FORM 2
THE PATENTS ACT, 1970
COMPLETE SPECIFICATION
(See Section 10)
CONTACT ACTUATING MECHANISM FOR SWITCHING
DEVICE
Numbered as dated
INVENTORS:
a) VIRENDER SINGH BURA
b) SATBIR SINGH
APPLICANT:
M/s. LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278, Mumbai, 400 001, Maharashtra,
INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION

CONTACT ACTUATING MECHANISM FOR SWITCHING
DEVICE
A) TECHNICAL FIELD
[0001] The present invention generally relates to an electrical power supply device and particularly to controllers used for domestic and industrial purposes. The present invention more specifically relates to the switching devices such as miniature circuit breaker, residual current circuit breaker, isolator and their auxiliary contacts, etc.
B) BACKGROUND OF THE PRESENT INVENTION
[0002] The electrical switching devices are used to protect the electrical circuitry and equipment from the damage due to an abnormal condition, such as an overload condition, a relatively high level short circuit or a fault condition.
[0003] The electrical switching devices typically have two operating handle positions corresponding to the status of the separable contacts. For example, these positions include an ON position, in which the separable contacts are closed and an OFF position in which the contacts are open. Some switching devices have a third position which corresponds to a tripped condition in which the contacts are tripped open.
[0004] Switching devices are usually installed in an enclosure so that the entire control and distribution network arranged in the form of metallic sheets and/or cable wires are


housed inside the enclosure. All the operating means are arranged outside the enclosure to prevent an access to the high voltage sections to eliminate the generation of a potential hazard. It is often desirable or essential that the settings of the switching devices remain undisturbed in the switching device during a maintenance operation. Unauthorized or inadvertent changing of the position of these breakers could result in unwanted interruptions to service or operations and serious damage to an electrical apparatus, or even serious harm to a person. For example, accidental actuation of a circuit breaker might result in electrocution or shock to a workman performing electrical work or repair on equipment downstream from the circuit breaker.
[0005] Therefore enough safety measures must be taken to prevent another person from inadvertently returning the circuit breaker handle to the ON position, when a worker is doing electrical work in an area other than the immediate vicinity of the circuit breaker box or electrical panel. One such safety measure is the addition of a locking assembly to the switching device to prevent the displacement of the circuit breaker operating handle.
[0006] A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.
[0007] The Magnetic circuit breakers are provided with a solenoid (electromagnet) whose pulling force increases with the magnitude of current. The circuit breaker's contacts are held closed by a latch. When the current passed through the solenoid increases beyond


the preset rating of the circuit breaker, the latch is released by the pulling force of the solenoid to permit the contacts to be opened by a spring action. Some types of magnetic breakers have a hydraulic time delay feature to allow brief surge current beyond a preset level for starting motor or energizing electrical equipment.
[0008] The Thermal breakers use a bimetallic strip, which is heated and bent with increased current, and is similarly arranged to release the latch. Such thermal breakers are commonly used with motor control circuits. Thermal breakers often have a compensation element to reduce the effect of ambient temperature on the device rating.
[0009] The Thermo magnetic circuit breakers are found mostly in distribution boards. The thermo magnetic circuit breakers include both an electromagnet that responds instantaneously to large surges in current (short circuits) and the bimetallic strip which responds with respect to less extreme but long -term over current conditions.
[0010] The Circuit breakers for larger currents are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism.
[0011] There are different technologies used in circuit breakers and they do not always fall into distinct categories. The commonly used circuit breakers in domestic, commercial and light industrial applications at low voltages (less than 1000 V) include a miniature circuit breaker (MCB) and a moulded case circuit breaker (MCCB).
[0012] A miniature circuit breaker (MCB) is used for a rated current of not more than 100 A. the trip characteristics are not adjustable normally. The MCB employs thermal or thermo-magnetic principles. The MCCB (Moulded Case Circuit Breaker) is used for a


rated current up to 1000 A. the MCCB uses the Thermal or thermal-magnetic operation. The trip current may be adjusted in MCCB.
[0013] In any kind of circuit breaker or switching device the operating mechanism plays a main role. Since the module width of the low voltage circuit breaker is very less (17.5 mm), the operating mechanism should be compact. Moreover, since a Rotary contact is used in the circuit breakers, some special mechanism needs to be devised to make and break the contacts quickly and safely.
[0014] The US patent no. 6 977 567 discloses a low voltage circuit breaker provided with a contact device in which a flange having a through hole is arranged at one side surface so that the force generated due to the passage of air through the flange is used to hit a latch to generate a trip quickly.
[0015] The US patent no. 6 853 277 discloses an auxiliary magnetic trip system for a circuit breaker. The trip system has a hold back system releasably coupled to trip lever mounted on an axis so that the movement of the trip lever is permitted or prevented based on two different electrical current levels.
[0016] The US patent no. 6 211 757 discloses a trip actuator or actuating an operating mechanism in a circuit breaker. The trip actuator'has an electromechanical device to which a signal is supplied to release a plunger to permit a trip arm to pivot in a preset direction to actuate an operating mechanism.
[0017] Thus the currently available circuit breaker utilizes several linkages to operate a trip mechanism to make and break the electrical contacts. None of the currently available


