Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Automatic circuit-interrupting devices
Reexamination Certificate
2002-04-23
2002-10-22
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Automatic circuit-interrupting devices
C335S011000, C335S013000, C335S020000
Reexamination Certificate
active
06469601
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to an under-voltage tripping device with an early-operation auxiliary switch that is used as an external accessory for general-purpose, low-capacity circuit breaker, e.g. a molded case circuit breaker (auto-breaker) for controlling an electric motor.
The above molded case circuit breaker is provided with various optional accessories, including an under-voltage tripping device. The under-voltage tripping device is installed on a side of a breaker main body and linked with an internal mechanism of the main body so as to trip the breaker when the voltage at the main circuit decreases excessively during conduction.
Furthermore, an under-voltage tripping device with an early-operation auxiliary switch is known, in which an under-voltage tripping mechanism composed of an electromagnet and a tripping lever, and an early-operation auxiliary switch connected to a conductive circuit of the electromagnet and linked with a handle mechanism of the breaker, are combined and built into a single unit case, so that when the handle is operated to close a main circuit contact of the circuit breaker after the breaker has performed a tripping operation, the early-operation auxiliary switch can be turned on to reset the circuit breaker. This under-voltage tripping device with an early-operation auxiliary switch is used to simultaneously break the main circuit and a circuit for the under-voltage tripping device if the circuit breaker is applied to a circuit for emergency stop of loads on an electric motor or the like.
Before explaining the under-voltage tripping device with the early-operation auxiliary switch contact, a configuration of a circuit breaker, e.g. auto-breaker, is shown in
FIGS. 6 and 7
. In
FIG. 6
, reference number
1
denotes a circuit breaker,
1
a
is a case of the breaker main body,
2
is a current-interrupting section provided with a main circuit contact and an arc-extinguishing chamber,
3
is an opening-and-closing mechanism section for the main circuit contact,
4
is an over-current tripping device, and
5
is a rotary operation handle disposed on a cover top surface of the case
1
a
. The operation handle
5
constitutes a handle mechanism that connects a gear mechanism
6
linking the operation handle
5
with the contact opening-and-closing mechanism
3
to a reset cam for controlling a drive lever for the early-operation auxiliary switch of an under-voltage tripping device (accessory).
Opening and closing operations of the circuit breaker
1
are well known. When the operation handle
5
is rotated from the OFF position to the ON position, a toggle link mechanism
3
a
of the contact opening-and-closing mechanism section
3
operates via the gear mechanism
6
to close the main circuit contact of the current interrupting section
2
via an opening and closing spring
3
b
and an opening and closing lever
3
c
. Conversely, when the operation handle
5
is rotated from the ON position to the OFF position, the toggle link mechanism
3
a
and the opening and closing lever
3
c
operate in an opposite way to open the main circuit contact of the current interrupting section
2
. Furthermore, when an over-current flows through the main circuit and causes the over-current tripping device
4
to release a latch mechanism
3
d
of the contact opening-and-closing mechanism section
3
, the opening-and-closing mechanism section
3
opens the main circuit contact to interrupt the current. In this regard, the operation handle
5
follows this trip operation to stop at a TRIP position midway between the ON position and the OFF position, thereby indicating that the circuit breaker has performed a trip operation.
Furthermore, after the breaker has performed the trip operation, when it is tried to set the breaker after the main circuit has been restored to a normal condition, the operation handle
5
is returned from the TRIP position to the RESET position (same as the OFF position) in order to reset the latch mechanism
3
d
of the contact opening-and-closing mechanism
3
. The operation handle
5
is then rotated to the ON position to close the main circuit contact in order to set the breaker.
Next, a basic structure and operation of the under-voltage tripping device with the early-operation auxiliary switch as an accessory, which is installed on a side of the main body of the circuit breaker for use, will be described with reference to
FIGS. 8 and 9
.
The under-voltage tripping device
10
is installed on a side of the case
1
a
of the circuit breaker
1
as an independent unit. A unit case
11
(the case
11
is made in a dimension so as to ensure that it does not protrude from the outward frame of the breaker main body) has external connection terminals (screw terminals)
12
a
to
12
d
arranged at the respective lateral ends thereof in different stages. The case contains the under-voltage tripping mechanism composed of a combination of an electromagnet
13
and a tripping lever
15
connected to the electromagnet, and an early-operation auxiliary switch
14
that opens and closes a conductive circuit for the electromagnet
13
in connection with the operation of a handle mechanism of the breaker main body. The external connection terminals
12
a
to
12
d
are arranged in different stages to facilitate a wiring operation required to install these terminals on a distribution board or a control board when connecting them to bus bars and branch bars of the main circuit laid in the board.
The tripping lever
15
has one end connected to an armature
13
a
of the electromagnet
13
, and a drive pin
15
a
drawn out laterally from the upper end of the lever through the unit case
11
is linked with a tripping plate assembled on the contact opening-and-closing mechanism section
4
of the breaker main body. Reference number
15
b
denotes a return spring that forces the tripping lever
15
downward.
The early-operation auxiliary switch
14
is composed of two vertical sets of early-operation contacts, each of which include a pair of fixed contacts
14
a
and a bridge-shaped movable contact
14
b
bridging the fixed contacts
14
a
, and an oscillating contact holder
14
c
that supports the movable contacts
14
b
together with contact springs and journals the lower ends of the movable contacts. An operating lever
14
d
, which operates in connection with the contact holder
14
c
, is located at the upper end of the switch
14
and linked with a drive lever
16
integrated into a handle section of the breaker main body. Furthermore, the drive lever
16
is operated in connection with a reset cam
17
connected to the operation handle
5
.
Furthermore, inside the case of the under-voltage tripping device
10
, the above described external connection terminals
12
a
to
12
d
are wired as follows: the terminal
12
a
is connected to the terminal
12
c
through the upper early-operation contact of the early-operation auxiliary switch
14
and a coil of the electromagnet
13
, and the terminal
12
b
is connected to the terminal
12
d
via the lower early-operation contact of the early-operation auxiliary switch
14
. In operation, when the under-voltage tripping device is attached to the circuit breaker
1
, the external connection terminals
12
a
and
12
b
are wired to the power supply side of the main circuit, while the other external connection terminals
12
c
and
12
d
are directly connected together, as shown in FIG.
10
.
In the above configuration, when the operation handle
6
of the circuit breaker
1
is rotated to the ON position, the early-operation auxiliary switch
14
of the under-voltage tripping device
10
is turned on via the drive lever
16
to supply power from the main circuit to the electromagnet
13
of the tripping mechanism, thereby allowing electric conduction through the electromagnet
13
. In this case, if voltage in the main circuit is normal, the attraction of the electromagnet
13
causes the tripping lever
15
to be pushed up against the spring force of the return
Asakawa Koji
Miura Masao
Barrera Ramon M.
Fuji Electric & Co., Ltd.
Kanesaka & Takeuchi
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