AU2016200621B2 - An electrical switchgear mechanism - Google Patents

Abstract

The present invention relates to an electrical switchgear assembly. The assembly includes an isolator including a pair of electrical isolator contacts, and an interrupter including a pair of electrical interrupter contacts. A driving mechanism is provided for driving open each pair of electrical contacts. Advantageously, an operator may manually open the contacts of both the isolator and interrupter using the driving mechanism. .1' ~L I! 1) 2 I __ 'Iv r--H 4 zj't~ [ 1 C) 0 7 ( K ~ A) ) -s ____________ ~ V [ \II H o 1 /6 o A ~c~+ ~TI o - i~ K] -J

Description

The present invention relates to an electrical switchgear assembly. The assembly includes an isolator including a pair of electrical isolator contacts, and an interrupter including a pair of electrical interrupter contacts. A driving mechanism is provided for driving open each pair of electrical contacts. Advantageously, an operator may manually open the contacts of both the isolator and interrupter using the driving mechanism.

2016200621 02 Feb 2016

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AUSTRALIA PATENTS ACT 1990

COMPLETE SPECIFICATION STANDARD PATENT

AN ELECTRICAL SWITCHGEAR MECHANISM

The following statement is a full description of this invention including the best method of performing it known to me:

2016200621 01 May 2018

AN ELECTRICAL SWITCHGEAR MECHANISM

TECHNICAL FIELD [0001] The present invention generally relates to electrical power switchgear.

BACKGROUND [0002] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

[0003] Electrical switchgear is used outdoors on overhead power lines and substation applications, usually between 10-38kV, to connect and disconnect electrical circuits. Typical switchgear includes electrical isolators or disconnect switches and circuit breakers or interrupters, whether used alone or in combination.

[0004] An interrupter such as a circuit breaker employing a vacuum interrupter is used to interrupt the circuit and break current flow, in the event of an overload or short circuit, to protect the circuit from damage. The interrupted current is either normal load current in normal operating conditions, or short circuit current in fault conditions. Not all interrupters are considered as isolators that are capable of providing safe isolation between load and source sides after interruption.

[0005] Additional electrical isolators are used, in the circuit and in series to the interrupter, to safely disconnect the electrical circuit for service or maintenance and ensure isolation. Invariably, switchgear contacts may need to be manually opened during maintenance or replacement of equipment in the circuit.

[0006] The preferred embodiment provides a means for controlling opening of the contacts of switchgear.

2016200621 01 May 2018

SUMMARY OF THE INVENTION [0007] According to one aspect of the present invention, there is provided an electrical switchgear assembly including:

an isolator including a pair of electrical isolator contacts;

an interrupter including a pair of electrical interrupter contacts for connection with the isolator in a circuit; and a driving mechanism for driving open or driving closed each pair of electrical contacts in a predetermined operating sequence;

the driving mechanism having a rotational actuator including at least one drive member and a driven member for sequential operation of the respective pairs of contacts, wherein the driven member is coupled to said at least one drive member by an eccentrically movable driving pin that engages and disengages with the driven member to operate the contact pairs in the predetermined sequence.

[0008] Advantageously, an operator may manually open the contacts of both the isolator and interrupter using the driving mechanism..

[0009] During opening, the isolator contacts may be linearly displaced by a greater extent than linear displacement of the interrupter contacts. The driving mechanism may drive open the interrupter contacts to interrupt current in the circuit, prior to driving open the isolator contacts when the isolator operates as an offload isolator. The driving mechanism may include a safety locking mechanism to prevent the isolator contacts from opening when the interrupter contacts are not already open.

[00010] The driving mechanism may drive closed the isolator contacts off-load, prior to driving closed the interrupter contacts to energise the circuit.

[00011] The rotational actuator may be rotated in forward and reverse directions to close and open the contacts respectively. The rotational actuator may be configured to rotate by a greater extent to close the isolator contacts than further rotated to close the interrupter contacts. The rotational actuator may be configured to rotate by a lesser extent to open the interrupter contacts than further rotated to open the isolator contacts. During opening or closing of the contacts, the isolator contacts may be

2016200621 01 May 2018 linearly displaced by a greater extent than linear displacement of the interrupter contacts.

