This application claims priority from provisional application
60/809,696, filed on May 31, 2006
FIELD OF THE INVENTION
The present invention relates to separable electrical connectors
and, more particularly, to improvements in separable electrical connectors such
as loadbreak connectors and deadbreak connectors, including a visible open indicator
for determining the switch position.
BACKGROUND OF INVENTION
High voltage switch assemblies with sub-atmospheric or
vacuum type circuit interrupters for electric power circuits and systems are well
known in the art, such as is shown in
U.S. Patent Nos. 4,568,804
. Encapsulated vacuum type switches or circuit breakers are also known,
as is shown in
U.S. Pat. Nos. 3,812,314
Insulated switches using vacuum bottles do not provide
means for visual inspection of the contacts to confirm that they are open (visible
break) or closed. Prior art switches were designed with contacts in a large gas
or oil filled cabinet which allowed a glass window to be installed for viewing the
contacts. However, there is no means of directly viewing contacts in vacuum bottles
since the bottles are made of metal and ceramic nontransparent materials. The seals
required to maintain the vacuum inside the vacuum bottle prohibit the installation
of a glass window.
In most switch assemblies and circuit breakers, a pair
of contacts acting in cooperation, one fixed and the other movable, are provided
for controlling and interrupting current flow. The contacts are housed in a controlled
atmosphere contact assembly that includes a glass or ceramic housing, commonly referred
to as a "bottle." A metal bellows is provided on one end of the bottle, and the
movable contact is linked to the inside of the bellows. An operating rod attached
to the outside of the bellows is moved in order to actuate the movable contact inside
the bottle. The interior of the bottle is maintained under a controlled atmosphere,
such as air under a low sub-atmospheric pressure, to protect the contacts from damage
caused by arcing when the contacts are opened and closed. The glass or ceramic wall
of the bottle provides a permeation resistant enclosure that maintains the controlled
atmosphere for the life of the device. Newer high voltage switches combine vacuum
switching with high dielectric strength EPDM rubber insulation as described in
U.S. Patent Nos. 5,667,060
to Luzzi, all of which are incorporated herein in their entirety.
Switches that have viewing windows are usually SF6 gas
insulated vacuum bottle type switches. In all cases, the contacts within the vacuum
bottle are not visible due to the method of construction. A user can view the actuating
mechanism through the gas and determine if the mechanism has moved open or closed.
This provides a visible indication of the switch position. However, the eventual
unavailability of SF6 gas as an insulator due to government regulations and ozone
issues is a major disadvantage for the prior art devices. In addition, prior art
devices are susceptible to leaks and they have had problems maintaining the SF6
gas within the switch.
The handle positions for prior art switches indicate the
position of the contacts in the vacuum bottle. A pointer on the handle indicates
closed when pointing in one direction and open when pointing in the other direction.
The connection from the handle to the bottle includes a plurality of components
which form a linkage. If these components do not function properly, the position
of the pointer may not correctly indicate the position of the contacts.
In contrast to the handles on switches, the handle position
of an interrupter does not always indicate the contact position even when the actuating
mechanism is operating properly. Therefore, interrupters typically have a viewing
indicator instead of a pointer. The handle of an interrupter is usually in one direction
for closed and the other direction for open. However, the handle can be in the closed
position with the contacts open when the interrupter trips due to an over current
event. Under these circumstances, the prior art viewing indicator shows that the
contact is open but the handle is in the closed position. This is similar to the
circuit breakers in a house. When the breaker trips, the handle does not move all
the way to the open position and it is necessary to move the handle to the open
position in order to reset the mechanism before it can be closed. The linkage from
the vacuum bottle to the viewing indicator of the interrupter also includes numerous
components (see FIG. 1C), which are subject to failure and a false indication
Typically, prior art insulated switches using vacuum technology
are sealed inside the vacuum bottle and hidden from view. The voltage source and
the load are connected to the switch but the switch contacts are not visible. The
only means for determining the status of the switch contacts is the position of
the switch handle. If the linkage between the handle and the switch contacts is
inoperative or defective, there is no positive indication that allows the operating
personnel to determine the position of the contacts. This can result in false readings
which can be very dangerous to anyone operating the switch or working on the lines.
Accordingly, the industry has recognized the need for insulated switches using vacuum
bottles that provide a reliable indication of the position of the contacts.
