  represents a magnetic device according to a second embodiment. 
         FIG. 8  shows the field lines of the magnetic field generated by the permanent magnet of the magnetic device of  FIG. 7 .  FIG. 8  also represents two microswitches at rest. 
         FIGS. 9A to 9C  represent, in a side view, the magnetic device of  FIG. 7  in three different positions and show the influence of the magnetic field generated by its permanent magnet on the state of the two microswitches. 
         FIG. 10  represents a variant of the detection device according to the invention implemented in a circuit breaker. 
         FIGS. 11A to 11C  illustrate the principle of operation of the detection device of  FIG. 10 . 
         FIG. 12  represents a microswitch such as that employed in the detection device of the invention. 
         FIGS. 13A and 13B  represent the microswitch of  FIG. 12  respectively in the open position and in the closed position, actuated by a permanent magnet. 
         FIG. 14  shows an example of a configuration of a signalling device controlled by two microswitches. 
     
    
    
     The detection device according to the invention is designed to be installed in a three-position electric circuit breaker  1 . In a known manner, a circuit breaker  1  comprises a casing  10  on which is mounted an actuation member consisting for example of an operating device  11  that pivots or rotates. In  FIGS. 1A to 1C , the operating device has the shape of a pivoting lever but it should be understood that it may equally take the shape of a rotating button. 
     The operating device  11  may be set in motion between three positions, an “On” (M) position, an “Off” (A) position and a “Trip” (D) position situated halfway between the “On” (M) position and the “Off” (A) position. The movement of the operating device from the “On” (M) position to the “Trip” (D) position is carried out automatically when an electric fault such as a short circuit is detected. In each of the three positions (M, A, D) of the operating device  11 , the circuit breaker is therefore respectively in the “On”, “Off” or “Trip” position. 
     The detection device comprises at least two adjacent microswitches  2   a ,  2   b  (both referenced  2 ) mounted on an electric signalling circuit C and designed to detect the state of the circuit breaker  1 . 
     Each of these microswitches  2   a ,  2   b  may be switched by an actuator between two positions, an open position ( FIG. 13A ) and a closed position ( FIG. 13B ). 
     According to the invention, between their two positions, these microswitches  2   a ,  2   b  are controlled by magnetic effect. Each of these microswitches  2   a ,  2   b  is sensitive to the orientation of the field lines L of a magnetic field generated by a magnetic actuator. This type of microswitch  2  is for example manufactured in MEMS (for “Micro-Electro-Mechanical System”) technology. 
     An exemplary configuration of a microswitch  2  sensitive to the orientation of the field lines L is represented in  FIGS. 12 to 13B . 
     A microswitch  2  sensitive to the orientation of the field lines L comprises a deformable ferromagnetic moveable membrane  20  that is able to be actuated in rotation about an axis of rotation (R) by the magnetic actuator. The membrane  20  is for example made of iron-nickel. 
     The membrane  20  has a longitudinal axis (A) and is connected, at one of its ends, by means of connecting arms  22   a ,  22   b , to one or more anchoring blocks  23  secured to a substrate  3 . The membrane  20  is capable of pivoting relative to the substrate  3  on its axis (R) of rotation perpendicular to its longitudinal axis (A). The connecting arms  22   a ,  22   b  form an elastic connection between the membrane  20  and the anchoring block  23  and are flexed when the membrane  20  pivots. The two microswitches  2   a ,  2   b  are for example made on one and the same substrate  3 . 
     At its distal end relative to its axis of rotation, the membrane  20  supports a moveable contact  21 . By pivoting, the membrane  20  may take at least two determined positions, an open position ( FIG. 13A ) in which two fixed electric tracks  31 ,  32  deposited on the substrate  3  are disconnected, or a closed position ( FIG. 13B ) in which the two tracks  31 ,  32  are connected together by the moveable contact  21  supported by the membrane  20 . 
