ELECTRICAL SWITCHING APPARATUS AND
OPENING ASSEMBLY THEREFOR HAVING ENGAGEMENT LOG
CROSS-REFERENCE TO RELATED APPLICATION
The instant application claims priority from U.S. Provisional Patent
Application Serial No. /909 460 filed November 27, 0 13, he disclosures of which
are incorporated herein by reference.
BACKGROUND
Field
The disclosed concept relates generally to electrical switching
apparatus and, more particularly, to electrical switching apparatus, such as circuit
breakers. The disclosed concept also relates to opening assemblies for electrical
switching apparatus.
Background Information
Electrical switching apparatus, such as circuit breakers, provide
protection for electrical systems from electrical fault conditions such as, for example,
current overloads, short circuits, abnormal voltage and other fault conditions.
Typically, circuit breakers include an operating mechanism, which opens electrical
contact assemblies to interrupt the flow of current through the conductors of an
electrical system response t such fault conditions as detected, for example, by a
trip unit. The electrical contact assemblies include stationary electrical contacts and
corresponding movable electrical contacts that are separable from the stationary
electrical contacts.
Figures A and , for example, show a portion of a power air circuit
breaker L The power air circuit breaker 1 uses opening springs 3 (one opening spring
3 is shown in simplified form in Figures 1 and 2) to achieve and maintain full opening
gap (e.g., separation of the electrical contacts) during opening and, in some cases, to
augment the opening speed to improve interruption. In order to minimize the required
closing energy, the minimum possible opening spring force and energy is desired.
Each opening spring 3 is attached at its moving end to an arm 5, which is f ed to the
poleshaft 7. This arrangement stretches the spring 3 from open length, Lo (Figure
1A) to closed length, Lc (Figure I B) as the poleshaft 7 rotates from open (Figure 1.A)
to closed (Figure B). The poleshaft is commonly designed to maintain a
substantially constant moment arm (see, for example, open moment arm. Mo of
Figure and closed moment arm, Mc of Figure B).
Achieving an maintaining full opening gap becomes especially
difficult after interruption, when debris and shunt behavior cause the opening force
requirement to increase. One option is to strengthen the opening springs. However,
strengthening the opening springs without a corresponding increase in closing springs
may lead to stalling and incomplete closures. Also, increased spri n forces result in
greater frictional forces that tend to resist desired movements of the circuit breaker.
The difficulty of closing against stronger opening springs is more pronounced late in
closing, once the moving contacts seat o the stationary contacts and the contact
springs become a contributing factor. Increasing th closing springs to overcome
stronger opening springs also adds cost, reduces life, and increases the reqiiirements
of some accessories such as, for example and without limitation, the closing solenoid
and the charging motor. The foregoing difficulties become progressively more
problematic as additional circuit breake poles are added.
There is, therefore, room for improvement in electrical switching
apparatus, such as circuit breakers, and in opening assemblies therefor
SUMMARY
These needs and others are met by embodiments of the disclosed
concept, which are directed to a opening assembly for electrical switching apparatus
such as, for example and without limitation, circuit breakers. Among other benefits,
the opening assembly arranges the opening springs in a manner which produces
relati vely large poieshaft torque at full open, to maintain open gap (e.g., separation of
the electrical contacts), and substantially zero torque near the closed state, to ease the
closing. Alternatively, the electrical switching apparatus can additionally include an
engagement lug that causes, instead of substantially zero torque, the application of a
torque at or near the closed state that is of a fixe and relatively small value
As on aspect of the disclosed concept, an opening assembly is
provided for an electrical switching apparatus. The electrical switching apparatus
includes a housing, separable contacts enclosed by the housing, and an operating
mechanism for opening and closing the separable contacts. The operating mechanism
includes a poleshaft. The opening assembly comprises: a spring link comprising a
first portion structured to be pivotabiy coupled to the poleshaft, and a second portion
disposed generally opposite of the first portion, the spring link being movable
between an open position and a closed position; and a number of opening springs each
including a stationary end structured to be coupled to the bousing, and a movable end
coupled to the second portion of the spring link. When the spring link is disposed in
the open position, the number of opening springs are structured to bias the spring link
and the poleshaft to maintain full separation of the separable contacts. When the
spring l nk i disposed in the closed position, the number of opening springs are
structured not to bias the poleshaft or are alternatively structured to bias the poleshaft
with fixed, readily ascertainable, and relatively small torque.