[00012] The driving mechanism may compress the contacts prior to opening or closing them. The driving mechanism may be locked in place with the contacts closed. The driving mechanism may include biasing means to facilitate opening of the contacts.

[00013] The isolator and interrupter may be serially interconnected in a circuit. The rotating actuator may include a drive shaft coupled to said at least one drive member. The rotating actuator may further include a driven member which is rotated responsive to rotation of the drive members. The drive shaft may extend through the driven member. The rotating actuator may include coaxial rotating drive and driven members. One member may rotate during opening of the isolator contacts whereas both members may rotate during opening of the interrupter contacts.

[00014] The driving mechanism may further include an isolator link coupled between the drive members and an isolator drive shaft. The isolator link may be bent. A driving pin for driving the driven member may be located at a free, bent end of the isolator link. The driving mechanism may further include an interrupter link coupled between the driven member and an interrupter drive shaft. The links may be pivotally coupled.

[00015] The driven member may define a recess for receiving the driving pin to effect locking of the driven member. The driven member may define one or more shelves for engaging with the driving pin. The driven member is suitably a disc that may include an eccentric curved edge.

[00016] The isolator may further include a drive shaft coupled to a movable one of the isolator contacts. The isolator may further include a compression spring located between the movable contact and the drive shaft. The interrupter may further include a drive shaft coupled to a movable one of the interrupter contacts. The interrupter may further include a compression spring located between the movable contact and the drive shaft.

2016200621 01 May 2018 [00017] According to another aspect of the present invention, there is provided a driving mechanism for driving open or closed two pairs of electrical switchgear contacts, the mechanism including a rotational actuator for rotating to open or close each pair of contacts.

[00018] According to another aspect of the present invention, there is provided a driving mechanism for driving open or closed two pairs of electrical switchgear contacts, the mechanism including a rotational actuator for rotating to open or close each pair of contacts in a predetermined operating sequence; the rotational actuator including at least one drive member and a driven member, wherein the driven member is coupled to said at least one drive member by an eccentrically movable driving pin that engages and disengages with the driven member to operate the contact pairs in the predetermined sequence.

[00019] According to another aspect of the present invention, there is provided a method for operating first switchgear and second switchgear in an electrical circuit, the first switchgear including a first pair of electrical contacts and the second switchgear including a second pair of electrical contacts, and a driving mechanism for sequentially operating the contact pairs; the driving mechanism having a rotary actuator including a driven member and at least one drive member coupled to the driven member by an eccentrically movable drive pin for engaging and disengaging the driven member, the method involving:

a) a) during a closing operation, the steps of:

• rotating the drive member in a first direction to cause closing of the first pair of contacts, without the drive pin engaging with the driven member;

• further rotating the drive member in the first direction whereby the drive pin engages with the driven member, which in turn causes closing of the second pair of contacts; and • locking the drive pin to the driven member to impede re-opening; or

b) during an opening operation, the steps of:

• rotating the drive member in a second, opposite direction to open the second pair of contacts;

2016200621 01 May 2018 • continuing to rotate the drive member in the second direction to cause the pin to release from locking with the driven member; and • further rotating the drive member in the second direction whereby the pin re-engages the driven member, which in turn causes opening of the first pair of contacts.

[00020] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS [00021] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

[00022] Figure 1 is a side view of an electrical switchgear assembly in accordance with an embodiment of the present invention, with both contact pairs in a fully open configuration;

[00023] Figure 2 is a perspective view of a driving mechanism of the switchgear assembly of Figure 1;

[00024] Figure 3 is a sectional side view of the driving mechanism of Figure 2 showing both driving and driven discs;

[00025] Figure 4 is a sectional side view of the driving mechanism of Figure 2 showing a driving disc arrangement;

[00026] Figures 5a-d are a series of sectional views of the switchgear assembly of Figure 1 showing the closing of contacts when the driving mechanism of Figure 2 is driven in an anticlockwise direction; and

2016200621 01 May 2018 [00027] Figures 6a-d are a series of sectional views of the switchgear assembly of Figure 1 showing the opening of contacts when the driving mechanism of Figure 2 is driven in a clockwise direction.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [00028] According to an embodiment of the present invention, there is provided an electrical switchgear assembly 100 as shown in Figure 1. The assembly 100 includes an isolator 102 including a pair of electrical isolator contacts 104a, 104b with wide separation and between which arcing does not normally occur. The assembly 100 further includes a vacuum interrupter 106 including a pair of electrical interrupter contacts 108a, 108b with comparatively narrow separation. A mechanical driving mechanism 110 is provided for driving open and closed each pair of electrical contacts 104, 108, and is configured to carefully control the sequence of the opening and closing of the contacts as explained in detail below. The isolator 102 and interrupter 106 are serially interconnected in an electrical circuit (not shown) for a load break application.