     One of the methods of actuating the membrane  20  consists in applying a magnetic field created by a permanent magnet  4 . The ferromagnetic membrane  20  moves between its two positions aligning itself on the field lines L of the magnetic field generated by the permanent magnet  4 . With reference to  FIGS. 13A and 13B , the magnetic field of the permanent magnet  4  has field lines L whose orientation generates a magnetic component BP 0 , BP 1  in a ferromagnetic layer of the membrane  20  along its longitudinal axis (A). This magnetic component BP 0 , BP 1  generated in the membrane  20  engenders a magnetic torque forcing the membrane  20  to take one of its positions, closed ( FIG. 13B ) or open ( FIG. 13A ). By moving the permanent magnet  4  relative to the membrane  20 , it is therefore possible to subject the membrane to two different orientations of the field lines L of the magnetic field of the permanent magnet  4  and to cause the membrane  20  to tilt between its two positions. 
     This principle of actuation is employed in the detection device according to the invention. 
     The detection device comprises a plate  5  that can move in translation, for example made of plastic, mechanically coupled to the operating device  11  and capable of taking three positions corresponding to the three states of the circuit breaker  1 . With reference to  FIGS. 1A to 1C , this plate  5  is for example mounted on a sliding rail and may take a low position ( FIG. 1A ) when the operating device  11  is in the “Off” (A) position, a high position ( FIG. 1B ) when the operating device  11  is in the “On” (M) position or a middle position ( FIG. 1C ), situated between the high position and the low position, when the operating device  11  is in the “Trip” (D) position. 
     The moveable plate  5  supports a magnetic device  40 ,  41  with one or two permanent magnets, designed to actuate the microswitches  2   a ,  2   b  between their two positions. 
       FIG. 3  shows a magnetic device  40  according to a first embodiment, comprising two identical permanent magnets  400 ,  401 . This magnetic device consists of a symmetrical part  402  having an E-shaped longitudinal section and made of ferromagnetic material. This ferromagnetic part  402  has two hollows each occupied totally by a permanent magnet  400 ,  401  flush with the top surface and the lateral surfaces of the ferromagnetic part  402 . 
     On its top face, the magnetic device  40  has successively a first end ferromagnetic portion, a first magnetic portion consisting of the first permanent magnet  400 , a second central ferromagnetic portion, a second magnetic portion consisting of the second permanent magnet  401  and a third end ferromagnetic portion. The arrangement of the permanent magnets  400 ,  401  in the ferromagnetic part  402  makes it possible to confine the field lines of the magnetic fields generated by the two permanent magnets  400 ,  401  around the magnetic device  40  ( FIG. 4 ). 
       FIG. 7  shows a magnetic device  41  according to a second embodiment comprising a single permanent magnet  410 . This magnetic device also comprises a symmetrical part  412  made of ferromagnetic material having, for its part, a U-shaped longitudinal section. The permanent magnet  410  is positioned symmetrically between the two branches of the U-shaped part, leaving a hollow on either side.  FIG. 8  shows the field lines L of the magnetic field generated by the permanent magnet  410  in this magnetic device  41 . The presence of the ferromagnetic part  412  also makes it possible to confine the field lines L around the magnetic device  41  ( FIG. 8 ). 
     On its top face, the magnetic device  41  according to this second embodiment has successively a first end ferromagnetic portion, a hollow, a central magnetic portion consisting of the permanent magnet  410 , a second hollow and a second end ferromagnetic portion. 
     According to the invention, the microswitches  2   a ,  2   b  enclosed in a casing  24  are mounted on a printed circuit  25  fixed opposite the moveable plate  5  ( FIGS. 1A to 1C ). 
     The microswitches  2   a ,  2   b  are positioned so that their axes of rotation (R) are parallel to the plane of translation of the moveable plate  5  and perpendicular to the direction of translation of the moveable plate  5 . 
     In a first configuration, the moveable plate  5  supports the magnetic device  40  with two permanent magnets  400 ,  401 . 
     In this first configuration, the two microswitches  2   a ,  2   b  are for example oriented in the same direction. 
     In the bottom position of the moveable plate  5  ( FIG. 1A ), the membranes  20  of the two microswitches  2   a ,  2   b  are both aligned in one and the same orientation of the field lines of the first permanent magnet  400 , forcing them into a closed position ( FIG. 5A ). 
