AU2019100518A4 - An Electrical Control Switchboard Assembly - Google Patents

Abstract

An electrical control switchboard assembly includes at least a first and a second adjoining compartment in fluid communication via a connecting interface, at least the first compartment configured for inclusion of electrical equipment. A blast shield-diffusion device is attached to at least one side of the connecting interface at a distance from the interface. The blast shield-diffusion device is configured such that when the electrical equipment fails causing an explosion, the blast shield-diffusion device prevents debris of the explosion from exiting the first compartment and enables flow of energy through the connecting interface between the adjoining compartments. C"f to

Description

AN ELECTRICAL CONTROL SWITCHBOARD ASSEMBLY

FIELD OF THE INVENTION

Various embodiments of an electrical control switchboard assembly are described herein.

BACKGROUND TO THE INVENTION

Electrical control switchboards are used for many applications, in many environments. Generally, a switchboard is a large single panel, frame, or assembly of panels on which are mounted, on the face, back, or both, switches, over-current and other protective devices, busbars, and usually instruments. The role of a switchboard is to allow the division of the current supplied to the switchboard into smaller currents for further distribution and to provide switching, current protection and possibly metering for those various currents. In general, switchboards may distribute power from transformers, to panel boards, control equipment, and, ultimately, to individual system loads.

Inside a switchboard there could be one or more busbars or cable connections.

These are flat strips of copper or aluminium to which the switchgear is connected. Busbars and cables carry large currents through the switchboard to take-off points and are supported by insulators or cable ties. Switchgear comprises a ‘functional unit’, which is electrical and mechanical elements that contribute to the fulfilment of the same function. The switchgear is connected to a terminal, which provides for connection of incoming and outgoing cable and busbar.

In the art, arrangement of busbars 801, functional units 802 and terminals 803 is categorised by a ‘form’. The form refers to internal separation of the busbars, functional units and terminals. Referring to Figure 8a-g, internal separation is achieved with of barriers or partitions (including metallic or non-metallic), insulation of live parts or an integral housing (i.e. moulded case circuit breaker).

Form 1 has no internal separation of the busbars, functional units and terminals from each other.

Form 2a has separation of the busbars from the functional units. Terminals are not separated from the busbars.

Form 2b has separation as for 2a, but the terminals are not separated from the functional units.

2019100518 13 May 2019

Form 3a has separation of the busbars from the functional units and each functional unit from the other units; terminals of each functional unit are not separated from each other; and terminals are not separate from the busbars.

Form 3b has separation as per 3a, but with the terminals separated from the busbar (and functional units).

Form 4a has separation of the busbars from the functional units and each functional unit from the other units; separation of the terminals for a functional unit from the busbars and those of any other unit; and terminals enclosed in the same compartment as the functional unit.

Form 4b has separation as per 4a, but with the terminals for each functional unit enclosed in their own space.

Many existing switchboards designed for outdoor use are Form 1 or Form 2.

Safety switches and fuses are included for protection of personnel. There may also be controls for the supply of electricity to the switchboard modules, coming from a supply generator or bank of electrical generators, or electrical supply authority and can include frequency control of AC power and load sharing controls, plus instruments showing frequency, voltages and currents.

Switchboards are generally metal enclosed and of dead front construction: no energized parts are accessible when the outer doors and escutcheon doors are closed. A switchboard may include a metering or control compartment separated from the power distribution conductors.

Invariably, however, these switchboards are accessed by personnel, and/or situated in public spaces. This brings into focus the safety issues surrounding a catastrophic failure of such a switchboard or section thereof.

Arc flash (flashover) occurs within an electrical system as a result of a lowimpedance connection through air to ground or another voltage phase in the system. The arc flash can be initiated through accidental contact, equipment which is underrated for the available short circuit current, contamination or tracking over insulated surfaces, deterioration or corrosion of equipment and/or parts, as well as other causes, and results in light and heat emission. An arc-flash can reach

2019100518 13 May 2019

20,000°C. Arc flash temperatures can liquefy or vaporize metal parts in the vicinity of the event such as copper, aluminium conductors or steel equipment parts.

This material rapidly expands in volume as it changes state from a solid to vapor, resulting in explosive pressure and sound waves. This is known as an arc blast, that can reach hundreds of kilopascals. The arc blast can knock workers off balance or off ladders and even throw them across the room against walls or other equipment.