[00029] Advantageously, an operator can manually open and close the contacts 104, 108 of both the isolator 102 and interrupter 106 using the driving mechanism 110 during maintenance or replacement of equipment in the circuit. The separation of the comparatively close interrupter contacts 108 alone would be insufficient, particularly if the vacuum interrupter 106 loses vacuum in which case the contacts 108 may be bridged by arcing at atmospheric pressure.

[00030] The isolator 102 further includes a linearly constrained drive shaft or drive rod 112 slidably coupled to a movable contact 104b of the isolator contact pair. A biasing means in the form of a compression spring 114 is located between the movable contact 104b and the drive shaft 112, and is compressed when the drive shaft 112 pushes the movable contact 104b into contact with a fixed or static contact 104a.

[00031] Similarly, the interrupter 106 further includes a linearly constrained drive shaft or drive rod 116 coupled to a movable contact 108b of the interrupter contact pair. A further biasing means in the form of compression spring 118 is located between

2016200621 01 May 2018 the movable contact 108b and the drive shaft 116, and is compressed when the drive shaft 116 pushes the movable contact 108b into contact with a fixed contact 108a.

[00032] Turning to Figure 2, the driving mechanism 110 includes a rotational actuator 200. The actuator 200 can be rotated in an anticlockwise and an clockwise direction (as shown) to close and open the contacts 104, 108 respectively. The rotating actuator 200 includes a central drive shaft 202 with transverse, longitudinal axis R and coupled to two drive discs 204a, 204b. The actuator 200 further includes a central driven disc 206 which undergoes rotation responsive to rotation of the drive discs 204. The drive shaft 202 extends through the driven disc 206 which, in turn, rotates about the shaft 202. The driving mechanism 110 further includes an eccentrically moving driving pin 208 that engages with and drives the driven disc 206. The pin 208 generally converges on axis R when shaft 202 is rotated counter-clockwise,and diverges when the shaft is driven clockwise.

[00033] Turning to Figure 3, the driving mechanism 110 further includes an isolator link 300 pivotally coupled between the drive discs 204 and the isolator drive shaft 112 at pivot 404. The driving mechanism 110 further includes an interrupter link 302 pivotally coupled between the driven disc 206 and the interrupter drive shaft 116, see pivots 312, 314. The driven disc 206 defines a recess 304 for receiving the driving pin 208. The driven disc further defines an engagement shelf 306 for engaging with the driving pin 208, and a clearance shelf 308 providing clearance for the driving pin 208 to move.

[00034] Rotating the drive shaft 202 in an anticlockwise direction causes the eccentrically moving driving pin 208 to engage with the shelf 306 and enter the recess 304, thereby driving the contacts 108 closed. The isolator contacts 104 are driven closed offload, prior to driving closed the interrupter contacts 108 to energise the circuit.

[00035] The driven disc 206 includes an eccentric curved edge 310. Driving the drive shaft 202 in a clockwise direction causes the driving pin 208 to diverge and eventually exit the recess 304 as explained below. The driving pin 208 will engage the base of the eccentric curved edge 310 should the interrupter contacts 108 not open,

2016200621 01 May 2018 thereby locking the contacts 104, 108 closed. In normal use, the interrupter contacts 108 are fully driven open to interrupt the current, prior to driving open the isolator contacts 104 when the isolator operates as an off-load isolator. In this manner, the driving mechanism 110 includes a further safety mechanism whereby the isolator contacts 104 are prevented from opening if the interrupter contacts 108 are fused together and/or cannot otherwise be opened.

