Medium voltage contactor

Systems, methods, techniques and apparatuses of contactors are disclosed. One exemplary embodiment is a contactor including an electric pole, a pair of plungers, and a pair of opening springs. The electric pole includes a fixed yoke member and a movable yoke member arranged respectively at a proximal position and a distal position with respect to a movable contact. The fixed yoke member includes a pair of through holes. The pair of second plungers are inserted in a corresponding through hole passing through the fixed yoke member and symmetrically positioned with respect to a main symmetry plane of the contactor, which is parallel to a displacement axis of the movable contact and perpendicular to a displacement plane of the movable contact. The pair of opening springs are symmetrically positioned with respect to the main symmetry plane.

The present invention relates to a contactor (e.g. a vacuum contactor) for medium voltage electric systems.

For the purpose of the present application, the term “medium voltage” (MV) relates to operating voltages at electric power distribution level, which are higher than 1 kV AC and 1.5 kV DC up to some tens of kV, e.g. up to 72 kV AC and 100 kV DC.

As is known, MV electric systems typically adopt two different kinds of switching devices.

A first type of switching devices, including for example circuit breakers, is basically designed for protection purposes, namely for carrying (for a specified time interval) and breaking currents under specified abnormal circuit conditions, e.g. under short circuit conditions.

A second type of switching devices, including for example contactors, is basically designed for manoeuvring purposes, namely for carrying and breaking currents under normal circuit conditions including overload conditions.

A widely used type of MV contactors is represented by MV vacuum contactors.

These apparatuses are quite suitable for installation in harsh environments (such as in industrial and marine plants) and are typically used in control and protection of motors, transformers, power factor correction banks, switching systems, and the like.

MV vacuum contactors comprise, for each electric pole, a vacuum bulb in which the electrical contacts are placed to mutually couple/decouple upon actuation by a suitable actuating device. Some MV vacuum contactors of the state of the art (of the so-called “bi-stable” type) adopt an electromagnetic actuator to move the movable contacts from a decoupled position to a coupled position with respect to the fixed contacts, and vice-versa.

Examples of these MV vacuum contactors are disclosed in patent applications EP1619707A1 and WO2011/000744.

As the electromagnetic actuator has to be fed with proper levels of electric power during both the closing and opening maneuvers of the movable contacts, these contactors are arranged with on-board electric energy storage systems (e.g. capacitor banks or batteries) and complex drive circuits to ensure a proper and, above all, safe operation thereof.

Therefore, these apparatuses may be of problematic usage and are generally quite time-consuming and expensive to assembly and manufacture at industrial level.

This last drawback is made even more critical when the electromagnetic actuator is provided (as it often occurs) with rare-earth permanent magnets notoriously produced with highly expensive materials.

Other MV vacuum contactors of the state of the art (of the so-called “mono-stable” type) adopt an electromagnetic actuator to move the movable contacts from a decoupled position to a coupled position with respect to the fixed contacts and opening springs to move the movable contacts from a coupled position to a decoupled position with respect to the fixed contacts.

Generally, currently available contactors of this type are provided with complex kinematic chains (normally including roto-translational mechanisms) to transmit forces to the movable contacts and with complex arrangements to house and guide the opening springs during operation.

Also these apparatuses typically have a cumbersome structure and are time-consuming and expensive to assembly and manufacture at industrial level.

The main aim of the present invention is to provide a contactor for MV electric systems that allows solving or mitigating the above mentioned problems.

More in particular, it is an object of the present invention to provide a contactor having high levels of reliability for the intended applications.

As a further object, the present invention is aimed at providing a contactor having a relative simple and space-saving structure.

Still another object of the present invention is to provide a contactor that can be easily manufactured at industrial level, at competitive costs with respect to the solutions of the state of the art.

In order to fulfill these aim and objects, the present invention provides a contactor, according to the following claim1and the related dependent claims.

In a general definition, the contactor, according to the invention, comprises one or more electric poles.

Preferably, the contactor, according to the invention, is of the multi-phase (e.g. three-phase) type, thereby comprising a plurality (e.g. three) of electric poles.

For each electric pole, the contactor, according to the invention, comprises a fixed contact and a movable contact.

The one or more movable contacts of the contactor are reversibly movable along corresponding displacement axes mutually parallel and lying on a common displacement plane.

