Monitored switch gear device

A monitored switch gear device that includes a switch gear, a plurality of magnets, a magnetic field sensor and a processing circuitry. The switch gear includes an opening/closing mechanism adapted to selectively open and close an electrical circuit. The opening/closing mechanism includes a pivotally mounted shaft configured to rotate about a pivot axis as the opening/closing mechanism moves between an open and a closed state. The magnets of the plurality of magnets are spaced from each other and fixedly attached to the shaft. The magnetic field sensor senses a magnetic field generated by each magnet of the plurality of magnets as the shaft pivots. Each magnet of the plurality of magnets defines a different angular position of the shaft detected by the magnetic field sensor in which the magnetic field sensor senses a respective magnet of the plurality of magnets. The processing circuitry computes a first angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the magnetic field generated by at least two magnets of the plurality of magnets as the shaft pivots in one direction.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to switch gear devices with a monitored opening and closing mechanism.

BACKGROUND OF THE DISCLOSURE

Conventionally, a switch gear device utilizes an opening and closing mechanism that selectively opens and closes an electrical circuit for instance via opening and closing electrical contacts embedded within the switch gear device. Such opening and closing mechanism typically contain several mechanically interconnected parts prone to wear out consequently limiting a longevity of whole switch gear device. Additionally, an external environment may further influence the longevity of the whole switch gear device causing the opening and closing mechanism to degrade prematurely when exposed for instance to an entry of humidity or excessive temperatures.

An impact of a switch gear device unexpected failure may be in some cases quite severe. Thus, rather than waiting for the opening and closing mechanism of the switch gear device to fail it is desirable to monitor its proper function and preemptively diagnose when the switch gear device needs to be replaced or repaired.

Therefore, it would be advantageous to have a switch gear device with a simple and a low cost monitored opening and closing mechanism.

SUMMARY OF THE DISCLOSURE

One aspect of the present disclosure is directed to a monitored switch gear device. The monitored switch gear device comprises a switch gear, a plurality of magnets, a magnetic field sensor and a processing circuitry. The switch gear includes an opening/closing mechanism adapted to selectively open and close an electrical circuit. The opening/closing mechanism comprises a pivotally mounted shaft configured to rotate about a pivot axis as the opening/closing mechanism moves between an open and a closed state. The magnets of the plurality of magnets are spaced from each other and fixedly attached to the shaft. The magnetic field sensor is configured to sense a magnetic field generated by each magnet of the plurality of magnets as the shaft pivots. Each magnet of the plurality of magnets defines a different angular position of the shaft in which the magnetic field sensor senses a respective magnet of the plurality of magnets. The processing circuitry is configured to compute a first angular speed of the shaft based on signals provided by the magnetic field sensor when it senses a magnetic field generated by at least two magnets of the plurality of magnets as the shaft pivots in one direction.

Additionally, the magnets of the plurality of magnets may be positioned equidistant from the pivot axis of the shaft.

Additionally, the magnetic field sensor may comprise a magneto resistive or a hall effect type sensor for the magnetic field sensing.

Additionally, the magnetic field sensor may comprise a switch type hall effect sensor and the magnetic field sensor may be configured to generate an electrical signal when it senses a magnetic field generated by a magnet of the plurality of magnets.

Additionally, the magnetic field sensor may comprise a unipolar Hall effect switch type sensor.

Additionally, the plurality of magnets may comprise four discrete magnets where each of the four discrete magnets defines an angular position of the shaft that corresponds to a specific position of the opening/closing mechanism between its open and closed state.

Additionally, an open position of the opening/closing mechanism may be defined as an angular position of the shaft of 0 degrees and the closed position of the opening/closing mechanism may be defined as an angular position of the shaft of A degrees. The four magnets may include a first magnet which may define a first angular position of the shaft of a1 degrees, a second magnet which may define a second angular position of the shaft of a2 degrees, a third magnet which may define a third angular position of the shaft of a3 degrees and a fourth magnet which may define a fourth angular position of the shaft of a4 degrees, with a4>a3>a2>a1.

Additionally, a1 may be comprised between 4% of A and 14% of A, a2 may be comprised between 20% of A and 36% of A, a3 may be comprised between 40% of A and 60% of A and a4 may be comprised between 70% of A and 90% of A.

Additionally, A may be comprised between 40 and 60 degrees.

