Title of Invention

CONTROL DEVICE WITH HYSTERESIS

Abstract

Device for control of an electric switching apparatus, comprising a control electromagnet provided with an arm mobile between a rest position and a working position under the action of a coil (20), an auxiliary contact (10) in a power supply circuit of the coil (20) and mechanical means (30) coupled with the mobile arm to activate the auxiliary contact. The mechanical means comprise two compression springs and a slide cooperating with the auxiliary contact to achieve hysteresis such that the open state of the auxiliary contact is obtained at the end of the travel distance bringing the mobile arm into the working position and that the closed state of the auxiliary contact is obtained at the end of the travel distance bringing the mobile arm into the rest positio

Full Text

CONTROL DEVICE WITH HYSTERESIS This invention relates to a device for control of an electromagnet in a low voltage electric switching apparatus, such as a contactor, relay, circuit breaker or contactor breaker, in which the excitation coil comprises an electric power supply circuit comprising an auxiliary contact. The invention also relates to a switching apparatus comprising such a control device. Switching apparatus have fixed pole contacts that cooperate with mobile pole contacts in order to switch an output side electric load. They also comprise a magnetic circuit comprising a mobile armature coupled to the mobile pole contacts controlled by an excitation coil when an electric excitation current passes through it. Operation generally takes place according to the following principle. In a first phase, called the inrush phase, a sufficiently high inrush current passes through the coil so that the mobile armature of the magnetic circuit, for example consisting of a mobile arm, is driven from a rest position to a working position. This displacement also causes displacement of the mobile contacts of the device poles. During a second phase called the hold phase, the arm moves into the working position as long as there is a sufficient hold current passing through the coil. In a third phase, called the drop phase, the excitation current disappears or reduces below a given threshold and the mobile arm returns from the working position to the initial rest position, for example due to return means such as a return spring, which also causes inverse displacement of the mobile contacts of the device poles. In a known manner, the inrush current necessary for the coil to control displacement of the arm mobile from the rest position to the working position, is greater than the hold current. This phenomenon is particularly true with direct current electromagnets. Consequently, if the current consumed by the coil remains the same during the inrush and hold phases, this will cause either an unnecessary temperature rise of the coil during the hold phase if the inrush current passes through it at all times, or bad displacement of the mobile arm if the hold current passing through the coil is insufficient for the inrush phase, with the risk of the pole contacts of the device getting stuck. This is why it is desirable to be able to modify the electric current passing through the coil as a function of the different phases. To achieve this, different means are already used. For example, a first means consists of designing an electromagnet with an additional secondary excitation coil connected in series with the main coil only during the hold phase, or connected in parallel with the main coil only during the inrush phase. Another means also consists of connecting a resistance in series with the main excitation coil and shunting it during the inrush phase using an auxiliary contact connected to the terminals of the resistance and which opens and closes under the control of displacement of the mobile arm. When the auxiliary contact is in the open state, the resistance is in series with the coil and the current passing through the coil is then less than the current that passes through the coil when the auxiliary contact is closed and the resistance is shunted. However, the auxiliary contact switching time is of overriding importance when opening and closing the contact. In the inrush phase, if the auxiliary contact is opened too early during the movement bringing the mobile arm from the rest position to the working position, bringing the resistance into series will reduce the electromagnetic force supplied by the coil. This electromagnetic force may then be insufficient for the arm to reach the working position satisfactorily. This can cause bad switching of the switching apparatus. Conversely, during the drop phase, if the auxiliary contact is closed too early during the movement bringing the mobile arm from the working position to