The spring link ma further comprise an intermediate portion
extending between the first portion and the second portion. The intermediate port n
may have an arcuate shape i order that, when the spring link is disposed in the closed
position, the spring link is structured to extend around a portion of the poleshaft:.
The poleshaft may include an arm extending outwardly therefrom.
The first portion of the spring link ma be structured to be pivotabiy coupled to the
arm. The spring link may be formed from a pair of substantially identical planar
members disposed opposite and spaced apart fro one another, wherein a portion of
the am of the poleshaft is structured to be disposed between the pair of substantially
identical pla ar members.
As another aspec of the disclosed concept, an electrical switchingapparatus
comprises: a housing; separable contacts enclosed by the housing; a
operating mechanism for opening and closing the separable contacts, the operating
mechanism including a pole shaft; and an opening assembly comprising: a spring link
comprising first portion pivotabiy coupled to the poleshaft, and a second portion
disposed generally opposite of the first portion, the spring link being movable
between an open posi tion and a closed position, and a number of opening springs each
including a stationary end coupled to the housing, and a movable end coupled to the
second portion of the spring link. When the spring link is disposed in the open
position the number of opening springs bias the sprin link and the poleshaft to
maintain M l separation of the separable contacts. When the spring link is disposed in
the closed position, the number of opening springs do not to bias the poieshaft o are
alternatively structured to bias the poieshaft with fixed, readily asceitainabie, and
relatively s al torque.
BRIEF DESCRIPTION OP THE DRAWINGS
A full understanding of the disclosed concept can be gained from the
following description of the preferred embodiments when read in conjunction with the
accompanying drawings in which:
Figures and are side elevation views of portions of a known
circuit breaker and opening assembly therefor, with Figure A corresponding to the
circuit breaker being open and Figure B corresponding to the circuit breaker being
closed;
Figure 2 is a . side elevation view of a Circuit breaker and opening
assembly therefor, in accordance with a first embodiment of the disclosed concept;
Figure 3 is an enlarged view of the opening assembly o Figure 2,
shown a positioned when the circuit breaker is open;
Figure 4 is the enlarged view of Figure 3 modified to show the
opening assembly when the circuit breaker is closed;
Figure 5 is an isometric view of a portion of the opening assembly of
Figure 4;
Figures 6A and 6B are side elevation views of portions of the circuit
breaker and opening assembly therefor, in accordance with an embodiment of the
disclosed concept, with Figure 6Ά corresponding to the circuit breaker being open and
Figure 6B corresponding to the circuit breaker being closed;
Figure 7 is a perspective view of an improved circuit breaker and an
opening assembly therefor in an OPEN condition in accordance with a second
embodiment of the disclosed and claimed concept;
Figure 8 is a view of the circuit breaker and opening assembly of
Figure , except depicting the circuit breaker in CLOSED condition;
Figure 9 i a s d elevational view of the circuit breaker of Figure 7;
Figure is a view similar to Figure 9, except depicting the circuit
breaker in a partially CLOSED state at a point a which a moment ar or engagement
lug s touching flange on the poleshaft; an
Figure is a view similar to Figure 1.0, except depicting the circuit
breaker in a CLOSED condition.
Similar numerals refer to similar parts throughout the specification.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Directional phrases used herein, such as, for example, left, right,
clockwise, counterclockwise and derivatives thereof, relate to the orientation of the
elements shown in the drawings and are not limiting upon the claims unless expressly
recited therein.
As employed herein, the statement that two or more parts are
"coupled" together shal mean that the parts are joined together either directly or
joined through one or more intermediate parts.
As employed herein, the term "number" shall mean one or an integer
greater than one (i.e., a plurality).
