AN IMPROVED THERMO MAGNETIC RELEASE FOR A CIRCUIT BREAKER
FIELO OF THE INVENTION
[0001] The present invention generally relates to circuit breakers. More particularly embodiments of the invention relates to an improved thermo magnetic release for a circuit breaker
PRIOR ART
[0002] Generally the function of circuit breakers is to electrically engage and disengage a selected circuit from an electrical supply and is normally incorporated in an electrical circuit to waistband current variations. The circuit breaker provides protection against persistent over current condition and against high current produced by short circuit. Depending on the intended use of the circuit breaker, these devices can comprise of one or more electric poles that constitute the interruption section of the circuit breaker. Further, each pole would comprise of at least one arc chute and two electrical contacts, a fixed one and a moving one, which can be mutually coupled/uncoupled. In turn, the contacts are connected electrically to the phase or neutral conductor associated with said pole by virtue of suitable connection terminals.
[0003] Each electrical pole, moreover, is provided with either a thermal sensor or a suitable current sensor, normally constituted either by a current sensing transformer, whose primary winding is constituted by the conductor to which said pole is connected, or by a magnetic relay whose winding coil is again constituted by said conductor. The magnetic relays can be regarded essentially as two-stage transducers, i.e., in the first stage the transducer is capable of convert initially the electric energy into magnetic energy and then in the second stage the magnetic energy is converted into mechanical energy. The critical part of a magnetic relay in fact comprises an electromagnet that has a plate made of ferromagnetic material, which subjects a suitable lever system to mechanical actions that depend cin the value of the magnetic field generated by die electromagnet. Further, the said magnetic field in turn depends on the intensity of the

current that circulates in the corresponding electrical conductor. The mechanical actions produced in the lever system are then appropriately directed in input to a protection unit, which causes the safety release or opening of tike circuit breaker.
[0004] Typically, the magnetic relays used in low-voltage circuit breakers can be of the fixed or adjustable type. There are devices, available in the prior art, wherein fixed type of magnetic relays have been incorporated. However, the fixed type magnetic relays have a drawback. In circuit breakers employing the fixed type magnetic relays, the air gap is kept constant does not ensure a constant flux linkage and saturation of electromagnet plate is not avoided. There are also devices available in the prior art, wherein adjustable type of magnetic relays have been incorporated in circuit breakers. In a device known to the prior art, an electromagnetic relay with adjustable tripping threshold for a low-voltage circuit breaker is utilized wherein the moving plate and/or the fixed element has a contoured body that is functionally connected to means for adjusting the tripping threshold. The tripping threshold is achieved by simultaneously varying the gap between the moving plate and the fixed element and the magnetic coupling between the moving plate and the core.
[0005] There is need for a thermo magnetic release assembly for a circuit breaker, which provides a mechanical adjustment to effectively vary the air gap between electromagnet systems and prevent the early saturation of the electromagnet. Further, there is a need for a thermo magnetic release assembly for a circuit breaker, which ensures high rating of the release and helps in achieving wide range of adjustability. Also, the thermo magnetic release assembly that is incorporated in a circuit breaker should effectively reduce the overall size of the cumquat breaker.
OBJECT OF THE INVENTION [0006] It is an object of the invention to provide an improved thermo magnetic release assembly for a circuit breaker. More particularly, it is an object of the invention to provide thermo magnetic release assembly, which effectively varies an- gap between electromagnet systems and prevents the early saturation of the electromagnet. [0007] It is an object of the invention to provide an unproved thermo magnetic release assembly for a circuit breaker, that ensures high rating of the release and helps in achieving wide range of adjustability.

[00081 It is also an object of the invention to provide an improved thermo magnetic release assembly that will effectively reduce the overall size of the circuit breaker.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] So that the manner in which the above recited features of the present invention can be understood in deadly, a more particular description of the invention, briefly summarized above, may be had by reference to various embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the mention may be admit to other equally effective embodiments.
[0010] Figure 1 shows outline diagram of the release assembly with new component
according to an example of the embodiment of the invention.
[0011]Figure 2 shows outline diagram of the isolative component according to an
example of the embodiment of the invention.
[0012] Figure 3 shows outline diagram of the torsion spring arrangement for
electromagnetic plates according to an example of the embodiment of the invention.
[0013] Figure 4 shows outline diagram of an assembly m which electromagnet is in open
position and at minimum rating level, according to an example of the embodiment of the
invention.
[0014] Figure 5 shows outline diagram of an assembly in which electromagnet is in
closed position and at minimum rating level, according to an example of the embodiment
of the invention.
[0015] Figure 6 shows outline diagram of an assembly in which electromagnet is in open
position and at maximum rating level, according to an example of the embodiment of the
invention.
[0016] Figure 7 shows outline diagram of an assembly in which electromagnet is in
closed position and at maximum rating level, according to an example of the embodiment
of the invention.