Additionally, A may be comprised between 49 and 51 degrees, a1 may be comprised between 5 and 7 degrees, a2 may be comprised between 16 and 18 degrees, a3 may be comprised between 27 and 29 degrees and a4 may be comprised between 39 and 41 degrees.

Additionally, the processing circuitry may be configured to compute the first angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the fourth and the third magnets as the shaft rotates and the opening/closing mechanism moves from the closed position to the open state.

Additionally, the processing circuitry may be configured to compute a second angular speed of the shaft based on signals provided by the magnetic field sensor when it registers the fourth and the second magnets as the shaft rotates and the opening/closing mechanism moves from the closed position to the open state.

Additionally, the processing circuitry may be further configured to compute a third angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the second and the first magnets as the shaft continues to rotate and the opening/closing mechanism moves from the closed position to the open state.

Additionally, the processing circuitry may be configured to compute a fourth angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the third and fourth magnets as the shaft rotates and the opening/closing mechanism moves from the open position to the closed state.

Additionally, the switch gear device may be a circuit breaker.

A further aspect is directed to a method of monitoring a switch gear device. The method comprising: rotating a shaft of an opening/closing mechanism and selectively opening or closing by the opening/closing mechanism an electrical circuit of a switch gear, wherein the shaft is pivotally mounted to rotate about a pivot axis and the shaft has a fixedly attached a plurality of magnets spaced from each other; sensing by a magnetic field sensor a magnetic field generated by at least two magnets of the plurality of magnets as the shaft rotates, wherein each magnet of the plurality of magnets defines a different angular position of the shaft in which the magnetic field sensor senses the magnets; and computing by a processing circuitry a first angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the at least two magnets of the plurality of magnets as the shaft rotates in one direction.

Additionally, in the method the plurality of magnets may comprise four discrete magnets where each of the four discrete magnets defines a different angular position of the shaft that corresponds to a specific travel position of the opening/closing mechanism between its open and closed state.

Additionally, in the method an open position of the opening/closing mechanism may be defined as an angular position of the shaft of 0 degrees and the closed position of the opening/closing mechanism is defined as an angular position of the shaft of A degrees. The four magnets may include a first magnet which defines a first angular position of the shaft of a1 degrees, a second magnet which defines a second angular position of the shaft of a2 degrees, a third magnet which defines a third angular position of the shaft of a3 degrees and a fourth magnet which defines a fourth angular position of the shaft of a4 degrees, with a4>a3>a2>a1.

Additionally, in the method a1 may be comprised between 4% of A and 14% of A, a2 may be comprised between 20% of A and 36% of A, a3 may be comprised between 40% of A and 60% of A and a4 may be comprised between 70% of A and 90% of A.

Additionally, in the method A may be comprised between 40 and 60 degrees.

Additionally, in the method A may be comprised between 49 and 51 degrees, a1 may be comprised between 5 and 7 degrees, a2 may be comprised between 16 and 18 degrees, a3 may be comprised between 27 and 29 degrees and a4 may be comprised between 39 and 41 degrees.

Additionally, the method may comprise: rotating the shaft of the opening/closing mechanism and opening the electrical circuit of the switch gear; and computing by the processing circuitry the first angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the fourth and the third magnet as the shaft rotates.

Additionally, the method may comprise: rotating the shaft of the opening/closing mechanism and opening the electrical circuit of the switch gear; and computing a second angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the fourth and the second magnet as the shaft rotates.

Additionally, the method may further comprises continue rotating the shaft and computing a third angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the second and the first magnet as the shaft rotates.

Additionally, the method may comprise rotating the shaft of the opening/closing mechanism and closing the electrical circuit of the switch gear and computing a fourth angular speed of the shaft based on signals provided by the magnetic field sensor when it senses the third and fourth magnets as the shaft rotates in one direction.

Additionally, in the method the switch gear device may be a circuit breaker or a contactor.

In a further aspect, the method of monitoring a switch gear device can be used in conjunction with, or as a part of, the monitored switch gear device as defined above.

Further areas of applicability will become apparent from the description herein. The description and specific examples in the summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DETAILED DESCRIPTION

In the figures, the same references denote identical or similar elements, unless stated otherwise. In the drawings, the size of each element or a specific portion constituting the element is exaggerated, omitted, or schematically shown for convenience and clarity of description. Thus, the size of each component may not entirely reflect the actual size. In the case where it is judged that the detailed description of the related known functions or constructions may unnecessarily obscure the gist of the present disclosure, such explanation will be omitted.