Figure 2 shows an opening assembly 1.00 for an electrical switching
apparatus such as, for example and without limitation. a circuit breaker 200, both n
accordance with a first embodiment of the disclosed and claimed concept. The circuit
breaker 200 includes a housing 202, separable contacts 204 (shown i simplified form
in Figure 2) enclosed by the housing 202, and an operating mechanism 206 (shown in
simplified form in Figure 2 for opening and closing the separable contacts 204. The
operating mechanism 206 includes a poleshaft 208 (best shown in the isometric view
of Figure 5 .
The openi assembly 0 i c des a spring in 2 having a first
portion 04 structured to be pivotably coupled to the poleshaft 208, and a second
portion 06 disposed generally opposite the fi rst portion 4 The spring link 02 is
movable between an ope position (Figures 2, 3, 5 an 6 and a closed position
(Figures 4 and 6B). The opening assembly 0 further includes a number of opening
springs 0 each including a stationary end 2 coupled to the circuit breaker housing
202, an a m able en 4 coupled to the second portion 6 of the aforementioned
spring link 102.
In view of the foregoing structure, when the spring link 2 is disposed
in the open position, shown in Figures 2 , 5 and 6A the opening spring(s) 0 is/are
structured to bias the spring link 02 and the poleshaft 20 (e.g., cotmterclockwise
fro the perspecti ve of Figure 2) to maintain full separation of the separable contacts
204 (Figure 2). in other words, the disclosed concept arranges the opening springs
and their attachment to the poleshaft 208, via the spring link 2, in a manner to
produce relatively large poleshaft torque at full open (e.g., without limitation, to
maintain open gap between the separable contacts 204 (Figure 2)). Additionally,
when the spring link 2 is disposed in the closed position of Figures 4 and 6B, the
opening spriiig(s) 10 is/are structured not to bias the poleshaft 208. other words,
substantially zero torque is applied by the opening spring(s) 11 in the closed state,
thereby reducing the required closing energy and. associated stress on circuit breaker
components. Furthermore, the reduced requirement or closing springs allows for a
reduction n closing energy or increased closing margins. Reduced closing energy
advantageously reduces the requirements on accessories (e.g., without limitation,
spring release; motor operator) and increases lifespan increased closing margins
accommodate changes and circuit breaker performance aft e interruption, without the
need for increased closing speeds and/or reduced contact springs. The specific
manner in which the disclosed opening assembly 0 achieves these benefits will be
described in greater detail hereinbelow.
Continuing to refer to Figure 2, and also to Figures 3-6B, the spring
link 10:2 of the disclosed opening assembly 100 further includes a intermediate
portion 0, which extends between the fust and second portions 04, 06 and
preferably has an arcuate shape. Such arcuate shape enables the spring link 02 to
extend around a portion of the circuit breaker poleshaft 208 when the spring link 1 2
is disposed in a closed position, shown in Figures 4 and 6B. As best shown in the
isometric view of Figure 5, the poleshaft 208 preferably includes an arm 210, which
extends outwardly from the poleshaft 208. Th first portion 1 4 of the spring li k 102
is structured to be p otably coupled to the arm . i th example shown a d
described herein, the spring link 102 is formed from a pair of substantially identical
pla ar members 130,132, which are disposed opposite and spaced apart from one
another. Accordingly a portion of the arm 2 of the poleshaft 208 is disposed
between the pair of substantially identi ca planar members 0, 2, shown. The
poieshait 208 further includes a pivot pin 220. which pivotably couples the spring link
2 to the poieshait arm 2 .
Continuing to refer to Figure 5, the spring li k 1.02 of the opening
assembly 0 further includes a projection 140 extending iateraliy outwardly from the
second portion 06 of the spring link 102. n the example of Figure the projection
is a pin 140. which extends laterally outwardly from the first side 142 of the spring
link 102, in a first direction, and laterally outwardly from the second side 144 of the
sprin link 0 2, in a second direction opposite the first direction. As partially shown
in the example of Figure 5 more than one opening spring may be employed, without
departing from the scope of the disclosed concept. For example, a first opening
spring 0 includes movable end 1 4 coupled to the pin 140 on the first side 142 of
the spring lin 2, and a second opening spring ' includes a movable end . ',
which is coupled to the pin 140 on the second side 4 of the spring link 02. t wil ,
however, be appreciated that any known or suitable alternative number, type and or
configuration of spring links (e.g., 02) and/or opening springs (e.g., without
limitation 0, ') could be employed. For economy of disclosure and ease of
illustration, only one opening assembly 00 and spring lin 2 therefor is described
n detail herein.
