US3573560A

US3573560A - Interlock system for metal enclosed switchgear having a fuse drawer and sliding panels

Info

Publication number: US3573560A
Application number: US858939A
Authority: US
Inventors: Edward J Rogers
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1969-09-18
Filing date: 1969-09-18
Publication date: 1971-04-06
Anticipated expiration: 1988-04-06
Also published as: GB1270189A

Abstract

A metallic housing encloses high voltage switchgear including a horizontally slidable fuse drawer having a switch pivoted on each side with vertically slidable access panels for the switches. An interlocking system prevents: opening of the fuse drawer and removal of the sliding panels unless both switches are open, closure of either of the switches with the fuse drawer open and replacing the panels in their fully closed positions after the fuse drawer is closed.

Description

United States Patent 1 1 3,573,560

[72] Inventor Edward J- Rogers [56] References Cited Chimflm UNITED STATES PATENTS [21] P 1,402,123 1/1922 Wadsworth 337/8 [22] 1969 3 309 576 3/1967 Sims 317/99 45 Patented Apr. 6, 1971 3 339 118 8/1967 name 317/114 [73] Assignee s & C Electric Company Chicago, Ill. Primary Examiner-E. A. Goldberg Assistant Examiner-Gerald P. Tolin Att0rney--Robert R. Lockwood [54] INTERLOCK SYSTEM FOR METAL ENCLOSED SWITCHGEAR HAVING A FUSE DRAWER AND G ABSTRACT: A metallic housing encloses high voltage mg switchgear including a horizontally slidable fuse drawer hav- [52] US. Cl 317/114, ing a switch pivoted on each side with vertically slidable ac- 200/50 cess panels for the switches. An interlocking system prevents: [51] Int. Cl H02b 1/04, opening of the fuse drawer and removal of the sliding panels l-lOlh 9/20 unless both switches are open, closure of either of the switches [50] Field of Search ZOO/50.15, with the fuse drawer open and replacing the panels in their fully closed positions after the fuse drawer is closed.

Patented April 6, 1971 4 Sheets-Sheet 1 FIG. I

- v V Ill v Patented April 6, 1971 4 Sheets-Sheet 8 Patented A ril 6, 1971 4 Sheets-Sheet 5 Patented April 6, 1971 4 Sheets-Sheet 4 INTERLOCK SYSTEM FOR METAL ENCLOSED SWITCIIGEAR HAVING A FUSE DRAWER AND SLIDING PANELS This invention is an improvement over the disclosure of Harner et al., U.S. Pat. No. 3,339,118, issued Aug. 29, 1967 and is adapted for use with the structure disclosed in a copending Emmett R. Beebe application.

In the application above referred to a fuse drawer is horizontally slidable in a metallic housing and has loop feeder switches on either side for connecting fuses which supply a load circuit for energization to either side of the loop circuit. Vertically slidable metallic panels overlie the switches and, when removed, provide access to them for inspection and servicing.

Among the objects of this invention are: To prevent opening of the fuse drawer if either of the switches is closed; to permit removal of either of the sliding panels only when both switches are open; to prevent closure of either of the switches when the fuse drawer is open; and to prevent replacement of either of the sliding panels to its fully-closed closed position except when the fuse drawer is open.

According to this invention a metallic housing is provided in which a fuse drawer is horizontally slidable. On either side of the fuse drawer there is a loop feeder switch for connecting fuses on the fuse drawer to either or both sides of a loop feeder circuit, the fuses being connected to a load circuit. To permit access to the switches for inspection and servicing vertically slidable metallic panels are provided on opposite sides of a panel of the fuse drawer on which the fuses are mounted. A manual switch operator for each switch includes a pivoted member that is moved between closed and open positions. The fuse drawer has upper and lower notched lock plates along each side with the notches arranged to receive upper and lower pivoted latch plates to lock the fuse drawer closed. The latch plates along each side are connected for conjoint pivotal movement. Each upper latch plate is connected to the respective pivoted member in such manner that the latch plates hold the fuse drawer closed when the switches are closed and disengage the lock plates when the switches are open to permit opening of the fuse drawer. Endwise slidable locking pins are arranged to overlie inwardly extending flanges of the slidable panels along their lower edges to prevent removal thereof. The locking pins are moved between panel locked and unlocked positions by panel lock levers on a pivoted shaft which is moved between panel-locked and panel-unlocked positions by detents on the fuse drawer. Extensions of the panel lock levers function as detents to engage the lower latch plates and prevent closure of the switches when the fuse drawer is open. If the fuse drawer is closed with the panels removed, the locking pins are moved to their panel locked positions and thus prevent downward movement of the panels to their fully-closed positions.