     In the top position of the moveable plate  5  ( FIG. 1B ), the membranes  20  of the two microswitches  2   a ,  2   b  are both aligned in one and the same orientation of the field lines of the second permanent magnet  401 , forcing them into an open position. 
     In the middle position of the moveable plate  5  ( FIG. 1C ), the membranes  20  of the two microswitches  2   a ,  2   b  are opposite the central ferromagnetic portion of the magnetic device  40 . The membrane  20  of the first microswitch  2   a  is aligned in an orientation of the field lines of the first permanent magnet  400  forcing it into a closed position and the membrane  20  of the second microswitch  2   b  is aligned in an orientation of the field lines of the second permanent magnet  401  forcing it into an open position. 
     In a second configuration, the moveable plate  5  supports the magnetic device  41  with a single permanent magnet  410 . In this configuration, the two microswitches  2   a ,  2   b  are for example oriented in a different direction, for example back-to-back along their axis of rotation (R). 
     In the bottom position of the moveable plate  5  ( FIG. 9A ), the membranes  20  of the two microswitches  2   a ,  2   b  are aligned in one and the same orientation of the field lines of the permanent magnet  410 , forcing a closed position on the membrane  20  of the first microswitch  2   a  and an open position on the membrane  20  of the second microswitch  2   b.    
     In the top position of the moveable plate  5  ( FIG. 9C ), the membranes  20  of the two microswitches  2   a ,  2   b  are aligned in one and the same orientation of the field lines of the permanent magnet  410 , this orientation being inverted relative to that of the field lines seen by the membranes  20  when the plate  5  is in the bottom position. The first microswitch  2   a  is then in the open position and the second microswitch  2   b  is in the closed position. 
     In the middle position of the moveable plate  5 , the two microswitches  2   a ,  2   b  are positioned symmetrically on either side of the axis of symmetry of the magnetic device  41  so that their membranes  20  are each aligned in the two different directions of the field lines of the permanent magnet  410 . The two back-to-back microswitches  2   a ,  2   b  are therefore in an open position. 
     In the two configurations, the two microswitches  2   a ,  2   b  are controlled to form, in each position of the plate  5 , a different open and/or closed combination of their membranes  20  and therefore generate on each occasion a different signal representative of the position of the moveable plate  5  and therefore of the position of the operating device  11  and of the state of the circuit breaker  1 . 
     According to a variant embodiment, the magnetic device consists of a single permanent magnet  43  mounted fixedly on a frame  60  actuated in rotation about an axis by a rail  61  mechanically coupled with the operating device  11  directly or indirectly by means of a mechanism interacting on the one hand with the operating device  11  and on the other hand with a trigger (not shown). In a known manner, this rail  61  can be moved in translation to take three positions: an “On” position, an “Off” position and a “Trip” position, depending on the state of the mechanism, in order to represent respectively the “On” state of the circuit breaker, its “Off” state and its “Trip” state. This type of device is described more fully in patents FR 2 834 379 and FR 2 827 703. 
     In this variant, the magnetic device is not actuated in translation but in rotation about an axis. A combination of a translation and rotary movement of the magnetic device may also be envisaged. 
     In rotation, the permanent magnet  43  subjects the two microswitches  2   a ,  2   b , for example enclosed in their casing  24 , to a magnetic field having field lines L of different orientations in order to force them into their open or closed position. 
     With reference to  FIGS. 11A to 11C , the permanent magnet  43  is operated in a rotary movement, above the microswitches  2 , about an axis parallel to the axes (R) of rotation of the membranes  20  and in the same direction. The microswitches  2   a ,  2   b  are for example oriented in the same direction and are positioned on either side of the axis (A 1 ) of the magnet  43  so that, when the permanent magnet  43  is parallel to the substrate  3  supporting the microswitches  2   a ,  2   b , the membrane  20  of the first microswitch  2   a , aligned in an orientation of the field lines L of the magnetic field of the permanent magnet  43 , is in an open position and the membrane of the second microswitch  2   b , aligned in an opposite orientation of the field lines L, is in the closed position ( FIG. 11B ). 
