Title of Invention

HOUSING FOR FUSED SWITCH

Abstract The present invention relates to a fused switch housing (I) suited to accommodate at least one fuse adapter (2) having a first and a second contact surface (10). The fused switch housing (I) comprises a first and a second set of terminals (15) for respectively connecting the fused switch to a first and a second external circuit, stationary contacts (12, 15, 16), and at least one moving contact (13). The fused switch housing also includes switching means cooperating with each of said moving contacts (13) for making an electrical connection between each of said first terminals (15) respectively with each of said first contact surfaces (10) as well as for making an electrical connection between each of said second terminals (15) respectively with each of said second contact surfaces (10) so that at least one of said connections with said contact surfaces is openable by moving said at least one moving contact (13) with the help of said switching means. Herein, at least one moving contact (13) is adapted to press directly against said first or second stationary contact surfaces so as to form an electrical contact.
Full Text Housing for fused switch
The present invention relates to a housing according to
the preamble of claim 1 for a fused switch.
Fused switches having a fused switch housing of the type
concerned herein are used, e.g., in electricity distribu-
tion, supply of electric equipment and in different types
of electric circuits. The function of a fused switch is
to pass electric current from a feeder circuit to a con-
sumer circuit via at least one fuse located in the fused
switch. Another function of the fused switch is to serve
as a circuit breaker between the feeder and consumer cir-
cuits permitting the electric connection between said
circuits to be interrupted when so required. A single
fused switch can be made to connect a plurality of elec-
tric circuits to each other. For instance, a three-phase
fused switch may comprise at least three first and second
contact members with conductor parts connecting said
members via fuses.
Conventionally, a fused switch includes at least one pair
of moving contacts and a fuse connected in series. In
modern fused switches the fuses are mounted in removable
fuse adapters in order to ease the task of fuse replace-
ment. This kind of switch design with a fuse adapter
facilitates the use of single fused switch housing in
conjunction with a number of different fuse types.
Thence, only the fuse adapter need to be selected compat-
ible with the fuse type in use. In a well-designed
adapter-type fused switch, fuse replacement is also
extremely safe to the person performing the operation.
The fuse adapter comprises contact parts on which the
fuse is easy to mount. The contact parts of the fuse
adapter also act as the electrical contact between the
fuse and the elements of the fused switch housing when
the adapter with the fuse is inserted in place. The
housing of the fused switch carries the stationary con-
tacts with their springed contact parts serving to form
an electrical contact with the mating contact parts of
the fuse adapter. In the switched circuit, the stationary
contacts of the switch housing located to both sides of
the fuse are arranged to cooperate either on both sides
with their respective moving contacts, or alternatively,
so arranged that on one side the stationary contacts
cooperate with the moving contacts and on the other side
are directly connected to the terminals of the external
circuit.
The path of current flowing through a conventional fused
switch passes from the input terminals of the fused
switch over the moving contact members and their contact
surfaces to the stationary contacts of the switch
housing, and therefrom, further over other connections to
the first contact parts of the fuse adapter. Subsequent
to the fuse adapter contact parts, current passes over
the interface between these contact parts and those of
the fuse proper, and then over the second, similar fuse
contact interface to the second contact parts of the fuse
adapter. Prior to reaching the output terminals of the
fused switch, the current must pass at least the contact
interface between the second contact parts of the fuse
adapter and the second stationary contact parts of the
fused switch. Resultingly, each current path of
conventional fused switches contains at least four
connections/contacts on the fuse and switch side of the
fuse adapter plus the internal connections of the switch
itself.
The number and quality of connections in a fused switch
affect the properties of the fused switch. This is
because each connection involves a separate interface
resistance that in turn causes additional heating of the
fused switch and thus reduces its load rating. Further-
more, the fabrication of any single connection is a
separate cost factor and each connection is a potential
origin of malfunction. Another aspect affecting the
current breaking capacity of a switch is. essentially
related to the number and operating speed of current-
breaking connections provided on the current path. The
greater the number of simultaneously operating air gaps
in series the faster the switch can quench a possible arc
striking between the contact surfaces of opening switch
members. Arcing causes undesirable wear in the switch and
generates interference in the form of electromagnetic
radiation, for instance. The quenching properties of the
contact gap arc are particularly important in DC
switches. AC switches are not so critical in this sense
inasmuch the current passing in an AC circuit over an arc
inherently crosses zero twice during each cycle.
Hence, the type and number of contacts acting as opening
gaps in a fused switch must be designed chiefly on the
basis of their current-breaking properties. In turn, the
