WO2013017909A1

WO2013017909A1 - Load break switch

Info

Publication number: WO2013017909A1
Application number: PCT/IB2011/002525
Authority: WO
Inventors: Amol Nivrathirao JADHAV; Ramesh Viswanathan IYER; Vasantha Kumar KANNAN
Original assignee: Abb Technology Ltd
Priority date: 2011-08-02
Filing date: 2011-10-21
Publication date: 2013-02-07

Abstract

The invention relates to a load break switch (200) and to an actuating mechanism thereof that provides a quick operation of closing, or opening, especially the closing of the contact assembly (201). The load break switch of the invention comprises one or more contact assembly, a source of energy (202) and an actuating mechanism. The source of energy been provided to drive the actuating mechanism. The actuating mechanism including its functional elements causes the quick operation of closing, or opening, especially the closing of the contact assembly.

Description

LOAD BREAK SWITCH

FIELD OF THE INVENTION

The invention relates to a load break switch, and more particularly to a making mechanism of a load break switch.

BACKGROUND

Load break switch is a switch that is capable of making, carrying and breaking currents under normal conditions and complies with isolating requirements or conditions under open condition. Load break switches are required to make a safe isolating distance between live parts and working object. Besides this, load break switches also cater to isolating faulty network portions, opening disconnector, connecting earthing device and eliminating eventual back feed to list a few.

In a load break switch, the closing and opening of the contact assembly becomes very important which are functionally significant for it. The closing and opening of the contact assembly, especially the closing of the contact assembly needs to be quick during the operation of closing the contact assembly when a short circuit peak is encountered, and also to eliminate the risk of arcing, or arcing beyond permissible level and of the welding or erosion of the contact assembly resulting therefrom due to slow operation during closing operation. Generally, the operation speed for closing or opening the contact assembly primarily depends on the speed of the motor which serves as a source that enables closing or opening operation in respect of the contact assembly.

Typically, the operating speed for closing or opening of the contact assembly increases in accordance with the rating of the load break switch and of the capacity thereof. This imposes a need to increase the speed of the motor to ensure quick closing operation, eventually this result in increasing the rating of the motor and of its size and power consumption.

Hence there is a need to achieve higher speed of operation for closing the contact assembly employing a suitable actuating mechanism and without rendering changes in respect of the motor. OBJECTS OF THE INVENTION

It is an object of the invention to provide a load break switch which offers higher speed of operation for closing the contact assembly.

It is also an object of the invention to provide a load break switch that is reliable in its operation.

Another object of the invention is to provide a load break switch that is simple in construction.

Yet another object of the invention is to provide a load break switch which has self latching and delatching of actuating mechanism.

SUMMARY OF THE INVENTION

Accordingly the invention provides a load break switch comprising atleast one contact assembly, a source of energy and an actuating mechanism. The contact assembly has a fixed contact and movable contact. The source of energy like motor is provided to drive atleast one actuating mechanism through crank and piston assembly. The actuating mechanism is provided with a compression spring for quick operation of closing, or opening the said contact assembly.

Accordingly the invention also provides atleast one actuating mechanism for a load break switch. The actuating mechanism comprises a piston assembly having a piston pipe and a piston, a compression spring, atleast one latch, a stopper assembly and housing. The piston pipe is connected to a source of energy at its one end. The compression spring is located axially at the other end of the piston pipe above the piston. The compression spring is movable and its movement is guided by a spring guide. The latch is guided by a latch guide and has a chamfered portion. The piston compresses the compression spring when moved accordingly by the piston pipe. The housing essentially has the compression spring and the latch guide is formed therein. A stopper assembly having a spring stopper and a stopper guide is provided for regulating the compression of the compression spring and of the latching of the housing having the compression spring. A cam profile is provided in the spring stopper to cause delatching of the housing which is achieved by the sliding movement of the latch against the said cam profile. The spring stopper has a cut portion at its lower end which corresponds to a projection provided at the bottom of the housing, so as to lock the housing and to prevent undesirable opening of the contact assembly upon closing of the contact assembly. BRIEF DESCRIPTION OF THE DRAWINGS:

With reference to the accompanying drawings in which:

Fig. la shows an existing load break switch with contact assembly in open position;

Fig. 1 b shows an existing load break switch with contact assembly in closed position;

Fig. 2a shows a load break switch in accordance with the invention with contact assembly in open position;

Fig. 2b shows a load break switch in accordance with the invention with contact assembly in closed position;

Fig. 2c shows the actuating mechanism of the load break switch in accordance with the invention when the contact assembly of the load break switch is in open position and the compression spring is not compressed;

Fig. 2d shows the actuating mechanism of the load break switch in accordance with the invention when the contact assembly of the load break switch is in open position and the compression spring is partially compressed;

Fig. 2e shows the actuating mechanism of the load break switch in accordance with the invention when the contact assembly of the load break switch is in open position and the compression spring is compressed sufficiently for quick operation of closing the contact assembly; and

Fig. 2f shows the actuating mechanism of the load break switch in accordance with the invention when the contact assembly of the load break switch is in closed position.

DETAILED DESCRIPTION

The invention is explained with reference to an exemplary embodiment in which Figs, l a and lb shows an existing load break switch (100) with contact assembly (101) in open and closed position respectively. The contact assembly (101 ) has a fixed contact (101a) and a movable contact (101b) that essentially defines the opening or closing of the said contact assembly (101) based on their alignment or positioning. A source of energy (102) such as motor drives a piston pipe (103) through a crank (104) connecting them to cause the opening or closing of the contact assembly. During the closing operation of the contact assembly (101 ), the motor (102) by an angular movement moves or pushes the piston pipe (103) connected to it through the crank (104). The piston pipe (103) accordingly moves the movable contact (101b) through an operating lever (105) thereby closing the contact assembly (101). Here, the contact assembly (101) is closed with its fixed contact (101a) and movable contact (101b) in contact with each other.

The closing operation is primarily dependent on the speed of the motor (102) so that angular displacement provided to the crank (104) and thereby corresponding movement of the piston pipe (103) is affected accordingly. However, with the increase of the capacity or rating of the load break switch, the operation speed for closing or opening, especially the closing needs to be quick. This is imperative to eliminate or to a greater extent avoid some implications relating to arcing between the contacts, erosion of the contact, welding etc. Currently, this is being achieved by increasing the speed of the motor (102) which eventually increases the speed of operation for closing or opening of the contact assembly (101). Coextensively, this is required to be achieved by increasing the rating of the motor (102) and hence its size and power consumption also.

The load break switch (200) in accordance with the invention as seen from Figs. 2a and 2b depicts open and closed position of the contact assembly (201) respectively. Also, Figs. 2c, 2d and 2e shows the actuating mechanism of the load break switch of the invention with its contact assembly in open position and respectively when the compression spring (206) is not compressed, partially compressed and sufficiently compressed. Fig. 2f shows the actuating mechanism of the load break switch of the invention with its contact assembly in closed position and the said actuating mechanism in locked position. This is to take care of short circuit forces during closed position of the contact assembly in service Figs. 2a through 2f may collectively be represented as Fig. 2 here after for the purpose of simplicity.

In Fig. 2, the load break switch (200) of the invention is driven by a source of energy (202) such as motor connected to a piston assembly having a piston pipe (203a) and a piston (203b) at one end through a crank (204). The rotational movement of the motor (202) exhibits movement of the piston assembly and of the latch (207) having a chamfered portion (208) fixed to the piston (203b). The piston (203b) compresses the compression spring (206) located coaxially with the piston (203b). The compression spring (206) having some charge required to retain its alignment or positioning, is guided by a spring guide (214) located coaxially within the compression spring (206). The compression spring (206) and the latch (207) are disposed in housing (213). The movement of the latch (207) along the axis of the housing (213) or of the axis of the piston pipe (203a) is guided by a latch guide (209) formed therein by a through cut portion on both the sides of the housing (213).