Each movable contact is reversibly movable between a first position, at which it is decoupled from the corresponding fixed contact, and a second position, at which it is coupled with the corresponding fixed contact.

The contactor, according to the invention, comprises an armature reversibly movable along a corresponding displacement direction parallel to the displacement axes of said movable contacts, between a third position and a fourth position.

Advantageously, the third and fourth positions of the movable armature correspond respectively to the first and second positions of the movable contacts of the contactor.

Preferably, said movable armature is shaped as a beam having a corresponding main longitudinal axis perpendicular to the displacement axes of said movable contacts and parallel to the displacement plane of said movable contacts.

The contactor, according to the invention, comprises, for each electric pole, a first plunger solidly connected with said movable armature and with a corresponding movable contact to transmit mechanical forces to said movable contact.

Each of said first plungers extends along a corresponding main longitudinal axis parallel or coinciding with the displacement axis of a corresponding movable contact of the contactor.

The contactor, according to the invention, comprises an electromagnetic actuator provided with a magnetic yoke forming a magnetic circuit.

Said magnetic yoke comprises a fixed yoke member and a movable yoke member.

The movable yoke member is reversibly movable, along a corresponding displacement direction parallel to the displacement axes of said movable contacts, between a fifth position, at which it is decoupled from said fixed yoke member, and a sixth position, at which it is coupled with said fixed yoke member.

Advantageously, the fifth and sixth positions of the movable yoke member correspond, respectively, to the third and fourth positions of the movable armature and, consequently to the first and second positions of the movable contacts of the contactor.

The electromagnetic actuator further comprises a coil wound around the fixed yoke member. Said coil is adapted to be fed by a coil current to make the fixed yoke member to magnetically interact with the movable yoke member and, as a consequence of such an interaction, move the movable yoke member from said fifth position to said sixth position or maintain said movable yoke member in said sixth position.

In particular, the electromagnetic actuator is adapted to provide a mechanical force to move the movable contacts of the contactor during a closing manoeuver of this latter or adapted to maintain the movable contacts of the contactor coupled with the respective fixed contacts, i.e. in the above mentioned second position (closing position).

The contactor, according to the invention, comprises one or more opening springs positioned between the fixed yoke member and the movable yoke member.

Said opening springs are adapted to provide a mechanical force to move the movable yoke member from said sixth position to said fifth position, upon interruption of the coil current feeding the coil of the electromagnetic actuator.

In particular, said opening springs are adapted to provide a mechanical force to move the movable contacts of the contactor during an opening manoeuver of this latter.

The contactor, according to the invention, comprises a plurality of second plungers coupled with said movable yoke member and said movable armature to transmit mechanical forces to said movable armature and, consequently, to move said movable contacts.

Each of said second plungers extends along a corresponding main longitudinal axis parallel to the displacement axes of said movable contacts.

Preferably, the displacement direction of said movable armature, the displacement direction of said movable yoke member, the main longitudinal axes of said first plungers and the main longitudinal axes of said second plungers lye on the displacement plane of said movable contacts.

Preferably, the contactor comprises, for each electric pole, a contact spring positioned between a corresponding fixed rest surface and said movable armature.

Each contact spring is adapted to provide a mechanical force directed in such a way to oppose to any separation of the electric contacts of the corresponding electric pole, when said electric contacts are in a closing position. In this way, possible bounces of the movable contacts due to electrodynamic repulsion phenomena are reduced when the contactor is in a closing state.

However, each contact spring advantageously provides also a mechanical force to move said movable armature from said third position towards said fourth position. In particular, the contact springs of the contactor are adapted to provide a mechanical energy to start moving said movable armature (and consequently the movable contacts of the contactor) during an opening manoeuver of this latter.

According to an embodiment of the invention:said fixed yoke member and said movable yoke member are arranged respectively at a proximal position and a distal position with respect to said movable contacts;the contactor comprises a pair of said second plungers symmetrically positioned with respect to a main symmetry plane of said contactor, said symmetry plane being parallel to the displacement axes of said movable contacts and perpendicular to the displacement plane of said movable contacts;the contactor further comprises a pair of said opening springs symmetrically positioned with respect to said main symmetry plane;said fixed yoke member comprises a pair of through holes, each of said second plungers being inserted in a corresponding through hole and passing through said fixed yoke member.

