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 and interrupters.

[0004] An interrupter such as 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 need to be manually opened during maintenance or replacement of equipment in the circuit.

[0006] The Applicant's application AU2015901341 discloses an electrical switchgear assembly including 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 can manually open the contacts of both the isolator and interrupter using the driving mechanism. [0007] The preferred embodiment provides an improvement to the electrical switchgear assembly of AU2015901341 .

SUMMARY OF THE INVENTION

[0008] According to one aspect of the present invention, there is provided an outdoor electrical switchgear assembly for a load break application, the assembly including:

a pair of electrical contacts;

a bushing defining an internal chamber in which the electrical contacts are located; and

a viewer in the bushing and for enabling viewing of the contacts.

[0009] Advantageously, an operator can view the electrical contacts to verify the status (e.g. open or closed) of the switchgear assembly. In particular, the operator may confirm that the contacts are open and that the associated circuit is safely isolated.

[00010] Preferably, the viewer includes a window. The window may include a window pane. The pane may be transparent or translucent. The pane may form a waterproof seal with the bushing. The bushing may include a body formed of resin. The pane may be molded within the bushing.

[00011] The internal chamber may be an enclosed air chamber in which the electrical contacts are located.

[00012] The assembly may further include another viewer in another bushing associated with another pair of contacts, and for enabling viewing of the other pair of contacts.

[00013] The assembly may further include yet another viewer in a housing, the housing for housing a driving mechanism for driving open or closed the pair of electrical contacts.

[00014] The electrical contacts may be isolator contacts located within the chamber. [00015] According to another aspect of the present invention, there is provided an outdoor bushing arrangement for a load break electrical switchgear assembly with a pair of electrical contacts, the bushing arrangement defining an internal chamber in which the electrical contacts are located and including a viewer for enabling viewing of the contacts.

[00016] According to another aspect of the present invention, there is provided an outdoor electrical switchgear assembly for a load break application, the assembly including:

first switchgear (e.g. an isolator) including a pair of electrical contacts;

second switchgear (e.g. an interrupter) including another pair of electrical contacts;

a driving mechanism for driving open each pair of electrical contacts; and a bushing arrangement defining an internal chamber in which one of the pairs of contacts is located and including a viewer for enabling viewing said one of the pairs of contacts.

[00017] The assembly may further include another bushing arrangement defining another internal chamber in which the other pair of contacts is located and including another viewer for enabling viewing of the other pair of contacts

[00018] According to another aspect of the present invention, there is provided an operation method for an outdoor electrical switchgear assembly for a load break application, the assembly including a pair of electrical contacts and a bushing defining an internal chamber in which the electrical contacts are located, the method involving viewing the contacts through a viewer in the bushing.

[00019] According to another aspect of the present invention, there is provided an outdoor electrical switchgear assembly including:

a pair of electrical contacts;

a dielectric insulator defining an internal chamber in which the electrical contacts are located; and

a viewer in the insulator and for enabling viewing of the contacts. [00020] According to another aspect of the present invention, there is provided an outdoor electrical switchgear assembly for a load break application, the assembly including:

a pair of electrical contacts;

a housing defining an internal chamber in which the electrical contacts are housed; and

a viewer in the housing and for enabling viewing of the contacts.

[00021] 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

[00022] 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:

[00023] Figure 1 is a side sectional view of a pole mounted electrical switchgear assembly, with both contact pairs in a fully open configuration;

[00024] Figure 2 is a side partially sectioned view of the electrical switchgear assembly of Figure 1 showing a bushing viewer in accordance with an embodiment of the present invention;

[00025] Figure 3 is a side partially sectioned view of the electrical switchgear assembly of Figure 2 with a contact pair viewed through the viewer in a closed configuration; and

[00026] Figure 4 is a perspective view of a bushing of the assembly of Figure 2. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[00027] AU2015901341 is incorporated herein by reference and discloses an outdoor electrical switchgear assembly 100 as shown in Figure 1 , which is suitable for mounting to an electricity pole and is so exposed to the elements (e.g. rain, wind).

[00028] 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 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 1 10 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. 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 contactsl 04, 108 of both the isolator 102 and interrupter 106 using the driving mechanism 1 10 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] Turning to Figure 2, the assembly 100 includes an isolator bushing 200 in which the electrical isolator contacts 104a, 104b are located, a metal tank 202 in which the driving mechanism 1 10 is located, and an interrupter bushing 204 in which the interrupter contacts 108a, 108b are located. Together, the bushings 200, 204 and tank 202 are sealed together and impede the ingress of moisture thereby suiting the assembly 100 to outdoor use.

[00031] The isolator bushing 200 is a dielectric insulator and includes a molded tubular body 206 formed of opaque and solid resin. A viewer 208 is provided in the bushing 200 and enables viewing of the isolator contacts 104a, 104b. Advantageously, an external operator can view the internal contacts 104a, 104b to verify their status (e.g. open or closed). In particular, the operator can confirm that the contacts 104a, 104b are open and that the associated circuit is safely isolated. [00032] The viewer 208 includes a window in the form of a window pane fitted to the resin body 206. The polymeric insulator pane is at least translucent, and preferably transparent. The pane is molded within the body 206 of the bushing 200 to form a waterproof seal with the bushing 200 and impede ingress of water. The assembly 100 thereby defines an internal sealed air chamber in which the contacts 104a, 104b are located and enclosed.

[00033] In practice, an operator can view the contacts 104a, 104b through the viewer 208 thereby readily determining the state of the assembly 100. In particular, the operator on the ground can view the contacts 104a, 104b which are up the electricity pole through the viewer 208, preferably using binoculars. As shown in Figure 2, the contacts 104a, 104b are separated indicating that the circuit is isolated. As shown in Figure 3, the contacts 104a, 104b are together indicating that the circuit is live and that caution must be exercised by the operator.

[00034] Turning to Figure 4, the bushing 200 may include multiple viewers 208 so that the contacts 104a, 104b can be viewed from several angles. Further, a flashlight can be shone through one viewer 208 whilst the illuminated contacts 104a, 104b are conveniently viewed through another viewer 208.

[00035] 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.

[00036] In one embodiment, the interrupter bushing 204 may take the same form as the isolator bushing 200 for enabling viewing of the interrupter contacts 108a, 108b.

[00037] In one embodiment, the assembly 100 further includes yet another viewer 208 in the tank 202 (i.e. housing) housing the driving mechanism 1 10.

[00038] In one embodiment, the bushing may include an internal contrasting screen such that the contacts 104a, 104b are located between the screen and the viewer to facilitate viewing of the contacts 104a, 104b. The contrasting screen may be brightly colored. In another embodiment, the contacts may be brightly colored to facilitate visibility. [00039] 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.

[00040] 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.