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Патент USA US3098152

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July 16, 1963
R. R. FARRELL
’
3,098,142
SWITCH HEAD CONSTRUCTION PERMITTING OBSERVATION OF CONTACT JAWS
Filed Aprilv 8, 1960
'
3 Sheets-Sheet 1
INVEN TOR.
190,558 7 E. f?zeffll
BY
July 16, 1963
R. R. FARRELL
7 3,098,142
's‘wrrca HEAD CONSTRUCTION PERMITTING OBSERVATION 0F CONTACT JAWS
Filed April 8, 1960
3 Sheets-Sheet 2
July 16, 1963
R.’ R‘ FARRELL
3,098,142
SWITCHHEAD CONSTRUCTION PERMITTING OBSERVATION OF CONTACT JAWS
Filed April 8, 1960
a Sheets-Sheet s
i: 5.5’.
40
76
5.7117.
INVENTOR.
£06156 7' e. F?ktefzl
BY
A rramgyw
United States Patent 0 ” "we
1
3,098,142
SWITCH HEAD CONSTRUCTION PERMITTING
OBSERVATION OF CONTACT JAWS
Robert R. Farrell, Toronto, Ontario, Canada, assignor to
I-T-E Circuit Breaker Company, Philadelphia, Pa, a
corporation of Pennsylvania
Filed Apr. 8, 1960, Ser. No. 26,927
2 Claims. (Cl. 200—168)
3,098,142
Patented July 16, 1963
2
A further object of this invention is to cut back the
skirts of a molded switch head so that the stationary
contact jaws cooperating with the switch head will be
exposed for visual observation when the switch head is
moved to its “01f” position without interfering substan
tially with the operation of the switch.
A still further object of this invention is to provide
a switch head having at least a partial transparent portion
therein of insulating material which permits visual ob
This invention relates to a switch head construction 10 servation of the stationary contact jaws.
These and other objects of this invention will become
for permitting visual observation of the contact jaws
apparent
from the following description when taken in
when the switch is in vthe “O?” position, and more spe
connection with the drawings, in which:
ci?cally is an improvement of the molded switch head
‘FIGURE 1 shows an ‘exploded perspective view of
shown in U.S. Patent No. 2,820,123 to L. W. Higgins
a
molded
switch head constructed in accordance with the
15
et al., entitled “Molded Switch Head,” issued January 14,
present
invention.
1958 and assigned to the assignee of the instant invention.
Molded switch heads as described in the above noted
patent are well known to the art, and are formed of a
FIGURE 2 shows a perspective interior view of one
of the telescoping portions of the switch head of FIG
URE 1.
contact member which is surrounded by an insulating
FIGURE 3 shows a side plan view of the assembled
medium. A pair of relatively stationary contacts enter 20
switch head of FIGURE 1.
FIGURE 4 shows a side cross-sectional view of the
switch
head of FIGURES 1 and 3 with the switch head in
the switch head. The insulating structure which carries
an “On” position.
the movable contact further includes .an insulating barrier
FIGURE 5 shows the switch head of FIGURE 4 in
which follows behind the movable contact when it is 25
cross-section, {and in the “Off” position.
moved to a disengaged position. Thus, arc interruption
FIGURE 6 shows a cross-sectional view of FIGURE 4
is achieved, ?rst, because of the interposition of the
along the lines 6——6 of FIGURE 4, and particularly il
insulating barrier between the movable contact and the
the insulating medium through a channel therein to en
gage the contact member or movable contact carried by
lustrates the manner in which the two halves of the
molded switch head telescope with respect to one an
30
head surrounding the contacts restricts the amount of
other.
oxygen or ionizable gas to which the arc is opened.
stationary contacts, and, secondly, because the insulating
FIGURE 7 shows a cross-sectional view of FIGURE 5
taken across the lines 7-7 of FIGURE 5 to particularly
show the manner in which the contact slug land biasing
be retained at all times so that when the movable switch
is moved to the fully “Off” position, the stationary con 35 spring are assembled within the switch head.