number of connections not participating in current turn-
off should be minimized.
Prior-art technology of fuse-adapter-type fused switches
is handicapped by having at least four connections per
each current path such that do not participate in the
actual switching operation.
It is an object of the invention to provide an entirely
new type of housing for a fused sVitch, wherein redundant
connections are eliminated.
The goal of the invention is achieved by a switch design
having at least some of the fuse adapter contact surfaces
which face those of the switch housing and make the elec-
trical connections between the fuse and the switch hous-
ing to additionally perform as opening/closing contacts
of the switch. Accordingly, the invention is based on
combining at least one of two connections which make the
electrical connections between the fuse and the switch
housing with its series-connected opening"/closing contact
so as to form a single contact-type connection.
More specifically, the fused switch housing according to
the invention is characterized by what is stated in the
characterizing part of claim 1.
The invention offers significant benefits.
With the exception of fuse connections, the fused switch
according to the invention need not necessarily have any
such internal connections that do not participate with
the circuit switching functions. The connections between
the fuses and contact parts of the fuse adapter are
required for implementing the adapter-type fused switch
design. Hence, with the aid of the invention, unnecessary
connections in the present fused switch construction are
disposed of.
The invention makes it possible to reduce the heating of
the fused switch under electrical load thus improving the
load rating of the switch. The simple construction of the
fused switch is also more reliable in service and more
cost-effective to produce.
In the following, the invention will be examined with the
help of exemplifying embodiments by making reference to
the attached drawings, in which:
Figure 1 shows a fused switch design according to the
invention in a view taken obliquely from above;
Figure 2 shows a fuse adapter suitable for use in the
fused switch illustrated in Fig. 1;
Figure 3 shows one current path in a fused switch
according to the invention; and
Figure 4 shows the current path of Fig. 3 in a view taken
obliquely from above.
In Fig. l is shown a fused switch suitable for control-
ling a three-phase circuit. The fused switch comprises a
fused switch housing 1, and connected to the fused switch
housing 1, three parallel-mounted fuse adapters 2 which
form a portion of the front surface of the fused switch.
Additionally, the fused switch front surface comprises a
control slot 3 amidst two fuse adapters 2 for mounting a
control device (not shown) on the fused switch. The
control device makes it possible to open or close the
switch contacts. In practice, the control device can be,
e.g., a handle.
The upper surface of the fused switch housing 1 has a set
of three terminals 4 for connecting the fused switch to a
first external circuit which may be either a feeder
circuit or a consumer circuit. The bottom side of the
fused switch housing 1 has a second set of corresponding
terminals for connecting the fused switch to a second
external circuit. In the fused switch embodiment shown in
the diagram, the first and second sets of terminals 4 are
connected to the fuse adapter 2 via the contact parts so
that two opening contact gaps are provided on both sides
between the terminal sets and the fuse adapter 2. In this
type of device, there is no difference whether the ter-
minals 4 of the upper or lower surface are connected to
the consumer circuit. If the opening contact gaps are
provided only between the second set of terminals 4 and
the fuse adapter 2, reasons of safety dictate that the
feeder circuit should preferably be connected to those
terminals 4 that are connected to the conductors of the
fuse adapters 2 via the opening/closing contacts.
Fig. 2 shows the fuse adapter 2 of the fused switch in a
view taken obliquely from behind the switch. The diagram
illustrates the fuse holder clips 5 made from a conduct-
ing material such as copper. The first end of each fuse
holder clip 5 is so bent that it forms a clinching leaf
spring slot suited to accommodate the ferrule 17 of the
fuse 14 (Figs. 3 and 4) . The fuse holder clips 5 are com-
plemented with springs 6 serving to press the contact
surfaces of the fuse holder clip 5 against the ferrule 17
of the fuse 14 (Figs. 3 and 4) thus assuring a good elec-
trical contact. The fuse holder clips 5 are mounted on
the fuse adapter 2 which is made from a dielectric mate-
rial such as a plastic. The first ends of the fuse holder
clips 5 are supported on the fuse adapter 2 by appropri-
ately shaped support brackets 7.
The second ends of the fuse holder clips 5 are supported
by contact support projections 8 made on the fuse adap-
ter 2. The contact support projections 8 and the fused
switch housing 1 have such a compatible design that when
the fuse adapter 2 is mounted in place, the contact sup-
port projections 8 will be inserted through openings made
to the fused switch housing 1 so as to protrude into the
interior of the fused switch housing 1. Thence, the se*"
cond ends of the fuse holder clips 5 form on the surface
of the contact support projections 8 such contact sur-
faces 9 that after their insertion into the interior of
the fused switch housing 1 can act as the first set of
contact surfaces 10. On the contact support projections 8
are also made stops 18 with cavities 19 remaining behind
the same. In the diagram are also illustrated spring-leaf
type auxiliary contacts 11 of a conducting material that
are electrically connected to the fuse holder clips 5.
The function of the auxiliary contacts 11 is to make an
electrical connection from both ferrules of the fuse and
