Electrical connectors – Including arc suppressing or extinguishing means
Reexamination Certificate
1998-05-27
2001-04-10
Donovan, Lincoln (Department: 2832)
Electrical connectors
Including arc suppressing or extinguishing means
C439S921000, C439S181000
Reexamination Certificate
active
06213799
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to a safety device for high voltage electrical equipment and, more particularly, to a device used on high voltage accessory products to reduce the risk of flashovers when a connector or insulated cap is removed from the accessory product. Specifically, the present invention relates to an anti-flashover ring that fits on an accessory product and prevents a flashover-promoting vacuum from forming between the accessory product and a connector as the connector is pulled off the accessory product.
BACKGROUND OF THE INVENTION
Safety is of paramount importance to line crew operators who deal with high voltage electrical equipment given the consequences of a mistake or an unfortunate occurrence. High voltage electrical equipment includes, but is not limited to, various sized bushing inserts, feed-through devices, multi-position junctions, and insulated or stand-off bushings. The foregoing equipment is usually held in a fixed position to receive mounting connectors such as appropriately sized elbow connectors, insulating caps and the like. Although interconnection between a particular type of accessory product and a connector is discussed herein, it will be appreciated that the existing problems and the solution is applicable to all accessory products and their connections.
One of the more dangerous tasks performed by an operator is disconnecting a live source of power by physically breaking a connection between the foregoing rather than throwing a switch. A risk in performing such a disconnect is that the electricity from the live end of the connection may arc or flashover to ground. Such a flashover can damage the equipment and may cause injury. For example, one such a flashover problem has been found to occur when elbow connectors are removed from bushing inserts.
A typical prior art bushing insert and elbow connector are depicted in
FIGS. 1 and 2
. The bushing insert is indicated generally by the numeral
10
while the cable or elbow connector is indicated generally by the numeral
12
. Bushing insert
10
includes a body with semi-conductive shielded collar
14
that is substantially cylindrical but may be slightly tapered. A semi-conductive shielded sheath
16
extends from one end of collar
14
. Sheath
16
and collar
14
provide protection and a ground shield for bushing insert
10
. The body also includes a non-conductive frusto-conical portion
18
or first portion extends outwardly from the other end of collar
14
and terminates at an annular locking groove
20
. A snuffer assembly
21
extends from frusto-conical portion
18
. Snuffer assembly
21
is provided to protect the internal components of bushing insert
10
. A shoulder wall or portion
22
forms the connection between collar
14
and frusto-conical portion
18
. Shoulder wall
22
is disposed at a substantial right angle with respect to collar
14
and joins frusto-conical portion
18
in a small chamfer. Bushing insert
10
provides an inner bore with an internal electrical connection components or conductive component therethrough to provide a medium for electrically connecting elbow connector
12
to other electrical distribution equipment. A second portion extends from collar
14
for connection to an equipment bushing well.
Elbow connector
12
includes a bushing port
24
having an interior wall
26
that is configured to tightly conform to frusto-conical portion
18
of bushing insert
10
. Bushing port
24
is thus configured to snugly engage bushing insert
10
when elbow connector
12
is locked on bushing insert
10
. This position is depicted in FIG.
1
. When elbow connector
12
is locked on bushing
10
, a lip
28
of bushing port
24
is positioned over a portion of collar
14
. Lip
28
includes a terminal wall or end
30
and an inner wall
32
. Lip
28
joins with the body of bushing port
24
forming a shoulder
34
having an end wall
36
. End wall
36
contacts shoulder wall
22
and inner wall
32
contacts collar
14
when elbow connector
12
is locked on bushing insert
10
. Furthermore, interior wall
26
of elbow connector
12
snugly engages frusto-conical portion
18
of bushing insert
10
when elbow connector
12
is locked on bushing insert
10
. Connecting elbow connector
12
to bushing insert
10
is enhanced by the presence of a high dielectric lubricant that may be used to provide a well lubricated fitting between bushing insert
10
and connector
12
. An electrical probe
37
, which is connected to an electrical cable, is concentrically disposed within bushing port
24
and extends into the electrical connection components within bushing insert
10
.
The problem encountered with the connection between bushing insert
10
and connector
12
in the prior art is depicted in FIG.
2
.
FIG. 2
shows a position of connector
12
as it is removed from bushing insert
10
. In this position, bushing port
24
and lip
28
have moved slightly off of bushing insert
10
forming gaps
38
between end wall
36
and shoulder wall
22
as well as between frusto-conical portion
18
and interior wall
26
. Gaps
38
form vacuums or partial vacuums given the tight connection between lip
28
and collar
14
as well as between bushing port
24
and frusto-conical portion
18
. Testing has revealed that an especially large vacuum occurs between end wall
36
and shoulder wall
22
as connector
12
is removed from bushing insert
10
. The existence of lubricant on these elements also aids the formation of a vacuum in gaps
38
. The existence of a vacuum or partial vacuum in gaps
38
increases the likelihood of a flash-over between electrical probe
37
and the shielded collar
14
over the insulated frusto-conical portion
18
. This flashover or electrical arc will damage bushing insert
10
and connector
12
, requiring their replacement.
It is thus desired in the art to provide a device that prevents the vacuums from forming between bushing insert
10
and connector
12
while connector
12
is removed from bushing insert
10
. Such a device ideally would be able to be retrofit onto existing bushing inserts such that the entire bushing insert would not have to be replaced to provide this benefit. Furthermore, the desired device could be easily manufactured to fit a wide variety of rated bushing inserts, junctions and other similar accessory products.
Another safety problem with bushing inserts and connectors is that the operator installing the connector on the insert does not always know when the connector is fully attached to and locked on the bushing insert. Although an experienced operator may develop a feel for a secure and locked connection between the two elements, the inexperienced operator who infrequently connects the items desires an indicator that tells them when the two elements are fully locked together. It is thus desired in the art to provide a device that gives an indication to the operator of when the connector is fully installed on the bushing insert. Such a device should ideally be able to be manufactured to fit a wide variety of bushing insert sizes and accessory products and be capable of being retrofit onto existing bushing inserts.
SUMMARY OF INVENTION
In light of the foregoing, it is a first aspect of the present invention to provide a device that prevents flashover between high voltage accessory products and a mating connector as they are separated from one another.
Another aspect of the present invention is to provide an anti-flashover device that prevents a vacuum from forming between an accessory product such as a bushing insert and a mating connector as the connector is removed from the bushing insert.
Yet another aspect of the present invention is to provide an anti-flashover device that may be retrofit onto existing bushing inserts and the like.
Still another aspect of the present invention is to provide an anti-flashover device that may be manufactured to fit a wide variety of differently sized bushing inserts and other accessory products.
A further aspect of the present invention is to provide an anti-fl
Decker Edward H.
Jazowski Roy E.
'Hubbell Incorporated
Bicks Mark S.
Donovan Lincoln
Goodman Alfred N.
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