FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: ELECTROMAGNETIC ACTUATION SYSTEM FOR SWITCHING DEVICES
2. Applicant(s):

(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to switching devices. More particularly the invention relates to an electromagnetic actuation system for switching devices.
BACKGROUND AND THE PRIOR ART
In many electromagnetic devices, permanent magnets are used to hold the moving/working element either in normal condition or in closed/latched position against the forces generated by contact springs so that no electrical energy is required to keep the working element in a particular position against the spring forces. Transition between two distinct positions is achieved by generating an electromagnetic field opposite to permanent magnet field to an extent that force generated by net field is sufficient to overcome the spring forces, in turn is effective enough to provide an actuation to the working element.
Some of the prior arts in related field of invention are as follows:
CN 201387838 provides a high-voltage circuit breaker of a pulse-driven linear motor type magnetic mechanism, which belongs to the technical field of the electrically switch in the high-voltage electrical engineering. The high-voltage circuit breaker is characterized in that a pulse-driven linear motor type magnetic mechanism is used for driving the arc extinguish chamber of a high-voltage circuit breaker to move, thereby realizing the switching-off and switching-on movement of the high-voltage circuit breaker. A permanent magnet is adopted in the pulse-driven linear motor type magnetic mechanism to match the magnetic circuit therein, thereby leading to the upward and downward movement of a live coil therein under the effect of ampere force. The switching-off and switching-on positions are maintained through the closure of the magnetic circuit. The excitation of the coil is provided by a pulse capacitor, and the coil and the pulse capacitor are controlled by an external control system. The utility model solves the technical problem that the traditional electromagnetic mechanism can not realize the long-stroke and high-power operation and the technical problems of actuation accuracy and speed control of

the operating mechanism of the existing ultra-high-voltage circuit breaker. The whole circuit breaker system has the advantages of simple control, direct operation and low cost.
DE 102006034818 (B3) provides a system comprising an electromagnetic contact drive for actuation of a moving contact (10), where a fix contact (15) works together with the moving contact. The adjustment is identified over a motor drive (30) that loads a bearing (20.1,20.2) to the contact force spring (20) with adjustment strength or an adjustment moment, where the spring leads to a change in the bearing position.
Thus there is a need to overcome the disadvantages of the prior arts. This present invention relates to an electromagnetic actuation system in which a permanent magnet is interposed in a magnetic circuit, formed in an electromagnetic block, including an armature and a pair of yokes so that magnetic flux of a coil in the electromagnetic block will act against magnetic flux of the permanent magnet for actuating the armature to cause contacts in a contact block in the switching device to toggle between two positions.
The electromagnetic actuation system of the kind referred to find its usefulness when the same is employed in a low voltage switching device like contactor, for making and breaking an electric path provided in connection with the other electric devices.
OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Another object of the present invention is to provide an electromagnetic actuation system for switching devices.
Another object of the present invention is to provide an actuation system with a better shock withstand capability, when in open gap or OFF condition.

These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
There is provided an electromagnetic actuation system for switching devices.
According to one embodiment of the present invention, there is provided an electromagnetic actuation system for switching devices comprising a permanent magnet (110) placed between flanges of top of main yoke (102) and upper yoke (101), said upper yoke having extended arm holding a pole contacting member of an armature; an electromagnetic system comprising a plunger with a pole contacting member, a coil wound on a bobbin passing through an axial hole, a yoke disposed peripherally about said coil; a plunger assembly comprising a plunger (103), a bottom plate (105) and a top plate (104) fixed to said plunger having a bridge coupling bracket (107) screwed therein; a bridge (106) carrying moving contacts couple with said bridge coupling bracket (107); a plurality of fixed contacts placed in a housing of a contactor; a return spring forcing a moving system towards said permanent magnet, said return spring adapted to open said contacts an electromagnet is switched off; and a magnetic cylinder inserted in axial hole of said bobbin.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
So that those having ordinary skill in the art will more readily understand how to construct an electromagnetic actuation system for switching devices in accordance with the present

disclosure, exemplary embodiments are described in details herein below with reference the accompanying drawings wherein:
Fig 1 illustrates the electromagnetic actuation system for switching devices.
Fig 2 illustrates the exploded view of the electromagnetic actuation system.
Fig 3 illustrates the internal assembly of the electromagnetic actuation system.
Fig 4 illustrates the top yoke connected to a top plate.
Fig 5 illustrates the top yoke disconnected to a top plate.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
Reference is first invited to Fig 1 where the Plunger assembly consisting of a plunger 103, top plate 104 and bottom plate 105, the top plate 104 being fixed to the plunger 103 with a bridge coupling bracket 107 screwed is shown.
Fig 2 shows different elements of the present invention separately. It shows upper yoke, plunger, permanent magnet etc.
Fig 3 shows the internal arrangement of the present invention.
Fig 4 shows top yoke connected to a top plate.