to the fuse condition monitoring terminals of the fused
switch. Thus, the auxiliary contacts facilitate a fuse
continuity test without any need for removing the fuse
from the fused switch.
Fig. 3 shows those parts of the fused switch that par-
ticipate in the formation of a current path through the
fused switch. The same parts are shown in Fig. 4 in a
view taken slightly obliquely from above. The current
path is formed by two stationary contacts 12, two moving
contacts 13, two fuse holder clips 5 and the fuse 14. The
stationary contact 12 is a member made of a conducting
material whose first end extends up to the terminal 4
(Fig. 1) so as to form the lug 15 of the terminal 14. The
second end of the stationary contact 12 extends at a
distance from the contact support projection 8 (Fig. 2)
of the mounted fuse adapter 2 thus forming a second set
of contact surfaces 16 aligned essentially parallel to
the first set of contact surfaces 10. The shape of the
moving contact 13 is made compatible with the contact
surfaces 10, 16 such that it facilitates the formation of
an electrical connection between said contact surfaces
10, 16.
The moving contacts 13 can be actuated by means of con-
ventional switching members capable of actuating the
moving contacts 13 in a spring-loaded manner from one
position to another. Such switching members may comprise,
e.g, springs connected to the moving contacts 13, trigger
elements limiting the movement of the moving contacts 13
and a handle serving to control the movement of the
switching members and to transmit the switch actuating
energy to the switching members. To open the switch, the
handle must be rotated, whereby energy is stored in the
actuating springs. After the handle is rotated suffi-
ciently far, the trigger elements release the moving con-
tacts 13 into a fast movement apart from the stationary
contact surfaces 10, 16. This arrangement serves to
shorten the duration of arcing between the contacts. In
the closing operation of the switch, the trigger elements
function in a similar manner, but now in a reverse
direction.
The switching members may also include interlock cams
(not shown) that cooperate with the moving contacts 13 or
alternatively, with other parts moving along with the
same, such as the support/control elements of the moving
contacts 13. The function of these interlock cams is to
prevent the mount ing/dismount ing of the fuse adapter 2 in
place in the fused switch when the switch is in its
closed position. This arrangement serves to prevent the
. closure/disconnection of a circuit by means of manual
insert ion/withdrawal of the fuse adapter 2. Due to the
slow speed of manual circuit connection/disconnection,
the result might be a long-lasting arc in both or only
one contact gap between the fuse holder clip 5 and its
respective moving contact 13. Such an arc could be
hazardous for both the switch and the person operating
the same.
Accordingly, the interlock cam is arranged to follow the
movement of the moving contact 13. In the exemplifying
embodiment, the interlock cam is so disposed and shaped
that in the closed position of the fused switch, the cam
extends past that contact surface of the moving contact
13 which is adapted to cooperate with the first contact
surface 10, whereby the cam passes over that edge of the
moving contact which faces the fuse adapter 2. Thus, when
the fuse adapter 2 is properly inserted to the fused
switch housing, the cam can enter a recess 19 which, when
viewed from the fused switch housing 1 towards the fuse
adapter 2, is left behind a stop 18 in the contact
support projection 8. Now, if an attempt is made to
remove the fuse adapter 2, the stop 18 meets the cam thus
preventing the removal of the fuse adapter 2. Respective-
ly, in a situation in which the switch is closed and the
fuse adapter 2 is removed, the cam meets the stop 18 thus
preventing the mounting of the fuse adapter 2 into the"
fused switch when the latter is in its closed position.
When the switch is turned into its open position, the cam
is withdrawn along with the moving contacts 13 from the
vicinity of the contact surfaces 10, 16, thus permitting
the mounting and dismounting of the fuse adapter- 2 with-
out the. interlock function of the cam and the 6t?┬ęp 18.
Advantageously, the cam and the stop 18 are made from a
dielectric material.
Accordingly, the fused switch embodiment shown in Figs. 3
and 4 has a total number of six internal connections.
Obviously necessary are also the feeder and consumer
circuit connections at the contact surfaces 15 of the
terminals 4. Hence, four of the six internal connections
can simultaneously act as opening/closing contact gaps.
These opening/closing contacts are formed by the connec-
tions between the first contact surfaces 10 and the
moving contacts 13, and respectively, between the second
contact surfaces 16 and the moving contacts 13. The non-
opening connections are required only between the fuse
holder clips 5 and the ferrules 17 of the fuses 14. These
two connections not participating in the switching func-
tions are necessary to assure an easy and safe fuse
change and to guarantee reliable function of the
opening/closing contact gaps.
Without departing from the scope and spirit of the inven-
tion, also embodiments different from those described
above may be contemplated. For instance, the number of
series-connected contacts with their mating contact
surfaces on each current path can be increased from that
mentioned in the described embodiments. Alternatively,
the number of opening/closing contact gaps can be
reduced, which means that the switch can be implemented
using one, two or three opening/closing contact gaps.
Herein, a hinged-type switch construction could be
contemplated with a single opening/closing contact gap
adapted to operate on at least one side of the fuse.
Then, the other end of the contact member could be taken
