IE72151B1

IE72151B1 - Improvements relating to circuit breakers

Info

Publication number: IE72151B1
Application number: IE930500A
Authority: IE
Inventors: Kenneth Neill; Keith Wray Ball
Original assignee: Square D Co
Priority date: 1992-07-17
Filing date: 1993-07-05
Publication date: 1997-03-26
Also published as: AU673534B2; IE930500A1; GB2268831A; JPH06511137A; GB2268831B; AU4682993A; WO1994002979A1; GB9215302D0

Abstract

A vented enclosure (10) is provided for moulded case circuit breakers and includes a venting arrangement to permit release of internal pressure caused in use by short circuit fault conditions. The venting arrangement is provided in the form of louvers (14) formed in the enclosure, or a blow-out panel (15) or a flap (16) mounted over an aperture formed in the enclosure, with the panel (15) or flap (16) being formed of synthetic plastic material.

Description

The invention relates to circuit breakers and more particularly to moulded case circuit breakers (M.C.C.B.), secondary enclosures therefor and to an Iline panelboard for mounting such circuit breaker enclosures.

With M.C.C.B's fitted with secondary enclosures problems can occur when such breakers open under short circuit conditions since gas and particles are generated under such conditions. This can cause problems with damage to the M.C.C.B. secondary enclosure by pressure build up and furthermore the generated particles can impair the dielectric withstand of the electrical circuits throughout the panelboard assembly.

It is an object of the present invention to obviate or mitigate these above disadvantages.

According to one aspect of the invention there is provided a secondary enclosure housing a moulded case circuit breaker, the secondary enclosure being formed with at least one venting arrangement to allow release of internal pressure caused by short circuit fault conditions, in use.

A venting arrangement may be provided in the form of a blow out panel or a flap mounted over an aperture formed in the secondary enclosure and the panel or flap may be formed of synthetic plastics material.

In addition or alternatively a venting arrangement may comprise louvres formed in the secondary enclosure. 2 721 51 Insulating barriers may be located to prevent vented exhaust particles from coming into contact with electrically live conductors, in use.

According to a further aspect of the invention there is provided an I-line panelboard locating therein a plurality of secondary enclosures as defined in any of the next preceding four paragraphs, the panelboard being formed to provide a central vertical expansion chamber located between two vertical stacks of juxtaposed plug-in secondary enclosures.

A panel of synthetic plastics material may be located ar the lower end of the expansion chamber for protecting a bus stack located therebelow.

A fixed or sprung loaded centre cover may be located over the vertical expansion chamber.

The foregoing and further features of the invention may be more readily understood from the following description of preferred embodiments thereof, by way of example, with reference to the accompanying drawings, in which:Fig. 1 is a perspective view of the front of an I-line panelboard; Fig. 2 is a side elevational view of a portion of the panelboard of Fig. 1 showing a centre cover located thereon; Figs. 3a and 3b are views, on enlarged scale, of the circled portion A of Fig. 2 showing alternative fixings for the centre cover; Fig. 4 is a side elevational view of an M.C.C.B. secondary enclosure plug-in unit inserted into the stack of the panelboard; Fig. 5 is an end elevational view of the end of the unit of Fig. 4 remote from the stack; Fig. 6 is an end elevational view of the other end of the unit of Fig. 4 adjacent to the stack; Fig. 7 is an end elevational view of an alternative arrangement to Fig. 6; Fig. 8 is a side elevational view of an alternative M.C.C.B. secondary enclosure plug-in unit, and Fig. 9 is an end elevational view in the direction of arrow B on Fig. 8.

Referring now firstly to Fig. 1 there is shown an I-line panelboard assembly 10 with two vertical stacks of plug-in enclosed M.C.C.B.'s 11 shown located in their plugged-in positions. Each of the M.C.C.B.'s secondary enclosures 11 is vented into a central vertical expansion chamber 12 and a cover '13 of synthetic plastics material is located at the lower end for protecting a bus stack (not shown) located therebelow. The M.C.C.B.'s secondary enclosures 11 may be vented in a plurality of forms with enclosure Ila being formed with a vent opening 14, enclosure lib having a panel 15 which is secured at its edges to form a blow-out panel and enclosure 11c having a flap 16 which is rigidly secured at one edge and which may he perforated, both the panel 15 and the flap 16 being formed of synthetic plastics material. The detail of such venting will be described in more detail hereinafter. Customer cabling compartments are located vertically at each side of the assembly 10 beneath panels 17. A central cover 18 (Fig 2) is located over the expansion chamber 12 in the position indicated by arrow 18.