FIGURE 8 is a side plan view of the switch head of
tacts entering the switch head are still within the head
FIGURE
5 in the disengaged position, and particularly
and enclosed by the “skirts” of the head, so that the
illustrates the manner in which the stationary contact jaws
tips of the stationary contacts are not observable. How
are rendered visible because of the cut-away skirt por
ever, it is often highly desirable that visual inspection of
the condition of the tips of the stationary contacts be 40 tion of the switch head.
FIGURE 9 illustrates a three-phase circuit interrupter
inspected.
contained in a housing enclosure where each of the phases
It has been found that the skirts covering the stationary
includes a switch head of the type shown in the preceding
contact portion after the switch head has been moved to
?gures.
its “Oif” position can be cut back so that the contact tips
FIGURE 10 is a side view of the assembled interrupter
of the stationary contacts can be observed without im 45
of FIGURE 9 with portions thereof cut away for illus
pairing the operation of the contacting device. That is
trating the position of the switch heads.
to say, the substantially airtight seal formed between
FIGURE 11 shows a second embodiment of the inven
the skirts of the switch head and the stationary contact
tion wherein the skirt portions of the switch head are not
jaws may be defeated after the switch head has been
moved a predetermined distance toward the “Off” posi 50 cut away, but are of a transparent insulating material to
permit visual observation.
tion. At this predetermined point, the arc has already
Referring now to the ?gures, the embodiment shows
been extinguished by the effect of the insulating barrier
the type of switch head shown in above noted Patent
and the airtight seal prior to the time that skirts leave
2,820,123, the exception being that the lower skirts of the
the contact jaws.
By cutting back the skirts, it is apparent that the con 55 switch head are cut away in part in accordance with the
present invention. More particularly, the molded switch
tact jaws will now be subject to visual observation.
head is formed of two insulating sections v1t} and 12 which
As a second embodiment of the invention, it has
telescope with respect to one another, as shown in FIG
been found that the complete switch head or portions
URES 1 and 6.
thereof which are adjacent the contact jaws can be made
The internal portions of telescoping sections 10 and 12,
of a transparent insulating material which may be a
as shown in FIGURES 1, 2, 6 and 7, are molded to pro
thermo-setting or thermo-plastic moldable compound.
vide means for seating movable contact slug 14 and a
One such compound which has been found to be useful is
biasing spring 16 which surrounds contact slug 14, as
the therm-o-plastic polycarbon sold under the trade name
shown in FIGURES 4, 5 and 7.
of Lexan, a registered trademark owned by the General
An insulating barrier 18 of FIGURES '1, 3, 4, 5 and 7
65
Electric Company.
is molded integral with switch head portion ‘10, and is
Accordingly, .a primary object ‘of this invention is to
positioned immediately below movable contact slug 14 for
provide a molded switch head which permits visual ob
purposes to be described hereinafter.
servation of the contact jaws.
It has always been though necessary that the substan
tially airtight enclosure formed by the switch head should
In order to move the switch head between an “On”
Another object of this invention is to provide visual
observation of the stationary contact jaws cooperating 70 and “OE” position, and to further rigidly maintain tele
with a molded switch head when the molded switch head
is moved to an “Off” position.
scoping portions 10 and 12 assembled, a bale 20 is pro
vided which has extending ears 22 and 24 which co
3,098,142
operate with molded extensions 26 and 28 respectively of
switch head portions 12 and 10 respectively, as best seen
in FIGURES 1 and ‘6. Thus, the bale holds the as
sembled unit together. Further to this, however, the bale
extends upwardly to form an operating portion 30 which
can receive an operating bar, such as bar 32 of FIGURES
3, 4, 5 and 7, and as will be more fully described here
inafter.