[00036] Turning to Figure 4, the isolator link 300 includes a pair of bent arms 402 only one of which 402a is visible in this sectional view (see also Fig. 2) between which the eccentrically moving driving pin 208 is mounted at a free end. Each link 300 is fastened to the drive shaft 112 and its corresponding drive disc 204 with pivots 404, 406 respectively. The isolator link 300 is constrained to move linearly at one end attached to drive shaft/rod 112 at pivot 404 and move rotationally proximate at another end where connected to drive disc 204a at pivot 406. This constraint produces a locus for the driving pin 208 that is eccentric to the drive shaft 202, particularly to transverse axis of rotation R (see Fig. 2) [00037] A method for operating the switchgear assembly 100 of an embodiment is now described with reference to a closing sequence as depicted in Figures 5a to 5d (collectively Figure 5), and to an opening sequence as depicted in Figures 6a to 6d of the accompanying drawings (collectively Figure 6).

[00038] Firstly, the sequential closing of contacts 104, 108 is described when the driving mechanism 110 is driven in an anticlockwise or reverse direction (see arrows in Figure 5).

[00039] Turning to Figure 5a, the drive shaft 202 is rotated in an anticlockwise direction. In turn, the drive discs 204 also rotate and cause the drive pin 208 to move away from shelf 308 of the driven disc 206. Initially, there is a lesser movement of the sliding isolator contact 104b.

[00040] Turning to Figure 5b, each isolator link 300 pushes against the isolator drive shaft 112 which, in turn, causes the isolator contacts 104 to come together. The driven disc 206 remains static and the interrupter contacts 108 remain open. The drive pin

2016200621 01 May 2018

208 does not engage with the eccentric curved edge 310 of the driven disc 206 as there is a small clearance.

[00041] Turning to Figure 5c, the level isolator link 300 pushes against the isolator drive shaft 112 which, in turn, causes compression of the spring 114 as the movable contact 104b rests against the static contact 104a. The drive pin 208 pushes against the shelf 306 and causes the anticlockwise rotation of the driven disc 206. In turn, the link 302 pushes the drive shaft 116 that causes the interrupter contacts 108 to close together to energise the circuit.

[00042] Turning to Figure 5d, the interrupter link 302 levels out and causes compression of the spring 118 as the movable contact 108b rests against the static contact 108a. The spirally converging drive pin 208, at the free end of bent links 300, enters the recess 304. The driving mechanism 110 is locked in place with the contacts 104, 108 closed. Note that links 300, 302 must compress the springs 114, 118 before the contacts 104, 108 can be opened, as described below. The angle of the links 300, 302 in an over-centre position (i.e. rotated beyond “level”) also impedes unlocking of the driving mechanism.

[00043] Secondly, the sequential opening of contacts 104, 108 is described when the driving mechanism 110 is driven in a forward or clockwise direction (see arrows in Fig. 6).

[00044] Turning to Figure 6a and under normal operating conditions where the interrupter contacts are not significantly fused together, the drive shaft 202 is rotated in a forward or clockwise direction. During rotation from the mechanism “contacts closed” position shown in Figure 5d, the drive pin 208 in the recess 304 initially drives the driven disc 206 in a clockwise direction in turn driving interrupter shaft 118 initially in a contact closing direction, until the isolator link 302 passes beyond the “level” position. The drive discs 204 also rotate and cause the spirally diverging drive pin 208 to eventually exit the recess 304 of the moving driven disc 206 as depicted in Figure 6a. As a safety feature in the event contacts are fused, the driving pin 208 will engage the base of the eccentric curved edge 310 should the interrupter contacts 108 not open, thereby locking the contacts 104, 108 closed. The link 302 pulls the interrupter drive ίο

2016200621 01 May 2018 shaft 116 and the compressed spring 118 contributes to forcing the interrupter contacts 108 apart, by withdrawing movable contact 108b from fixed contact 108a.

[00045] Turning to Figure 6b, the interrupter contacts 108 initially open whilst the isolator contacts 104 remain closed. The drive pin 208 has exited the recess 304 and is just clear of the eccentric curved edge 310 of the driven disc 206 as drive disc rotates 204 further clockwise as depicted in Figure 6c.

[00046] Turning to Figure 6c, the isolator link 300 pulls the linearly constrained isolator drive shaft 112 which, in turn, causes the movable contact 104b to separate from the static contact 104a, also initially assisted by the spring 114.