As shown i Figures 6A and 6Ί the housing 202 of the example
circuit breaker 200 includes a side plate 230 and at least one protrusion 240, which
extends outwardly f om the side plate 230, as shown. The stationary end 0 of each
of the number of opening springs (e.g., 0) is coupled to a corresponding one of the
at leas one protrusions 240
As shown in Figure 4 and 6B, in operation, when the spring link 102 is
disposed i a closed position, the first portion 104 and the second portion 1 6 are
generally disposed on opposite sides of the poieshait 208, as shown. It will be
appreciated that this result n the pivot pin 220, the poleshaft 208, and the opening
spri ng s .0 being substantially aligned along an axis 300. As shown, opening
spring(s) 0 , pin 140, poleshaft 208, pivot pin 220, and protrusion 240 are generally
all aligned with axis 300. Accordingly, it will be appreciated that such alignment
correspondingly results in substantially zero moment arm (see, for example, moment
•1
arm : 0 in Figure 6B). In other words, substantially zero torque is applied by the
opening spring(s) to the spring link 2 or poieshait 208 in the closed position.
thereby reducing requirements for the closing springs and allowing a reduction in
closing energy, as well as increased closing margins, as previously discussed
hereinabove.
t will also be appreciated that the spring ink design of the
disclosed opening assembly 00 achieves a moment arm, Mo, as desired, when the
spring link 102 is disposed in the open position of Figure 6A. As shown by
comparing Figure 6A to Figure 6B, it will be appreciated that the opening spring
length Lo, when the spring link 102 is in the open position of Figure 6A is relati vely
similar to the closed spring length e when the spring link 102 is disposed in the
closed positron of Figure 6B. This, in combination with the aforementioned closing
moment arm, Mc being substantially zero (see Figure 6B), have profound beneficial
effects on the circuit breaker's operation. For example, the disclosed opening
assembly 0 consumes less than 40 percent of the energy of conventional closing
spring designs. Furthermore, the opening assembly 0 is capable of producing about
20 percent more poieshaft torque at full ope and st l consuming less of about half of
the energy of conventional designs.
Accordingly, among other benefits, the disclosed opening assembly
0 provides unique spring Sink 2 and opening spring 0 arrangement, which
effectively functions to produce desired poieshaft torque at full open (e.g., without
limitation, to maintain open gap between separable contacts 204 (Figure 2)} and
substantially zero torque in the closed state, thereby reducing the required closing
energy and associated stress.
A n improved opening assembly 400 and an improved circuit breaker
500 of which the opening assembly 400 is apart are depicted generally in Figures 7-
, both being i accordance with a second embodiment of the disclosed and claimed
concept. As will be set forth in greater detail below, the opening assembly 400 and
circuit breaker 500 are substantially similar to the opening assembly 0 and the
circuit breaker 200, except that the opening assembly 400 is configured to apply a
non-zero torque to poieshaft 508 when the circuit breaker 500 is in CLOSED
condition.
The opening assembly 400 can be sai to include a spring link 402 that
includes a first portion 404 and a second portion 406 t at a e opposite one another.
The opening assembly 400 further includes a . set of opening springs 410, each of
which has a stationary end 4 that is coupled with the circuit breaker 500 and a
movable en 4 4 opposite thereto that is coupled with the second portion 406. More
particularly, the spring link 402 further includes a projection 440 mounted on the
second portion 406, and the movable ends 4 4 are situated on the projection 440. The
projection 440 is a pi that extends laterally outwardly in a first direction from first
side of the spring link 402, and that extends laterally outwardly in a second direction
from a second side of the spring link 402. The first and second directions are opposite
one another. The spring link 412 further includes an intermediate portion 420 that
extends between the first and second portions 404 and 406 All of this is similar to
the opening assembly 0.