In accordance with the present invention, the skirt
portions or walls 33 and 34- of head portion 10 do not
extend completely downwardly so that they will surround
the stationary contact jaws when the switch head is moved
to an “Off” position. This may be understood with ref
erence to FIGURES 4 and 5 which show the switch head
in an “On” and “Off” position respectively with respect
to contact jaws 36 and 38. Thus, in FIGURE 4, when
the switch head is in the “On” position, it will be seen
that the switch head is depressed so that the contact jaws
36 and 38 extend upwardly and into engagement on either
side of contact slug 14 with biasing spring 16 biasing the
ate the switch heads 52, 54 and 56 of FIGURE 9 be
tween the “On” position of FIGURE 4 to the “Off” posi
tion of FIGURE 5, the operating rod 32 (FIGURES 4
and 5) is provided with one end pivoted at pivot 74 and
its other end connected to an operating handle 76. When
the operating handle 76 is rotated upwardly to bring the
switch heads to their “Off” position (shown in FIGURES
9 and 10), in accordance with the present invention, the
skirts of the switch heads are shortened, and the “OE”
position raised to a higher position than previously at
tained, whereby the ends of contacts 36 and 38 are made
visible from either side of box 40. Conversely, the skirts
can be considerably foreshortened whereby the switch
may be installed in presently existing equipment, and still
render the stationary contacts visible when the switch
heads are in the “Off” position.
‘In an alternative embodiment of the present invention,
and as is speci?cally illustrated in FIGURE 11, the skirts
of the switch, such as skirt 32 may have the same length
20 as was previously used whereby the stationary contacts,
contact jaws toward this engagement.
such as contacts 36 and 38, will always be within the con
It will be noted in FIGURE 4 that a substantial air
tact passages provided in the molded switch head so that
tight seal is ‘formed in the volume occupied by contact
the interior of the switch head is always enclosed. In
slug 14 by virtue of the stationary contact members 36 and
order,
however, to provide visibility of the contact ends,
38 entering the channels formed in the switch head. In
a transparent insert 78 is provided at the bottom of the
the past, when the switch head was moved to the “Off”
skirt which serves as a window, for example, for contact
position, it was felt necessary that the tips of the contact
38. This transparent insert is of an insulating material,
jaws be retained in these channels to always seal off this
such as a thermoplastic polycarbon, and may be of any
small volume. It has been found, however, that this
presently available transparent thermo-setting or thermo
volume need not be sealed after substantial are inter
ruption occurs, and that, in fact, this seal may be defeated
after arc interruption which occurs after a relatively short
motion of the switch head to the “Off” position.
In accordance with the present invention, and follow
ing this observation, the lower skirt portions of the switch
head are cut back so that, as shown in FIGURE 5, the
skirt portions 32 and 34 will clear the ends of stationary
plastic moldable compound.
Although this invention has been described with respect
to its preferred embodiments it should be understood that
[many variations and modi?cations will now be obvious
to those skilled in the art, and it is preferred, therefore,
that the scope of this invention be limited not by the spe
cific disclosure herein but only by the appended claims.
What is claimed is:
contacts ‘36 and 38 when the switch head is moved to its
1. In a molded switch head; said molded switch head
“OI‘I'” position. Since these skirt portions clear the mov
having
an internal chamber; said internal chamber hav
able contacts, visual observation of the contacts will now 40
ing a ?rst contact element mounted therein; said molded
be possible, as shown in FIGURE 8 which shows a side
plan view of FIGURE 5, and clearly illustrates how the
foreshortened skirt 32 exposes the contact tip of contact
38. In a like manner, the foreshortened skirt 34 will
expose contact 36 to visual observation from the opposite
side of the switch head.
