FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Rotary Convertible Electrical Contact"
2. APPLICANT:
(a) NAME: Larsen & Toubro Limited
(b) NATIONALITY: Indian Company registered under the
provisions of the Companies Act-195 6.
(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.

Rotary Convertible Electrical Contact
Field of the invention
The present invention relates to contacts used as an auxiliary contact for electrical contactor, and more particularly, to a rotary convertible normally-open or normally-closed electrical contact.
Background of the invention
In present technologies, contact blocks have either normally-closed or normally-open contacts to control current flowing in an electrical circuit. These contact blocks are mounted on outer surface of electrical contactor and works simultaneously with the operation of the contactor main contacts. Specifically, stationary contacts of the contact block can be converted to either normally-closed or normally-open contacts by moving actuator in translational movement The actuator contains moving contacts which bridges the stationary contacts, thus forming either normally-closed or normally-open contacts.
The currently used contact blocks are provided generally with one normally-open and one normally-closed contact. The contacts in the contact block can be used as only provided by manufacturer. If user wants different combinations of contacts, for example, two normally-open or two normally-closed, the user needs to purchase an additional contact block for satisfying the requirement.
It is common to use contact block having either normally closed or normally open contacts to control the current flowing in electrical circuit The contact block generally consists of a first pair of stationary contacts and a pair of movable contacts attached to an actuator. The actuator is biased such that the movable contacts are either in closed or open position with relation to first

stationary contacts. It is also known to have a second pair of stationary contacts spaced apart from the first pair of stationary contacts such that the pair of movable contacts are located between the first and second stationary contacts, thus allowing the contact block to have one normally open contact and one normally closed contact. Specifically, in prior contact block to have one normally open and one normally closed contact, it is required to have four stationary contacts and two moving contacts. However, the extra set of the stationary contacts increases the physical size of the contact block and significantly increases the cost since two additional stationary contacts are required. If an application requires two contacts of same type (either NO or NC), the contact blocks are stacked together. This stacking of the contact blocks also provides additional cost of the contact block.
In other types of circuit control devices, it is sometimes required to operate an additional control circuit by same operator as that of main circuit. For example, in contactor auxiliary circuit, the contacts are controlled by operator which moves along with movement of electromagnet of the contactor. For these applications, it is common to provide an auxiliary contact. The auxiliary contact is generally contained within an enclosure and includes a pair of stationary contacts, a pair of movable contacts mounted on the actuator, a biasing spring, and a pair of wire terminal connectors. The auxiliary contact enclosure is mounted on the outside of the circuit control device enclosure in a location that permits access to the primary contactor actuator such that the auxiliary contact can be operated simultaneously with the primary contactor.
The auxiliary contacts, like the contact blocks, are available in either a normally open or normally closed function and must be purchased separately as an accessory for the control device. This means that an inventory of both normally open and normally closed contacts is required separately to ensure that the desired auxiliary contact is available when required. Specifically, figure 6 shows

the contact block (11) used in present technology. The contact block (11) is placed above the surface of a contactor (12).
Accordingly, there exists a need to provide a contact block assembly which overcomes drawbacks of the prior art.
Objects of the invention
An object of the present invention is to provide a contact block which is comparable in cost to a single function contact block.
Another object of the present invention is to provide a contact block which can be easily converted from normally open to normally closed contact.
Yet another object of the present invention is to provide a circuit control device with auxiliary contact that can be easily converted from normally open to a normally closed contact (or vice versa).
Summary of the invention
Accordingly, the present invention provides a rotary convertible contact assembly for a circuit control device. The rotary convertible contact assembly comprises a first actuator having a cavity thsrewithin for containing a spring therein. The first actuator includes a top end and a bottom end. Further, the rotary convertible contact assembly comprises a second actuator detachably positioned at the top end of the first actuator. The second actuator includes a first knob capable of being engaged with a contactor and moving in translational motion along with the contactor to push the first actuator down, and a second knob rotatabaly mounted thereon. The second knob rotates the first actuator in circular motion. Furthermore, the rotary convertible contact assembly includes a first stationary contact and a second stationary contact positioned on one side of the first actuator to form a singe contact, a third stationary contact positioned on