circuit breaker or switching device has a compact operating mechanism and an additional mechanism to make and break the electrical contacts quickly and safely. The circuit breakers used in low voltage applications are mostly used for domestic purposes. Hence there is a space constraint and a compelling need for the space saving type circuit breaker.
C) OBJECT OF THE INVENTION
[0018] The primary objective of the present invention is to provide a compact contact arrangement of the fast-break type, particularly intended for low voltage switching devices.
D) SUMMARY OF THE INVENTION
[0019] The abovementioned shortcomings, disadvantages and problems are addressed herein and which will be understood by reading and studying the following specification
[0020] The present invention provides a compact fast break — type contact arrangement in a switching device to make and break the electrical contacts quickly and safely. According to one embodiment of the present invention, a switching device is provided with compact fast actuating type contacts so that the breaking of contacts takes place very quickly. The switching device a compact switching mechanism provided with a rotary contact to make and break electrical contacts quickly and safely.


[0021] According to one embodiment of the present invention, the circuit breaker assembly has a knob connected to a connecting link and to a first operating lever through a U- pin. One end of the connecting link is coupled to the knob while the other end of the connecting link is connected to a rotary contact through a pivot so that the movement of the connecting link is transferred to the rotary contact. The movement of the connecting link is used to make and break the electrical contacts. The other end of the first operating lever connected to the knob is lockingly engaged to a locking lever. When the locking lever is moved on its own axis, the first lever is released from the locking lever to trip a contact breaker mechanism. When the first lever is locked with the locking lever, the connecting link is moved due to the movement of the knob to rotate the rotary contact to make or break the electrical contacts.
[0022] According to one embodiment of the present invention, the breaker mechanism has a unique design and a compact structure so that the mechanism may be used effectively and efficiently in a half module with a width of 9 mm. The operating time is greatly reduced due to the usage of fewer link mechanisms. The operating Knob will be moved to OFF position, even when the moving contact is held forcibly by just rotating locking lever.
[0023] Thus the embodiments of the present invention provide a switching mechanism with a compact structure and unique design to make and break the electrical contacts quickly and safely.
[0024] These and other objects and advantages of the present invention will become readily apparent from the following detailed description taken in conjunction with the accompanying drawings.


E) BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:
[0026] FIG. 1 illustrates a side sectional view of a switching device according to one embodiment of the present invention with the switch held in ON position to establish electrical contacts at four locations.
[0027] FIG. 2 illustrates a side sectional view of a switching device according to one embodiment of the present invention with the switch held in OFF position to break the electrical contacts at four locations.
[0028] FIG. 3 illustrates a side sectional view of a switching device according to one embodiment of the present invention.
[0029] FIG. 4 illustrates a side sectional view of an electrical contact switching mechanism in an assembled condition in a switching device according to one embodiment of the present invention.
[0030] FIG. 5 illustrates a side sectional view of an electrical contact switching mechanism in an unassembled condition in a switching device according to one embodiment of the present invention.


[0031] Although specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.
F) DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0032] In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments which may be practiced is shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that the logical, mechanical and other changes may be made without departing from the scope of the embodiments. The following detailed description is therefore not to be taken in a limiting sense.
[0033] The present invention provides a compact fast break - type contact arrangement in a switching device to make and break the electrical contacts quickly and safely. According to one embodiment of the present invention, a switching device is provided with a switching mechanism having a rotary contact to make and break the electrical contacts quickly, easily, efficiently and safely.
[0034] According to one embodiment of the present invention, the circuit breaker assembly has a knob connected to a connecting link and to a first operating lever through a U- pin. One end of the connecting link is coupled to the knob while the other end of the connecting link is connected to a rotary contact through a pivot so that the movement of the connecting link is transferred to the rotary contact. The movement of the connecting link is used to make and break the electrical contacts. One end of the first


operating lever is connected to the knob while the other end of the operating lever is lockingly engaged to a locking lever. When the locking lever is moved on its own axis, the first operating lever is released from the locking lever to trip a contact breaker mechanism. When the first lever is locked with the locking lever, the connecting link is moved due to the movement of the knob to rotate the rotary contact to make or break the electrical contacts.
[0035] According to one embodiment of the present invention, the breaker mechanism has a unique design and a compact structure so that the mechanism may be used effectively and efficiently in a half module with a width of 9 mm. The operating time is greatly reduced due to the usage of fewer link mechanisms. The operating Knob will be moved to OFF position, even when the moving contact is held forcibly by just rotating locking lever.
[0036] Thus the embodiments of the present invention provide a switching mechanism with a compact structure and unique design to make and break the electrical contacts quickly and safely.
[0037] The FIG. 1 shows a side sectional view of a switching device according to one embodiment of the present invention with the switch being held in the ON position while the FIG. 2 shows a side sectional view of the switching device according to one embodiment of the present invention with the switch being held in the OFF position. FIG. 3 illustrates a sectional view of the switching device according to one embodiment of the present invention.