directly to the input/output terminal of the external
circuit. This type of a switch with a single opening/
closing contact gap could be readily implemented using a
flexible conducting member. The moving contacts can also
be of the knife-blade type.
We Claim :
1. Fused switch housing (1) suited to accommodate at
least one fuse adapter (2) having a first and a second
contact surface (9), said fused switch housing (1)
comprising
- first and second terminals (4) for connecting
the fused switch to a first and a second external
circuit, and
- stationary contacts (12), at least one moving
contact (13) and switching means such as herein
described cooperating with each of said moving
contacts (13), said elements serving to make an
electrical connection between said first terminals
(4) and said first contact surface (9) as well as
to make an electrical connection between said
second terminals (4) and said second contact
surface (9) so that at least one of said
connections is openable by moving said at least
one moving contact (13) with the help of said
switching means,
characterized in that for making said electrical
contact, said at lest one moving contact (13) is
adapted to press against such a first contact surface
(10) which simultaneously acts as said first or second
contact surface (9) of the fuse adapter (2) mounted in
said fused switch housing (1) .
+2. Fused switch housing (1) as claimed in claim 1,
wherein the first end of said at least one stationary
contact (12) comprises a connection surface (15) of the
terminal (4) and the second end of the same has a
second contact surface (16) against which said moving
contact (13) is adapted to press for forming an
electrical connection between said first contact
surface (10) and said second contact, surface (16) .
3. Fused switch housing (1) as claimed in claim 2,
wherein the current path from said connection surface
(15) of said first terminal (4) to the surface of said
moving contact (13) adapted to press against said first
contact surface (10) is formed by
- a stationary contact (12),
- the contact formed between said second contact
surface (16) and said moving contact (13), and
- a moving contact (13).
4. Fused switch housing (1) as claimed in claim 2,
wherein said switch housing comprises a second moving
contact (13) and a second stationary contact (12) whose
one end forms a connection surface (15) of the second
terminal (4) and the other end forms another second
contact surface (16) against which said second moving
contact (13) is adapted to press for forming an
electrical connection between another first contact
surface (10) and said another second contact surface
(16) .
5. Fused switch housing (1) as claimed in claim 4,
wherein said switching means are adapted to move each
of said moving contacts (13) substantially
simultaneously when the electrical contacts are closed
and opened.
6. Fused switch housing (1) as claimed in any one of
claims 1 to 5, comprising
- first and second contacts (4) in sets of three
terminals,
- stationary contacts (12) connected to said sets
of first and second contacts (4), and
- moving contacts (13) adapted, to press at least
against the contact surface of said stationary
contact (12) connected to said first terminal (4).
7. Fused switch housing (1) as claimed in any one of
claims 1 to 6, wherein each moving contact (13) is
provided with at least one interlock cam adapted to
move along with said moving contact (13) , said cam
being adapted to extend, in a direction which is the
same as the insertion mounting direction of the fuse
adapter (2), past that contact surface of the moving
contact (13) which is adapted to cooperate with said,
first contact surface (10).
8. Fuse adapter for use in conjunction with the fused
switch housing (1) as claimed in claim 7, said fuse
adapter comprising
a fuse adapter housing (2) with two contact
support projections (8) adapted to extend into the
interior of said fused switch housing (1), and
two conducting fuse holder clips (5) mounted in
said fuse adapter housing (2), whereby the first
ends of said fuse holder clips are adapted to
provide electrical contacts mating with the
ferrules (17) of a fuse (14) and the second ends
thereof to extend as far as to the surface of said
contact support projections (8) so as to form
contact surfaces (9) ,
wherein said contact support projections
(8) are provided for each moving contact (13) with at
least one stop (18) adapted to cooperate with said cam
moving along with said moving contact (13) so as to
prevent the mounting of said fuse adapter (2) into said
fused switch housing (1) or alternatively, dismounting
the same from said fused switch housing (1) when said
moving contact (13) is switched into its closed
position.
The present invention relates to a fused
switch housing (1) suited to accommodate at
least one fuse adapter (2) having a first and
a second contact surface (10). The fused
switch housing (1) comprises a first and a
second set of terminals (15) for respectively
connecting the fused switch to a first and
a second external circuit, stationary contacts
(12, 15, 16), and at least one moving contact
(13). The fused switch housing also includes
switching means cooperating with each of
said moving contacts (13) for making an
electrical connection between each of said first
terminals (15) respectively with each of said
first contact surfaces (10) as well as for making
an electrical connection between each of said
second terminals (15) respectively with each
of said second contact surfaces (10) so that at
least one of said connections with said contact
surfaces is openable by moving said at least
one moving contact (13) with the help of said
switching means. Herein, at least one moving
contact (13) is adapted to press directly against
said first or, second stationary contact surfaces
so as to form an electrical contact.