Referring now to Fig.2 there is shown the panelboard bus stack 19, the central cover 18 which is located over the expansion chamber 12 and a stack barrier 20 located between stack 19 and cover 18. Fig. 3a shows, on enlarged scale, the circled portion A in Fig. 2 and shows the detail of an assembly 21 comprising a nut and bolt fixing with a pre-loaded spring to enable release movement of cover 18 should there be excessive pressure build-up within chamber 12. Fig. 3b shows a similar view to Fig 3a but with a fixed nut and bolt assembly 22.

Referring now to Figs. 4 and 5 there is shown an enclosure 11 which is plugged-in to stack 19. With this enclosure 11 the outer end face is formed with venting louvres 23 which may be provided as an alternative or additional to an aperture 14, panel 15 or flap 16 at the stack engaging end. Cable entry into the enclosure 11 is via holes 24 which are drilled to suit the cable size to be utilized.

Referring now to Fig. 6 there is shown an end elevational view of the enclosure 11c of Fig·. 1 on enlarged scale. The flap 16 is rigidly located along the base by screws 25 and a slotted perforation 26 provided to enable hinging or snap-off with pressure build up within enclosure lie. Fig. 7 shows a similar view to Fig. 6 for the enclosure 11b, in which panel 15 is located by the edges of screw mounted washers 27 so as to provided a blow-out panel with pressure build up within enclosure 11b.

Referring now to Figs. 8 and 9 there is shown a further enclosure 11 which may have any of the previously described venting arrangements and also have protection of the electrical connections 28 from contamination from generated particles when the breaker opens under short circuit conditions. An insulating barrier 29 is provided at the outer edges of the connections and further barriers 30 are provided between the connections. Furthermore barriers 31 are located over and around the terminal pads 32 of the breaker.

Hence it will be seen that when breakers open under short circuit conditions the arrangements shown provide venting of gas pressure/particles to both prevent mechanical damage which could result in the environmental degree of protection being impaired and that particles released to not contaminate the electrical connections.

Claims

1. A secondary enclosure housing a moulded case circuit breaker, the secondary enclosure being formed with at least one venting arrangement to allow release of internal pressure caused by short circuit fault conditions, in use.

2. A secondary enclosure as claimed in claim 1 wherein a venting arrangement comprises a blow out panel attached over an aperture formed in the secondary enclosure.

3. A secondary enclosure as claimed in claim 1 wherein a venting arrangement comprises a flap mounted over an aperture formed in the secondary enclosure.

4. A secondary enclosure as claimed in claim 2 or 3 wherein the panel or flap is formed of synthetic plastics material.

5. A secondary enclosure as claimed in any preceding claim wherein a venting arrangement comprises louvres formed in the secondary enclosure.

6. A secondary enclosure as claimed in any preceding claim including insulating barriers located to prevent vented exhaust particles from coming into contact with electrically live conductors, in use.

7. An I-line panelboard locating therein a plurality of secondary enclosures as claimed in any preceding claim, the panelboard being formed to provide a central vertical expansion chamber located between two vertical stacks of juxtaposed plug-in secondary enclosures .

8. A panelboard as claimed in claim 7 wherein a cover of synthetic plastics material is located'at the lower end of the expansion chamber for protecting a bus stack located therebelow. 5

9. A panelboard as claimed in claim 7 or 8 having a fixed or sprung loaded centre cover located over the vertical expansion chamber.

10. A secondary enclosure housing a moulded case circuit breaker substantially as hereinbefore described 10 with reference to Figs 4 to 9 of the accompanying drawings .

11. An I-line panelboard locating a plurality of circuit breaker assemblies substantially as hereinbefore described with reference to the

12. 15 accompanying drawings.