[0038] With respect to the FIGS. 1, 2 and 3, an operating knob 2 is connected to a U-Pin 6. The U-Pin 6 is then connected to an operating lever 5 and to a connecting link 4. One end of the connecting link 4 is coupled to the knob 2 through the U-pin 6, while the other end of the connecting link 4 is attached to a rotary contact 1 through a pivot 3. The movement of the connecting link 4 is transferred to the rotary contact 1 with the help of a pivot 3 so that the connecting link 4 is moved by operating the knob 2 to rotate the rotary contact 1 to make and break the electrical contacts 8. One end of the operating lever 5 is coupled to the knob 2 through, the U-pin 6, while the other end of the operating lever 5 is lockingly engaged to a locking lever 7.
[0039] The FIGS. 4 and 5 indicate the side sectional view of a switching mechanism in an assembled and in an unassembled condition respectively in a switching dev ice according to one embodiment of the present invention.
[040] With respect to FIGS 4 and 5, an operating Knob 2 is connected to a connecting link 4 and to an operating lever 5 through a U- pin 6. The other end of the operating lever 5 is locked with a locking lever 7. When the locking lever 7 is moved about its own axis, the operating lever 5 is released from the locking condition to trip a contact switching mechanism. The other end of the connecting link 4 is connected to the rotary contact 1 through a pivot 3. When the operating lever 5 is locked, the knob 2 is operated to move the connecting link 4 will to rotate the rotary contact 1 to make or break the electrical contacts.


G) ADVANTAGES OF THE PRESENT INVENTION
[0041] The various embodiments of the present invention provide a switching device with a switching mechanism having a unique design and compact structure. Since the switching mechanism has a compact structure, the mechanism may be used in a module with a small width of 9mm. The number of linkages used in the operating mechanism is reduced to reduce the operating time to obtain a fast acting contact making and braking mechanism reliably and safely. The operating Knob will be moved to OFF position, even when the moving contact is held forcibly by just rotating the locking lever.
[0042] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the present invention described herein and all the statements of the scope of the invention which as a matter of language might be said to fall there between.


CLAIMS
What is claimed is:
1. An electrical contact actuating mechanism for switching device comprising:
an operating knob;
an operating lever connected to said operating knob;
a locking lever engaged to said operating lever;
a connecting link operably coupled to said operating knob; and
a rotary contact coupled to said connecting link;
wherein said operating knob is moved to displace said connecting link to move said rotary contact to make or break electrical contacts.
2. The mechanism according to claim 1, wherein said operating lever is connected
to said operating knob through a pin.
3. The mechanism according to claim 2, wherein said pin is a U-shaped pin.
4. The mechanism according to claim 1, wherein said connecting link is coupled to
said operating knob through a pin.
5. The mechanism according to claim 4, wherein said pin is a U-shaped pin.
6. The mechanism according to claim 1, wherein said operating lever and said
connecting link are coupled to said operating knob through a same pin.
7. The mechanism according to claim 6, wherein the pin is a u-shaped pin.
8. The mechanism according to claim l, wherein said connecting link is coupled to
said rotary contact through a pivot.
9. The mechanism according to claim 1, wherein said operating knob is moved
between ON and OFF positions.
10. The mechanism according to claim 1, wherein said locking lever locks or releases the operating lever.
11. The mechanism according to claim 1, wherein said rotary contact has plurality of arms to make and break contact with plurality of stationary contacts.
12. The mechanism according to claim 1, wherein the operating knob is moved to displace the rotary contact to enable the arms of the movable contacts to make and brake with stationary electrical contacts.
13. The mechanism according to claim 11, wherein the rotary contact has 4 arms.

To,
The Controller of Patents,
The Patent office,
At Mumbai


ABSTRACT
According to one embodiment of the present invention, a contact actuating mechanism is provided with a rotary contact to make and break electrical contacts. An operating knob is connected an operating lever and to a connecting link through a U-shaped pin. The operating lever is lockingly engaged with a lock lever. The connecting link is also coupled to the rotary contact through a pivot so that the operating knob is moved to displace the connecting link to move the rotary contact to make and break with electrical contacts.
13 Claims, 5 Drawing Sheets.