In the drawings:

FIG. 1 is a perspective view of metal-enclosed switchgear in which the interlocking mechanism of this invention is embodied, the metal enclosure being shown in outline by broken lines in order to permit illustration of the switchgear comprising fuses and switches within the enclosure;

FIG. 2 is a perspective view, at a reduced scale, of the metallic housing shown in FIG. 1, the view being taken looking generally from the rear;

FIG. 3 is a horizontal view looking downwardly underneath the top panel of the metal enclosure shown in FIG. 1 and illustrates, somewhat diagrammatically, the arrangement of the switches and the interlock mechanism;

FIG. 4 is a view in front elevation of the interlocking mechanism shown in FIG. 3, the illustration here also being somewhat diagrammatic in character;

FIG. 5 is a vertical sectional view at an enlarged scale showing a portion of the fuse drawer and how the detents thereon are arranged to pivot a shaft which controls interlocks for the sliding panels;

FIG. 6 is a view, at an enlarged scale, taken generally along line 6-6 of FIG. 4;

FIG. 7 is a view in elevation taken generally along line 7 7 of FIG. 6;

FIG. 8 illustrates diagrammatically the circuit connections for the fuses and switches in the metal enclosure shown in FIGS. 1 and 2.

In FIGS. 1 and 2 the reference character 10 designates, generally, a metallic housing that is adapted to be mounted on a concrete pad and it constitutes, generally, a support structure for electrical switchgear mounted therein. The metallic housing 10 has vertical sidewalls 11 and I2 and a slidable top panel 13 which is described in more detail in the Beebe application above referred to. Horizontally slidably mounted in the metallic housing 10 is a fuse drawer that is indicated, generally, at 14 and is provided with a fuse drawer panel 15 which, in part, closes off the front side of the metallic housing 10. Insulators 16 extend rearwardly from the fuse drawer panel 15 and fuses 17 extend endwise thereof having fuse ter minals 18 at their distal ends for insertion in plug-in contacts 19 that are carried by insulators 20 which extend forwardly from an inner rear panel 21. Cable terminators 22, FIG. 2, are provided on the rear side of the panel 21 to permit connection to a load circuit.

As shown diagrammatically in FIG. 8 the ends of the fuses 17 mounted on the insulators 16 are provided with laterally and inwardly extending

contact anns

24 and 25 that are arranged, in the closed position of the fuse drawer 14, to have contact engagement with

contact plates

26 and 27 of loop feeder switches that are indicated, generally, at 28 and 29. It will be noted that the

loop feeder switches

28 and 29 are located on opposite sides of the fuse drawer 14 and that

switch blades

30 and 31 extend from the

contact plates

26 and 27 and are arranged to be pivoted through

arc chutes

32 and 33 into engagement with

stationary switch contacts

34 and 35 on which the

arc chutes

32 and 33 are mounted. Insulators 36 and 37 support the

stationary switch contacts

34 and 35 and are mounted on and extend forwardly from rear members 38 and 39 of switch support structures that are indicated, generally, at 40 and 41. It will be understood that the

switch support structures

40 and 41 are suitably mounted within the metallic housing 10 and therewith provide a support structure for switchgear cable terminators 42 and 43, FIG. 2, which are located on the rear side of the panel 21 to provide connections to the loop feeder circuit from the

stationary switch contacts

34 and 35.