According to an embodiment of the invention:said fixed yoke member comprises a main portion in a proximal position with respect to said movable contacts and shaped as a beam having a main longitudinal axis perpendicular to the displacement axes of said second movable contacts and parallel to the displacement plane of said movable contacts;said fixed yoke member further comprises a pair of lateral limb portions, each of said lateral limb portions being positioned at a corresponding end of said main portion and protruding from said main portion towards said movable yoke member, each of said lateral limb portions having a corresponding free end in a distal position with respect to said movable contacts, the free ends of said lateral limb portions being coupled with said movable yoke member, when said movable yoke member in said sixth position;said fixed yoke member further comprises an intermediate limb portion positioned between said lateral limb portions and protruding from said main portion towards said movable yoke member, said intermediate limb portion having a corresponding free end in a distal position with respect to said main portion;said movable yoke portion is shaped as a beam having a main longitudinal axis perpendicular to the displacement axes of said second movable contacts and parallel to the displacement plane of said movable contacts.

Preferably, the free ends of said lateral limb portions are coupled with said movable yoke member, when said movable yoke member in said sixth position.

Preferably, the free end of said intermediate limb portion is separated from said movable yoke member, when said movable yoke member in said sixth position.

Preferably, the coil of said electromagnetic actuator is wound around the intermediate limb portion of said fixed yoke member.

Preferably, each through hole of said fixed yoke member is coaxial with a corresponding lateral limb portion of said fixed yoke member.

Preferably, each second plunger of said contactor is inserted in a corresponding through hole and passes through a corresponding lateral limb portion of said fixed yoke member and the main portion of said fixed yoke member.

Preferably, each opening spring of the contactor is coupled with the main portion of said fixed yoke member and with said movable yoke member.

Preferably, each opening spring of the contactor is positioned coaxially with a corresponding lateral limb portion of said fixed yoke member and outwardly surrounds said corresponding lateral limb portion.

Preferably, the contactor, according to the invention, is of the vacuum type. In this case, for each electric pole, the contactor comprises a vacuum chamber, in which a corresponding pair of movable and fixed contacts is placed to be mutually coupled/decoupled.

With reference to the figures, the present invention relates to a contactor1for medium voltage (MV) electric systems.

The contactor1comprises a breaking section11and an actuation section12, which respectively include the electric poles and the actuation components of the contactor.

Taking as a reference a normal installation position of the contactor, shown in the cited figures, the breaking section11is overlapped to the actuation section12.

The contactor1comprises an outer case2preferably made of electrically insulating material of known type (e.g. thermoplastic materials such as polyamide or polycarbonate or thermosetting materials such as polyester or epoxy resins and the like).

The outer case2is adapted to be fixed to a support (not shown) during the installation of the contactor1.

The contactor1comprises one or more electric poles3.

Preferably, the contactor1is of the multi-phase type, more particularly of the three-phase type, as shown in the cited figures.

Preferably, each electric pole3comprises a corresponding insulating housing35, which is part of the outer case2at the breaking section11of this latter.

Preferably, each housing35is formed by an elongated (e.g. cylindrical) hollow body of electrically insulating material of known type.

Preferably, each housing35defines an internal volume, in which the components of the corresponding electric pole3are accommodated.

Advantageously, each electric pole3comprises a first pole terminal36and a second pole terminal37, which may be mechanically fixed to the housing35by means of flanges.

The pole terminals36,37are adapted to be electrically connected with a corresponding electric conductor (e.g. a phase conductor) of an electric line.

For each electric pole3, the contactor1comprises a fixed contact31and a movable contact32, which are electrically connected to the first and second pole terminals36,37respectively.

The movable contacts32are reversibly movable, along corresponding displacement axes33(e.g. forming the main longitudinal axes of the electric poles3) that are mutually parallel (FIG. 1) and lye on a common displacement plane34(FIG. 2).

In particular, the movable contacts32are reversibly movable (see the corresponding bidirectional displacement arrowFIG. 5) between a first position A (opening position), at which they are decoupled from the corresponding fixed contacts31, and a second position B (closing position), at which they are coupled with the corresponding fixed contacts31(FIGS. 5-6).