the rest position of the mobile arm, the resistance will be shunted too early, causing an increase in the residual current in the coil which could then supply energy opposing the drop movement of the arm, which would also cause bad switching of the switching apparatus. There is a risk of the pole contacts being welded in both cases. Document WO0120632 shows a device comprising a permanent magnet that is used to create hysteresis between the movement of the mobile arm and switching of an auxiliary contact responsible for connecting or not connecting a resistance in the power supply circuit of a coil in a switching apparatus. This hysteresis offsets the auxiliary contact switching at the required moment, However, the magnetisation force of a permanent magnet varies with the temperature. Since this device may be placed adjacent to heating elements of the electromagnet, there is therefore a risk that the precise opening and closing times of the auxiliary contact are not reproducible, and depend on usage conditions of the device. Furthermore, a magnet can attract metallic particles that may prevent the electrical contacts from closing properly and can increase costs. This is why the purpose of the invention is a simple, inexpensive and robust device that optimises the switching time of an auxiliary contact in a coil power supply circuit in a stable manner, regardless of the usage conditions of the switching apparatus. The device must avoid any premature reduction in the inrush current of the coil, during most of the inrush phase. During the hold phase, the device circulates a hold current less than the inrush current. Conversely, the device must prevent any unwanted increase in the residual coil current during most of the drop phase. Furthermore, the solution must be able to provide very fast switching of the auxiliary contact. To achieve this, the invention describes a control device for an electric switching apparatus, comprising: a control electromagnet provided with an excitation coil and a mobile magnetic arm between a rest and a working position under the action of the coil, to switch contacts of the poles of the switching apparatus, an electric power supply circuit of the coil comprising an auxiliary contact that can be activated between an open state and a closed state, - mechanical means coupled with the mobile arm to activate the auxiliary contact and providing a hysteresis function such that the open state of the auxiliary contact occurs close to the end of the travel distance bringing the mobile arm into the working position and the closed state of the auxiliary contact takes place close to the end of the travel distance bringing the mobile arm into the rest position. The device is characterised in that the mechanical means comprise a slide acting on a mobile contact bridge of the auxiliary contact and provided with a first arm and a second arm, and a fixed pin of the mobile arm, placed between the two arms and acting on the first arm to activate the slide in one direction and on the second arm to activate the slide in the opposite direction-According to one feature, the mechanical means comprise two compression springs cooperating to make a mechanism for going past the neutral point in the travel distance of the slide. This mechanism advantageously enables a fast cut of the auxiliary contact. The pin pulls the slide beyond the neutral point of the travel distance during the travel distance bringing the mobile arm into the working position, and during the travel distance bringing the mobile arm into the rest position. According to another feature, the distance between the pin and the first arm of the slide in the rest position causes a neutral inrush travel distance for the pin. Similarly, the distance between the pin and the second arm of the slide in the working position causes a neutral drop travel distance for the pin. Other features and advantages will appear in the detailed description given below with reference to an embodiment given as an example and represented by the attached drawings in which: figure 1 shows a simplified example of an electrical diagram of a power supply circuit to the coil according to the invention, figure 2 diagrammatically shows the displacement curve of the mobile arm of the electromagnet with time and the corresponding variation in the state of the auxiliary contact, figure 3 shows details of the slide travel distance with respect to the travel distance of the pin fixed to the arm, in both directions, figures 4a to 4d show the different positions of an embodiment of the invention; figure 4a in the rest position R, figure 4c in the working position T, figure 4b during the movement of the slide from the position R to the position T (RT direction) , figure 4b during the movement of the slide from