The sound blast can cause eardrums to rupture resulting in temporary or permanent hearing loss. Molten metal can be sprayed by the blast throughout the vicinity. Solid metal debris and other loose objects, such as tools, can be turned into deadly projectiles by the explosion. The bright flash from the event can result in temporary or permanent blindness. All of these will most likely result in equipment damage or destruction, as well as personnel injury, and possibly death.

Currently, personal protective equipment (PPE) is employed by personnel as shielding from the radiation of an arc flash. There are several categories of PPE, the most extreme being category 4 arc flash protection PPE, which is similar to a bomb suit. However, the PPE may be ineffective against the flying objects, molten metal, and violent concussion that the arc blast can produce.

Generally, switchboards are labelled and marked with the necessary administrative level controls. However, in some cases, personnel servicing or operating outdoor remote switchboards may choose not to wear the required PPE, possibly due to lack of supervision or perceived low risk of incident occurrence, or both.

In an attempt to alleviate some of the potential damage from an arc blast, switchboards have been designed to exhaust the products of arc blast via chimneys or vents to exterior environs, but this too can pose a significant hazard for personnel nearby.

It is necessary for energy to be released from the switchboard housing in the event of an arc blast. However, it would be desirable to be able to contain substantially the damaging or dangerous effects of an arc blast inside an electrical control switchboard, and even more desirable for that switchboard to retain functionality or partial functionality after an arc blast event, particularly in a modular assembly of switchboards. Also, from a personnel safety perspective, higher order engineering design and control that provides passive protection irrespective of personnel compliance or ability, is preferred.

2019100518 13 May 2019

SUMMARY OF THE INVENTION

According to one aspect of the invention, there is provided an electrical control switchboard assembly including:

at least a first and a second adjoining compartment in fluid communication via a connecting interface, at least the first compartment configured for inclusion of electrical equipment; and a blast shield-diffusion device attached to at least one side of the connecting interface at a distance from the interface, such that when the electrical equipment fails causing an explosion, the blast shield-diffusion device prevents debris of the explosion from exiting the first compartment and facilitates dissipation of energy through the connecting interface between the adjoining compartments.

The electrical control switchboard may be a low voltage electrical control switchboard. Low voltage can be from about 415V AC to about 690V AC.

The connecting interface of the assembly may be a wall between the first and second adjoining compartments. Substantially a central third of the wall may have one or more apertures or perforations to effect the fluid communication.

The assembly of the invention may include more than two compartments connected in a modular fashion, such that each compartment is in fluid communication with at least one other compartment of the assembly.

The assembly of the invention may also include an escutcheon door on a front face of each compartment of the assembly, each escutcheon door in turn being enclosed by an outer door.

The blast shield-diffusion device of the invention may be attached to each side of each connecting interface of each compartment of the assembly of the invention.

Each blast shield-diffusion device may be sized to substantially cover the fluid communication means of the connecting interface, configured, when attached, to retain fluid communication between adjoining compartments. Upon explosion in a first compartment, the at least one blast shield-diffusion device in the first compartment attenuates solid debris resulting from the explosion and prevents movement of that debris beyond the first compartment. The blast shield-diffusion device also dissipates pressure, heat and energy from the explosion by directing those components around the blast shield-diffusion device and through the connecting interface into an adjoining compartment. The surface of the blast shield-diffusion device facing into the

2019100518 13 May 2019 compartment blocks a direct pathway for the products of an explosion to an adjoining compartment: the indirect pathway around the blast shield-diffusion device ensures that the energy effects of an explosion are contained within the assembly, and the debris is contained within a single compartment of the assembly.

It is envisaged that the assembly of the invention may be effective where the electrical failure and resultant explosion are caused by an arc flash and arc blast.

The blast shield-diffusion device of the invention may include a planar, substantially rectangular portion, and a rim extending operably inward around the periphery of the rectangular portion.

The blast shield-diffusion device of the invention may also include on an inner surface adjacent the connecting interface, a layer of material with an irregular profile. The material may cover part or all of the inner surface. The material may be a mesh of metal or any other material with irregular profile or may include protrusions. The material functions to further dissipate the energy, pressure and heat generated in the explosion.

The escutcheon doors of the assembly of the invention may be reinforced to enhance the structural integrity of the assembly during and after an explosion. The escutcheon doors may include reinforced beam structures, doubling structures, optimised placement of locks and number of locks, and optimal placing of hinges and number of hinges. The escutcheon doors of the assembly are thereby configured to remain in place during and after an explosion, ensuring the safety of a person, animal or equipment in the proximity of the assembly.

