Claims:We claim:

1. An electromagnetic tripping mechanism comprising:
a fixed magnet,
a moving magnet configured at a predetermined distance from the fixed magnet;
a current carrying conductor surrounding the fixed magnet;
a magnetic screw mounted on a support , characterized in that the magnetic screw has a conical shape and is placed in a plane normal to fixed magnet tightening plane;
wherein by moving the magnetic screw towards the moving magnet or away from the moving magnet, the air-gap between moving magnet and the fixed magnet can be increased or decreased respectively which facilitates the calibration of magnetic release.

2. The electromagnetic tripping mechanism as claimed in claim 1, wherein the magnetic screw comprises a cone having screw attached to the cone.
, Description:
Field of the invention

The present invention relates to electromagnetic tripping mechanism, and more particularly, the present invention relates to a calibration/adjustment of an electromagnetic release/tripping mechanism.

Background of the invention

Electromagnetic tripping mechanisms for circuit-breakers include a fixed magnetic circuit excited by the current passing through a pole and a movable magnetic member held by a return spring against a stop at a certain distance from the fixed magnetic circuit, thus defining the initial working gap of the tripping mechanism.

The magnetic release in current electromagnetic tripping mechanism is such that when current flows through a conductor holding the fixed magnet, magnetic field is produced in the fixed magnet. To complete the path of magnetic field, the fixed magnet attracts the moving magnet towards it with magnetic force generated. When the moving magnet is attracted towards the fixed magnet with the help of magnetic force, it trips the mechanism of the release. This phenomenon occurs at a particular current setting that is X times the rated current In (X * In). The tripping band is between (.8 * X * In) to (1.2 * X * In). The non-tripping of the release to be observed below (.8 * X * In). To achieve the release performance, the magnetic release has to be calibrated to obtain the desired performance for the above mentioned band.

To perform calibration, two parameters are considered. If non-tripping of the magnetic release is observed, air gap is reduced between the moving magnet and the fixed magnet to increase the magnetic force and calibrate the release as per requirement.

In another case, if early-tripping of the release is observed, the air gap is increased between the moving magnet and the fixed magnet to reduce the magnetic force and calibrates the release as per requirement.

However, in the existing magnetic release, tightening plane of calibration screw is same as fixed magnet tightening plane in the conductor as shown by A in figure 1 and 2. Hence, the calibration is not possible for the release construction where screw needs to be placed in the plane normal to the tightening plane of the fixed magnet into the conductor.

Referring figure 1 and 2, there is shown an existing configuration of the electromagnetic tripping mechanism having a support (1), a magnetic screw (2), a magnetic spring (3), a fixed magnet (4), a hinge point (5), a moving magnet (6), and a current carrying conductor (7). In this mechanism, the release construction is such that the fixed magnet (4) tightening plane is same as calibration screw (2) tightening plane. Therefore, the calibration is not possible for the release construction where screw (2) needs to be placed in the plane normal to the tightening plane of the fixed magnet (4) into the conductor (7).

Accordingly, there exists a need to provide a system for calibration of electromagnetic tripping mechanism, which overcomes above-mentioned drawbacks.

Objects of the invention

An object of the present is to provide freedom to place the calibration screw in the plane normal to fixed magnet tightening plane.

Summary of the invention

Accordingly, the present invention provides an electromagnetic tripping mechanism. The electromagnetic tripping mechanism comprises a fixed magnet, a moving magnet configured at a predetermined distance from the fixed magnet, a current carrying conductor surrounding the fixed magnet, a magnetic screw mounted on a support. The electromagnetic tripping mechanism is characterized in that the magnetic screw has a conical shape and is placed in a plane normal to fixed magnet tightening plane. Wherein upon moving the magnetic screw towards the moving magnet or away from moving magnet, the air-gap between moving magnet can be increased or decreased respectively which facilitates the calibration of magnetic release.

Brief description of the drawings

Figure 1 and 2 shows electromagnetic tripping mechanism in accordance with the prior art;

Figure 3 shows a schematic drawing of an electromagnetic tripping mechanism, in accordance with the present invention; and

Figure 4a and 4b shows a schematic drawing of a magnetic screw of the electromagnetic tripping mechanism of figure 3.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides an electromagnetic tripping mechanism. The
electromagnetic tripping mechanism provides a novel calibration screw wherein the calibration can be achieved even after calibration screw tightening plane and fixed magnet tightening plane are normal to each other.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.

Referring now to figure 3, there is shown an electromagnetic tripping mechanism (100) (hereinafter “the mechanism (100)”) in accordance with the present invention. The mechanism (100) comprises a fixed magnet (10), a moving magnet (20), a current carrying conductor (30), a magnetic screw (40) and a support (50).

The moving magnet (20) is configured at a predetermined distance from the fixed magnet (10). The fixed magnet (10) surrounds the current carrying conductor (30). Further, the magnetic screw (40) is mounted on a support (50). The mechanism (100) is characterized in that the magnetic screw (40) has a conical shape and is placed in a plane normal to fixed magnet (10) tightening plane as shown in figure 3.

Wherein by moving the magnetic screw (40) towards the moving magnet (20) or away from moving magnet (20), the air-gap between moving magnet (20) and the fixed magnet (10) can be increased or decreased respectively which facilitates the calibration of magnetic release. Specifically, the calibration of the magnetic release is achieved even after calibration magnetic screw (40) tightening plane and the fixed magnet (10) tightening plane are normal to each other shown by B in figure 3.. This is achieved through the conical slope given on the magnetic screw (40) over the threaded potion of the screw. By moving the screw towards moving magnet (10) or away from moving magnet (20) the air-gap between moving magnet (20) and the fixed magnet (10) can be increased or decreased respectively. This facilitates the calibration of magnetic release.

In an embodiment, the magnetic screw (40) comprises a cone (40a) having a screw (40b) attached to the cone as shown in figure 4A. The adjustment of the screw (40) is done from the screw head side to increase or decrease the air gap between the moving magnet (20) and the fixed magnet (10) to increase or reduce the magnetic force and calibrate the release as per requirement,. The head can be selected based on ease in calibration.

In another embodiment, the cone (40a) and the screw (40b) are made as integral part as shown in figure 4b.

In an embodiment, the conical shape of magnetic screw (40) facing towards the magnetic release is applicable based on calibration requirement irrespective of material, slope and size of cone of the magnetic screw (40).

Advantages of the invention

1. The mechanism (100) gives freedom to place the calibration magnetic screw in the plane normal to fixed magnet tightening plane.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.