Access for inspection and servicing of the

loop feeder switches

28 and 29 is provided through openings in the front of the metallic housing 10 which are closed by vertically slidable

metallic panels

44 and 45. Their construction is described in more detail in the copending Beebe application above referred to. As will appear hereinafter provision is made for preventing opening movement of the fuse drawer 14 when the

loop feeder switches

28 and 29 are closed. Also provision is made for preventing removal of the

slidable panels

44 and 45, except when the fuse drawer 14 has been withdrawn. Further, the

panels

44 and 45 cannot be removed except when the top panel 13 is moved rearwardly as shown in FIG. 1 to uncover their upper ends.

In FIG. 3 it will be observed that the

switch blades

30 and 31 are arranged to be pivoted about vertical axes by

arms

46 and 47 which are connected by

links

48 and 49 to

arms

50 and 51 which are pivoted with a snap action by spring operators, generally indicated at 52 and 53, which may be constructed as disclosed in a copending Bernatt-Gelfand application. The

spring operators

52 and 53 are operated manually on pivotal movement of

tool receiving shafts

54 and 55. A suitable crank or wrench-type of tool can be attached to the upper ends of the

shafts

54 and 55 or suitable operating handles can be permanently secured thereto. As shown in FIG. 1, access to the

shafts

54 and 55 or other manually-operated operators can be had only when the top panel 13 is moved rearwardly.

In order to interlock the operation of the

loop feeder switches

28 and 29 with the fuse drawer I4, pivoted

members

56 and 57 are connected to and pivot conjointly with the

shafts

54 and 55. The

members

56 and 57 are generally sectorshaped and have

arcuate slots

58 and 59 that are arranged to receive

ends

60 and 61 of connecting members or

rods

62 and 63 which extend horizontally generally toward each other with their

inner ends

64 and 65 pivotally connected to

upper drawer latches

66 and 67 as shown more clearly in FIG. 4. The

upper drawer latches

66 and 67 are pivoted at 68 and 69 on the support structure of the metallic housing and they have

latch arms

70 and 71 extending therefrom for latching engagement with

upper latch plates

72 and 73 which extend rearwardly from the fuse drawer panel along opposite sides.

Lower latch plates

74 and 75 also extend rearwardly from opposite sides of the fuse drawer panel 15 near its lower end. The upper end lower latch plates 72-75 are of similar construction and the lower latch plate 75 is shown in elevation in FIG. 6 where it will be observed it is provided with a notch 77. The other latch plates are provided with similar notches for receiving the

latch arms

70 and 71 in the case of the

upper latch plates

72 and 73. The

upper drawer latches

66 and 67 are generally in the form of bellcranks and have arms .80 and 81 to which ends 82 and 83 of vertical links or

rods

84 and 85 are pivotally connected. The lower ends of the links or

rods

84 and 85, indicated at 86 and 87, are pivotally connected to

lower drawer latches

88 and 89 which, in turn, are pivoted at 90 and 91 on the support structure forming a part of the metallic housing 10. Latch

arms

92 and 93 which extend from the

lower drawer latches

88 and 89 are arranged to engage notches in the

lower latch plates

74 and 75 as described above and shown in FIG. 6.

As long as the loop feeder switch 29 remains in the closed position, shown in FIG. 3, the pivoted member 57 occupies the position shown by full lines and the

latch arms

71 and 93 engage the

respective latch plates

73 and 75 and thus prevent opening movement of the fuse drawer 14. When the loop feeder switch 29 is opened, the pivoted member 57 is moved to the position shown by broken lines with the result that the upper and

lower drawer latches

67 and 89 are shifted to the positions thereof shown by broken lines in FIG. 4. The

latch arms

71 and 93 are moved out of the notches in the

respective latch plates

73 and 75 and, insofar as they are concerned, the fuse drawer 14 in unlocked. However, it will be understood that the drawer 14 cannot be opened until the other loop feeder switch 28 is opened and the

latch arms

70 and 92 are moved out of latching engagement with the

respective latch plates

72 and 74.