the position T to the position R (opposite direction TR), figures 5 and 6 show two other simplified examples of the electrical diagram for a coil power supply circuit according to the invention, A low voltage electric switching apparatus, particularly a contactor, a relay, circuit breaker or a contactor breaker is required to switch an electric load such as an electric motor, using mobile contacts of poles that can be held in contact with or separated from fixed contacts of poles. For example in a double break device, each pole of the device comprises two fixed contacts cooperating with two mobile contacts fixed onto a pole contact holder, free to move between a rest position R and a working position T, In the case of "closing" contacts, the pole contacts are held in the working position T. In the case of "opening" contacts, the pole contacts are held in the rest position R. The control electromagnet of the device is provided with an excitation coil 20, of the type powered with direct current, and a magnetic circuit comprising a mobile arm that is fixed to the pole mobile contact holders. The mobile arm is driven in a direction when an electrical excitation current passes through the excitation coil. The mobile arm is driven in the other direction by a return spring and/or possibly for example by magnets, when there is no coil current. With reference to the example in figure 1, the main excitation coil 2 0 of a control electromagnet is connected in series with a resistive component between terminals Al, A2 of the coil power supply circuit of a switching apparatus. In the event, the resistive component is composed of one or preferably two resistances 25a, 25b connected in parallel so as to generate a smaller temperature increase in each resistance, compared with a resistive component with the same value but that is composed of a single resistance. An auxiliary contact 10 could be in the open state 0 or in the closed state F and is connected in parallel with resistances 25a, 25b, so that resistances 25a, 25b can be shunted when it is in the closed state F. It would also be possible to use three or more resistances in parallel in an equivalent manner, Therefore as already indicted, when the auxiliary contact 10 is in the open state 0, the current I circulating in the coil 20 and in the resistances 25a, 25b is less than the current circulating in the coil alone when the auxiliary contact 10 is in the closed state F. In this way, it is easy to obtain an electromagnetic force created by the coil 2 0 that varies as a function of the position of the auxiliary contact 10. This simple solution is advantageous, particularly for direct current electromagnets for which it is important to reduce consumption during the hold phase. Figure 2 is a first curve showing a simplified view of the curve for displacement of the mobile arm as a function of time. In its initial position, it is assumed that the arm is in the rest position R. When a sufficient excitation current I passes through the coil 2 0, the mobile arm is driven by an electromagnetic force from the rest position R to the working position T. This step corresponds to the inrush phase denoted PI. Since the inrush phase PI requires a great deal of energy, the auxiliary contact 10 has to be closed during the inrush phase PI to obtain a maximum current I in the coil 20 and it must remain closed as long as possible to facilitate movement of the arm into the T position. In a hold phase denoted P2, the arm is simply held in a working position and the required energy is lower. The auxiliary contact 10 then has to remain open so as to reduce the current consumed in the coil 20, which avoids unnecessarily increasing its temperature, and possibly seriously damaging it. Thus, the size of the electromagnet can advantageously be optimised, since a high current can be circulated only during the phase PI which is short. When the coil current I disappears or drops below a predetermined threshold (for example corresponding to a residual voltage at the coil terminals equal to 10% of the nominal voltage according to standard IEC947-1), the coil is no longer capable of holding the arm in the working position T and the return spring pulls the arm towards the rest position R, which forms the drop phase denoted P3. However, it is important that the auxiliary contact only closes at the end of this phase P2. If it closes prematurely, there will be an increase in the residual current circulating in the coil 20 and therefore in the electromagnetic force. If the arm has not returned sufficiently close to its rest position R, this can slow down the mobile arm while in an intermediate position and there will therefore be a risk that the contacts of the poles of the device could close with a low contact pressure or zero contact