Turning now toFIG.1, a simplified perspective view of a monitored switch gear device1is depicted. The monitored switch gear device1comprises of a switch gear9including an opening/closing mechanism. The opening/closing mechanism selectively opens and closes an electrical circuit (not shown). The electrical circuit may comprise one or more electrical contacts actuated by the opening/closing mechanism. The electrical contacts may be comprised within the switch gear9and actuated by the opening/closing mechanism. The opening/closing mechanism has a pivotally mounted shaft5that rotates in the direction of double arrow4about a pivot axis3as the opening/closing mechanism moves between an open and a closed state. The shaft5may be pivotally held6in a bracket2made for instance of a metal sheet or a plastic composite. The shaft5may be on one side pivotally held inside a plain bearing attached to the bracket2or held within the bracket2. The shaft5may have attached a plurality of magnets (shown inFIG.2) that are spaced from each other. The magnets may be attached to the shaft via an optional holder11coupled to the shaft5. The monitored switch gear device1further has a magnetic field sensor7configured to sense a magnetic field generated by each magnet of the plurality of magnets as the shaft5pivots. The magnetic field sensor7may be rigidly coupled to the bracket2so that it does not move when the shaft pivots5. The magnetic field sensor7may face a one side of the holder11where the plurality of magnets is held. The magnetic field sensor7may sense the magnetic field generated by each magnet of the plurality of magnets (shown inFIG.2) as the shaft5pivots4about the pivot axis3and magnets of the plurality of magnets passes the magnetic field sensor7. The magnetic field sensor7may comprise a one or more magneto resistive and/or hall effect type sensor(s) for the magnetic field sensing. When the magnetic field sensor comprises a magneto resistive type sensor it may be a giant magnetoresistance (GMR) type sensor. The magnetic field sensor7may also comprise a one or more switch type Hall effect sensor. The magnetic field sensor7may be configured to generate an electrical signal when it senses a magnet of the plurality of magnets. Sensing a magnet by the magnetic field sensor7means sensing or registering a magnetic field of the magnet by the magnetic field sensor7. A processing circuitry8is depicted in proximity of the magnetic field sensor7, however, the processing circuitry8may be located elsewhere. The processing circuitry8computes a first angular speed of the shaft5based on signals provided by the magnetic field sensor7when it senses at least two magnets of the plurality of magnets as the shaft5pivots in one direction.

Moving toFIG.2, an exemplary perspective simplified view of a portion20of the monitored switch gear device1is depicted. In this exemplary view the shaft34is pivotable about a pivot axis33as shown by the arrows27. The plurality of magnets22,23,24,25are attached to the shaft34via a holder26connected to the shaft34. Shown in the figure the plurality of magnets comprises four discrete magnets22,23,24,25where each of the four discrete magnets22,23,24,25defines an angular position of the shaft that corresponds to a specific position of the opening/closing mechanism between its open and closed state. There may be a different number, for instance 2, 3 or 5 or more, of magnets comprised in the plurality of magnets. The magnets of the plurality of magnets22,23,24,25are spaced from each another and located on a one side of the holder26. The magnets22,23,24,25may be positioned equidistant from the pivot axis33of the shaft34. The magnetic field sensor32is located to face the side of the holder26on which the magnets22,23,24,25are arranged. The magnetic field sensor senses a magnetic field generated by each magnet22,23,24,25of the plurality of magnets as the shaft34rotates about the pivot axis33and magnets of the plurality of magnets passes the magnetic field sensor32. Then each magnet22,23,24,25of the plurality of magnets defines a different angular position of the shaft34in which the magnetic field sensor32respectively senses the magnets22,23,24,25of the plurality of magnets. The magnetic field sensor32may be attached to a printed circuit board (PCB)31to which the processing circuitry30may be also attached.