For locking the vertically

slidable panels

44 and 45 against removal advantage is taken of their

lower intumed flanges

94 and 95 which are shown somewhat diagrammatically in FIG. 4. Lockpins 96 and 97, generally L-shaped, are endwise slidably mounted in

guides

98 and 99 with the ends of the long arms arranged to overlie the upper sides of the

lower intumed flanges

94 and 95 of the

panels

44 and 45 as illustrated in FIG. 6. The

short arms

100 and 101 of the lockpins 96 and 97 extend through slotted openings one of which is indicated at 103 in

lockpin levers

104 and 105 that are secured to the ends of a shaft 106 which is pivoted in bearing brackets 107 which are suitably mounted on the support structure within the metallic housing 10. For pivoting the shaft 106 to withdraw the lockpins 96 and 97 from overlying relation to the

flanges

94 and 95 of the

panels

44 and 45 an arm 110 is secured to the shaft 106. As shown more clearly in FIG. 5 a detent in the form of a pin 111 extends laterally from the lower part of the fuse drawer 14. When the fuse drawer 14 is opened and moved sufficiently far, the detent or pin 111 engages the distal end of the arm 110 and shifts it to the position shown by broken lines in FIG. 5 or sufficiently far to withdraw the lockpins 96 and 97 from locking engagement with the

panels

44 and 45. Since this occurs only when the fuse drawer 14 is moved toward the open position, the

panels

44 and 45 can be removed only when this occurs. When the fuse drawer 14 is closed a second detent in the form of a pin 112 engages the opposite side of the arm 110, as shown in FIG. 5, to pivot the shaft 106 and thereby the lockpin levers 104 and 105 to return the lockpins 96 and 97 to their locking positions. The unlocked position of the lockpin lever 105 is shown by broken lines in FIG. 6. The shaft 106 is held in either operated position by a friction spring 113, FIGS. 6 and 7, which is secured at 114 to the support structure within the metallic housing 10. The distal end 115 of the friction spring 113 bears against the shaft 106. Thus it is necessary for one or the other of the detents or pins 111 or 112 to engage the arm 110 to cause a pivotal movement of the shaft 106.

It will be noted that, when the fuse drawer 14 is open, the lockpins 96 and 97 are withdrawn and the

panels

44 and 45 can be removed. Should the fuse drawer 14 be closed without first replacing the

panels

44 and 45, the lockpins 96 and 97 are moved to their locking positions on engagement of the arm 110 by the detent or pin 112. Now, if an attempt is made to replace the

panels

44 or 45, their lower intumed flanges 94 and will engage the upper sides of the lockpins 96 and 97 and it will not be possible to replace the

panels

44 and 45 fully in their closed positions.

When the fuse drawer 14 is open, it is undesirable that the loop feeder switches 28 and 29 be closed. In order to prevent such closure,

detents

116 and 117 in the form of extensions of the lockpin levers 104 and are arranged to engage

arcuate surfaces

118 and 119 on the lower drawer latches 88 and 89. FIGS. 6 and 7 show the lower drawer latch 89 and the detent 117 by broken lines in the positions that they occupy when the fuse drawer 14 is open. By preventing pivotal movement of the lower drawer latches 88 and 89 the links or

rods

84 and 85 prevent movement of the upper drawer latches 66 and 67 and thereby of the connecting members or

rods

62 and 63. As a result the pivoted

members

56 and 57 are held in their open positions and pivotal movement of the

tool receiving shafts

54 and 55 is prevented. Accordingly operation of the

spring operators

52 and 53 cannot be effected and the loop feeder switches 28 and 29 cannot be closed. FIG. 3 shows by broken lines the position of the pivoted member 57 corresponding to the switch open position. It will be understood that the pivoted member 56 occupies a similar position when the drawer 14 is open.