The manner in which the switch heads are assembled
in an operating unit is illustrated in FIGURES 9 and 10
for the case of a multiphase unit. FIGURES 9 and 10
show a housing 40'having a door 42 hinged thereto which
is movable between the closed position of FIGURE 10
to the'open position of FIGURE 9. A base of insulating
material 44 is secured to the bottom of housing 40 and
receives a ?rst set of terminals 46, 48 and 50 which may
switch head having an elongated skirt de?ning a channel
extending from said internal chamber to an area ex
ternal of said molded switch head; a second contact ele
ment; means mounting said second contact element ad
jacent said molded switch head, whereby the end of said‘
45 second contact element is adapted to enter said internal
chamber through said channel to engage said ?rst contact
element; said molded switch head and said second con
tact element being movable with respect to one another
between an engaged and disengaged position whereby
said ?rst and second contact elements are engaged in
said engaged position and disengaged in said disengaged
position; at least said end portion of said second contact
element located within the volume de?ned by said molded
have the form of an L-shape, and serve the purpose of
switch head’ at said engaged and disengaged position; said
one of the contact jaws, such as contact jaws 36 or 38 of 55
end positioned within said internal chamber correspond
FIGURES 4 and 5 for respective switch heads 52, 54
ing to said engaged position; said end positioned within
and 5 6.
The second stationary contact for switch heads 52, 54
and 56 is then shown as conductor elements having ter
said channel corresponding to said disengaged position,
and located a predetermined distance from said first con
element; said elongated skirt clearing the end of said
minals 58, 60 and 62. Thus, terminals 46, 4'8 and 50' and 60 tact
second
contact element when said molded switch head
terminals 58, 60 and 62 are electrically connected to sta
is in said disengaged position with respect to said second
. tionary contacts of the type shown in FIGURES 4 and 5
contact element whereby said end of said second contact
as stationary contacts 36 and 38 ‘for receiving respective
element is exposed for visual inspection; said channel in
switch heads.
A second set of terminals 64, ‘66 and 68‘ for each 65 cluding barrier means operatively positioned adjacent‘
said second contact element to guide the movement be
of the respective phases of the interrupter of FIGURES
9 and 10 are then provided which are adapted to receive
tween said disengaged and engaged positions.
2. In a molded switch head; said molded switch head
plug-in fuses (not shown) which are to be connected in
having an internal chamber; said internal chamber hav
series with a respective switch head. The terminals 46,
48 and ‘50 may then receive electrical connections brought 70 ing a contact slug mounted therein; said internal cham
ber having an insulation member extending from the bot
into box ‘40 through knock-out 70 while terminals 64,
tom of said contact slug to an area external of said molded
66 and 68 may be connected to cables from the load being
switch head; said molded switch head having a skirt
controlled by the switch, for example, to a neutral bar
member surrounding said insulation member and de?n
assembly 72. The neutral bar assembly 72' permits the
complete load connection to be made. In order to oper 75 ing a ?rst and second channel on either side of said in
sulation member respectively extending from said in
3,098,142
5
contact members are exposed for visual observation; said
channels including barrier means operat-ively positioned
internal chamber thnongh said ?rst and second channels
respectively; said molded switch head and said ?rst and
second contact members being relatively movable be
tween an engaged and disengaged position; said contact
slug engaging said ?rst and second contact members
when said molded switch head is in said engaged posi
tion; at least said end portions of said ?rst and second
contact members locate-d within the volume de?ned by
said molded switch head at said engaged and disengaged
positions; said ends positioned within said internal cham—
ber corresponding to said engaged position; said ends po
sitioned Within said ?rst and second channels correspond
ing to said disengaged position, and located a {predeter
6
mined distance from said contact slug; said elongated
skint clearing the ends of said ?rst and second contact
members when said molded switch head is in said disen
gaged position whereby said ends of said ?rst and second
ternal chamber to said area external of said molded
switch head; a ?rst and second contact member; means
mounting said ?rst and second contact members adjacent
said molded switch head, whereby the ends of said ?rst
and second contact members are adapted to enter said
adjacent said second ‘contact member to guide the move
ment between said ‘disengaged and engaged positions.
References Cited in the ?le of this patent
UNITED STATES PATENTS
15
2,323,476
2,491,272
2,668,891
2,820,123
2,820,866
2,866,964
Lantz _______________ __ July 6,
Knapp ______________ .._ Dec. 13,
Driescher ___________ _._ Feb. 9,
Higgins et al. ________ _._ Ian. 14,
Graybill et a1. _______ __ Jan. 21,
Neidenberg et a1 _______ __ Dec. 30,
1943
1949
1954
1956
1958
1958
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