Moving toFIG.3, showing a side view of an exemplary arrangement of the plurality of magnets41,42,43,44with respect to the shaft54and the magnetic field sensor49. The magnets41,42,43,44are fixedly attached to the shaft55. The shafts pivots about an axis that is perpendicular to the shown axis45and55. The magnets41,42,43,44may be attached to the shaft55via a holder as shown inFIG.2. The plurality of magnets is formed by four discrete magnets41,42,43,44, however, there may be a different number of discrete magnets such as 2, 3, 5 or more magnets. Each of the discrete magnets41,42,43,44defines an angular position50,51,52,53of the shaft54that corresponds to a specific position of the opening/closing mechanism between its open and closed state. As the shaft54pivots in one of directions56the plurality of magnets passes in proximity of the magnetic sensor49. The magnetic field sensor49senses a magnetic field of each of the discrete magnets of the plurality of magnets41,42,43,44as they pass in proximity of it. The magnetic field sensor49may be attached to a printed circuit board (PCB)48to which the processing circuitry47may be also attached. Angular movement of the opening/closing mechanism between its open and closed state is represented by an arc line with arrows A. One benefit of such angular arrangement of discrete magnets41,42,43,44in relation to the shaft54and the sensor49is that when the opening/closing mechanism moves to selectively opens or closes an electrical circuit, then via the related pivot of the shaft54a signal from the magnetic field sensor49can be utilized to monitor progress of the opening or closing of the electrical circuit and consequently monitor the switch gear operation.

Depending on the monitored switch gear, an angular position and number of discrete magnets may vary. In one exemplary implementation an open position of the opening/closing mechanism is defined as an angular position of the shaft54with respect to the sensor as 0 degrees and the closed position of the opening/closing mechanism is defined as an angular position of the shaft54of A degrees. The discrete magnets of the plurality of magnets41,42,43,44may include a first magnet41which defines a first angular position50of the shaft54of a1 degrees, a second magnet42which defines a second angular position51of the shaft of a2 degrees, a third magnet43which defines a third angular position53of the shaft of a3 degrees and a fourth magnet44which defines a fourth angular position53of the shaft54of a4 degrees, with a4>a3>a2>a1.

In one exemplary implementation a1 is comprised between 4% of A and 14% of A, a2 is comprised between 20% of A and 36% of A, a3 is comprised between 40% of A and 60% of A and a4 is comprised between 70% of A and 90% of A. Shafts54complete angular movement in one direction A may be comprised between 40 and 60 degrees. In yet another exemplary implementation A is comprised between 49 and 51 degrees, a1 is comprised between 5 and 7 degrees, a2 is comprised between 16 and 18 degrees, a3 is comprised between 27 and 29 degrees and a4 is comprised between 39 and 41 degrees.

Moving toFIG.4, showing an exemplary arrangement of the plurality of discrete magnets as described in the embodiment ofFIG.3. As shown each discrete magnet of the plurality of magnets61,62,63,64is directionally magnetized so that it has both North and South magnetic pole on the side that passes the magnetic field sensor67as the shaft69pivots. Each discrete magnet of the plurality of magnets61,62,63,64may be a permanent magnet made of NdFeB (Neodium Iron Bore) or SmCo (Samarium Cobalt) or AlNiCo (Aluminum Nickel Co-bait) and may have its remanence Br equal or higher than 0.9 Tesla (9 000 Gauss). Preferably, each discrete magnet of the plurality of magnets61,62,63,64may be a permanent magnet and may have its remanence Br comprised between 0.9 Tesla (9 000 Gauss) and 1.5 Tesla (15 000 Gauss). An airgap between a center of the magnetic field sensor67and a center of a respective passing magnet61,62,63,64as the shaft pivots may be comprised between 1 milli-meter and 2.4 millimeters.

Further, the magnetic field sensor67is arranged to sense the magnetic field variation generated by both North and South magnetic poles of each discrete magnet of the plurality of magnets61,62,63,64when the shaft69pivots as the opening/closing mechanism moves either from an open to close or a close to open position. As depicted the magnetic field sensor67may be placed on a printed circuit board (PCB)66. An optional second magnetic field sensor65may be placed on opposite side of the PCB66or both magnetic fields sensors may be placed next to each other on one side of the PCB66. The magnetic field sensor and the optional second magnetic field sensor may be of the same type and provide mutually redundant signals. One benefit of having two magnetic sensors of the same type providing redundant signals is to improve precision and reliability of the sensed shaft's69angular position. Alternatively, the magnetic field sensor67and the optional second magnetic field sensor65may be of different sensor type and/or provide a different signal. In one example the magnetic field sensor67may comprise a Hall effect switch type magnetic sensor or more specifically a unipolar Hall effect switch type sensor.