pressure ("stop on poles"), making welding of the poles inevitable. According to the invention, the auxiliary contact 10 is activated by the mobile arm using mechanical means. Therefore these mechanical means need to be arranged to satisfy the requirements mentioned above, in other words such that the open state 0 of the contact 10 occurs slightly before the end of the travel distance of the mobile arm in the position T, and conversely such that the closed state F of the contact 10 occurs slightly before the end of the travel distance of the mobile arm in the R position. In the embodiment shown in figures 4a to 4d, the auxiliary contact 10 has a mobile bridge 11 moving along a translation axis X and carrying elements of mobile contacts cooperating with elements of fixed contacts 15, 16. Figure 4a shows the auxiliary contact 10 in the closed state F in which a current circulates between terminals 18, 19 of the auxiliary contact 10. Figure 4c shows an auxiliary contact 40 in the open state 0. The mobile bridge 11 of the auxiliary contact 10 can be activated by mechanical means 21, 30. In the preferred embodiment, these mechanical means comprise a slide 3 0 connected to the mobile bridge 11 and a pin 21 fixed to the mobile arm and acting on the slide 30. The slide 30 is mobile along the X translation axis. It comprises a longitudinal body from which a first arm 31 and a second arm 32 at a distance of the first arm 31 move in the same direction, for example perpendicular to the X axis. The mobile bridge 11 is fixed to the slide 3 0 through a contact pressure spring 14 and a limit stop 37. A first end of the pressure spring 14 bears on one end 3 5 of the body of the slide 3 0 and the other end of the spring 14 bears on the mobile bridge 11. Between the two arms 31, 32, there is a pin 21 fixed to the mobile arm either directly or indirectly, for example using any intermediate connecting part. Therefore a displacement of the arm causes a displacement of the pin 21 along the X axis. The pin 21 is arranged so that it can pull the slide 3 0 in an RT direction (in other words Rest towards Working direction) bearing on the first arm 31, and moving the slide in an opposite direction TR (in other words Working towards Rest direction) bearing on the second arm 32. First ends of the two compression springs 33, 34 are fixed at a point 38 onto the slide body 30. The other ends of the springs 33, 34 are fixed to attachment points 43, 44 of the device housing. The two springs 33, 34 and the attachment points 43, 44 extend on each side of the slide 30 symmetrically about the X axis. The springs 33, 34 thus form a mechanism to pass the neutral point M in the travel distance of the slide. The median neutral point M is formed by the intersection between the X axis and the perpendicular axis formed by points 43, 44 and corresponds to the maximum compression of springs 33, 34. Depending on the position of the point 3 8 with respect to this neutral point M, the slide 30 is forced in one direction or the other direction by the springs 33, 34. The change from the RT direction to the TR direction of the drive force applied by the springs 33, 34 on the slide 30 takes place at the time that the point 38 goes past the neutral point M. The attachment points 43, 44 of the springs 33, 34 are made with bearing points, such as "blade" bearings. The electrical device also comprises stop means 42, 45, for example formed by the housing of the device, against which the ends of the body of the slide 3 0 bear to limit its displacements. The device operates as follows: In the initial position in figure 4a, the pin 21 connected to the mobile arm is in the rest position R. The slide 30 is pushed by springs 33, 34 in the TR direction and one end of the body of the slide close to the second arm 32 remains in contact with a stop 42. The springs 33, 34 thus keep the slide 3 0 in the rest position R. The auxiliary contact 10 is then in the closed state under the action of the pressure spring 14 on the mobile bridge 11, to keep a satisfactory contact pressure. The force exerted by the springs 33, 34 along the X axis is greater than the force exerted by the spring 14, so as to keep the slide 30 in the R position and to maintain good closing pressure of the auxiliary contact 10. In this stable position R, the distance between the pin 21 and the first arm 31 is equal to a value Cnl, When the current passing through the coil 2 0 is sufficient to move the mobile arm, the pin 21 will begin a displacement in the RT direction. This displacement comprises firstly a neutral inrush distance corresponding to the length Cnl before the pin 21 comes into contact with the first arm 31. The pin 21 then drives the slide 30 through the arm 31 until the point 38 passes the neutral point M, passing along a