The passage of the movable contacts32from the first position A to the second position B represents a closing manoeuver of the contactor1whereas the passage of the movable contacts32from the second position B to the first position A represents an opening manoeuver of the contactor1.

Preferably, the contactor1is of the vacuum type.

In this case, for each electric pole3, the contactor1comprises a vacuum chamber39that may be of known type.

In each vacuum chamber39, a corresponding pair of movable and fixed contacts31,32is placed and can be mutually coupled/decoupled.

The contactor1comprises a movable armature7reversibly movable along a displacement direction parallel to, and preferably co-planar with, the displacement axes33of the movable contacts32(see the corresponding bi-directional displacement arrowFIG. 5).

In particular, the movable armature7is reversibly movable between a third position C and a fourth position D (FIGS. 5-6).

The third and fourth positions C, D of the movable armature7advantageously correspond to the first and second positions A, B of the movable contacts32, respectively.

Preferably, the movable armature7is formed by a beam of metallic material of known type (e.g. non-ferromagnetic steel or aluminium), which has a corresponding main longitudinal axis perpendicular to the displacement axes33of the movable contacts32and parallel to the displacement plane34of said movable contacts.

Preferably, the armature7is part of the actuation section12of the contactor1, at a proximal position with respect to the movable contacts32.

The contactor1comprises, for each electric pole3, a first plunger8of non-ferromagnetic, electrically insulating material of known type (e.g. (e.g. thermoplastic materials such as polyamide or polycarbonate or thermosetting materials such as polyester or epoxy resins and the like).

Each plunger8is solidly connected with the movable armature7and with a corresponding movable contact32to transmit mechanical forces to the movable contacts32, when the movable armature7is actuated.

Each plunger8may be solidly fixed to the movable armature7and the corresponding movable contact32by means of fixing means of known type.

Preferably, each plunger8extends along a corresponding main longitudinal axis parallel (and preferably co-planar) to or coinciding with the displacement axis33of a corresponding movable contact32of the contactor.

Each plunger8is at least partially accommodated in the internal volume defined by the housing35of a corresponding electric pole3.

The contactor1comprises an electromagnetic actuator4.

The electromagnetic actuator4is advantageously part of the actuation section12of the contactor1, at a distal position with respect to the movable contacts32.

In practice, the electromagnetic actuator4is placed in a lower position with respect to the movable armature7taking as a reference a normal installation position of the contactor1, as shown in the cited figures.

The electromagnetic actuator4is provided with a magnetic yoke41-42of ferromagnetic material of known type (e.g. Fe or Fe, Si, Ni, Co alloys) to form a magnetic circuit.

In the cited figures (see e.g.FIGS. 7-8), the parts made of ferromagnetic material of the magnetic yoke41,42are shown with dotted lines for illustrative purposes only.

The magnetic yoke of the electromagnetic actuator4comprises a fixed yoke member41and a movable yoke member42.

The fixed yoke member41may be solidly fixed to outer casing2of the contactor by means of fixing means of known type.

The movable yoke member42is reversibly movable, along a corresponding displacement direction parallel to, and preferably co-planar with, the displacement axes33of the movable contacts32(see the corresponding bi-directional displacement arrowFIG. 5).

In particular, the movable yoke member42is reversibly movable between a fifth position E, at which it is decoupled from the fixed yoke member41, and a sixth position F, at which it is coupled with the fixed yoke member41.

Advantageously, the fifth and sixth positions E, F of the movable yoke member42correspond respectively to the third and fourth positions C, D of the movable armature7and consequently, to the first and second positions A, B of the movable contacts32.

In view of the above, it is evident that:the movable yoke member42passes from the fifth position E to the sixth position F to perform a closing manoeuver of the contactor;the movable yoke member42passes from the sixth position F to the fifth position E to perform an opening manoeuver of the contactor;when the the movable yoke member42is in the fifth position E, the movable contacts32are decoupled from the corresponding fixed contacts31(opening position);when the the movable yoke member42is in the sixth position F, the movable contacts32are coupled with the corresponding fixed contacts31(closing position).

The electromagnetic actuator4further comprises a coil44wound around the fixed yoke member41.

The coil44is adapted to be electrically connected to an auxiliary power supply (not shown) so as to receive a coil current IC from this latter.