However, the spring link 402 of the opening assembly 400 further
includes an engagement lug 424 tha is situated on the intermediate portion 420 a a
location relatively closer to the second portion 406 than to the first portion 404. At a
transitional position situated generally between the OPEN and CLOSED conditions of
the circuit breaker 500, the en as e ent u 424 is enuaseable with the poleshaft 508
and advantageously alters the kinematic relationship among the opening springs 4 0,
the spring link 402, and the poleshaft 508. This ca be desirable i certain
circumstances.
The poleshaft 508 has an arm 5.10 formed thereon tha protrudes
outwardly therefrom. The arm 0 includes a flange that i of a partially annular
shape and that protrudes radially outwardly from the poleshaft 508 When the circuit
breaker 500 is in the transitional position. as is depicted generally n Figure 10, the
torque applied by the opening springs 4 on the poleshaft 508 is generally at
mini u . However, the engagement lug 424 engages the flange 5IS at the
transitional position, and further movement of the circuit breaker 500 from the
transi tional position of Figure 10 toward the CLOSED position of Figures 8 and
results in an increase in the torque applied by the opening springs 4 1 on the poleshaft
508.
More part c lar , and as can be seen in. Figure 9, a pivot pin 520 on
the first portion 404 is pivotably mounted to the flange 5 and thus pivotably coupies
the spring link 402 to the poleshaft 508. The tension of the opening springs 41 is
applied to the poleshaft 508 in the OPEN configuration of the circuit breaker 500 of
Figures 7 and 9. The stationary ends 2 of the opening springs 410 are coupled with
protrusion 540 on the circuit breaker 500 Since the second portion 406 of the
spring Sink 402 and the movable ends 414 of the opening springs 4 that are
connected therewith are generally unconstrained in the OPEN state it can be seen that
the protrusion 540, the second portion 40 , and the pivot pin 520 ail lie along an axis
of force 654A of the opening springs 410. That is, since the second portio 406 and
the movable ends 4 of the opening springs 410, while being coupled together, are
otherwise generally freely movable i pivoting motion about the pivot pin 520, the
tension in the opening springs 4 causes the second portion 406 to be aligned along
an axis that extends between the protrusion 540 and the pivot pin 520, which is the
axis of force 654A. A tens e force of the opening springs 0 in the OPEN condition
of the circuit breaker 500 is applied at a given distance from the rotational axis of the
poleshaft 508, with the given distance in the OPEN state being indicated by a moment
ann 660A Such tensile force of the opening springs 410 along the axis of feree 654A
that is applied at a distance from the axis of rotation of the poleshaft 508 that is
characterized by the moment ann 660A results in a torque 664A that is applied to the
poleshaft 508.
As the poleshaft 508 rotates from the OPEN condition in the clockwise
direction (from the perspecti ve of Figures 9- } toward the transitional position of the
circuit interrupter 500 (which is depicted in Figure 10), the movement of the pivot pi
520 results in the pivot pin 520, the protrusion 540 and the second portion 406
remaining aligned with one another along another axis of force 654B. In the
transitional position, the tensile force of the opening springs 4 is applied to the
poleshaft 508 at a moment arm 660B tha is relatively shorter than the moment arm
660 That is, in the OPEN condition of the circuit breaker 500 of Figure 9. the axis
offeree 65 is at a first angle of force 668A with respect to a segment 672 that can
be said to extend between the rotational axis of the poleshaft 508 and th location on
the protrusion 540 that is contacted by the opening springs 410. Such segment 672 is
generally of a distance 650 that can either be considered to be unvarying or that can
be easily calculated based upon the position of the stationary ends 412 of the opening
springs 410 on the protrusion 540 at any given position of the circuit breaker 500
between the OPEN and CLOSED conditions. Since the angle of force 66 and the
distance 650 are both either known or knowahle, a length of the moment arm 660A
can be calculated. When the dimension of the moment a m 660A is combined with
the tension in the opening springs 4 0 which is applied at that distance from the
rotational axis of the poleshaft 508, the torque 664A can be calculated. Likewise, the
torque 664 can be calculated for the moment arm 660B and an angle of force 668B
at the transitional position, w th the resultant torque 6648 being of relatively lesser