One possible example of utilization of such unipolar Hall effect switch type sensor as the magnetic field sensor67is depicted inFIG.5showing an exemplary implementation of the unipolar Hall effect switch type sensor for sensing a magnetic field generated by the discrete magnets of the plurality magnets75,76,77as they pass the unipolar Hall effect switch type sensor when the shaft5,34,54,69rotates. Arrow78shows a direction of magnets movement in time as the shaft rotates and a curve72shows an intensity of sensed magnetic field of the plurality of magnets75,76,77as they pass in time the unipolar Hall effect switch type sensor. As depicted the unipolar Hall effect switch type sensor ofFIG.5may have a first and second switching point thresholds BRP, BOP triggered by a level of a positive magnetic field. In one example the magnetic field sensor67may comprise a unipolar Hall effect switch type sensor having a first switching point BOP set between 0.006 Tesla (60 gauss) and 0.0245 Tesla (245 gauss) and the second switching point BRP set between 0.003 Tesla (30 gauss) and 0.009 Tesla (90 gauss). As depicted inFIG.5the first switching point BOP may be a magnetic field threshold73for switching the unipolar Hall effect type switch on and the second switching point BRP may be a magnetic field threshold74for switching the unipolar Hall effect type switch off.

Curve79depicts a switching dependence of the unipolar Hall effect switch type sensor on the intensity of the sensed magnetic field. In one example falling edges of the unipolar Hall effect switch type sensor output, as it is switched from on to off, may be used for determining time duration T1, T2 that takes two or more magnets of the plurality of magnets75,76,77to pass the unipolar Hall effect switch type sensor as the shaft rotates 5, 34, 54, 69. The time duration T1, T2 together with a known angular positions of the discrete magnets of the plurality of magnets75,76,77can be used to determine a rotational speed of the shaft5,34,54,69. As shown inFIG.5each discrete magnet of the plurality of magnets75,76,77is directionally magnetized so that it has both North and South magnetic pole on the side that passes the Hall effect switch type sensor employed as the magnetic field sensor67. There may be more than three discrete magnets of the plurality of magnets used75,76,77. Additionally, the discrete magnets75,76,77ofFIG.5may be three of four magnets depicted inFIG.4and the Hall effect sensor may be used in the exemplary arrangement of the plurality of discrete magnets as depicted inFIG.4and described in the embodiment ofFIG.3. One benefit of such arrangement is that it is possible to achieve a high switching point accuracy of less than 1 degree of shaft's rotation. Another benefit of using a Hall effect switch type magnetic sensor is its very low cost. Further benefit is in sensing robustness as the Hall effect switch reacts only to a fixed threshold level of magnetic field that is assured by the presence of both magnetic poles that the magnetic field sensor67senses for each of the discrete magnets of the plurality of magnets61,62,63,64. In case of the optional magnetic field sensor65is used it may also comprise a Hall effect switch type magnetic sensor or more specifically a unipolar Hall effect switch type magnetic field sensor.

Moving toFIG.6, an exemplary illustration showing a graph80of a shaft's5,34,54,69rotation versus time during an actuation of the opening/closing mechanism between its closed and open states. The shaft's5,34,54,69angular position versus time during the actuation of the opening/closing mechanism is graphically represented as a line95. Each intersections of the line95by a dashed line81,83,85,86,88,90,92, and94depicts an exemplary point where a magnet of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64passes the magnetic field sensor7,32,49,67as the shaft5,34,54,69rotates. These intersections relate to specific shaft's angular positions a1, a2, a3 and a4 as defined above and shown inFIG.3that correspond to specific positions of the opening/closing mechanism between its open and closed state. As described above the magnetic field sensor7,32,49,67generates a signal when it senses the magnetic field generated by the respective magnet passing the magnetic field sensor7,32,49,67. Based on the signals the processing circuitry8,30,47may compute an angular speed of the shaft5,34,54,69as the shaft pivots in one direction. The processing circuitry8,30,47may compute plurality of angular speeds of the shaft5,34,54,69as it rotates in one direction based on depicted time durations x1, x2, x3, x4, x5, x6 between the signals generated by the magnetic field sensor and known specific shaft's angular positions a1, a2, a3 and a4 defined by the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64. Each of the plurality of angular speeds then may be related to a speed of partial actuation of the opening/closing mechanism between its closed and open states. In other words, as the opening/closing mechanism actuates between its closed and open state the speed of the actuation may not be linear and may be advantageously divided into plurality of speeds each related to a particular portion of an actuation movement that can be advantageously related to a movement of a particular electrical circuit that the opening/closing mechanism selectively open and close. In one example such portions of interest may closely relate to an opening speed, closing speed, damping speed. Such portions may be further related to a rebound and holding of an electrical circuit of a circuit breaker. Graph80ofFIG.5will be further used in description of flow diagrams depicting in following embodiments of a method of monitoring a switch gear device.