When the coil44is fed by a coil current IC, the fixed yoke member41magnetically interacts with the movable yoke member42as the magnetic flux generated by the coil current IC circulates along the magnetic circuit formed by the fixed yoke member41and the movable yoke member42.

The magnetic interaction between the fixed yoke member41and the movable yoke member42makes the movable yoke member42to move from the fifth position E to the sixth position F, if the yoke members41-42are still decoupled, or makes the movable yoke member42to remain in the sixth position F, if the yoke members41-42are already coupled.

The magnetic interaction between the fixed yoke member41and the movable yoke member42, in fact, causes the generation of a magnetic force that makes the movable yoke member42to couple or remain coupled with the fixed yoke member41in order to close any possible airgap between these two ferromagnetic elements.

Besides, it is evidenced that the above described interaction between the fixed yoke member41and the movable yoke member42occurs irrespectively of the direction of the coil current IC, which may thus be positive or negative according to the needs.

In view of the above, it is evident that the electromagnetic actuator4is adapted to provide a mechanical force to perform a closing operation (passage from the first position A to the second position B of the movable contacts32) of the contactor or to provide a mechanical force to maintain the contactor in a closing state (movable contacts32in the second position B—closing position).

The contactor1comprises one or more opening springs6positioned between the fixed yoke member41and the movable yoke member42.

The opening springs6store elastic energy when the movable yoke member42moves from the fifth position E to the sixth position F.

The opening springs6release the stored elastic energy to move the movable yoke member41from the sixth position F to the fifth position E, when the movable yoke member is free to move away from the sixth position F (i.e. when the fixed yoke member41and the movable yoke member42stop magnetically interacting upon interruption of the coil current IC feeding the coil44).

In view of the above, it is evident that the opening springs6are adapted to provide a mechanical force to perform an opening operation (passage from the second position A to the first position A of the movable contacts32) of the contactor.

Preferably, the opening springs6have their ends operatively connected with the fixed yoke member41and the movable yoke member42, according to a fixing arrangement of known type.

Preferably, in order to ensure a proper positioning of the movable yoke member42and consequently of the movable contacts32during an opening manoeuver, the opening springs6are operatively installed in such a way to be in a biasing state (i.e. slightly compressed) when the movable yoke member42is in the sixth position F.

Preferably, the opening springs6are made of non-ferromagnetic material of known type (e.g. non-ferromagnetic stainless steel).

As it will better emerge from the following, the opening springs6are advantageously part of the actuation section12of the contactor1and are preferably structurally integrated with the electromagnetic actuator4.

The contactor1comprises a plurality of second plungers5of non-ferromagnetic, electrically insulating material of known type (e.g. non-ferromagnetic stainless steel or other non-iron-based metallic materials).

Each plunger5is solidly connected with the movable yoke member42and the movable armature7to transmit mechanical forces to the movable armature7and consequently to the movable contacts32, when the movable yoke member42is actuated by a magnetic force upon the magnetic interaction with the fixed yoke member41or by a force provided by the opening springs6.

Each plunger5may be solidly fixed to the movable armature7and the movable yoke portion42by means of fixing means of known type.

Preferably, each plunger5extends along a corresponding main longitudinal axis parallel (and preferably co-planar) to the displacement axes33of the movable contacts32of the contactor. As it will better emerge from the following, the plungers5are advantageously part of the actuation section12of the contactor1and are preferably structurally integrated with the electromagnetic actuator4.

Preferably, the contactor1comprises, for each electric pole3, a contact spring9positioned between a corresponding fixed rest surface91and the movable armature7.

The contact springs9store elastic energy when the movable armature7moves from the third position C to the fourth position D as a consequence of a movement of the movable yoke member42from the fifth position E to the sixth position F.

The contact springs9release the stored elastic energy when the movable armature7start moving from the fourth position D to the third position C, when the movable yoke member42is free to move from the sixth position F to the fifth position E.

Each contact spring9is adapted to provide a mechanical force directed in such a way to oppose to any separation of the electric contacts of the corresponding electric pole, when said electric contacts are in a closing position.

However, in view of the above, it is evident that the contact springs9are adapted to provide a mechanical force to start moving the movable contacts32of the contactor during an opening manoeuver of this latter.

As shown in the cited figures, the rest surface91for each contact spring9may be a surface portion of a shaped insulating element91A accommodated in the internal volume defined by the housing35of a corresponding electric pole3, in a distal position with respect to the movable contacts32.