The compression of the compression spring (206) by the piston pipe (203a) and piston (203b) is regulated by a stopper assembly. The stopper assembly includes a spring stopper (210) which is held in position by a retaining spring (211). The spring stopper (210) arrests the movement of the housing (213) with the aid of a stopper guide (212) provided along the side of the housing (213) so as to facilitate compression of the compression spring (206). This way, self latching of the housing (213) for the compression of the compression spring (206) is made possible. The latching of the housing (213) is sustained during and until the end of the compression of the compression spring (206) sufficient to cause quick operation of closing the contact assembly (201).

The compression of the compression spring (206) being effected with the movement of the piston (203b), during which, the chamfered portion (208) of the latch (207) slides over a cam profile (215) provided in the inner portion of the spring stopper (210) against the pull offered by the retaining spring (21 1 ) so as to cause an angular movement of the spring stopper (210). The angular movement of the spring stopper (210), at the end of sufficient compression of the compression spring (206) releases the housing from the latching thereby making self delatching of the housing (213) possible.

Upon delatching of the housing (213), the charging of the compression spring (206) sufficiently made through compression of the compression spring (206) against the upper portion of the housing (213), is discharged resulting in a movement of the housing (213). This movement of the housing (213) accordingly operates the operating lever (205). Since, operating lever (205) being connected to the movable contact (201b), moves the movable contact (201b) towards the fixed contact (201a) thereby engaging the movable contact (201 b) with the fixed contact (201a) and thus closing the contact assembly (201). The compression spring (206) upon discharging the charge gained during compression, however maintains some charge that is required to retain its alignment or positioning. It is to be noted that the speed of operation for closing the contact assembly (201 ) is effected with increased speed and is quick which is caused by the actuating mechanism that functionally include compression spring (206), spring guide (214), housing (213) with latch guide (209), latch (207), spring stopper (210) with cam profile (215), retaining spring (21 1), stopper guide (212), piston pipe (203a) and piston (203b). Such quick operation for closing the contact assembly (201) does not require an increase in rotational speed or power of the motor (202).

Upon closing of the contact assembly (201), the closed position of the contact assembly (201) is maintained as until required, by arresting the movement of the housing (213) and locking the housing (213) thereof in a position so as to maintain the closed position of the contact assembly (201 ) and to prevent undesired opening of the contact assembly (201). The locking of the housing (213) is effected by an engagement between a cut portion (216) located at the bottom of the spring stopper (210) and the projection (217) located at the bottom portion of the housing (213), which is caused by the angular movement and engagement therein of the cut portion (216) of the spring stopper (210)

The operation for opening of the contact assembly (201) is also quite simple, in which the motor (202) provides a rotational movement in opposite direction as compared to closing operation moves the crank (204) connected to it, accordingly. The movement of the crank (204) effects an angular displacement of the housing (213) and of the projection (217) thereof disengaging from the cut portion (216) of the spring stopper (210) thereby unlocking the housing (213). This further enables the crank to pull the piston pipe (203a) and the piston (203b) downward which in turn pulls the housing (213). With the downward movement of the housing (213), the operating lever (205) connected to the housing (213) moves the movable contact (201b) away from the fixed contact (201a) causing the operation for opening the contact assembly (201).

The invention is not restricted by the preferred embodiment described herein in the description. It is to be noted that the invention is explained by way of exemplary embodiment and is neither exhaustive nor limiting. Certain aspects of the invention that not been elaborated herein in the description are well understood by one skilled in the art. Also, the terms relating to singular form used herein in the description also include its plurality and vice versa, wherever applicable. Any relevant modification or variation, which is not described specifically in the specification are in fact to be construed of being well within the scope of the invention.

Claims

WE CLAIM:

1. A load break switch comprising:

one or more contact assembly;

a source of energy to drive atleast one actuating mechanism; and

characterized in that the said actuating mechanism is provided with a compression spring for quick operation of closing, or opening the said contact assembly.