' Fig 5 shows top yoke disconnected to top plate.
The invented system is thus an electromagnetic actuation system for switching devices.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly in the present invention an Electromagnetic actuation system consists of a pair of Yokes (Top and Bottom), plunger with top and bottom plates. A bridge containing moving contacts is connected to the Plunger system by means of bridge coupling bracket. A coil containing specific number of turns and having definite resistance is wound around the limb of coil former. The coil is supplied with DC supply .The flux thus generated links with yokes and plunger arrangement through air. This flux produced, interacts with the permanent magnet flux generates a net magnetic field, which provides sufficient force to overcome spring forces fitted in system causing a transition of plunger system towards its other rest position. The transition of plunger system also causes the movement of bridge along with it. This result in contact closure and flow of current in the circuit connected across the inlet and outlet terminals of switching device. Thus the system is kept in ON condition or in hold on condition using electromagnetic force which acts against the spring forces, also responsible for keeping the system in OFF condition i.e. maintaining a certain contact gap under the influence of force generated by permanent magnet, to restrict the flow of current. Permanent magnet provides additional force along with spring system in open gap condition. This force ensures perfect closing of NC contacts with adequate contact pressure. Moreover permanent magnet holds the plunger (moving system) in open condition i.e. when DC coil is not energized and gives better shock withstand capability to the system with reduced return spring strength.
According to the present invention, the objects can be attained by the provision of an electromagnetic system consisting of plunger part with a pole-contacting member, a coil is wound on a. bobbin passing through an axial hole thereof the plunger part of the armature for its axial displacement, a yoke is disposed to be peripherally about the coil, an upper yoke is screwed to the lower yoke for its fixing. Permanent magnet is placed in the gap between the upper and

lower yoke flanges; the upper yoke with its extended arm holds the pole-contacting member of the armature so as to restrict its motion due to NC contact spring force in the counter direction.
The movable contacts of the contact system are caused through a coupling means by the displacement of the armature to make and break the moving contacts with fixed contacts. The lower yoke is further made to oppose the other end of the plunger part so as to extend perpendicularly and adjacent thereto, and a magnetic cylinder of an axial length sufficiently larger than a width of the lower yoke at the portion opposing the other end of the plunger part and of an inner diameter slightly larger than an outer diameter of the plunger part of the armature is inserted in the axial hole of the bobbin to beat the position of the lower yoke portion opposing the other end of the plunger part.
The presented invention consists of a set yokes (top yoke 101 and bottom yoke 102) which carries both permanent magnet as well as coil flux, Plunger assembly consisting of a plunger 103, top plate 104 and bottom plate 105, the top plate 104 being fixed to the plunger 103 with a bridge coupling bracket 107 screwed in. The bridge 106 that carries the moving contacts is coupled with the bracket 107 and a set of fixed contacts are placed in the housing of the contactor, thus the movement of the plunger 103 and hence the bridge 106 leads to opening and closing of contacts.
The requirement in open condition for a device like control contactor is to have a considerable shock withstand, so that, accidental closing/opening of contacts does not take place in case of a sudden shock upon the device. The purpose of using a permanent magnet 110 is also to provide the shock withstand capacity, either fully or partially. In the proposed scheme, the permanent magnet 110 is placed in the volume devised between the flanges of top of the main (lower) yoke 102 and the upper yoke 101, it is in such a way that its field lines pass through the top flange 104 of the plunger 103 which mates with the upper yoke 101 (housing permanent magnet) as shown in the conventional setting, the open condition, as already explained, is maintained with a satisfactory return spring, in the current case, however, the open condition is maintained by a permanent magnet of required strength, with its flux lines passing through the upper yoke 101 and the plunger 103, there results a sticking force between the two, depending on the chosen

magnet, a corresponding force needs to be exerted to push the plunger 103 down and close the
contacts.
Hence the choice of magnet is based on the required shock withstand, the return spring is needed to open the contacts after the electromagnet has been switched off, in the present invention, the return spring is to be designed to value that is sufficient to bring the moving system (plunger 103, bridge 106) to a sufficient proximity of the permanent magnet 110 field from where the magnet field will pull it up and the mating of the plunger top flange 104 with auxiliary/upper yoke 101 is re-established.
In this invention safety to the user is ensured by encapsulating the wires such that there are minimum chances of the product failing due to inter phase shorting as mentioned above.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:
1. An electromagnetic actuation system for use in switching devices, said system comprising:
a permanent magnet means (110) placed between flanges of top of a main yoke (102) and an upper yoke (101), said upper yoke having extended arm holding a pole contacting member of an armature;
an electromagnetic system comprising a plunger with a pole contacting member, a coil wound on a bobbin passing through an axial hole, a yoke disposed peripherally about said coil;
a plunger assembly comprising a plunger means (103), a bottom plate (105) and a top plate (104) fixed to said plunger having a bridge coupling bracket (107) screwed therein;
a bridge means (106) carrying moving contact means couple with said bridge coupling bracket (107);
a plurality of fixed contact means placed in a housing of a contactor;
a return spring means forcing a moving system towards said permanent magnet, said return spring adapted to open said contacts an electromagnet is switched off; and
a magnetic cylinder inserted in axial hole of said bobbin.
2. System as claimed in claim 1 wherein said plunger means (103) and said bridge means (106) adapted to provide opening and closing of said contacts.
3. System as claimed in claim 1 wherein said permanent magnet means (110) having field lines passing through a top flange (104) of said plunger (103) and further mating with a upper yoke (101).

4. System as claimed in claim 1 wherein said moving system comprising said plunger (103) and said bridge (106).
5. System as claimed in claimed 1 further comprising a lower yoke adapted to oppose other end of said plunger.
6. An electromagnetic actuation system for switching devices as herein described and illustrated with reference to accompanying drawings.