The configuration of the assembly results in functional isolation of the compartment in which an explosion occurs. An explosion in an assembly of the invention causes probable functional failure in only the first compartment in which the explosion occurred. The remaining compartments of the assembly of the invention remain functional after the explosion.

The assembly of the invention may be used outdoors, on fixed platforms, indoors, underground or in maritime environments.

The assembly of the invention may also be used as a motor control centre for machinery, plants and equipment used in public utilities, mines, heavy industry and the like.

2019100518 13 May 2019

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a drawing of a front perspective view of an assembly of the invention.

Figure 2 is a drawing of the assembly of Figure 2, with the outer doors and an escutcheon door absent.

Figure 3 is a drawing of the assembly of Figures 2 and 3, with all outer doors and escutcheon doors, and internal equipment, absent.

Figure 4 is a front sectional plan view of an assembly of the invention.

Figure 5 is a cross-sectional view of a portion of an assembly of the invention, including two embodiments of the blast shield-diffusion device of the invention.

Figure 6 is a cross-sectional view of a portion of an assembly of the invention, including two alternative embodiments of the blast shield-diffusion devices of the invention.

Figure 7 is an exploded view of two of the blast shield-diffusion devices and the corresponding connecting interface depicted in Figure 6.

Figures 8a through 8g are representations of separation forms 1,2a, 2b, 3a, 3b, 4a,

4b respectively.

DESCRIPTION OF EMBODIMENTS

Figure 1 shows a front perspective view of an electrical control switchboard assembly 10 of the invention. The assembly 10 includes five compartments 12, 14, 16, 18, 20. The compartments have respective outer doors 22, 24, 26, 28, 30 in the closed position. Each compartment is configured to contain electrical equipment including main switches, motor control switches, variable speed drives and soft starter controls, RTU/PLC systems, distribution boards, metering and other controls, or can be empty, functioning as a spare compartment should that be needed at a future date.

The compartments and outer doors can be manufactured from any practicable material, including steel, stainless steel, galvanised steel, or aluminium.

Figure 2 shows the front perspective view of the electrical control switchboard assembly 10 of Figure 1, without at least outer doors 22, 24, 26, 28, 30.

In addition, compartment 14 is shown with its escutcheon door removed.

2019100518 13 May 2019

Compartments 12, 18 and 20 of Figure 1, include escutcheon doors 32, 34, 36, respectively. Escutcheon door 32, for example, includes distribution section circuit breakers 40 ,42 and gauge 44.

Escutcheon doors of the invention include particular placement of locks and hinges, numbers of locks and hinges, optimised to reduce the distance between support points. Escutcheon doors of the invention may also include reinforcing beam structures, and on larger doors, doubling structures to increase the stiffness of the doors.

For example, escutcheon door 36 shows four locks 41 and two heavy duty hinges 45, approximately equi-spaced to minimise bending, which would in turn compromise the sealing of equipment protruding though the escutcheon door, and around the edges of the door. In another embodiment, escutcheon door 34 has three locks and three hinges. The inside of the escutcheon doors has additional stiffening structures (not shown) to distribute loads to fixings. Lock tangs (not shown) are also strengthened.

Escutcheon door 32 includes other strengthening options to stiffen the door and maintain sealing around the distribution circuit breakers 40, 42. Sealing detail (not shown) around these circuit breakers 40, 42 ensures that there is no direct pathway for pressurised gas to pass out of the compartment. In addition, the escutcheon door 32 carries a backing box (not shown) to exclude or reduce pressure behind the large surface area of the meter unit 44.

These aspects of the escutcheon doors of the invention prevent distortion of the escutcheon doors under increased internal pressure of an explosion and prevent door failure from increased load on the locks.

Outer doors can be constructed to an IP66 standard (‘dust tight’ and protected against heavy seas or powerful jets of water). Alternatively, outer doors can be constructed to an IP56 ingress protection standard. These doors can include shielded and filtered air circulation vents to enable cooling of internal heat-generating components, such as variable speed drives and soft starters, used in motor control centre applications.