In operation, when the loop feeder switches 28 and 29 are closed and the fuse drawer 14 is closed, the upper drawer latches 66 and 67 and the lower drawer latches 88 and 89 hold the fuse drawer 14 against opening movement. Since the fuse drawer 14 is closed, the lockpins 96 and 97 prevent removal of the

panels

44 and 45. When both of the loop feeder switches 28 and 29 are opened the upper drawer latches 66 and 67 are moved out of engagement with the

upper latch plates

72 and 73 and, at the same time, the lower drawer latches 88 and 89 are moved out of latching engagement with the

lower latch plates

74 and 75. Then the fuse drawer 14 can be opened. When it has been opened sufficiently far, the pin or detent 111 engages the arm and pivots the shaft 106 to withdraw the lockpins 96 and 97 from overlying relation with the lower

inturned flanges

94 and 95 of the

panels

44 and 45. Then the

panels

44 and 45 can be removed. With the lockpins 96 and 97 withdrawn, the

detents

116 and 117 prevent pivotal movement of the lower drawer latches 88 and 89 to prevent pivotal movement of the pivoted

members

56 and 57, thereby preventing closure of the loop feeder switches 28 and 29.

Iclaim:

1. An interlocking fuse and switch system comprising:

a support structure,

a fuse drawer slidable horizontally on said support structure,

a fuse carried by said fuse drawer,

a switch having a switch blade pivoted on said support structure to one side of said drawer,

contact means interconnecting said fuse and said switch blade,

a panel vertically slidable on said support structure alongside of said fuse drawer, overlying said switch and permitting access thereto when removed,

manual means for operating said switch blade between closed and open positions including a pivoted member having closed and open positions corresponding to closed and open positions of said switch blade,

fuse drawer locking means connected to said pivoted member for unlocking said fuse drawer when said pivoted member is in said open position and locking it when said pivoted member is in said closed position,

panel locking means preventing removal of said panel, and

means for unlocking said panel locking means when said fuse drawer has been opened to a predetermined position.

2. The interlocking fuse and switch system according to claim 1 wherein means prevent movement of said pivoted member to closed position while said fuse drawer is open.

3. The interlocking fuse and switch system according to claim 1 wherein means operable in response to closing movement of said fuse drawer lock said panel in place.

4. The interlocking fuse and switch system, according to claim 1 wherein said fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer,

a drawer latch pivoted on said support structure for entering the notch of said latch plate to lock said fuse drawer closed, and

a connecting member between said pivoted member and said drawer latch.

5. The interlocking fuse and switch system according to claim 1 wherein said panel locking means includes:

a lockpin endwise movable into and. out of locking engagement with said panel, a lockpin lever connected to said lockpin, a shaft pivoted on said support structure having said lockpin lever secured thereto, an arm secured to said shaft, and detent means on said fuse drawer for engaging said shaft for moving said lockpin between locked and unlocked positions with respect to said panel. 6. The interlocking fuse and switch system according to claim 5 wherein means on said panel engage said lockpin when said fuse drawer is closed with said panel removed and prevent movement of said panel to fully-closed position.

7. The interlocking fuse and switch system according to claim I wherein said fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer, a drawer latch pivoted on said support structure for entering the notch in said latch plate to lock said fuse drawer closed, and a connecting member between said pivoted members and said drawer latch, and said panel locking means includes: a lockpin endwise movable into and out of overlying relation to a part of said panel,

a lockpin lever connected to said lockpin,

a shaft pivoted on said support structures having said lockpin lever secured thereto, and

detent means on said fuse drawer for engaging said arm, to

pivot said shaft.

8. The interlocking fuse and switch system according to claim 7 wherein said fuse drawer locking means includes:

a second notched plate secured to said fuse drawer,

a second drawer latch pivoted on said support structure for entering the notch in said second latch plate also to lock said fuse drawer closed, and

a link interconnects said pivoted latches, and

a detent on said shaft is arranged to engage said second drawer latch while said fuse drawer is open to prevent movement of said pivoted member to closed position while said fuse drawer is open.