Preferably, the contact springs9have an end solidly with the movable armature7in a known manner and an opposite free end not connected with the respective rest surfaces91.

As a consequence, when the movable armature7moves from the third position C to the fourth position D, the contact springs9move solidly with the movable armature7for a given distance and abut against the respective rest surfaces91(thereby being subject to compression) only when the movable armature7is in the nearby of the fourth position D.

Additionally, when the movable armature7moves from the fourth position D to the third position C, the contact springs9release the stored elastic energy and then decouple from the respective rest surfaces91and move solidly with the movable armature7for a given distance, until the movable armature reaches the third position C.

According to an embodiment of the invention (shown in the cited figures), the fixed yoke member41and the movable yoke member42are arranged respectively at a proximal position and a distal position with respect to the movable contacts32.

In other words, according to this aspect of the invention, the fixed yoked member41is placed between the movable armature7and the movable yoke member42.

According to this embodiment of the invention:the contactor1comprises a pair of second plungers5symmetrically positioned (i.e. equally spaced) with respect to a main symmetry plane10of the contactor, which is parallel to the displacement axes33of the movable contacts32and perpendicular to the displacement plane34of said movable contacts;the contactor1comprises a pair of opening springs6symmetrically positioned with respect to the main symmetry plane10of the contactor;the fixed yoke member41comprises a pair of through holes410passing through the whole thickness of the fixed yoke member41measured along the displacement plane34of the movable contacts32. The through holes410are symmetrically positioned (i.e. equally spaced) with respect to a main symmetry plane10of the contactor and each second plunger5is inserted in a corresponding through hole410and passes through the fixed yoke member41to operatively connect the movable yoke member42and the movable armature7.

This embodiment of the invention provides a high level of structural integration between the electromagnetic actuator4, the second plungers5and the opening springs6. This allows remarkably reducing the overall size of the actuation section12of the contactor1.

Furthermore, the through holes410operate as coaxial guides for the plungers5of the contactor, thereby improving the movement precision of the plungers5and of the movable armature7.

In addition, the symmetric arrangement of the electromagnetic actuator4, the second plungers5and the opening springs6allows improving the distribution of forces transmitted to the movable contacts32, thereby avoiding or mitigating possible load unbalances.

This allows reducing the mass of the components of the actuation chain of the movable contacts32, e.g. the mass of the movable armature7and of the first and second plungers8,5and, on the other hand, achieving high precision levels in positioning of the movable contacts and in terms of movement simultaneity with which said movable contacts are actuated.

Preferably, on the internal surface of each through holes410, one or more elements or layers410A of anti-friction material of known type (e.g. polymers such as PTFE, POM reinforced with lubricating additives such as molybdenum disulfide) are arranged to facilitate the sliding of the second plungers5during the maneuvers of the contactor.

According to an embodiment of the invention, the fixed yoke member41has an E-shaped structure, which is provided with a plurality of limb portions412,413extending distally with respect to the movable contacts32of the contactor.

According to this embodiment of the invention, the fixed yoke member41comprises a main portion411in a proximal position with respect to the movable contacts32.

Preferably, the main portion411is formed by a shaped beam of ferromagnetic material, which has a main longitudinal axis perpendicular to the displacement axes33of the second movable contacts32and parallel to the displacement plane34of said movable contacts.

The main portion411of the fixed yoke member41may be formed by a shaped packed beam structure including multiple overlapped strips of ferromagnetic material of known type (e.g. having thickness of 2-4 mm) and, possibly, one or more strips of electrically insulating material of known type.

Preferably, the main portion411has opposite free ends411A, which are fixed to the outer casing2by means of suitable fixing means of known type.

According to this embodiment of the invention, the fixed yoke member41comprises a pair of lateral limb portions412, each positioned at a corresponding end411A of the main portion411and symmetrically arranged (i.e. equally spaced) with respect to the main symmetry plane10of the contactor.

The limb portions412protrude from the main portion411towards the movable yoke member42, which is distally positioned with respect to the movable contacts32.

Each of the limb portions412has a corresponding free end412A in a distal position with respect to the movable contacts32.

The free ends412A of the lateral limb portions412are adapted to couple with the movable yoke member42, when this latter reaches the sixth position F.