2. The load break switch as claimed in claim 1, wherein the said contact assembly comprises a fixed contact and a movable contact.

3. The load break switch as claimed in claim 1, wherein the said source of energy is a motor.

4. An actuating mechanism for a load break switch comprising:

a piston assembly having a piston pipe and a piston, said piston pipe connected to a source of energy at one end;

wherein the said actuating mechanism comprises a compression spring disposed axially at the other end of the said piston rod;

atleast one latch axially fixed to the said piston;

a stopper assembly for regulating the charging of the said compression spring; and

a housing containing the said compression spring and the said atleast one latch.

5. The actuating mechanism as claimed in claim 1 or 4, wherein the said compression spring is guided by a spring guide located axially within the said compression spring and movable axially within the said piston pipe.

6. The actuating mechanism as claimed in claim 4, wherein the said latch has a chamfered portion and guided by a latch guide formed therein in the said housing.

7. The actuating mechanism as claimed in claim 4, wherein the said piston is provided for compressing the compression spring against the upper portion of the housing by a corresponding movement of the said piston pipe.

8. The actuating mechanism as claimed in claim 4, wherein the upper portion of the said housing is coupled to an operating lever that is connected to the said movable contact

9. The actuating mechanism as claimed in claim 4, wherein the said stopper assembly has a spring stopper held in position by a retaining spring.

10. The actuating mechanism as claimed in claim 9, wherein the said spring stopper is provided for arresting the movement of the housing or of the latching thereof with the aid of a stopper guide fitted to the said housing in order to facilitate compression of the compression spring by the said piston aided by the said piston pipe.

1 1. The actuating mechanism as claimed in claim 6 or 9, wherein the said latch is provided with the said chamfered portion for making a sliding movement against the cam profile located in the said spring stopper so as to delatch or release the said housing from latching at the end of or after the compression of the said compression spring.

12. The actuating mechanism as claimed in claim 11, wherein the said chamfered portion of the said latch is provided for causing an angular movement of the spring stopper along its pivotal axis and against the pull of the said retaining spring in order to delatch or release the said housing from latching at the end of or after the compression of the said compression spring and to cause upward movement of the said housing.

13. The actuating mechanism as claimed in claim 1 1 or 12, wherein the said housing is coupled to the said operating lever for causing movement of the movable contact connected to the said operating lever thereby effecting closing of the said contact assembly during upward movement of the said housing.

14. The actuating mechanism as claimed in claim 4, wherein the said stopper assembly includes a cut portion located at the bottom of the said spring stopper.

15. The actuating mechanism as claimed in claim 4 or 14, wherein the said housing has a projection disposed at its bottom portion that correspond to the space created therein by the said cut portion in the said spring stopper.

16. The actuating mechanism as claimed in claim 14 and 15, wherein the said cut portion in the said spring stopper and the said projection in the said housing are provided to engage or disengage with each other.

17. The actuating mechanism as claimed in claim 16, wherein the said cut portion in the said spring stopper and the said projection in the said housing engages with each other for arresting the movement of the said housing and locking thereof, and to prevent undesired opening of the said contact assembly upon closing of the said contact assembly.

18. The actuating mechanism as claimed in claim 16, wherein the said cut portion in the said spring stopper and the said projection in the said housing disengages from each other for allowing the movement of the said housing and to release locking thereof, in order to allow opening of the said contact assembly, through angular movement of the said projection in the said housing caused by corresponding movement of the crank of the motor, during opening of the said contact assembly.

19. The actuating mechanism as claimed in claim 1 or 4, wherein the said piston is pulled by the said source of energy and the said piston pipe connected thereto causing downward movement of the said housing and of the actuating assembly.

20. The actuating mechanism as claimed in claim 19, wherein the said housing is coupled to the said operating lever for causing movement of the movable contact connected to the said operating lever thereby effecting opening of the said contact assembly during downward movement of the said housing.