Air circuit breaker

Details Air circuit breaker Air circuit breaker

2001-11-30

2004-02-17

Donovan, Lincoln (Department: 2832)

Electricity: magnetically operated switches, magnets, and electr

Electromagnetically actuated switches

With motor

C200S050010

Reexamination Certificate

active

06693502

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a draw out type air circuit breaker, and in particular to an interlock apparatus for indicating the position in a draw out type air circuit breaker which is capable of indicating accurately a disconnected position, a testing position and a connected position when a breaker is pushed in /pulled out from a cradle.
2. Description of the Prior Art
Generally, an air circuit breaker is installed between an electrical load and an electrical power source in order to protect the load equipment such as a motor and a converter, etc. and a line from an abnormal current (a short circuit, a ground fault, an excess current) generated in an electric circuit such as a power transmission/distribution line and private electricity generating facilities, etc., it means a breaker using air as a medium is for extinguishing an arc generated while opening/closing of contacts.
An air circuit breaker is divided into a fixed type fixedly installed between power source and a load and a drawer type in which a breaker is movable so as to be separated from power source and a load in order to facilitate maintenance and secure stability.
FIG. 1
is a side view illustrating a state in which a cradle is separated from a breaker body in a general draw out type air circuit breaker.
The general draw out type air circuit breaker includes a cradle
100
having an opened side and installed a power source connection terminal
60
connected to power source and a load connection terminal
62
connected to a electrical load equipment, a breaker body
200
movable so as to be pushed in or pulled out from the cradle
100
and performing a circuit cut-off operation in an abnormal current occurrence, and an interlock apparatus
300
for indicating a position of the breaker body
200
by being interlocked with a translocation of the breaker body
200
when the breaker body
200
is pushed in or pulled out from the cradle
100
.
Herein, connectors
64
,
66
are respectively connected to the power connection terminal
60
and the load connection terminal
62
of the cradle
100
, the connectors
64
,
66
are respectively inserted into a power source connection terminal
68
and a load connection terminal
70
projected from the breaker body
200
and are electrically connected.
And, the cradle
100
includes a guide rod
72
for guiding the translocation of the breaker body
200
when the breaker body
200
is pushed in/pulled out.
FIG. 2
is a side view illustrating an interlock apparatus of a drawer type air circuit breaker in accordance with the prior art, and
FIG. 3
is a front view illustrating the interlock apparatus of
FIG. 2
viewing from the right side.
The interlock apparatus in accordance with the prior art includes a base frame
102
fixed to the breaker body
200
, shown in
FIG. 1
, a lead screw
104
supported by the base frame
102
so as to be rotatable, a screw pipe
106
fixed to the cradle
100
and be inserted by the lead screw
104
, an interlock apparatus
300
installed on the base frame
102
and for indicating a position of the breaker body
200
when the lead screw
104
is meshed with the screw pipe
106
, and a locking device
110
connected to the interlock apparatus
300
and locking a position when the breaker body
200
is placed at a disconnected position, a testing position and a connected position.
The interlock apparatus
300
includes a lead bar
112
disposed in parallel with the lead screw
104
, contactable to one wall surface of the cradle
100
and retreating relatively when the lead screw
104
is meshed with the screw pipe
106
and linearly moves, a cam
114
connected to the lead bar
112
and installed in the base frame
102
so as to be rotatable for transforming a horizontal linear movement from the retreating lead bar
112
into rotating movement, and a indicating means
150
connected to the side of the cam
114
and for indicating a position of the breaker body
200
in accordance with the rotation of the cam
114
.
The lead bar
112
is constructed in one body, one portion of the lead bar
112
is extended in parallel with the lead screw
104
, the other portion of the lead bar
112
is constructed as a curved rod shaped member having a predetermined length so as to be inserted into a slot
118
provided in the cam
114
.
And, a breakaway preventing member
120
for preventing a breakaway of the lead bar
112
from the slot
118
is installed to the end of the lead bar
112
inserted into the slot
118
. And, a return spring
122
for providing an elastic force on the lead bar returning to an original position after operation is installed between the breakaway preventing member
120
and the base frame
102
.
The cam
114
has a hinge portion
126
so as to be rotatably installed on the base frame
102
, a slot
118
in which the lead bar
112
is inserted is formed at the lower portion of the cam
114
so as to be curved a certain times at a predetermined angle, and a connection pin
124
connected to an indicating plate
116
placed at the front of the hinge portion
126
.
As depicted in
FIGS. 2 and 3
, the indicating means
150
includes the indicating plate
116
linearly moving up or down when the cam
114
rotates by being inserted by the connection pin
124
installed to the cam
114
and having a color indicating portion (not shown) on the upper front surface for indicating a position of the breaker body
200
with colors. A front plate
130
is fixedly installed to the base frame
102
at the front of the indicating plate
116
and having three indicating windows
138
,
140
,
142
for respectively indicating a position (a disconnected position, a test position, a connected position) of the color indicating portion of the indicate plate, a handle insertion hole
134
in which a handle (not shown) for rotating the lead screw
104
is inserted at the center portion. A guide plate
132
placed at the rear of the indicating plate
116
and for guiding the up or down movement of the indicating plate
116
.
FIGS. 4 and 5
are state diagrams illustrating an operation state of a main parts of an interlock apparatus in accordance with the prior art.
In an interlock apparatus of a air circuit breaker in accordance with the prior art, in order to connect the cradle
100
to the breaker body
200
, the breaker body
200
is placed on a guide rod
72
of the cradle
100
and is pushed in, accordingly the breaker body
200
is moved into the cradle
100
. When the lead screw
104
contacts to the screw pipe
106
according to the moving of the breaker body
200
and a user rotates the lead screw
104
by using the handle, the lead screw proceeds into the screw pipe
106
while rotating.
Then, the two connection terminals
68
,
70
projected from the breaker body
200
are connected to the two connectors
64
,
66
installed to the cradle
100
, accordingly the power source terminal
60
and the load terminal
62
are connected.
When the lead screw
104
proceeds, the lead bar
112
contacts to one wall surface of the cradle
100
, herein the lead bar
112
moves in a direction opposite to the lead screw
104
. As described above, when the lead bar
112
retreats, it rotates the cam
114
in the counter-clock wise while moving along the slot
118
of the cam
114
, by the rotation of the cam
114
the indicate plate
116
moves up. Herein, the indicating portion
40
provided on the indicating plate
116
is displayed one of the three indicating windows
138
,
140
,
142
of the front plate
130
in order to indicate a present position of the breaker body
200
.
In more detail, when the two connection terminals
68
,
70
projected from the breaker body
200
and the connectors
64
,
66
installed to the cradle
100
are not connected each other, the circuit is in the cut-off state, at the same time the lead screw
112
is totally separated from the screw pipe
106
, the indicating portion
40
of the indicating plate
116
is displayed on the lowest indicating window
138
of the three

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