9. An interlocking fuse and switch system comprising:

a support structure,

a drawer slidable horizontally on said support structure intermediate its ends,

a fuse carried by said drawer,

a switch on each side of said drawer each having a switch blade pivoted on said support structure,

contact means interconnecting said fuse and said switch blades,

a panel vertically slidable on said support structure along each side of said drawer, overlying the respective switch and permitting access thereto when removed,

manual means for operating each switch blade between closed and open positions each including a pivoted member having closed and open positions corresponding to closed and open positions of the respective switch blade,

fuse drawer locking means connected to each pivoted member for unlocking said fuse drawer when each pivoted member is in the respective open position and locking it when each pivoted member is in its closed position,

panel locking means individual to each of saidpanels preventing removal thereof, and

means for unlocking each panel locking means when said fuse drawer has been opened to a predetermined position.

10. The interlocking fuse and switch system according to claim 9 wherein means prevent movement of each of said pivoted members to its closed position while said fuse drawer is open.

11. The interlocking fuse and switch system according to claim 9 wherein means operable in response to closing movement of said fuse drawer lock each of said panels in place.

12. The interlocking fuse and switch system according to claim 9 wherein each fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer,

a connecting member between each pivoted member and the respective drawer latch.

13. The interlocking fuse and switch system according to claim 9 wherein said panel locking means includes:

a lockpin endwise movable into and out of locking engagement with the respective panel,

a lockpin lever connected to each lockpin,

a shaft pivoted on said support structure having each lockpin lever secured thereto,

an arm secured to said shaft, and

detent means on said fuse drawer for engaging said arm to pivot said shaft for moving said lockpin between locked and unlocked positions with respect to said panels.

14. The interlocking fuse and switch system according to claim 13 wherein means on each panel engage the respective lockpin when said fuse drawer is closed with either of said panels removed and prevent movement of the respective panel to fully-closed position.

15. The interlocking fuse and switch system according to claim 9 wherein each fuse drawer locking means includes:

a notched latch plate secured to said fuse drawer,

a connecting member between each pivoted member and the respective drawer latch, and said panel locking means includes:

I a lockpin lever connected to each lockpin,

an arm secured to said shaft, and

detent means on said fuse drawer for engaging said arm tov pivot said shaft for moving said lockpins between locked and unlocked positions with respect to said panels.

16. The interlocking fuse and switch system according to claim 15 wherein each fuse drawer locking means includes:

a second notched plate secured to said fuse drawer,

a second drawer latch pivoted on said support structure for a detent on said shaft is arranged to engage said second entering the notch in said second latch plate also to lock drawer latch while said fuse drawer is open to prevent said fuse drawer closed, and movement of either of said pivoted members to closed a link interconnects said pivoted latches, and position while said fuse drawer is open.

Claims

1. An interlocking fuse and switch system comprising: a support structure, a fuse drawer slidable horizontally on said support structure, a fuse carried by said fuse drawer, a switch having a switch blade pivoted on said support structure to one side of said drawer, contact means interconnecting said fuse and said switch blade, a panel vertically slidable on said support structure alongside of said fuse drawer, overlying said switch and permitting access thereto when removed, manual means for operating said switch blade between closed and open positions including a pivoted member having closed and open positions corresponding to closed and open positions of said switch blade, fuse drawer locking means connected to said pivoted member for unlocking said fuse drawer when said pivoted member is in said open position and locking it when said pivoted member is in said closed position, panel locking means preventing removal of said panel, and means for unlocking said panel locking means when said fuse drawer has been opened to a predetermined position.

4. The interlocking fuse and switch system according to claim 1 wherein said fuse drawer locking means includes: a notched latch plate secured to said fuse drawer, a drawer latch pivoted on said support structure for entering the notch of said latch plate to lock said fuse drawer closed, and a connecting member between said pivoted member and said drawer latch.

5. The interlocking fuse and switch system according to claim 1 wherein said panel locking means includes: a lockpin endwise movable into and out of locking engagement with said panel, a lockpin lever connected to said lockpin, a shaft pivoted on said support structure having said lockpin lever secured thereto, an arm secured to said shaft, and detent means on said fuse drawer for engaging said shaft for moving said lockpin between locked and unlocked positions with respect to said panel.