Referring to Figure 2, removal of the escutcheon and outer doors from compartment 14 enables visualisation of a blast shield-diffusion device 46 of the invention. Figure 3 shows the assembly 10 of the invention with all outer and escutcheon doors removed. Blast shield-diffusion device 46 in compartment 14, blast shield-diffusion

2019100518 13 May 2019 device 48 in compartment 18, and blast shield-diffusion device 50 in compartment 20 are now visible. For example, blast shield-diffusion device 46 is mounted onto the wall 52 dividing compartments 12 and 14. The wall 52 includes perforations or apertures 54 enabling fluid communication between compartments 12 and 14. Blast shield-diffusion device 46 is mounted at a distance from the wall 52, covering the apertures 54, such that pressure and gas from an explosion in compartment 14 can move around the blast shield-diffusion device 46 and through the apertures 54, but not but has no direct pathway into an adjoining compartment. Simultaneously, the blast shield-diffusion device attenuates solid debris from the explosion. In this way, the energy, pressure and gas from an explosion in compartment 14 is dissipated within the assembly 10, and solid debris is contained within compartment 14. Due to this containment, after the explosion, the remainder of the compartments in the assembly can be accessed and are still functional, at least for minimal operation.

Blast shield-diffusion devices of the invention may be included in an assembly of the invention at either or both sides of any connecting interface between compartments of that assembly. For example, figure 4 shows a front sectional plan view of a second assembly 60 of the invention, which includes blast shield-diffusion devices 62 on either side of all connecting interfaces between compartments of this assembly.

Figure 5 shows a cross sectional view of a portion of a connecting interface 70 between two compartments of an assembly of the invention, with blast shielddiffusion devices 72, 74 on either side of the interface 70, over apertures or perforations 76 in the interface 70. In this example, the blast shield-diffusion device 74 (and similarly for blast shield-diffusion device 72) comprises a planar, substantially rectangular portion 78 and a rim 79 extending operably inward from a periphery of the portion 78. The device 74 is mounted such that the enclosed inner surface 81 faces the apertures 76 of the interface 70. The blast shield-diffusion devices 72, 74 are mounted to the interface 70 using internally threaded hollow spacers or bosses 82 and bolts 83 that pass through the portions 78 and are threaded into the bosses 82. The bosses 82 are dimensioned so that the blast shield-diffusion devices 72, 74 are an optimal distance from the interface 70. The optimal distance between the interface 70 and the planar portion 78 of the blast shield-diffusion device 74 is any distance that enables fluid communication between compartments, such as from 20mm to 40mm. The same applies to blast shield-diffusion device 72. This ensures that pressure and gas can move through spaces 86, between the portions 78 and the interface 70, and the apertures 76, while solid debris is attenuated by the portion 78.

2019100518 13 May 2019

The spacers or bosses 82 can be of aluminium. They can have a diameter of about 25 mm with an M8 internal thread. These can suit an M8 stainless steel bolt with a stainless steel star washer. Other forms of spacer and fastener can be used, depending on requirements. The spacers 82 can be attached to the interface 70 with welds 84 that fully weld the spacers 82 to the interface 70, to further secure the blast shield-diffusion devices 72, 74 in place. The welds 84 can be 5 mm fillet welds. It will be appreciated that these characteristics of dimension and material are illustrative in nature. Various other characteristics of dimension and material could be selected depending on specific requirements. It is to be noted that the interface 70 is not penetrated in order to secure the devices 72, 74 to the interface 70. Thus, the structural integrity of the interface 70 is not reduced or diminished by the fastening of the devices 72, 74 in position.

An alternate fixing arrangement is shown in Figure 7, discussed below.

The blast shield-diffusion device can be manufactured from any practicable material, such as marine grade aluminium or stainless steel, or any material equivalent to the material of manufacture of the assembly.

Figure 6 shows the blast shield-diffusion devices of Figure 5, further including a discontinuous or textured surface 90 on the inner surface 81,83 of the blast shielddiffusion devices 74, 72. The textured surface 90 functions to further dissipate and disrupt the energy, pressure and gas flow from an explosion in an adjacent compartment, which flows through the apertures 76 and impacts the textured surface 90. The textured surface may be any material that will effectively disrupt the flow or passage of those elements, including expanded metal, woven wire mesh, moulded and woven polymer. The textured surface may have a regular texture, such as woven products, or may be randomly textured, or a combination of the two.

The textured surface 90 may be attached to the blast shield-diffusion device in any practicable manner, for example tack-welded if the metal of the textured surface is compatible with the metal of the blast shield-diffusion device, or may be fitted onto the inner surface 81,83 of the blast shield-diffusion device without attachment. In this case, the textured surface 90 is held in place by the same fasteners as the associated blast shield-diffusion device.

