Electricity: circuit makers and breakers – Switch activation inhibitor – Actuator locking device
Reexamination Certificate
2002-09-30
2004-02-24
Mai, Anh (Department: 2832)
Electricity: circuit makers and breakers
Switch activation inhibitor
Actuator locking device
C200S043150, C200S043190
Reexamination Certificate
active
06696651
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
BACKGROUND OF THE INVENTION
The present invention relates to electrical circuit breakers including motor controllers and, in particular, to a lockout preventing unauthorized activation of a circuit breaker or motor controller.
Safety practice requires that electrically powered machines be isolated from power before adjustment, maintenance, or repair of the machine by a human operator. Such isolation must be done in a manner to prevent accidental reconnection.
This isolation may be accomplished by opening the circuit breaker associated with the machine and locking the circuit breaker toggle in the “off” position using a “sealed” wire connection or a padlock and a special locking fixture. As used herein, the term “circuit breaker” should be considered to include manual motor controllers and the like.
Referring to
FIG. 1
, a prior art single-pole, miniature-style circuit breaker
10
, includes a front escutcheon plate
12
having an outer edge
14
and an opening
16
therein through which a toggle operator
18
extends. The toggle operator
18
pivots in a longitudinal direction
20
between a downward OFF position
22
(as shown in FIG.
1
), and an upward ON position
24
. A free end of the toggle operator
18
is attached to a transversely extending bar toggle
26
that may be easily operated by a person's finger.
Referring also to
FIG. 2
, a prior art lockout
30
for such a circuit breaker
10
uses an aluminum extrusion having a transversely extending channel
32
with opposed lower wall
34
and upper wall
36
. The channel
32
is sized to receive the toggle bar
26
when it is in the OFF position. A set screw
38
passes through the upper wall
36
into the channel
32
so that the toggle bar
26
may be captured between a tooth
40
projecting inward from lower wall
34
and a pointed tip of the set screw
38
.
The upper wall
36
attaches to a foot
42
which abuts the escutcheon plate
12
at a front upper edge
14
of escutcheon plate
12
. In this way, motion of the toggle bar
26
in an upward arc along the longitudinal axis
20
, such as would tip the lockout
30
, is resisted by pressure of the foot
42
against the front surface of the escutcheon plate
12
. As shown in the drawing, for some circuit breakers
10
, the foot
42
of the lockout
30
is very close to the edge
14
of the escutcheon plate
12
and may slip over that edge
14
allowing activation of the circuit breaker
10
despite the lockout
30
.
The head
46
of the set screw
38
extends into an opening of an eye
44
attached generally to the upper wall
36
and providing a cylindrical transverse aperture. An access hole
48
in the wall of the eye
44
, opposite the head
46
of the set screw
38
, allows insertion of a screwdriver blade
50
to engage the head
46
for tightening the set screw
38
against the toggle bar
26
or loosening it therefrom.
Referring also to
FIG. 3
, a shackle
52
of a padlock may be inserted through the eye
44
to block access by the screwdriver blade
50
to the head
46
of the set screw
38
. Generally, the shackle
52
must be somewhat smaller than the diameter of the eye
44
because of the protrusion of the head
46
into the aperture of the eye
44
. The transverse extending eye
44
requires that the shackle
52
be positioned so that the case
54
of the padlock lies across adjacent circuit breakers
10
′ and
10
″ interfering with operation of these circuit breakers
10
′ and
10
″ and preventing the use of a second lockout on these adjacent circuit breakers
10
′ and
10
″.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a mechanical lockout also engaging a toggle bar of a circuit breaker but in which the eye is positioned to allow a padlock used with the lockout to hang edgewise. This change in the orientation of the padlock reduces or eliminates interference between the padlock and adjacent circuit breakers and/or lockouts on those circuit breakers. An improved foot on the lockout includes a heel engaging an aperture of the escutcheon plate of the circuit breaker preventing slippage of the lockout with movement of the toggle bar of the circuit breaker. The set screw of the lockout is further mounted in a counter bore below the surface of the eye allowing proportionally larger shackled locks and improved tamper resistance.
More specifically, the present invention provides a lockout for a circuit breaker having a toggle operator switchable between an ON and OFF position. The lockout includes a transverse channel having opposed first and second walls for receiving the toggle operator therebetween, the first wall including a hole extending therethrough. A screw fitting within the hole can be extended toward the second wall by rotation of the screw to clamp the toggle operator within the channel. A foot attached to the channel engages a portion of the circuit breaker, other than the toggle operator, to resist switching of the toggle operator when the toggle operator is clamped in the channel. A longitudinal eye is attached to the first wall to receive a padlock shackle along a direction substantially perpendicular to the channel so that the shackle blocks access to the head of the screw.
Thus, it is one object of the invention to provide an improved orientation of the eye of a lockout allowing adjacent circuit breakers to be operated or to be locked out without interference from the padlock.
The screw may be a set screw having its head positioned within a counter bore of the hole so that the received shackle covers the counter bore.
Thus it is another object of the invention to eliminate access to the head of the set screw and to allow the use of a larger diameter shackle associated with commonly available padlocks and/or to reduce the necessary size of the eye.
The hole may open into the longitudinal eye.
Thus, it is another object of the invention to prevent movement of the shackle within the eye from allowing access to the set screw.
The toggle of the circuit breaker may extend from an opening in an escutcheon plate and the foot may include a heel portion fitting within the opening.
Thus, it is another object of the invention to provide a more positive lockout that cannot be defeated by a sliding of the lockout mechanism along the surface of the escutcheon plate.
The foot may also include a toe fitting over the outer edge of the escutcheon plate.
Thus it is another object of the invention to provide a positive indication of a proper fitting of the lockout to the circuit breaker that may indicate that the lockout is not being used on the toggle when the toggle is in the OFF position as is desired.
The eye may be oriented so that the shackle of the padlock is substantially vertical when the circuit breaker is mounted so that the toggle operator is switched in a vertical direction.
Thus, it is another object of the invention to allow the padlocks to hang stably without gravitationally induced twisting and interference.
The channel may fully cover the toggle operator when the toggle operator is positioned within the channel.
Thus, it is another object of the invention to better enclose the toggle to reduce tampering and removal of the operator by twisting.
Alternatively, the channel may extend at least two times the length of the toggle operator to engage toggle operators of adjacent circuit breakers.
It is thus another object of the invention to provide the ability to lockout multiple adjacent circuit breakers.
These particular features, objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.
REFERENCES:
patent: 4733029 (1988-03-01), Kobayashi et al.
patent: 5147991 (1992-09-01), Jordan, Sr.
patent: 5449867 (1995-09-01), Kelaita et al.
patent: 5817998 (1998-10-01), Siebels et al.
Drake Dennis
Koopmeiners David
Schmidt Dennis
Fishman M.
Mai Anh
Rockwell Automation Technologies Inc.
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