Circuit breaker

Details Circuit breaker Circuit breaker

2001-11-02

2002-06-25

Barrera, Ramon M. (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Electromagnetically actuated switches

Automatic circuit-interrupting devices

C335S013000, C335S017000

Reexamination Certificate

active

06411183

ABSTRACT:

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a circuit breaker such as an autobreaker that is applied to the protection of a low-voltage distributing facility from overcurrents, the circuit breaker being provided with an auxiliary switch that acts as an attached device that enables the breaker to detect the ON and OFF status of main circuit contacts as electrical signals.
FIGS.
4
(
a
) and
4
(
b
) show the construction of a circuit breaker such as an autobreaker having an internal attached switch installed in the main body thereof. In these figures, reference numeral
1
denotes a main body case of the breaker,
2
denotes a main-circuit breaking section incorporated in the case
1
,
3
denotes a toggle-link opening and closing mechanism section,
4
denotes an overload current tripping device,
5
denotes an operating handle,
6
denotes an opening and closing lever, described later in detail,
7
denotes a cassette-type attached switch (auxiliary switch for detecting the ON and OFF status of main circuit contacts as electric signals) installed in the main body case
1
as an internal attached device (option), and
8
denotes another attached switch (alarm switch responsive to an output from an alarm output plate that detects the trip operation of the breaker).
The opening and closing mechanism section
3
comprises a toggle link mechanism responsive to an ON/OFF operation of the operating handle
5
or an output from the overload current tripping device
4
, and the opening and closing lever
6
that operates synchronously with the toggle link mechanism to open or close the main circuit contacts. Furthermore, the opening and closing lever
6
is a seesaw-type lever that pivots vertically around a support shaft
6
b
as shown in FIG.
5
. The opening and closing lever
6
has an operating end
6
a
located opposite. the top of a contact shoe holder
2
b
supporting a movable contact shoe
2
a
of the main circuit contact breaking section
2
as shown in FIG.
7
. During an OFF operation, the opening and closing lever
6
is driven clockwise by the force of an urge spring to strike the movable contact shoe holder to open the main circuit contacts. In contrast, during an ON operation, the opening and closing lever
6
is pivoted counterclockwise, causing the movable contact shoe holder
2
b
to recede upward, so that following this motion the main circuit contacts are closed. Furthermore, a tip
6
c
(see
FIG. 5
) of the other end of the opening and closing lever
6
functions as an opening and closing actuator for attached switch
7
, installed in the main body case
1
.
In the above construction, when the operating handle
5
is manually set to the ON/OFF position, the opening and closing lever
6
of the opening and closing mechanism section
3
is pivoted to open or close the main circuit contacts of the breaking section
2
. Conversely, if an overload current flows through the main circuit, an output signal from the tripping device
4
causes the opening and closing mechanism section
3
to perform a trip operation to open the main circuit contacts, a commonly-known process.
Unlike the above-described process, the attached switch
7
has a fixed contact
7
b
, a bridging movable contact
7
c
, a movable contact shoe holder (vertically movable slider)
7
d
, and a return spring
7
e
for urging and biasing the movable contact
7
c
to an opened and separated position, all these components being incorporated in the case
7
a
. Furthermore, the arm-shaped operating lever
7
f
is connected to the movable contact shoe holder
7
d
and exposed from a front surface of the case
7
a
, as shown in FIGS.
6
(
a
) through
6
(
c
); the attached switch
7
is a spring return limit switch. The attached switch
7
is installed in an accessory housing section defined in a top surface side of the main body case
1
like a cassette, as shown in FIG.
3
. At this installed position, the operating lever
7
f
is located opposite the tip
6
c
of the opening and closing lever
6
of the breaker main body, as illustrated in FIG.
5
.
The attached switch
7
operates as follows. In an ON state in which the main circuit contacts of the breaker are closed, the tip of the opening and closing lever
6
, which has been pivoted counterclockwise, is lowered to push down the movable contact shoe holder
7
d
of the attached switch
7
using the force of the return spring
7
e
, thereby opening and separating the movable contact shoe
7
c
from the fixed contact shoe
7
b
(the switch contacts are turned off), as illustrated in FIG.
7
. Then an OFF signal from this switch allows the detection of the ON state of the main circuit contacts of the breaker. Conversely, in an OFF state in which the trip operation is performed due to a handle operation or the tripping device to open the main circuit contacts, the tip
6
c
of the opening and closing lever
6
, which has been pivoted clockwise, thrusts the operating lever
7
f
of the attached switch
7
upward against the force of the return spring
7
e
to close the movable contact
7
c
/fixed contact
7
b
, thereby causing a main circuit contact OFF signal to be output to an exterior. The attached switch
7
in the illustrated example performs ON and OFF operations in response to the opening and closing of the main circuit contacts of the breaker, respectively. In contrast, however, an attached switch that performs the ON operation when the main circuit contacts are closed, and the OFF operation when the contacts are opened, may be used.
With the above construction, in which the attached switch
7
is composed of a spring-return switch and in which the operating lever
7
f
is located opposite the tip
6
c
of the opening and closing lever
6
of the breaker main body, if an error occurs in which the built-in contacts of the attached switch are welded together, then a misdetection problem may result as follows:
If the attached switch
7
operates correctly, the attached switch
7
responds to the pivoting operation of the opening and closing lever
6
of the breaker main body to correctly detect the ON/OFF state of the circuit breaker, as described in FIG.
7
. If, however, the built-in contacts of the attached switch
7
are welded together, when the main circuit contacts are turned on again after the trip operation of the circuit breaker, the attached switch
7
remains contact-welded and does not perform the OFF operation, even though the opening and closing lever
6
is pivoted counterclockwise to leave the operating lever
7
f
of the attached switch
7
to recede downward. In this regard, the force of the return spring
7
e
shown in FIG.
6
(
c
) is not great enough to cause the welded contacts to be separated from each other. Thus, although the circuit breaker is actually in the ON state, the attached switch
7
continues to output a signal indicating that the main circuit contacts of the breaker are in the OFF state. Consequently, a maintenance worker may mistakenly determine that the circuit breaker is off, and if the worker touches a load-side circuit, he or she may unexpectedly get an electric shock.
The present invention is provided in view of these points, and it is an object thereof to provide an improved circuit breaker in which, even if the built-in contacts of the attached switch installed in the circuit breaker are welded together during operation, the contacts of the welded attached switch are forcibly separated from each other using the force of the pivoting operation of the opening and closing lever of the breaker main body so that the ON/OFF states of the main circuit contacts can be correctly detected.
SUMMARY OF THE INVENTION
To attain the above object, the present invention provides a circuit breaker comprising an opening and closing mechanism section for opening and closing the main circuit contacts according to a handle operation or an output from an overload current tripping device, the opening and closing mechanism section including a seesaw-type opening and closing lever that piv

Affiliated with

Also associated with

Rating

Circuit breaker does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Circuit breaker, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit breaker will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2933615