Figure 7 is an exploded view of the two blast shield-diffusion devices 72, 74 attached to the interface 70. The textured surface 90 is included or located on the inner surface 81 the of blast shield-diffusion device 74 (figure 6), fitting flush with the inner

2019100518 13 May 2019 surface and thereby surrounded by blast shield-diffusion device rim 79 (partially shown - see also figure 5). The blast shield-diffusion device 74 is attached to the interface 70 with at least one threaded bolt 85 which passes through an aperture 92 in the interface 70 and through the textured surface 90 and blast shield-diffusion device 74. The spacer 82 is threaded onto the bolt 85 between the blast shielddiffusion device 74 and the interface 70, to ensure an optimum space between the blast shield-diffusion device 74 and the interface 70. The nut 80 secures the bolt 85 in place. Similarly, the blast shield-diffusion device 72 is secured in place on an opposite side of the interface 70.

Such placement and securing of blast shield-diffusion devices of the invention, optionally including reinforcing of escutcheons doors as discussed above, ameliorates or mitigates the effects of an arc blast or explosion in one compartment of an assembly of the invention. This can reduce the chances the arc blast or explosion disabling the entire assembly. This can also reduce the chances of blast material exiting the assembly to cause injury or death or damage to personnel, property or passers-by. An electrical control switchboard assembly of the invention can facilitate the containment of an arc blast or explosion within the assembly and may isolate function loss to the compartment in which the explosive event occurred.

In addition, weld gaps or distances can be optimised to enable the assembly to elastically yield under arc blast pressure. This optimisation can result in diffusion exhaust pathways between the welds to provide at least partially controlled venting of arc blast explosion products.

The assembly of the invention enables construction of an arc-flash containment modular compact outdoor switchboard system. The assembly, using a Form 3b modular configuration (see Figure 8e), enables users to readily access the switchboard while it is energised. This optimises asset utilisation by streamlining maintenance tasks and faultfinding while the switchboard is in service.

The assembly is compact because it does not require cable ducts or secondary devices for safety.

The assembly of the invention can include mechanisms for permitting the indirect leakage of gases resulting from an arc blast. Such mechanisms can be in the form of weld patterns, such as stitch weld configurations, that allow the gases to pass between various components of the assembly and out of the assembly. In use, an operator is usually positioned at or near a door of the assembly. Thus, the assembly

2019100518 13 May 2019 of the invention can include door stiffeners, such as metal plates, for example steel plates, welded to the inside of door panels of the assembly. Other forms of stiffeners can also be appropriate, such as beams or frameworks.

An assembly of the invention is also well-suited to testing different configurations of compartments, as it can be assembled from different combinations and arrangements of compartments in a modular fashion, for different applications.

VALIDATION TESTING

While many switchboard characteristics can be verified by calculation or by extrapolation of an existing design, AS61439.1 requires that certain features can only be certified by testing: like arc-fault containment. The strategy for a modular design for an assembly of the invention was required because it is difficult to test for arc fault containment for every variation in general switchboard assemblies for outdoor switchboards employed by industry and public utilities.

The test unit assembly of the invention had four different sized compartments including blast shield-diffusion devices of the invention, a wide range of functional escutcheons doors including reinforcements of the invention, and two variants of exterior doors.

Each compartment was representative of compartment/module dimensions accommodating switchboard functions used in 95% of outdoor switchboards built by the owner for heavy industry, resources and utilities users.

The test assemblies were built and fitted out with VSD and Soft Starter, Distribution section, MCCBs, external button controls, meter enclosures, RTU/PLC sections. This enabled a wide variety of switchboard assemblies to be built that easily scale up to incorporate combinations of these tested and certified compartments.

Testing was also done with an assembly of the invention with the minimum number of compartments. This represented a worst-case scenario for testing.

Assemblies of the invention were built, tested and certified in two materials: marine grade aluminium and stainless steel.

All tests were completed and complied with arcing due to internal fault (IEC/TR 61641:2014). All protection devices were tested for both load and line side, including the main incomer MCCB. Verification and Certification bytesting conducted at Lane

2019100518 13 May 2019

Cove, NSW testing facility during March 2018, was for20,000Afor0.3 sec duration, on both line and load side of all protective devices.

The assemblies were tested to the new AS/NZS 61439.1 standard and certified for arc fault containment (IEC/TR 61641:2014) and IP66 ingress protection.