     In  FIG. 11A , the permanent magnet  43  is inclined in the anticlockwise direction so that the membrane  20  of the first microswitch  2   a  is aligned in an orientation of the field lines L forcing it into an open position and so that the membrane  20  of the second microswitch  2   b  is aligned in an orientation of the field lines L forcing it also into an open position. 
     In  FIG. 11C , the permanent magnet  43  is inclined in the clockwise direction so that the membrane  20  of the first microswitch  2   a  is aligned in an orientation of the field lines L of the permanent magnet  43  forcing it into a closed position and so that the membrane  20  of the second microswitch  2   b  is aligned in an orientation of the field lines L of the permanent magnet  43  forcing it also into a closed position. 
     Depending on the state of the two microswitches  2   a ,  2   b , a different signal may be transmitted by a signalling device  7  ( FIGS. 1A to 1C ) comprising the signalling electric circuit C represented in  FIG. 14  and controlled by the two microswitches  2   a ,  2   b . The diagram shown in  FIG. 14  is only an example and is in no way limiting. The signalling device  7  may be mounted on the casing  10  of the circuit breaker or be remote relative to the latter. 
     The signalling device represented in  FIG. 14  is suitable for operating when in a first state of the circuit breaker  1 , the two microswitches  2   a ,  2   b  are open, in a second state of the circuit breaker  1  the first microswitch  2   a  is open and the second microswitch  2   b  is closed and in a third state of the circuit breaker, the first microswitch  2   a  is closed and the second microswitch  2   b  is open. These combinations are those obtained with the detection device described above, furnished with the magnetic device  41  according to the second embodiment. 
     This electric circuit C comprises for example four branches C 1 , C 2 , C 3 , C 4  in parallel. Two branches C 1 , C 2  are each controlled by one of the microswitches  2   a ,  2   b . A diode D 1 , D 2  is mounted in series with each of the microswitches, one being oriented on-state and the other off-state. The other two parallel branches C 3 , C 4  of the circuit C each support an LED (for “Light Emitting Diode”) L 1 , L 2 , one being oriented on-state and the other off-state. 
     When the first microswitch  2   a  is closed and the second microswitch  2   b  is open, the first LED L 1  is on and the second LED L 2  is off. This combination corresponds for example to the “Off” state of the circuit breaker  1 . 
     When the first microswitch  2   a  is open and the second microswitch  2   b  is closed, the first LED L 1  is off and the second LED L 2  is on. This combination corresponds for example to the “On” state of the circuit breaker  1 . 
     When both microswitches  2   a ,  2   b  are open, both LEDs L 1 , L 2  are on. This combination corresponds for example to the “Trip” state of the circuit breaker  1 . 
     According to the invention, based on the two microswitches  2   a ,  2   b , the issue therefore is to draw up a truth table representing the states of each of the microswitches  2   a ,  2   b  depending on the position of the moveable plate  5  and the state resulting from the LEDs of the signalling device. This truth table differs depending on the initial configuration of the microswitches  2   a ,  2   b.    
     The signalling device  7  may be remote and may be incorporated into a monitoring system designed to monitor the state of several circuit breakers mounted on one and the same board or dispersed in different locations. Advantageously, in this system, the electric signals obtained at the output of the detection device of a circuit breaker  1  are for example sent to a communication bus connected for example to a central computer terminal responsible for processing the signals received and displaying the states of all the circuit breakers thus connected to the bus. The display may be achieved by means of an illuminated board with LEDs or the screen of the terminal. 
     According to the invention, it is possible to detect more than three mechanical states by employing more than two microswitches arranged in an appropriate manner. 
     It is well understood that, depending on the position of the magnetic device, the states of the microswitches are dependent on their orientation, on the geometry of the permanent magnet(s) employed or the method of actuating the magnetic device. The various combinations obtained, described above, are not limiting and other configurations may be envisaged. 
     It is well understood that it is possible, without departing from the context of the invention, to imagine other variants and enhancements of detail and even to envisage the use of equivalent means.