[00047] Turing to Figure 6d, the isolator contacts 104 are pulled fully open by isolator link 300 as drive disc 206 rotates further clockwise. The drive pin 208 also moves up close to the clearance shelf 308 of the driven disc 206 and the interrupter contacts 108 are fully open.

[00048] The rotational actuator 200 of the embodiment is configured to rotate by a greater extent to close the isolator contacts 104 than further rotated to close the interrupter contacts 108. Similarly, the actuator 200 is configured to rotate by a lesser extent to open the interrupter contacts 108 than further rotated to open the isolator contacts 104. During opening and closing of the contacts 104, 108, the isolator contacts 104 are linearly displaced by a greater extent than the interrupter contacts 108, thereby providing reliable isolation for the load break application. The drive discs 204 rotate during opening and closing of the isolator contacts 104, whereas the driven disc 206 remains static. The drive discs 204 and driven disc 206 all rotate during opening and closing of the interrupter contacts 104.

[00049] Owing to the motion of the links 300, 302, the driving mechanism 110 compresses the contacts 104, 108 prior to opening and closing them. Advantageously, compressing the contacts 104, 108 prior to opening facilitates breaking of any fusing between the contacts which may otherwise cause them to stick.

[00050] A person skilled in the art will appreciate that many embodiments and variations can be made without departing from the ambit of the present invention.

2016200621 01 May 2018 [00051] The preferred embodiment disclosed the use of an atmospheric or air break isolator 102 and a vacuum interrupter 106. Other embodiments may instead use other types of electrical contacts, included those suited to load breaking or isolation of electrical circuits.

[00052] The driving mechanism 110 may further include a secondary pin 320 which extends between the drive discs 204a, 204b for improved structural rigidity. Another shelf 322 of the driven disc 206 (see Fig. 3) provides clearance for the secondary pin 320 to move during rotation of the operating mechanism 300.

[00053] The driving mechanism of the embodiment provides a number of advantages over prior art switch operating mechanisms, including in relation to improved contact weld breaking, safety locking in the event of welded interrupter contacts and/or manufacture and mounting of switchgear. Periodically electrical contacts of interrupters are welded together due to heat of fault current flowing or current arcing. In the embodiment, if the interrupter contacts are welded, the main driving springs can assist to break the welds because the driving pin is disposed in the slotted recess when the contacts try to open. This configuration of drive pin can produce an impact that is more effective in weld breaking than a static opening force. [00054] In the event the interrupter fails to open due to welds, the associated isolator will remain closed due to the driving pin being retained in the slot. This is a safe way for switchgear to fail. In the prior art, allowing a linked isolator to open will potentially result in an explosion or at least dramatic failure of the switchgear. Furthermore, the rotary actuator of the embodiment includes discs for driving the interrupter and for driving the isolator that lie on the same axis of rotation. This arrangement allows for easier assembly and mounting arrangements, especially in switchgear employing solid dielectric insulation such as epoxy or silicone (as opposed to SF6 gas arrangements) that are much easier to achieve.

[00055] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

2016200621 01 May 2018 [00056] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

EDITORIAL NOTE

Application No. 2016200621

Please Note: The description ends on page 12 and the claims commence on page 12.

2016200621 01 May 2018

Claims (23)

1. The claims defining the invention are as follows:

   1. An electrical switchgear assembly including:

   an isolator including a pair of electrical isolator contacts; an interrupter including a pair of electrical interrupter contacts for connection with the isolator in a circuit; and a driving mechanism for driving open or driving closed each pair of electrical contacts in a predetermined operating sequence;

   the driving mechanism having a rotational actuator including at least one drive member and a driven member for sequential operation of the respective pairs of contacts, wherein the driven member is coupled to said at least one drive member by an eccentrically movable driving pin that engages and disengages with the driven member to operate the contact pairs in the predetermined sequence.
2. 2. An electrical switchgear assembly as claimed in claim 1, wherein an operator can manually open the contacts of both the isolator and interrupter using the driving mechanism.
3. 3. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein during opening, the isolator contacts are linearly displaced by a greater extent than linear displacement of the interrupter contacts.
4. 4. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the driving mechanism drives open the interrupter contacts to interrupt current in the circuit, prior to driving open the isolator contacts when the isolator operates as an off-load isolator.
5. 5. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the driving mechanism includes a safety locking mechanism to prevent the isolator contacts from opening when the interrupter contacts are not already open.