other side of the first actuator opposite to the first stationary .contact and the second stationary contact and a Z-shaped movable contact attached to the top end of the first actuator. The Z- shaped movable contact is capable of bridging any one of the first stationary contact and the second stationary contact with the third stationary contact to form normally-closed contact When the first knob pushes the first actuator down due to the contactor movement, the Z-shaped movable contact moves away from the first stationary contact and the third stationary contact thereby opening the normally-closed first stationary contact and the third stationary, and rotating the second knob rotates the first actuator in circular motion which causes the Z-shaped movable contacts to move away from the first stationary contact, the second stationary contact and the third stationary contact to form normally-open contact and when the first knob is further moved down by the contactor motion, the first actuator moves down to bridge the second stationary contact and the third stationary contact to close the normally open contact.
Brief description of the drawings
Figure 1 shows a rotary convertible contact assembly in normally-closed position, in accordance with the present invention;
Figure 2. shows the rotary convertible contact assembly of figure 1 when operated from the normally-closed position;
Figure 3 shows the rotary convertible contact assembly of figure 1, in normally-open position, in accordance with the present invention;
Figure 4 shows the rotary convertible contact assembly of figure 3 when operated from normally-open position;

Figure 5 shows a perspective view of the rotary convertible contact assembly, in accordance with the present invention; and
Figure 6 shows a contact block mounted on surface of an electrical contactor, in accordance with the prior art.
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 a rotary convertible contact assembly for a circuit control device. In the present invention in order to have one normally closed and one normally open contact, only three stationary contacts and one Z-shaped moving contact are required. The action of changeover of contacts is rotary as opposed to translational in prior contact block.
Referring now to figure 1-5, there are shown various views of a rotary convertible contact assembly (100), (hereinafter, 'the assembly (100)') in accordance with the present invention. The assembly (100) includes a first actuator (10), the second actuator (20), a first stationary contact (30), a second stationary contact (40), a third stationary contact positioned (50) and a Z-shaped movable contact (60).
The first actuator (10) is a hollow elongated actuator having a cavity (12) . therewithin. The cavity (12) includes a spring (not shown) therein. The spring contained in the cavity (12) of the first actuator (10) supports the Z-shaped movable contact (60) to its one end. The first actuator includes a top end (14)

and a bottom end (16). The first actuator (10) is connected to the second actuator (20).
Specifically, the second actuator (20) is detachably positioned at the top end (14) of the first actuator (10). The second actuator (20) is hollow part and includes a first knob (22) positioned thereon. The first knob (22) is capable of being engaged with a contactor of the circuit breaker device and moves in translational motion along with the contactor thereby pushing the first actuator (10) down. Since the second actuator (20) is to be engaged with the contactor, the second actuator cannot be rotated. Thus, the second actuator (20) is made hollow. The second actuator (20) further includes a second knob (24) rotatabaly mounted thereon. The second knob (24) is passed from inside the second actuator (20). Thus, the second actuator (20) moves only in translational movement so as to push the first actuator (10) down and when rotated, the second knob (24) rotates the first actuator (10) in circular motion. The first actuator (10) detachably secured to the second actuator (20) influences action of the various contacts.
Specifically, the first stationary contact (30) and the second stationary contact (40) are positioned on one side of the first actuator (10) to form a singe contact. Specifically, the first stationary contact (30) and the second stationary contact (40) are mounted on a single frame such that the contact buttons (35) of each contact face each other. Further, the third stationary contact (50) is positioned on other side of the first actuator (10) opposite to the first stationary contact (30) and the second stationary contact (40). Furthermore, the Z-shaped movable contact (60) is attached movably to the top end (14) of the first actuator (10). The Z- shaped movable contact (60) is capable of bridging any one of the first stationary contact (30) and the second stationary contact (40) with.the third stationary contact (50) to form normally-closed contact. However, it may be noted that the Z- shaped movable contact (60) bridges only one of the first stationary contact (30) and the second stationary contact (40) with the third