According to this embodiment of the invention, the fixed yoke member41further comprises an intermediate limb portion413positioned between the lateral limb portions412.

The limb portion413protrudes from the main portion411towards the movable yoke member42.

Preferably, the limb portion413is positioned along the main symmetry plane10of the contactor.

The limb portion413has a corresponding free end413A in a distal position with respect to the movable contacts32.

Preferably, the limb portion413is not intended to couple with the movable yoke member42during the operation of the contactor.

Thus, even when said movable yoke member in the sixth position F, the free end413A of the intermediate limb portion413is still separated from the movable yoke member by an air gap50.

This solution remarkably simplifies the manufacturing of the fixed yoke member41as lower tolerances can be employed in the realization of the of the limb portions412,413.

Further, it allows achieving an improved distribution of the magnetic flux along the magnetic circuit formed by the fixed yoke member41and the movable yoke member42when these latter ferromagnetic elements magnetically interact one with another.

Preferably, the fixed yoke member41comprises a pair of through holes410, which are symmetrically positioned (i.e. equally spaced) with respect to the main symmetry plane10of the contactor and are coaxial with a corresponding lateral limb portion412thereof.

In practice, each through hole410passes through the whole length of the respective lateral limb portion412and the whole thickness of the main portion411at a corresponding end411A of this latter.

Preferably, each second plungers5of the contactor is inserted in a corresponding through hole410and passes through a corresponding limb portion412and the main portion411of the fixed yoke member41.

This solution further improves the precision of movement of the plungers5as these latter are guided by more extended coaxial guides.

Preferably, each opening spring6of the contactor is coupled with the main portion411of the fixed yoke member41and with the movable yoke member42.

Preferably, each opening spring6is positioned coaxially with a corresponding limb portion412of the fixed yoke member41and outwardly surrounds said corresponding limb portion.

This solution remarkably simplifies the structure of the actuation section12of the contactor.

Further, the lateral limb portions412operate as guides for the opening springs6of the contactor, thereby improving the operation of these latter.

As shown in the cited figures, each of the limb portions412may be formed by hollow tubes (having a circular or polygonal section) of ferromagnetic material of known type that may be fixed to the main portion411by ferromagnetic fixing means of known type.

Similarly, the limb portions413may be formed by a solid tube (having a circular or polygonal section) of ferromagnetic material of known type that may be fixed to the main portion411by fixing means of known type.

This solution remarkably simplifies the manufacturing process of the fixed yoke member41as the limb portions412,413may be easily obtained by means of an extrusion manufacturing process.

According to this embodiment of the invention, the movable yoke member42is formed by a shaped beam of ferromagnetic material of known type, which has a main longitudinal axis perpendicular to the displacement axes33of the second movable contacts32and parallel to the displacement plane34of said movable contacts.

The movable yoke member42may be formed by a shaped packed beam structure including multiple overlapped strips of ferromagnetic material of known type (e.g. having thickness of 2-4 mm) and, possibly, one or more strips of electrically insulating material of known type.

The operation of the contactor1is now described.

Opening State of the Contactor

When the contactor1is an opening state:the movable contacts32are in the first position A (opening position, i.e. decoupled from the fixed contacts31), the movable armature7is in the third position C and the movable yoke member42is in the fifth position E, i.e. decoupled from the fixed yoke member41and separated from this latter by an airgap;the opening springs6are not compressed (with respect to their biasing state);the contact springs9are not compressed and are decoupled from the respective rest surfaces91;the coil44is not fed and no magnetic field is generated;the fixed yoke member41and the movable yoke member42do not magnetically interact.

The opening state of the contactor1is stably maintained by the opening springs6, which prevent any movement of the movable yoke member42away from the fifth position E, given the fact that other forces are not applied to this latter.

Closing Manoeuvre of the Contactor

To perform a closing manoeuvre of the contactor1, a coil current IC is supplied to the coil44. Preferably, a launch current pulse, which has a launch value IL and a launch duration TL, is supplied (FIG. 9).

As the coil44is fed by the coil current IC, a magnetic flux is generated and circulates along the magnetic circuit formed by the fixed yoke member41and the movable yoke member42.