magnitude than the torque 664A
t is noted however, that when the poleshaft 508 is rotated fr o the
transitional position of Figure toward the CLOSED condition of Figure 1 , the
engagement of th e engagement lug 424 with the flange 5 causes the second portion
404 to pivot slightly away fro the segment 672. That is, in the CLOSED condition
of Figure , the opening springs 4 exert a tensile force along an axis of feree 654C
that extends along an axis that includes the second portion 406 and the protrusion 540,
but which is spaced from the pivot pin 520. The axis of force 654C results in a
different angle of force 668C and a resultant moment ar 660C that is relatively
greater than the moment arm 66GB. Since the moment arm 660C is relatively greater
than the moment arm 6 0B an since the opening springs 4 exert a greater tensile
force in the CLOSED condition of Figure 1 than in the transitional position of Figure
, the resultant torque 664C applied to the poleshaft 508 in the CLOSED condition
of the circuit breaker 500 is relatively greater than the torque 6 B applied to the
poleshaft 508 in the transitional position of Figure Ϊ 0 . Tha is, when the engagement
lug 424 engages the flange 5. of d e poleshaft 508 at the transitional position, and
with continued rotatio of the poleshaft 508 from the transitional position toward the
CLOSED condition of the circuit breaker 500, the second portion 406 and the
movable ends 414 of the opening springs 4 have movement that is no longer freely
movable and rather is constrained by the engagement of the pivot pin 520 and the
engagement lug 424 with the arm 510 and the flange 518, and due to the tension
applied to the spring link 402 by the opening springs .
The engagement of the engagement lug 424 with the flange 8 of the
poieshaft 508 thus constrains the second portion 406 and the movable ends 4 such
that their point of conjunction can be said to rotate at a . fixed distance from the ax s of
rotation of the poieshaft 508 when the poieshaft 508 moves between the transitional
position and the CLOSED condition of the circuit breaker. Such motion has the effect
of changing the moment arm between the values depicted with the moment arms
660B and 660C This results in residual torque 664C being applied to the poieshaft
508 by the opening springs 410 in the CLOSED position of the circuit breaker 500
that is depicted generally Figures 8 and . The torque 664C is advantageously
configured such that it overcomes the static and dynamic friction that can he said to
exist between the poieshaft 508 and the other components of the circuit breaker 500,
whereby the torque 664C is sufficient to initiate movement of the poieshaft 508 away
fro the CLOSED position of the circuit breaker 500 and toward the OPEN condition
of the circuit breaker 500.
Such relatively increased torque 64 (as compared with the torque
664B in the CLOSED condition of the circuit breaker 500 advantageously minimizes
any hesitation due to friction that might otherwise hamper rapid movement of the
circuit breaker 500 away from the CLOSED position. The residual torque 664C that
results from engagement of the engagement lug 424 with the flange 528 of the
poieshaft 508 additionally results in a relatively ascertainable value for the torque
64C which overcomes or at least ameliorates the effects of dimensional tolerances
within the components from which the circuit breaker 500 is .manufactured. That is, if
the circuit breaker 500 is configured to have essentially zero torque at its CLOSED
positions, variations in tolerance of the components of the circuit breaker 500 could
result in a slight torque being applied to the poieshaft 5 8 in either the clockwise or
the counter-clockwise directions from the perspective of Figure 11. While such a
torque would still be very' small, its magnitude in comparison with zero torque can be
significant. However, by configuring the circuit breaker 500 to advantageously have
the torque 664C at its CLOSED condition with the torque 664C being readily
ascertainable (based on the foregoing), any slight variations in the magnitude of the
actual torque applied to the poieshaft 508 at the CLOSED condition of the circuit
breaker 500 would likely be relatively insignificant in comparison with the magnitude
of the torque 664 1 Stated otherwise, a slight torque that ca .resul t from variations i
tolerance ay be significant in comparison with zero torque but is of relatively less
significance when compared with nominal non-zero level of torque. As such, the
provision of the torque 664C in he CLOSED condition of the circuit breaker 500
improves the reliability of its function, which is desirable.
