FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Electro-Magnetic Actuating System For Circuit Breakers"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-1956.
(c) ADDRESS: LARSEN & TOUBRO LIMITED,
L&T House, Ballard Estate, P. O. Box: 278, Mumbai 400 001, India
3. PREAMBLE TO THE DESCRIPTION:
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Electro-Magnetic Actuating System For Circuit Breakers
Field of the invention
The present invention relates to circuit breakers, and more particularly, to electro-magnetic actuating system for circuit breakers.
Background of the invention
An electromagnetic actuator, also called as magnetic release is the main operating system of circuit breakers. The electromagnetic actuator includes magnetic frame, a moving core, a plunger for tripping mechanism and a coil. The coil input is driven by AC or DC supply depending on the application or can be energized for sensing abnormal conditions or for required specifications. When current passes through the release coil, a magnetic field is produced. The magnetic field attracts the moving core, which try to overcome reluctance of air gap. The electromagnetic actuator requires more NI in open condition. As the moving core goes near to the magnetic frame, reluctance of the electromagnetic actuator is reduced. Therefore, flux linkage increases and NI requirement reduces. The plunger is propelled by the moving core and the force developed by magnetic circuit can hold the moving core and magnetic frame together depending upon the application or plunger connected to it will give signal for any abnormal condition to the tripping unit connected. -
The electromagnetic actuator can be designed as per application requirement such as continuous hold application where in normal running condition, the electromagnetic actuator keeps system close and when requires to open, withdraw the coil supply or provide opposite magnetic field. Sometimes in a distribution system, the electromagnetic actuator system is used to sense the abnormal condition and give a trip signal to a tripping unit so that system reliability can be assured.

The current practice in electromagnetic actuator is to employ a fixed core, a moving core, a frame and a coil around it which increases component therein and cost associated therewith. Accordingly, there exists a need to provide electromagnetic actuator which overcomes drawbacks of the prior art.
Objects of the invention
An object of the present invention is to eliminate a fixed core so as to reduce one component in a magnetic actuating system thereby reducing cost thereof.
Another object of the present invention is to provide a moving core profile such that it gives advantage of reduced effective air gap as well as it will maintain the required magnet gap for controlling tripping characteristic of the used product.
Yet another object of the present invention is to provide a novel magnet coil so that full copper volume as well as total current path can be utilized to effective turns which will help in maintaining optimum NI.
Summary of the invention
Accordingly, the present invention provides an electro-magnetic actuating system for circuit breakers. The electro-magnetic actuating system comprises a moving core capable of moving vertically, a plunger capable of being propelled by the moving core, a magnetic frame having an upper bend and a lower bend, a coil welded to the magnetic frame in a space provided by the upper bend of the magnetic frame and a spring. The current path between the upper bend and the lower bend contributes in completing effective turn of the coil as current flows through the coil, which in turn helps in producing more flux. When current passes through the coil, a magnetic field is produced which attracts the moving core thereby overcoming reluctance of the air gap, and when the coil is energized, the moving core moves downwards in order to complete the magnet

flux path till the magnetic frame surface and links more flux with respect to the magnetic frame surface which helps in reducing active airgap.
Brief description of the drawings
Figure 1 shows a perspective view of a transverse motion mechanism of electromagnetic actuating system in accordance with the present invention;
Figure 2 shows an exploded perspective view of the actuating system of Figure
l;
Figure 3 is assembled view of the electromagnetic actuating system in first position;
Figure 4 is a view representing the electromagnetic actuating system in close condition; and
Figure 5 is a view representing coil welding to show actual effective turns.
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 embodiments.
The present invention provides an electro-magnetic actuating system for circuit breakers. The electro-magnetic actuating system eliminates a fixed core so as to reduce one component in a magnetic actuating system. Further, the electromagnetic actuating system provides a moving core profile such that it gives