DETAILED DESCRIPTION OF INVENTION
[0017] The invention provides an unproved thermo magnetic release for a circuit breaker. More particularly embodiments of the invention provides thermo magnetic release which is an integral part of the molded case circuit breaker and it particularly varies the aif gap between the electromagnet system which helps to increase the reluctance of the flux path between electromagnetic plates which in turn helps in preventing the early saturation of the electromagnet. Further this helps in varying the air gap between electromagnetic plates and adjusts the spring force.
[0018] Figure 1 shows an outline diagram of the thermo magnetic release assembly according to an embodiment of the invention. The thermo magnetic release assembly which comprises of the new electromagnet adjustment component (4), adjustment knobs (1), Bi-metal adjustment component (2), heater (3) torsion spring (5), electromagnet core (6) and electromagnetic plate(7).
[0019] Figure 2 shows new electromagnet adjustment component (4) according to an example of the embodiment of the invention.
[0020] Figure 3 shows torsion spring (5) arrangement provided for the electromagnetic plates (7) that help in holding the electromagnetic plates (7) in desired position, according to an example of the embodiment of the invention.
[0021] Figure 4 shows an assembly in which electromagnet is in open position i.e. it is not attracted. In this condition, the torsion spring is in contracted position spring force greater than the electromagnetic force and this is at minimum rating level, according to an example of the embodiment of the invention.
[0022] Figure 5 shows an assembly in which electromagnet is in closed position i.e. it is in attracted position. In this case spring force is less than electromagnetic force and this is at its minimum rating level, according to an example of the embodiment of the invention. [0023] Figure 6 shows an assembly in which electromagnet is in open position i.e. it is not attracted here spring force is greater than the electromagnetic force and it is in its maximum retag level, according to an example of the embodiment of the invention. [0024] Figure 7 shows an assembly in which electromagnet is in closed position i.e. it is in attracted position. In this case spring force is less than electromagnetic force and this is at maximum rating level, according to an example of the embodiment of the invention.

[0025] In an example of the invention the thermo magnetic release assembly as described in detail earner herein is designed for 3 pole operation. The said assembly consists of heater (3), plurality of electromagnetic core (6), electromagnetic plate (7) and torsion spring (5). Further the assembly consists of a pair of adjustment knob (1), an electromagnet adjustment component (2) and bi metal adjustment component (3) which is also the component that gives the output of the release.
[0026] The electromagnetic system consists of a core and a movable part. The movable part is hinged as shown in Figure 1. The movable part can rotate about its hinged pout. The arrangement of the torsion spring (5) is such that h always opposes the electromagnetic force and holds the electromagnetic part in its open position. The electromagnet adjustment component (4) as shown in Figure 2 helps to vary the air gap which is present when the electromagnetic system is in open position. [0027] Further, when the electromagnet adjustment component (4) is adjusted with the help of the adjustment knob (1) to its minimum position the air gap between electromagnetic plates (7) is less so the force required to pull the movable part is low. The torsion spring (5) adjustment as well as electromagnetic part arrangements in open and closed position as shown in Figure 4 and Figure 5.
[0028] However, when the electromagnet adjustment component (4) is adjusted with the help of the adjustment knob (1) to its maximum position, air gap between electromagnetic plate (7) is more so the force required to pull the movable part is more but the current flowing is high at this position which produces enough force for the electromagnetic part to get attracted as shown in Figure 6 and Figure 7. [0029] As mentioned above, the varying air gap increases the reluctance and decreases flux density which in turn prevents the early saturation of the electromagnet.

We claim:
1. An improved thermo magnetic release mechanism for a circuit breaker, the said
mechanism comprising-.
an electromagnet core rigidly mounted horizontal to the floor of the casing
of the circuit breaker
an electromagnetic plate mounted above the electromagnetic core and
configured to move about a perpendicular axis defined by the fixed
electromagnetic core;
a hi natal adjustment member configured to receive the output food the
electromagnet and transducer it to the output of release;
an electromagnet adjustment member coupled to one end of the
electromagnetic core in an opposing manner to the electromagnetic plate
and provided with an adjustment knob for varying the air gap created at
the electromagnetic core; and
a torsion spring mounted on the electromagnet adjustment member and
coupled to the electromagnetic plate;
2. An improved thermo magnetic release mechanism of claim 1, wherein the adjustment knob is positioned on the external surface of the casing of the circuit breaker to enable access to the adjustment knob.
3. An unproved thermo magnetic release mechanism of claim 1, wherein the movement of the adjustment knob results in alteration of the air gap between the electromagnetic plate and the bi- metal adjustment member.
4. An improved thermo magnetic release mechanism of claim 1, wherein the movement of the electromagnetic plate is achieved through the torsion spring coupled to the electromagnetic plate.
5. An improved thermo magnetic release mechanism of claim 1, further wherein the movement of the torsion spring is achieved by the electromagnetic force generated by the electromagnetic core.
6. An improved thermo magnetic release mechanism of claim 1, wherein the torsion spring provides the required spring force to counteract the electromagnetic force to achieve a sustained alteration of air gap.

7. An improved thermo magnetic release mechanism of claim 1, wherein the hi
metal adjustment provides overload adjustment and also it takes the output from
electromagnet and converts it as the output of release.
8. An improved thermo magnetic release mechanism of as illustrated by drawings
and as described in the specification.
9. An improved thermo magnetic release mechanism as claimed in claims 1 -8,
wherein the said mechanism is configured in a multi-pole circuit breaker
10. An improved thermo magnetic release mechanism as claimed in claim 1 -8
ftirther comprising at least each one additional electromagnetic core,
electromagnetic plate, bi -metal adjustment member, electromagnet adjustment
member, torsion spring configured in a multi-pole cu-cuit breaker.