SUMMARY OF THE INVENTION
In accordance with the present invention, a visible open
indicator for high voltage vacuum interrupters and switches, which use a vacuum
bottle having a high voltage contact and an actuating element that opens and closes
the contact, is provided. The visible open indicator includes: an actuating mechanism
that operates the actuating element; a housing that contains the actuating mechanism;
an indicator attached to the actuating mechanism, wherein the indicator shows that
the contact is in an open position or closed position; a viewing window extending
through the housing, wherein the viewing window is aligned with the indicator so
that the indicator can be viewed through the viewing window. The housing can be
constructed from a solid dielectric material, preferably EPDM rubber.
The indicator includes a first indicating portion and a
second indicating portion. The first indicating portion is visible through the viewing
window when the contact is open and the second indicating portion is visible through
the viewing window when the contact is closed. The actuating mechanism can include
a linkage formed by a plurality of components. In preferred embodiments, the actuating
mechanism includes a first end and a second end and the actuating mechanism is connected
to the actuating element on the first end and a handle on the second end. In a most
preferred embodiment, the actuating mechanism includes an assembly that connects
the indicator to the actuating element. In one embodiment, the assembly can include
a connector and an insulated rod. In another embodiment, the assembly consists essentially
of a connector, a screw and an insulated rod.
The high voltage vacuum interrupters and switches can include
an inlet connection for a voltage load having a first centerline and the viewing
window can have a second centerline. The distance between the two centerlines is
kept to a minimum, preferablyless than 6 inches and more preferably less than 5
inches. In addition, the housing is preferably made from a solid dielectric material.
BRIEF DESCRIPTION OF THE FIGURES
The preferred embodiments of the visible open indicator
for high voltage vacuum interrupters and switches of the present invention, as well
as other objects, features and advantages of this invention, will be apparent from
the following detailed description, which is to be read in conjunction with the
accompanying drawings wherein:
FIG. 1A is a side view of a prior art high voltage switch
in a vacuum bottle with an actuating mechanism operating a position indicator for
FIG. 1B is a plan view of a prior art high voltage switch
in a vacuum bottle with an actuating mechanism operating a position indicator for
FIG. 1C is the prior art high voltage switch illustrated
in FIG. 1A with an exploded view of the actuating mechanism.
FIG. 2 is a sectional view of the visible open indicator
showing the contact in the vacuum bottle and position indicator.
FIG. 3 is a sectional view of the visible open indicator
illustrated in FIG. 2 with an exploded view of the actuating mechanism and indicator.
FIG. 4 is a side view of an interrupter with a viewing
FIG. 5 is a side view of a switch with a viewing window.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides visual indication of the
position of high voltage contacts sealed in a vacuum bottle for switches and interrupters.
The contacts cannot be viewed directly through the nontransparent wall of the vacuum
bottle and, therefore, it is necessary to locate the visual indicator on the outside
of the bottle. The housings for some prior art switches are constructed of solid
dielectric materials, such as ethylene propylene diene monomer ("EPDM") rubber,
and position indicators on the outside of the housing indicate when the switch is
in the open or closed position. In order to move the indicator, numerous components
in the linkage (Figure 1 C) that connects the vacuum bottle actuating element and
the indicator must function correctly.
The present invention improves the reliability by moving
the viewing window closer to the vacuum bottle and using fewer connections between
the vacuum bottle actuating element and the indicator. In preferred embodiments,
maximum reliability is provided by moving the viewing window as close to the vacuum
bottle as the electrical field will allow. This reduces the number of actuating
mechanism components between the vacuum bottle contacts and the viewing window to
a minimum. Consequently, the risk of a connection failure or a false reading is
The visible open indicator of the present invention is
used with high voltage vacuum interrupters and switches that include a high voltage
contact in a vacuum bottle. The vacuum bottle is provided with an actuating element
that opens and closes the contact. The actuating element has a shaft that extends
outside the vacuum bottle and passes through one or more seals, which maintain the
vacuum inside the bottle. An actuating mechanism, which is external to the vacuum
bottle, operatively connects to the actuating element (See
U.S. Patent Nos. 5,667,060
to Luzzi.) The actuating mechanism includes a linkage that has a plurality
of components and that can be connected to a handle for manual opening and closing
the contacts and/or a motor operator. The actuating mechanism is enclosed in a housing
and provided with a viewing window that allows the actuating mechanism to be viewed
through the wall of the housing. The viewing window is sealably installed in an
aperture in the wall of the housing using methods well know to those skilled in
the art, preferably using a sealant such as an epoxy.
An indicator is attached to the actuating mechanism and
aligned so that its location corresponds to the location of the viewing window.