Moving toFIG.7, that depicts an exemplary flow diagram of a method100of monitoring a switch gear9as for example shown inFIG.1and further detailed in any ofFIG.2,3or4. The method100may begin at step101by rotating a shaft5,34,54,69of an opening/closing mechanism and selectively opening or closing by the opening/closing mechanism an electrical circuit of the switch gear9. The shaft5,34,54,69may be pivotally mounted to rotate about a pivot axis3,33and the shaft5,34,54,69has a fixedly attached a plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64spaced from each other. The plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64may be attached to the shaft5,34,54,69as shown inFIG.2,3or4. The method in step102senses, by a magnetic field sensor7,32,49,67, a magnetic field generated by at least two magnets of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64, as the shaft5,34,54,69rotates. Each magnet of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64may define a different angular position of the shaft5,34,54,69in which the magnetic field sensor7,32,49,67senses a respective magnet of plurality of magnets. In step103a processing circuitry8,30,47computes a first angular speed of the shaft5,34,54,69based on signals provided by the magnetic field sensor7,32,49,67when it senses the magnetic field generated by the at least two magnets of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64as the shaft5,34,54,69rotates in one direction. As shown in theFIG.2,3or4the plurality of magnets may comprise four discrete magnets22,23,24,25,44,43,42,41,64,63,62,61, where each of the four discrete magnets defines an angular position of the shaft5,34,54,69that corresponds to a specific position of the opening/closing mechanism between its open and closed state. Depending on the monitored switch gear9an angular position and number of discrete magnets may vary and there may be a different number, for instance 2, 3 or 5 or more, of magnets comprised in the plurality of magnets22,23,24,25,44,43,42,41,64,63,62,61. In one exemplary implementation an open position of the opening/closing mechanism is defined as an angular position of the shaft with respect to the magnetic field sensor7,32,49,67of 0 degrees and the closed position of the opening/closing mechanism is defined as an angular position of the shaft54of A degrees. Then four discrete magnets of the plurality of magnets22,23,24,25,44,43,42,41,64,63,62,61may include a first magnet22,41,61which defines a first angular position50of the shaft54of a1 degrees, a second magnet23,42,62which defines a second angular position51of the shaft of a2 degrees, a third magnet24,43,63which defines a third angular position53of the shaft of a3 degrees and a fourth magnet25,44,64which defines a fourth angular position53of the shaft54of a4 degrees, with a4>a3>a2>a1.

In one exemplary implementation, a1 is comprised between 4% of A and 14% of A, a2 is comprised between 20% of A and 36% of A, a3 is comprised between 40% of A and 60% of A and a4 is comprised between 70% of A and 90% of A. Shaft5,34,54,69complete angular movement in one direction A may be comprised between 40 and 60 degrees. In yet another exemplary implementation A is comprised between 49 and 51 degrees, a1 is comprised between 5 and 7 degrees, a2 is comprised between 16 and 18 degrees, a3 is comprised between 27 and 29 degrees and a4 is comprised between 39 and 41 degrees.