Documents:

in-pct-2000-379-kol-granted-abstract.pdf

in-pct-2000-379-kol-granted-assignment.pdf

in-pct-2000-379-kol-granted-claims.pdf

in-pct-2000-379-kol-granted-correspondence.pdf

in-pct-2000-379-kol-granted-description (complete).pdf

in-pct-2000-379-kol-granted-drawings.pdf

in-pct-2000-379-kol-granted-examination report.pdf

in-pct-2000-379-kol-granted-form 1.pdf

in-pct-2000-379-kol-granted-form 13.pdf

in-pct-2000-379-kol-granted-form 3.pdf

in-pct-2000-379-kol-granted-form 5.pdf

in-pct-2000-379-kol-granted-gpa.pdf

in-pct-2000-379-kol-granted-letter patent.pdf

in-pct-2000-379-kol-granted-reply to examination report.pdf

in-pct-2000-379-kol-granted-specification.pdf

in-pct-2000-379-kol-granted-translated copy of priority document.pdf


Patent Number 213781
Indian Patent Application Number IN/PCT/2000/00379/KOL
PG Journal Number 03/2008
Publication Date 18-Jan-2008
Grant Date 16-Jan-2008
Date of Filing 10-Oct-2000
Name of Patentee ABB OY
Applicant Address STROMBERGINTIE 1, FI-00380 HELSINKI
Inventors:
# Inventor's Name Inventor's Address
1 MATTLAR HARRI JUNGSUNDSVAGEN 809, FIN-65760, ISKMO
2 MAENPAA ILMARI PUNARINNANKATU 22, FIN-65320, VAASA
PCT International Classification Number H 01 H 85/86
PCT International Application Number PCT/FI99/00354
PCT International Filing date 1999-04-28
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 980933 1998-04-28 Finland