travel distance denoted Cpl (figure 4a) . The force generated by the arm is obviously much greater than the force exerted by the springs 33, 34 along the X-axis, which is why the pin 21 can easily pull the slide 30 as far as the neutral point M, without disturbing operation of the arm. Figure 4b shows the passage through the neutral point M in the RT direction. In this intermediate position, the pin 21 is still driving the first arm 31 and the auxiliary contact 10 is still in the closed state. When the pin 43, 44 passes through the point 38, the force exerted by the springs 33, 34 will be inverted and will pull the slide 30 in the RT direction without encountering any resistance, until the end 3 5 of the slide close to spring 14 is in contact with stop 45, passing through a distance denoted Cp2 (see figure 4c) . Therefore during the travel distance Cp2 in the RT direction, the slide is acted upon by springs 33, 34. The spring 14 will then be completely relaxed and the auxiliary contact 10 will change to the open state, for example due to stop 37 of slide 30. The device is designed such that the auxiliary contact 10 preferably opens at the beginning of the travel distance Cp2, when the point 3 8 is at a distance d beyond the neutral point M. In the RT direction, the neutral point M is passed before the auxiliary contact 10 opens and before complete relaxation of spring 14. Therefore the auxiliary contact 10 remains firmly closed as long as the neutral point M has not been reached. Moreover, this arrangement enables very fast switching of the contact 10, since as soon as the neutral point M is passed, the force in the springs 33, 34 will facilitate sudden opening of the auxiliary contact 10 advantageously accelerating separation between the bridge 11 and the fixed contacts 15, 16. This thus avoids damaging contact disks by minimising any arc extinguishing that appear when the contacts open. The position thus obtained is the working position T shown in figure 4c. In this position T, the arm 31 is then no longer fixed to the pin 21, and its position is stable due to the mechanism for going past the neutral point of the slide travel distance that pushes the slide in contact with the stop 45. In this stable position T, the distance between the pin 21 and the second arm 32 is equal to a value Cn2. When the current in the coil 20 drops below a predetermined threshold, the arm leaves the T position under the action of the return means and the pin 21 therefore begins a displacement in the opposite direction TR, This displacement comprises firstly a neutral drop distance corresponding to the length Cn2, before the pin 21 comes into contact with the second arm 32. The pin 21 then drives the slide 30 through the arm 32 until the point 3 8 goes past the neutral point M, going along the travel distance Cp2 in the TR direction. The force generated by the arm is obviously much greater than the force exerted by the springs 33, 34 along the X axis, which means that the pin 21 can easily drive the slide 30 as far as the neutral point, without disturbing operation of the arm. The auxiliary contact 10 preferably changes to the closed state F shortly before the end of the travel distance Cp2 in the TR direction, when the point 38 is at a distance d before the neutral point M. Figure 4d shows the change of the neutral point to the TR direction. In this intermediate position, the pin 21 still drives the second arm 32. At the time that the axis 43, 44 goes past through the point 38, the force exerted by the springs 33, 34 will be inverted and will very quickly move the slide 30 in the TR direction until the end of the slide close to the second arm 32 is in contact with the stop 42, passing through the distance Cpl. The position thus obtained is the rest position R shown in figure 4a. In this position R, the second arm 32 is then no longer fixed to pin 21, and the position is stable due to the mechanism for going past the neutral point of the slide travel distance. Therefore with reference to figure 3, the distance travelled as pin 21 moves between the R and T positions in the RT direction is equal to (Cnl + Cpl + Zl) . This safety distance zl is equal to the distance through which the pin 21 passes after the slide 30 passes through the neutral point M, It is essential to guarantee that the pin 21 will always drive the slide 3 0 beyond the neutral point M, and therefore that the slide 30 will be able to open the auxiliary contact 10, regardless of the tolerances of the various mechanical parts of the switching apparatus. The distance travelled in the TR direction by the pin 21 is equal to (Cn2 + Cp2 + Z2) between the T and R positions, the safety distance z2 having the same purpose in the TR direction as the distance zl in the RT direction. The distance travelled