6. The interlocking fuse and switch system according to claim 5 wherein means on said panel engage said lockpin when said fuse drawer is closed with said panel removed and prevent movement of said panel to fully-closed position.

7. The interlocking fuse and switch system according to claim 1 wherein said fuse drawer locking means includes: a notched latch plate secured to said fuse drawer, a drawer latch pivoted on said support structure for entering the notch in said latch plate to lock said fuse drawer closed, and a connecting member between said pivoted members and said drawer latch, and said panel locking means includes: a lockpin endwise movable into and out of overlying relation to a part of said panel, a lockpin lever connected to said lockpin, a shaft pivoted on said support structures having said lockpin lever secured thereto, and detent means on said fuse drawer for engaging said arm to pivot said shaft.

8. The interlocking fuse and switch system according to claim 7 wherein said fuse drawer locking means includes: a second notched plate secured to said fuse drawer, a second drawer latch pivoted on said support structure for entering the notch in said second latch plate also to lock said fuse drawer closed, and a link interconnects said pivoted latches, and a detent on said shaft is arranged to engage said second drawer latch while said fuse drawer is open to prevent movement of said pivoted member to closed position while said fuse drawer is open.

9. An interlocking fuse and switch system comprising: a support structure, a drawer slidable horizontally on said support structure intermediate its ends, a fuse carried by said drawer, a switch on each side of said drawer each having a switch blade pivoted on said support structure, contact means interconnecting said fuse and said switch blades, a panel vertically slidable on said support structure along each side of said drawer, overlying the respective switch and permitting access thereto when removed, manual means for operating each switch blade between closed and open positions each including a pivoted member having closed and open positions corresponding to closed and open positions of the respective switch blade, fuse drawer locking means connected to each pivoted member for unlocking said fuse drawer when each pivoted member is in the respective open position and locking it when each pivoted member is in its closed position, panel locking means individual to each of said panels preventing removal thereof, and means for unlocking each panel locking means when said fuse drawer has been opened to a predetermined position.

12. The interlocking fuse and switch system according to claim 9 wherein each fuse drawer locking means includes: a notched latch plate secured to said fuse drawer, a drawer latch pivoted on said support structure for entering the notch of said latch plate to lock said fuse drawer closed, and a connecting member between each pivoted member and the respective drawer latch.

13. The interlocking fuse and switch system according to claim 9 wherein said panel locking means includes: a lockpin endwise movable into and out of locking engagement with the respective panel, a lockpin lever connected to each lockpin, a shaft pivoted on said support structure having each lockpin lever secured thereto, an arm secured to said shaft, and detent means on said fuse drawer for engaging said arm to pivot said shaft for moving said lockpin between locked and unlocked positions with respect to said panels.

15. The interlocking fuse and switch system according to claim 9 wherein each fuse drawer locking means includes: a notched latch plate secured to said fuse drawer, a drawer latch pivoted on said support structure for entering the notch of said latch plate to lock said fuse drawer closed, and a connecting member between each pivoted member and the respective drawer latcH, and said panel locking means includes: a lockpin endwise movable into and out of locking engagement with the respective panel, a lockpin lever connected to each lockpin, a shaft pivoted on said support structure having each lockpin lever secured thereto, an arm secured to said shaft, and detent means on said fuse drawer for engaging said arm to pivot said shaft for moving said lockpins between locked and unlocked positions with respect to said panels.

16. The interlocking fuse and switch system according to claim 15 wherein each fuse drawer locking means includes: a second notched plate secured to said fuse drawer, a second drawer latch pivoted on said support structure for entering the notch in said second latch plate also to lock said fuse drawer closed, and a link interconnects said pivoted latches, and a detent on said shaft is arranged to engage said second drawer latch while said fuse drawer is open to prevent movement of either of said pivoted members to closed position while said fuse drawer is open.