While specific embodiments of the disclosed concept have been
described in detail, it will be appreciated by those skilled in the art that various
modifications and altemaiives to those details could be developed in ight of the
overall teachings of the disclosure. Accordingly the particular arrangements
disclosed are meant to be i ustrativ only and not limiting as to the scope of the
disclosed concept which is to be given the full breadth of the claims appended and
an and ai equivalents thereof.
CLAIMS
What is claimed s :
. An opening assembly (400) for an electrical switching apparatus (500), the
electrical switching apparatus including a housing, a set of separable contacts enclosed by
the housing, and an operating mechanism structored to move the separable contacts
between and OPEN condition and a CLOSED condition, the operating mechanism
including a poleshaft (508), said opening assembly comprising;
a spring link (402) comprising a first portion (404) structured to be
p vota y coupled to said poleshaft. and a second portion (406) disposed generally
opposite of the first portion, the spring link being movable between an open position and
closed position; and
a number of opening springs (410) each including a stationary end (412)
structured o be coupled to the housing, and a movable end (4 ) coupled to the second
portion of said spring link,
wherein in the OPEN condition the number of opening springs and the
spring link a e structured to apply first torque to bias the poleshaft to maintain full
separation of said separable contacts,
wherein in a transitional position situated between the OPEN and
CLOSED conditions the number of opening springs and the spring link are structured to
bias the poleshaft at an intermediate torque that is less than the first torque in magnitude,
and
wherein in the closed position of the spring li k the number of opening
springs are structured to bias the poleshaft with another torque that is greater tha the
intermediate torque but less than the first torque.
2 The opening assembly of claim 1 wherein said spring link further
comprises an intermediate portion (420) that extends between th first portion and th
second portion and further comprises an engagement lug (424) disposed on the
intermediate portion; wherein in th transitional position the engagement lug is structured
to engage the poleshaft; and wherein the engagement lug engaged with the poleshaft is
structured to increase a moment arm 60) of a tensile force of the number of opening
springs applied to the poleshaft.
3. The opening assembly of claim 1 wherein said poleshaft includes an am
extending outwardly therefrom; and wherein the first portion of said spring link is
structured to be pivotably coupled to sai a .
4. The opening assembly of claim 3 wherein said spring link is formed from
a pair of substantially identical planar members disposed opposite and spaced apart from
one another; and wherein a portion of said arm of said poleshaft is structured to be
disposed between said pa r of substantially identical planar members.
5 . The opening assembly of claim 3 wherein said poleshaft further includes a
pivot pin (520); and wherein the first portion of said spring link is structured to be
pivotably coupled to said arm of sa d poleshaft by said pivot pin.
6. The opening assembly of clai 5 wherein said spring lin further
comprises a projection (440 exte di g laterally outwardly from the second portion of
said spring link; and wherein the movable end of each of said number of springs is
coupled to said proj ection
7. The opening assembly of claim 6 wherein said spring link further
comprises a first side and a second side; wherein said projection is pin; an wherein
said pin extends laterally outwardly from the first side of said spring link in a first
direction and laterally outwardly from the second side of said spring link in a second
direction opposite the first direction
8. The opening assembly of claim 7 wherein said number of opening springs
comprises a first opening spring and a second openin spring; wherein the movable end
of said first opening spring is coupled to said pin on the fi rst side of said spring link ; and
wherein the movable end of said second opening spring is coupled to said pin on the
second sid of said spring ink
9. The opening assembly of claim 7 wherein the housing of said electrical
switching apparatus includes a side plate and at least one protrusion (540 extending
outwardly from said side plate; and wherein the stationary end o each of said number of
opening springs s structured to be coupled to a corresponding one of sai at least one
protrusion.
10. The opening assembly of claim 9 wherein, when said spring link is
disposed in said closed position, the first portion and the second portion are structured to
be disposed on opposite sides of said poleshaft and said pivot pin, sai poleshaft, and said
number of opening springs are substantially aligned.
11 . An electrical switching apparatus (500 comprising:
a housing;
separable contacts enclosed by the housing;
an operating mechanism for opening and closing said separable contacts,
said operating mechanism including pole shaft; and
the opening assembly (400) of Claim .