by the slide 30 in the RT or the TR direction is equal to (Cpl + Cp2), the neutral point M is approximately at the mid-point of this travel distance. Therefore, in the RT direction, the auxiliary contact 10 will open 0 after a travel distance Cnl of the pin 21 followed by a travel distance (Cpl + d) of the slide 30. Conversely, in the TR direction, the auxiliary contact 10 will close F after a travel distance Cn2 of the pin 21 followed by a travel distance (Cp2 - d) of the slide 30. Therefore the hysteresis generated by mechanical connecting means between the mobile arm of the control electromagnet and the auxiliary contact of the coil power supply circuit is related mainly to existence of the neutral inrush distance Cnl in the RT direction separating the pin 21 from the first arm 31, and in the TR direction of the neutral drop distance Cn2 that separates the pin 21 from the second arm 32. With the invention, it is thus possible to design a simple and economic hysteresis that is very precise, particularly because it only includes purely mechanical elements. According to one embodiment mentioned as an example for a given type of electric switching apparatus, travel distances Cpl and Cp2 are chosen to be equal to 2 mm, Cnl 3.5 mm, Cn2 3.9 mm, distance d 0.3 mm, safety distance zl 0.9 mm and safety distance z2 0.5 mm. Taking these example values, the travel distance of pin 21 is then 6.4 mm in both directions and the travel distance of the slide 30 is 4 mm. During the inrush phase, the auxiliary contact 10 opens 5.8 mm after the R position, in other words when the mobile arm has passed along approximately 90% of its RT distance. Therefore, the open state 0 occurs a short distance or a short time before the end of the 6.4 mm travel distance moving the mobile arm into the working position T. The kinetic energy stored by the moving arm at this instant is then sufficient to allow it to complete the remaining 10% to reach the T position under satisfactory conditions for the switching apparatus, despite the fact that the auxiliary contact is open and therefore the current circulation in the coil 20 has dropped. Conversely, during the drop phase, the auxiliary contact 10 closes at a distance 5.6 mm after the T position, in other words when the mobile arm has travelled about 87% of the TR distance. Therefore the closed state F actually occurs close to or at a short distance or a short time from the end of the 6.4 mm travel distance moving the mobile arm into the rest position R. At this moment, the magnetic circuit of the arm is sufficiently open so that the closure of the auxiliary contact 10 generating an increase in the residual current circulating in the coil 2 0 can no longer significantly hinder completion of the remaining distance so as to reach the T position satisfactorily for the switching apparatus. In general, it is considered that the hysteresis generated by the mechanical means 3 0 according to the invention must be such that the open state 0 of the auxiliary contact 10 during the inrush phase PI only occurs when about 8 0% of the travel distance bringing the mobile arm into the working position T has already been completed, to obtain satisfactory results and avoid the disadvantages mentioned above. Similarly, the hysteresis created by the mechanical means 3 0 must be such that the closed state of the auxiliary contact 10 during the drop phase P3 only occurs when about 80% of the travel distance bringing the mobile arm into the rest position R has already been completed. In the variants in figures 5 and 6 of the circuit in figure 1, the coil power supply circuit comprises a main coil 20, an auxiliary contact 10 and a secondary coil 21 or 22. In the configuration in figure 5, a small secondary coil 21 is added in series with the main coil 20, It is wound on the same core as the coil 2 0 but is composed of a thinner conducting wire and therefore with higher resistance. It is shunted in the inrush phase PI when the auxiliary contact 10 is closed F. If the contact 10 is closed, the resistance of the coil 20 is lower and the current is maximum. Then, when the contact 10 is open, the resistance increases quickly because the conducting wire of the secondary coil 21 with higher resistance and the coil power supply circuit then consumes less current. In the configuration in figure 6, the secondary coil 22 is connected in parallel with the main coil 20 only when the auxiliary contact 10 is closed, in the inrush phase PI. Thus, the maximum number of ampere turns available in the inrush phase PI is combined with a lower resistance because the two coils are connected in parallel. The coil 20 is sized so that it alone controls the hold phase P2 during which the auxiliary contact 10 is open, the resistance then being increased and the current