advantage of reduced effective air gap as well as it will maintain the required magnet gap for controlling tripping characteristic of the used product. The present invention provides a moulded case circuit breaker with improved mechanism which provides elimination of components from the mechanism of a moulded case circuit breaker keeping features same. The moulded case circuit breaker with improved mechanism reduces the cost and assembly time and hence increases productivity thereof. Further, the moulded case circuit breaker with improved mechanism leads to lesser friction and overall performance.
Referring now to figure 1 and 2, there is shown an electro-magnetic actuating system (hereinafter 'the system (100)'), in accordance with the present invention. The system (100) comprises a moving core (10), a plunger (20), a magnetic frame (30), a coil (40), and a spring (50).
The moving core (10) is capable of moving vertically. The moving core (10) is designed in such a way that the moving core (10) fulfils the requirement that magnet gap enclosed by the coil (40) helps in flux linkage and also provides reduced effective magnet gap keeping actual gap as required which reduce VA requirement. The moving core (10) rotates the plunger (20).
The plunger (20) is capable of giving signal for any abnormal condition or required specifications to a tripping unit connected thereto when moved by the moving core (10).
Further, the magnetic frame (30) includes an upper bend (22) and a lower bend (24). The lower bend (24) is connected to an external current carrying conductor. The magnetic frame includes the coil (40) welded thereof.
Specifically, the coil (40) is an electromagnetic coil. The coil (40) is welded to the magnetic frame (30) in a space provided by the upper bend (22) of the magnetic frame (30). The current path between the upper bend (22) and the

lower bend (24) contributes in completing effective turn of the coil (40) as current flows therethrough. This is in turn helps in producing more flux, and when current passes through the coil (40), a magnetic field is produced which attracts the moving core (10) thereby overcoming reluctance of the air gap. The spring (50) is attached to the lower end of the moving core (10). Specifically, when the coil (40) is energized, the moving core (10) moves downwards in order to complete the magnet flux path till the magnetic frame (30) surface and links more flux with respect to the magnetic frame (30) surface which helps in reducing active airgap.
Referring to figure 3, which represents an initial assembled condition of the system (100) wherein a magnet gap is shown. The state of system (100) is de-energized and the moving core (10), and the magnetic frame (20) are in open condition. As the coil (40) is energized, the moving core (10) moves downwards in order to complete the magnet flux path until fixed magnetic frame (30) surface. Front profile of the moving core (10) is designed in such a way that as the moving core (10) moves downwards, the moving core (10) help in linking more flux with respective magnetic frame (30) surface. The step in moving core (10) helps in reducing active airgap but still maintains designed gap. Figure 4 represents system (100) in which the moving core (10) is touching the fixed magnetic frame (20).
As shown in figure 5, the magnetic frame (30) profile is designed in such a way that upper bend (22) of the magnetic frame (30) gives proper space for easy welding of the coil (30) end and the lower bend (24) is capable of being connected to external current carrying conductor. Accordingly, the current path between a upper bend (22) and a lower bend (24) of the magnetic frame (30) contribute in completing effective turn of the coil (40) as current flow therethrough which in turn helps in producing more flux. From starting led of the coil (40) to lower bend, thee effective turn from which current will flows is 2 wherein copper is used for 1.75 turns only.

Advantages of the invention
1. The system (100) provides magnetic characteristic as per application without fixed core.
2. The system (100) provides a moving core profile such that the moving core gives benefit of effectively less magnet gap and more actual gap for tripping
3. The system (100) provide a coil and the magnetic frame profile for effective contribution in generating NI.
4. The system (100) is cost effective electro-magnetic actuating system.
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, 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 omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim
1. An electro-magnetic actuating system for circuit breakers, the electro
magnetic actuating system comprising;
a moving core capable of moving linearly;
a plunger capable of being propelled by the moving core, the plunger capable of giving signal for any abnormal condition to a tripping unit connected thereto when moved by the moving core;
a magnetic frame having an upper bend and a lower bend, the lower bend connected to an external current carrying conductor;
a coil welded to the magnetic frame in a space provided by the upper bend of the magnetic frame, wherein the current path between the upper bend and the lower bend contributes in completing effective turn of the coil as current flows through the coil, which in turn helps in producing more flux, and when current passes through the coil, a magnetic field is produced which attracts the moving core thereby overcoming reluctance of the air gap; and
a spring attached to the lower end of the moving core, wherein, when the coil is energized, the moving core moves towards frame in order to complete the magnet flux path till the magnetic frame surface and links more flux with respect to the magnetic frame surface which helps in reducing active airgap.
2. The electro-magnetic actuating system as claimed in claim 1, wherein the coil is an electromagnetic coil.
3. The electro-magnetic actuating system as claimed in claim 1, wherein fixed core is eliminated.

4. The electro-magnetic actuating system as claimed in claim 1, wherein the moving core has a unique profile.