   2016200621 01 May 2018
6. 6. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the driving mechanism drives closed the isolator contacts offload, prior to driving closed the interrupter contacts to energise the circuit.
7. 7. An electrical switchgear assembly as claimed in any preceding claim, wherein the rotational actuator can be rotated in forward and reverse directions to close and open the contacts, respectively.
8. 8. An electrical switchgear assembly as claimed in any preceding claim , wherein the rotational actuator is configured to (i) rotate by a greater extent to close the isolator contacts than further rotated to close the interrupter contacts, and (ii) rotate by a lesser extent to open the interrupter contacts than further rotated to open the isolator contacts.
9. 9. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the rotational actuator includes a transverse drive shaft coupled to said at least one drive member.
10. 10. An electrical switchgear assembly as claimed in claim 9, wherein the driving pin moves eccentrically relative to rotation of a longitudinal axis of the transverse drive shaft.
11. 11. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the driving mechanism further includes an isolator link coupled between said at least one drive member and an isolator drive rod.
12. 12. An electrical switchgear assembly as claimed in claim 11, wherein the driving pin is mounted on the isolator link to produce said eccentric movement.
13. 13. An electrical switchgear assembly as claimed in either claim 11 or claim 12, wherein the driving pin for driving the driven member is located at a free, bent end of the isolator link.

    2016200621 01 May 2018
14. 14. An electrical switchgear assembly as claimed in any one of the preceding claims wherein the drive mechanism further includes an interrupter link coupled between the driven member and an interrupter drive rod.
15. 15. An electrical switchgear assembly as claimed in claim 14, wherein the driven member defines a recess for receiving the driving pin to effect locking of the driven member.
16. 16. An electrical switchgear assembly as claimed in either claim 14 or claim 15, wherein the driven member defines one or more shelves for engaging with the driving pin.
17. 17. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the driven member is a disc which includes an eccentric curved edge engageable by the driving pin.
18. 18. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the rotational actuator includes coaxial rotating drive and driven members.
19. 19. An electrical switchgear assembly as claimed in claim 17, wherein one member of the rotational actuator rotates during opening of the isolator contacts whereas both members rotate during opening of the interrupter contacts.
20. 20. An electrical switchgear assembly as claimed in any one of the preceding claims, wherein the driving mechanism is locked in place with both pairs of contacts closed.
21. 21. A driving mechanism for driving open or closed two pairs of electrical switchgear contacts, the mechanism including a rotational actuator for rotating to open or close each pair of contacts in a predetermined operating sequence; the rotational actuator including at least one drive member and a driven member, wherein the driven member is coupled to said at least one drive member by an eccentrically movable driving pin that engages and disengages

    2016200621 01 May 2018 with the driven member to operate the contact pairs in the predetermined sequence.
22. 22. A driving mechanism as claimed in claim 21 wherein:

    the driving pin is mounted on a link coupled between said at least one drive member and a drive rod of a contact pair to produce said eccentric movement.
23. 23. A method for operating first switchgear and second switchgear in an electrical circuit, the first switchgear including a first pair of electrical contacts and the second switchgear including a second pair of electrical contacts, and a driving mechanism for sequentially operating the contact pairs; the driving mechanism having a rotary actuator including a driven member and at least one drive member coupled to the driven member by an eccentrically movable drive pin for engaging and disengaging the driven member, the method involving:

    a) during a closing operation, the steps of:

    • rotating the drive member in a first direction to cause closing of the first pair of contacts, without the drive pin engaging with the driven member;

    • further rotating the drive member in the first direction whereby the drive pin engages with the driven member, which in turn causes closing of the second pair of contacts; and • locking the drive pin to the driven member to impede re-opening; or,

    b) during an opening operation, the steps of:

    • rotating the drive member in a second, opposite direction to open the second pair of contacts;

    • continuing to rotate the drive member in the second direction to cause the pin to release from locking with the driven member; and • further rotating the drive member in the second direction whereby the pin re-engages the driven member, which in turn causes opening of the first pair of contacts.

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