Shown inFIG.8is an exemplary flow diagram detailing an opening phase110of the method100of monitoring a switch gear9. The opening phase110, begins by rotating the shaft5,34,54,69having attached four discrete magnets22,23,24,25,41,42,43,44,61,62,63,64each magnet defining a different angular a1, a2, a3, a4 position of the shaft5,34,54,69and opening an electrical circuit of the switch gear9. In a step112then the magnetic field sensor7,32,49,67senses a magnetic field generated by at least two magnets of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64as the shaft5,34,54,69rotates. Then, in step113, the processing circuitry8,30,47computes a first angular speed of the shaft5,34,54,69based on signals provided by the magnetic field sensor7,32,49,67when it senses the fourth25,44,64and the third magnet24,43,63as the shaft rotates. InFIG.6the opening phase110of the method100is illustrated as a portion of the line95that represents the shaft's5,34,54,69angular position versus actuating time as described above. Intersections of the line95by dashed lines81,83,85,86depicts exemplary points where a magnet of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64passes, and is sensed by, the magnetic field sensor7,32,49,67as the shaft5,34,54,69rotates during the opening phase110. In the example shown inFIG.6the first angular speed relates to time durations x1 and intersections of the line95by dashed lines81and83and area82corresponding to signals provided by the magnetic field sensor7,32,49,67when it senses the fourth25,44,64and the third24,43,63magnet as the shaft5,34,54,69rotates. One benefit of calculating the first angular speed is that its value can be closely correlated to an opening speed, in one example an initial opening speed, of the switch gear being monitored. In such case computation of the first angular speed may provide a useful information concerning status of the switch gear9contacts being opened. Change of the first angular speed then may be indicative for instance of a corrosion or micro welds of the contacts.

In one example, as depicted inFIG.9, the opening phase110of the method100of monitoring a switch gear9may comprises a step121of rotating the shaft5,34,54,69of the opening/closing mechanism and opening the electrical circuit of the switch gear9. The opening phase110of the method100of monitoring a switch gear9may further comprises step123of computing a second angular speed of the shaft5,34,54,69based on signals provided by the magnetic field sensor7,32,49,67when it senses the fourth25,44,64and the second23,42,62magnet as the shaft5,34,54,69rotates. In the example shown inFIG.6the second angular speed relates to time durations x2 and intersections of the line95by dashed lines81and84and areas82and84corresponding to signals provided by the magnetic field sensor7,32,49,67when it senses the fourth25,44,64and the second23,42,62magnet as the shaft5,34,54,69rotates. One benefit of calculating the second angular speed is that its value can be closely correlated to an overall opening speed of the switch gear9. In such case monitoring of the first angular speed may provide a useful information concerning status of switch gear opening. Change of the second angular speed then may be indicative for instance of mechanical issues negatively influencing opening speed of the switch gear that may be an important quality for some switch gear devices such as circuit breakers or contactors.

Optionally, the opening phase110of the method100of monitoring a switch gear9may further comprises a step131, depicted onFIG.10, comprising continuation of rotating the shaft5,34,54,69and computing a third angular speed of the shaft based on signals provided by the magnetic field sensor7,32,49,67when it senses the second and the first magnet as the shaft5,34,54,69rotates. In the example shown inFIG.6the third angular speed relates to time durations x3 and intersections of the line95by dashed lines85and86corresponding to signals provided by the magnetic field sensor when it senses the second23,42,62and the first22,41,61magnet as the shaft5,34,54,69rotates. One benefit of calculating the third angular speed is that its value may provide a useful information concerning status of a dampening mechanism optionally utilized in switch gears to eliminate contact bouncing upon opening.

Shown inFIG.11is an exemplary flow diagram detailing a closing phase140of the method100of monitoring a switch gear9. The closing phase140begins with a step141of rotating the shaft5,34,54,69having attached four discrete magnets each magnet defining a different angular a1, a2, a3, a4 position of the shaft5,34,54,69and closing an electrical circuit of the switch gear9. As the shaft5,34,54,69rotates the magnetic field generated by the discrete magnets22,23,24,25,41,42,43,44,61,62,63,64is sensed142by the magnetic field sensor7,32,49,67and a fourth angular speed is computed based on signals provided by the magnetic field sensor7,32,49,67when it senses the third24,43,63and the fourth25,44,64magnet as the shaft5,34,54,69rotates in one direction. InFIG.6the closing phase140of the method100is illustrated as intersections of the line95by dashed lines88,90,92and94depicting exemplary points where a magnet of the plurality of magnets22,23,24,25,41,42,43,44,61,62,63,64passes, and is sensed by, the magnetic field sensor7,32,49,67as the shaft5,34,54,69rotates during the closing phase140. In the example shown inFIG.6the fourth angular speed relates to time duration x6 and intersections of the line95by dashed lines92and94and area93corresponding to signals provided by the magnetic field sensor7,32,49,67when it senses the third24,43,63and the fourth25,44,64magnet as the shaft5,34,54,69rotates in one direction. One benefit of calculating the fourth angular speed is that its value may provide a useful information concerning status of a dampening mechanism optionally utilized in switch gears to eliminate contact bouncing upon closing the electrical contacts.