consumption reduced. Other variants of the power supply circuit are also possible like that indicated in document FR2 8 07871 that comprises two coils installed either in series or in parallel depending on the state of two auxiliary contacts. Obviously, without going outside the scope of the invention, it would be possible to imagine other variants and improvements to details and even to envisage the use of equivalent means. In particular, it would be possible for the slide 3 0 to be mobile in rotation, for example about a median axis, instead of being mobile in translation. CLAIMS 1. Device for control of an electric switching apparatus, comprising: a control electromagnet provided with an excitation coil (20) and a magnetic arm mobile between a rest position (R) and a working position (T) under the action of the coil (20), to switch contacts of the poles of the switching apparatus, an electric power supply circuit of the coil (20) comprising an auxiliary contact (10) that can be activated between an open state (O) and a closed state (F), mechanical means (3 0) coupled with the mobile arm to activate the auxiliary contact (10), and providing a hysteresis function such that said open state (0) occurs close to the end of the travel distance bringing the mobile arm into said working position (T) and said closed state (F) occurs close to the end of the travel distance bringing the mobile arm into said rest position (R) , characterised in that the mechanical means comprise a slide (30) acting on a mobile contact bridge (11) of the auxiliary contact (10) and provided with a first arm (31) and a second arm (32) , and a pin (21) fixed to the mobile arm, placed between the two arms and acting on the first arm (31) to activate the slide (30) in one direction (RT) and on the second arm (32) to activate the slide (30) in an opposite direction (TR). 2. Control device according to claim 1, characterised in that the mechanical means comprise two compression springs (33, 34) cooperating with the slide (3 0) for making a neutral point (M) mechanism in the travel distance of the slide (30). 3. Control device according to claim 2, characterised in that the pin (21) pulls the slide (30) beyond said neutral point (M) of the travel distance of the slide (30). 4. Control device according to claim 2, characterised in that, during the travel distance bringing the mobile arm into said working position (T) , the auxiliary contact (10) opens after the slide (30) has passed said neutral point (M) , under the action of the compression springs (33, 34), 5. Control device according to claim 4, characterised in that, in said rest position (R) , the slide (30) is held in position by the compression springs (33, 34) , 6. Control device according to claim 1, characterised in that the power supply circuit of the coil (20) comprises one or several resistances (25a, 25b) that are shunted by the auxiliary contact (10) in said closed state (F). 7. Control device according to claim 1, characterised in that the power supply circuit of the coil (20) comprises one auxiliary coil (21) in series with the coil (2 0) and that is shunted by the auxiliary contact (10) in said closed state (F). 8. Control device according to claim 1, characterised in that the power supply circuit of the coil (20) comprises one auxiliary coil (22) in parallel with the coil (20) and supplied when the auxiliary contact (10) is in said closed state (F). 9. Control device according to claim 1, characterised in that the distance between the pin (21) and the first arm (31) of the slide (30) in said rest position (R) causes a neutral inrush travel distance (cnl) for the pin (21), and the distance between the pin (21) and the second arm (32) of the slide (30) in said working position (T) causes a neutral drop travel distance (cn2) for the pin (21) . 10. Electric switching apparatus, characterised in that it comprises at least one control device according to one of the preceding claims. 11. A device for control of an electric switching apparatus substantially as herein described with reference to the accompanying drawings.

Documents:

380-CHE-2004 CORRESPONDENCE OTHERS 19-01-2012.pdf

380-CHE-2004 OTHER PATENT DOCUMENT 19-01-2012.pdf

380-CHE-2004 POWER OF ATTORNEY 16-12-2011.pdf

380-CHE-2004 AMENDED PAGES OF SPECIFICAITON 16-12-2011.tif

380-CHE-2004 AMENDED CLAIMS 16-12-2011.pdf

380-CHE-2004 EXAMINATION REPORT REPLY RECEIVED 16-12-2011.pdf

380-CHE-2004 FORM-3 16-12-2011.pdf

380-CHE-2004 OTHER PATENT DOCUMENT 16-12-2011.pdf

380-che-2004-abstract.pdf

380-che-2004-claims.pdf

380-che-2004-correspondnece-others.pdf

380-che-2004-description(complete).pdf

380-che-2004-drawings.pdf

380-che-2004-form 1.pdf

380-che-2004-form 26.pdf

380-che-2004-form 3.pdf

380-che-2004-form 5.pdf

380-che-2004-other documents.pdf