When the actuating mechanism closes the contacts, the indicator is moved towards
the vacuum bottle. When the actuating mechanism opens the contacts, the indicator
is moved away from the vacuum bottle. In a preferred embodiment, the indicator is
provided with a first indicating portion or indicia for the open contact position
and a second indicating portion or indicia for the closed contact position. Most
preferably, the first indicia is a green indicator for an open contact and a red
indicator for a closed contact. The viewing window and the indicator are designed
so that the first indicating portion is visible through the viewing window when
the contact is open and the second indicating portion is visible through the viewing
window when the contact is closed.
In another preferred embodiment, the actuating mechanism
includes an assembly that connects the indicator to the actuating element and a
first end connected to the actuating element and a second end connected to a handle.
The assembly includes a connector and an insulated rod and, more preferably, a connector,
a screw and an insulated rod. The indicator is preferably attached to the first
connector at a minimum distance from the actuating element. This reduces the number
of actuating mechanism components between the actuating element and the indicator
and provides greater reliability. The housing for the actuating mechanism can be
constructed from a solid dielectric material; preferably, a hard rubber material
and, most preferably, EPDM rubber. The aperture for the viewing window is formed
either when the housing is fabricated using methods well know to those skilled in
the art, such as injection molding, or after the housing is formed by cutting or
drilling an opening that extends through the wall of the housing.
The visible open indicator of the present invention can
be used with either a high voltage vacuum interrupter or a high voltage switch,
which has an inlet connection with a first centerline for the high voltage source.
The viewing window is located in an aperture in the actuating mechanism housing
that is connected to the interrupter or switch. The aperture/viewing window has
a second center line that is less than 6 inches from the first centerline and, preferably,
less than 5 inches. Of course, actual distances may vary.
FIG. 1A and FIG. 1B show a prior art high voltage vacuum
switch 900 having a vacuum bottle 902 and an actuating mechanism 904. The position
of the contacts is shown by an open-closed indicator 906 at the end of the actuating
mechanism 904. The actuating mechanism 904 includes numerous components and connections
which may fail or malfunction and cause a false indication of the position of the
contact. This can cause accidents and places the health of operating and maintenance
personnel in jeopardy. FIG. 1C is an exploded view of the actuating mechanism 904
and shows the numerous components and connections in detail. The present invention
provides a more reliable indicator by eliminating many of these components and connections.
FIGs. 2 and 3 show an embodiment of the present invention
in which a vacuum bottle 20 is attached to a housing 14 to form a switch or interrupter
assembly 10. The vacuum bottle 20 contains a contact 28 and has a first end 24 that
connects to a voltage source and a second end 26 that connects to a load. An actuating
element 22 on the first end 24 connects to the actuating mechanism 30 for either
a switch or interrupter. In a preferred embodiment, the actuating mechanism 30 includes
an assembly 32 that has a snap connector 34, a screw 36 and an insulated rod 38.
The snap connector 34 is secured to the actuating element 22, preferably with a
screw 36, and the insulated rod 38 is attached to the snap connector 34. An indicator
40 for the contact 28 is then attached to the insulated rod 38. Preferably, the
indicator has a red portion 44 (for indicating the contact 28 is closed) and a green
portion 46 (for indicating the contact 28 is open).
A viewing window 42 extends through the housing 14 so that,
when the actuating mechanism opens or closes the contact 28, the red portion 44
or green portion 46 of the indicator 40 is aligned with the viewing window 42 and
shows the position of the contact 28. In a preferred embodiment, the housing 14
is made from a solid dielectric material and the viewing window 42 is located in
an aperture 41 in the wall 43 of the housing 14. The viewing window 42 is located
as close as possible to the centerline of the inlet connection 29 for the loadin
order to minimize the number of components in the actuating mechanism 30 between
the actuating element 22 and the indicator 40. Preferably, the distance (L) between
the centerline of the viewing window 42 and the centerline of the inlet connection
29 is less than 6 inches and most preferably less than 5 inches.
FIG. 4 shows an interrupter assembly 110 with an operating
handle 150 which is connected to the actuating mechanism for opening and closing
the contact 28 (see FIG. 3). The viewing window 142 extends through the housing
114 in close proximity to the vacuum bottle 120. Similarly, FIG. 5 shows a switch
assembly 210 with an operating handle 250 which is connected to the actuating mechanism
for opening and closing the contact. The viewing window 242 in the housing 214 is
located a between the operating handle 250 and the vacuum bottle 220. The viewing
window 242 can also be located at any position on the circumference of the housing
214. This allows the viewing window 242 to be observed from different angles.
Thus, while there have been described the preferred embodiments
of the present invention, those skilled in the art will realize that other embodiments
can be made without departing from the spirit of the invention, and it is intended
to include all such further modifications and changes as come within the true scope
of the claims set forth herein.