As the fixed yoke member41and the movable yoke member42are initially separated by an airgap, a magnetic force is exerted on the movable yoke member42to close such an air gap. The movable yoke member42thus moves from the fifth position E to the sixth position F.

The launch value IL and the launch duration TL are advantageously set to obtain a magnetic force sufficiently high to move the movable yoke member42for a given distance against an opposition force exerted by the opening springs6.

During the movement of the movable yoke member42, the opening springs6are compressed, thereby storing elastic energy.

During its movement, the movable yoke member42transmits mechanical forces to the movable armature7through the second plungers5.

The movable armature7thus moves from the third position C to the fourth position D.

When the movable armature7has reached a given distance to the fourth position D, the contact springs9, which move together with the movable armature7, come in contact with their respective rest surfaces91and start being compressed thereby storing elastic energy.

During its movement, the movable armature7transmits mechanical forces to the movable contacts32through the first plungers8.

The movable contacts32move from the first position A to the second position B.

As soon as the movable contacts reach the second position B and couple with the respective fixed contacts31, the opening maneuver is completed and the contactor1is in a closing state.

Closing State of the Contactor

When the contactor1is a closing state:the movable contacts32are in the second position B (closing position, i.e. coupled with the fixed contacts31), the movable armature7is in the fourth position D and the movable yoke member42is in the sixth position F, i.e. coupled with the fixed yoke member41;the opening springs6are compressed (with respect to their biasing state);the contact springs9are compressed;the coil44is still fed by a coil current IC, preferably having a holding value IH different than the launch value IL (FIG. 9), and a magnetic field is generated;the fixed yoke member41and the movable yoke member42magnetically interact.

The closing state of the contactor is stably maintained by continuously feeding the coil44, so that a magnetic force is continuously exerted on the movable yoke member42against an opposition force exerted by the opening springs6and the contact springs9.

The holding value IH of the coil current IC is advantageously set to obtain a magnetic force sufficiently high to maintain the movable yoke member42coupled with the fixed yoke member41against an opposition force exerted by the opening springs6and the contact springs9.

The holding value IH of the coil current IC may thus be lower than the launch value IL, so that the electric power dissipation of the coil44is reduced.

Opening Manoeuvre of the Contactor

To perform an opening manoeuvre of the contactor1, the coil current IC supplied to the coil44is interrupted.

No magnetic force is exerted on the movable yoke member42anymore.

The opening springs6can release the stored elastic energy and exert a force to move the movable yoke member42from the sixth position F to the fifth position E.

During its movement, the movable yoke member42transmits mechanical forces to the movable armature7through the second plungers5.

The movable armature7thus moves from the fourth position D to the third position C.

At the beginning of its movement, the movable armature7is further subject to a force exerted by the contact springs9.

When the movable armature7has reached a given distance from the fourth position D, the contact springs9, which move together with the movable armature7, decouple from their respective rest surfaces91.

During its movement, the movable armature7transmits mechanical forces to the movable contacts32through the first plungers8.

The movable contacts32thus move from the second position B to the first position A.

As soon as the movable contacts reach the first position A, the opening maneuver is completed and the contactor1is in an opening state.

The contactor1, according to the invention, provides remarkable advantages with respect to the known apparatuses of the state of the art.

In the contactor1, the movable contacts32perform linear bidirectional movements that are driven by mechanical forces transmitted along axes parallel (and preferably co-planar) with the displacement axes33of the movable contacts. This solution provides a remarkable simplification of the actuation chain of the movable contacts32, which allows improving the precision with which the movable contacts32are actuated.

The contactor1, according to the invention, is thus characterised by high levels of reliability for the intended applications.

In the contactor1, the electromagnetic actuator4, the opening springs6and the plungers5are arranged with high levels of structural integration, which allows obtaining a very compact and robust actuation section with relevant benefits in terms of size optimization of the overall structure of the contactor.

The contactor1, according to the invention, is of relatively easy and cheap industrial production and installation on the field.

The contactor1thus conceived is susceptible to numerous changes and variants, all of which are in the scope of the inventive concept as defined by the appended claims; additionally, all details can be replaced by other equivalent technical elements. For example, the number of elements as well as their configuration can be varied provided they are suitable for their scope; further, it is possible to perform any combination of the illustrative examples previously described. In practice, the materials, as well as the dimensions, can be of any kind depending on the requirements and state of the art.