TEST RESULTS

IEC/TR 61641:2014 - Protection of Personnel Criteria Requirements After Arc-flash Incident	TEST RESULT
Doors and covers did not open	Complied
No parts are ejected	Complied
No holes were formed in the accessible parts of the enclosure	Complied
Vertical indication did not ignite (no external flash)	Complied
Equipotential bonding arrangement of accessible parts remained effective	Complied
No propagation of arc or other areas of the assembly	Complied
Satisfied the dielectric test	Complied

The validation tests above were carried out on the smallest practicable assembly, being an assembly of four compartments. It will be appreciated that, because the invention enables diffusion of explosion products throughout an assembly of the invention, the greater the number of compartments in an assembly, the more effective the containment will be. It is to be understood that these examples are not limiting. Different sizes and configurations of compartments, giving alternate assemblies, are within the scope of the invention, as is the use of all practicable ranges of arc fault currents. In addition, various locks incorporated in variations of the escutcheon doors of the invention are envisaged. These can also provide controlled yielding and explosion product pathways under arc blast pressures.

The appended claims are to be considered as incorporated into the above description.

It is to be understood that the terminology employed above is for the purpose of description and should not be regarded as limiting. The described embodiments are intended to be illustrative of the invention, without limiting the scope thereof. The

2019100518 13 May 2019 invention is capable of being practised with various modifications and additions as will readily occur to those skilled in the art.

When any number or range is described herein, unless clearly stated otherwise, that number or range is approximate. Recitation of ranges of values herein are intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value and each separate subrange defined by such separate values is incorporated into the specification as if it were individually recited herein.

Words indicating direction or orientation, such as “front”, “rear”, “back”, etc, are used for convenience. The inventor(s) envisages that various embodiments, including single sided, double-sided, triple-sided and four-sided embodiments, can be used in a non-operative configuration, such as when presented for sale. Thus, such words are to be regarded as illustrative in nature, and not as restrictive.

References provided below are current at the time of filing the application. The references refer to industry standards and testing regimes used in the development of the present invention. The references also refer to articles and reports regarding safety and incidents in the industry.

References

1. H IEEE 1584-2018- IEEE Guide for Performing Arc-Flash Hazard Calculations.

2. https://www.leafelectricalsafety.com/blog/ieee-1584-changes-the-end-of-arc-flashcalculations-as-we-know-them

3. AS/NZS 61439.1:2016 Appendix ZD cl.ZDI

4. http://arcadvisor.com/faq/threshold-incident-energy-second-degree-burn

5. Queensland Work Health and Safety Act 2011 https://www.legislation.qld.gov.au/view/pdf/inforce/current/act-2011-018

6. Australia Institute of Company Directors - Risk Management https://aicd.companydirectors.com.au/~/media/cd2/resources/director- resources/director-tools/pdf/05446-5-12-mem-director-rob-risk-management_a4web.ashx

7. Workplace Health and Safety Queensland - eSafe Incident Alert https://www.vision6.com.aU/v/15149/1808572364/email.html?k=8T ptmsdfdXOY2qgZ LHtc7_tyXaVRnpYMZpj2nqHTsgs

2019100518 13 May 2019

8. http://www.engineeringsafety.com.au I 5 Arc Incidents in Australia UPDATED T&D Oct_Nov 2016, by Brett Cleaves, Engineering Safety

9. Johnson, Dave, Arc Flash Statistics, ISHN, May 31,2013 https://www.ishn.com/articles/96001-arc-flash-statistics

10. SafeWork Australia Guide to the Model Work Health and Safety Act https://www.safeworkaustralia.gov.au/system/files/documents/1702/guide-to-the-whs act-at-21-march-2016.pdf

Claims (5)

1. An electrical control switchboard assembly including:

at least a first and a second adjoining compartment in fluid communication via a connecting interface, at least the first compartment configured for inclusion of electrical equipment; and a blast shield-diffusion device attached to at least one side of the connecting interface at a distance from the interface, configured such that when the electrical equipment fails causing an explosion, the blast shield-diffusion device prevents debris of the explosion from exiting the first compartment, and enables flow of energy through the connecting interface between the adjoining compartments.

2. The electrical control switchboard assembly as claimed in claim 1, wherein the electrical control switchboard is a low voltage electrical control switchboard and the connecting interface of the assembly is a wall between the first and second adjoining compartments.

3. The electrical control switchboard assembly as claimed in claim 2, wherein substantially a central third of the wall has one or more perforations to effect the fluid communication.

4. The electrical control switchboard assembly as claimed in claim 3, wherein the blast shield-diffusion device substantially covers the perforations and includes a planar portion positioned parallel to the connecting interface and a rim extending operatively inward towards the interface and around the periphery of the planar portion.

5. The electrical control switchboard assembly as claimed in any one of the preceding claims, wherein the blast shield-diffusion device includes, on an inner surface adjacent the connecting interface, a layer of material with an irregular profile.