stationary contact (50) at one time. Specifically, figure 5 shows the exploded view of the assembly (100).
Referring to figure 1, there is shown the assembly (100) in first position i.e. in normally-closed position, in accordance with the present invention. In first position, the Z-shaped movable contact (60) bridges the first stationary contact (30) and the third stationary contact (50). Thus, there is electrical connection between the first stationary contact (30) and the third stationary contact (50). This forms the normally-closed contact between the first stationary contact (30) and the third stationary contact (50). Further, the second actuator (20) having a first knob (22) engaged with the contactor of the circuit breaker, moves in translational motion along with the contactor and pushes the first actuator (10) down in a direction as shown by an arrow in figure.2. The moving of the first actuator (10) moves the Z-shaped movable contact (60) away from the first stationary contact (30) and the third stationary contact (50) and consequently opens the first stationary contact (30) and the third stationary contact (50). Thus the normally-closed contact opens as the first actuator (10) moves.
Referring now to figure 3, there is shown the assembly (100) in second position. When application requires normally-open contact, it can be achieved by just rotating the second knob (24) by 180 degree angle, thus rotating the first actuator (10) as well as the Z-shaped moving contact (60). This rotary motion is shown by an arrow in figure.3. In this position, the Z-shaped moving contact (60) is not touching any of first stationary contacts (30), the second stationary contact (40) and the third stationary contact (50). Thus there is no electrical connection between the first stationary contacts (30), and the second stationary contact (40) with the third stationary contact (50). This forms the normally-open contact between the second stationary contact (40) and the third stationary contact (50). When detached, the second actuator (20) moves because of the contactor action thereby moving the first actuator (10) in a direction shown by an arrow in figure 4. This bridges the second stationary contact (40) and the

third stationary contact (50) and thus making the electrical connection therebetween. Thus the normally-open contacts are closed as the first actuator (10) moves.
Specifically, figure 4 shows the assembly (100) when operated from the second position so as to close the contacts. The arrow shows the translational motion of the first actuator (10) and Z-shaped movable contact (60). Thus, operating the first actuator (10) in a direction shown by thick arrow in the figure 4, wherein the normally-open contact are closed.
Advantages of the invention
1. The assembly (100) requires only three stationary contacts and one Z-shaped
moving contact in order to have one normally closed and one normally open
contact, thus reducing cost of the assembly (100).
2. The action of changeover of contacts in the assembly (100) is rotary as
opposed to translational in prior contact block.

3. With the assembly (100), a user is provided with flexibility to choose required
contact depending on his requirement or application.
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. A rotary convertible contact assembly for a circuit control device, the rotary convertible contact assembly comprising:
a first actuator having a cavity therewithin for containing a spring therein, the first actuator having a top end and a bottom end;
a second actuator detachably positioned at the top end of the first actuator, the second actuator having a first knob capable of being engaged with a contactor and moving in translational motion along with the contactor to push the first actuator down, and a second knob rotatabaly mounted thereon, the second knob rotates the first actuator in circular motion;
a first stationary contact and a second stationary contact positioned on one side of the first actuator to form a singe contact;
a third stationary contact positioned on other side of trie first actuator opposite to the first stationary contact and the second stationary contact;
a Z-shaped movable contact attached to the top end of the first actuator, the Z- shaped movable contact capable of bridging any one of the first stationary contact and the second stationary contact with the third stationary contact to form normally-closed contact;
wherein when the first knob pushes the first actuator down due to the contactor movement, the Z-shaped movable contact moves away from the first stationary contact and the third stationary contact thereby opening the normally-closed first stationary contact and the third stationary, and rotating the second knob rotates the first actuator in circular motion which causes the Z-shaped movable contacts to move away from the first stationary contact, the second stationary contact and the third stationary contact to form normally-open contact and when the first knob is further moved down by the contactor motion, the first actuator moves down to bridge the second stationary contact and the third stationary contact to close the normally open contact.

2. The rotary convertible contact assembly as claimed in claim 1, wherein the second actuator is engaged with the contactor by the first knob.
3. The rotary convertible contact assembly as claimed in claim 1, wherein the second actuator is hollow.
4. The rotary convertible contact assembly as claimed in claim 1, wherein the second knob used for rotating the first actuator is passed from inside the second actuator.