Note: Descriptions are shown in the official language in which they were submitted.
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RECEPTACLE DEVICE HAVING CIRCUIT INTERRUPTING AND REVERSE
WIRING PROTECTION
FIELD OF INVENTION
The present invention relates to a receptacle device, particularly a ground
fault circuit
interrupter (GFCI) or an arc fault circuit interrupter (AFCI), which provides
protection to
humans and property against faults in electrical equipment and in electrical
supply and
distribution systems so that upon detection of a fault condition, the
receptacle device interrupts
the electric supply circuit. The receptacle device is also capable of
protecting against faults
caused by reverse wiring.
BACKGROUND OF THE INVENTION
Safety associated with the use of household appliances is a great concern for
people.
This is especially the case as more and more electronic devices are used in
homes today.
Accordingly, this is desired to provide the electric receptacles in the walls
of ordinary
households with safety features. However, most receptacles in homes are
ordinary receptacles
without the capability to protect against leakage of electric current. When
these ordinary
receptacles are used, leakage of electric current or a shock hazard may occur.
Receptacles with safety features that guard against the leakage of electric
current, such as a
ground fault circuit interrupter (GFCI) and an arc fault circuit interrupter
(AFCI), have been in
existence since the early 1970's. However, until recently, most of these
receptacles did not
possess a reverse wiring protection feature.. Reverse wiring means that load
wires are
mistakenly connected to a line side of the receptacle and line wires are
mistakenly connected
9207090.1
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to a load side of the receptacle. When this occurs, although the input end and
the output end
of the receptacle are still electrically connected, the receptacle no long
provides fault-
protection. Without a reverse wiring protection feature, a consumer, after
mistakenly
reversing the line wire and load wire connections to the receptacle may be
misled to believe
that the receptacle is still functioning properly and will detect a fault
condition. However, the
consumer does not know that the fault-protection feature is not operational.
The continued
use of a reverse wired receptacle might cause injury to users and damage to
the household
electronic appliances, as well as damage to real property.
Accordingly, there is a need for a circuit-interrupting device that provides
reverse
wiring protection and that may also protect against fault conditions, such as
ground faults and
arc faults, among others.
SUMMARY OF THE INVENTION
To solve the above problems, embodiments of the present invention provide a
circuit
interrupting device, such as a GFCI or an AFCI. This type of circuit
interrupting device is
suitable for installation in an output box in a wall of an ordinary household,
such as a typical
wall receptacle. When the input and output wires are mistakenly connected in a
reverse
manner during installation of the receptacle, the receptacle prevents an
electric connection
between the input end and output end of the receptacle. Thus, when the input
wire is
mistakenly connected to the output end of the receptacle and the output wire
is mistakenly
connected to the input end of the receptacle, there is no electric voltage
output from the
receptacle. Only when the wires of the receptacle are properly connected can
the receptacle
be reset and the output end provide a voltage output.
Embodiments of the present invention provide a receptacle mainly comprising an
upper cover, an intermediate support, and a base. A mounting strap is
installed between the
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upper cover and the intermediate support, and an electric circuit board is
installed between
the intermediate support and the base.
The upper cover comprises an electric output plug, a test button, and a reset
button.
The mounting strap comprises a ground point that is connected to a ground
receptacle
of the electric output plug through an opening in the upper cover.
The intermediate support comprises a pair of output conductors made of
conductive
materials. The two output conductors each have pieces corresponding to the hot
receptacle
and the white receptacle on the electric output plug on the upper cover. The
output
conductors also comprise, respectively, electric contacts corresponding to
electric contacts on
a flexible electric input piece on the electric circuit board. A test button
switch piece is
located between one of the output conductors and the test button.
The electric circuit board comprises a pair of flexible input components
having four
flexible input fingers, a differential transformer for testing for leakage of
electric current, a
solenoid coil having a plunger therein, a reset button bias member, and a
flexible switch.
The flexible input components are located on both sides of a central opening
in the
reset button bias member and passes through the differential transformer to
connect to the
electric input point. The flexible input fingers include two pairs of electric
contacts, one pair
of the electric contacts correspond to a pair of the electric contacts on the
output conductor in
the intermediate support, while the other pair corresponds to a pair of
electric contacts on the
output conductors.
The base encloses the electric circuit board and the intermediate support.
Both sides
of the base comprise, respectively, a pair of electric input connection screws
and a pair of
electric output connection screws connected in parallel. The electric input
connection screws
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connect to the flexible input components in the electric circuit board, and
the electric output
connection screws connect to the electric output metal pieces in the base.
The reset button bias member is comprised of a cylinder located underneath the
reset
button. A central opening is provided in the reset button bias member, a
movable L-shaped
latch is arranged at the bottom of the reset button bias member. The latch has
an opening. A
directional lock is located inside the reset button bias member and vertically
passes through
the central opening. The directional lock has a bottom surface, and a locking
groove is
located above and close to the bottom surface of the directional lock. A
spring is provided on
the directional lock and biases the reset button. Another spring is also
located between one
side of the reset button bias member and the latch component.
The flexible switch is located between the reset button bias member and the
electric
circuit board. The flexible switch is made of flexible conductive material. A
first end of the
flexible switch is attached to the electric circuit board and is connected to
a resistor. The
resistor is coupled to an anode of a rectifier circuit on the electric circuit
board. A second end
of the flexible switch has a protruding pinpoint contact corresponding to a
contact on the
electric circuit board, which is in turn connected to a gate trigger of a
silicon-controlled
rectifier (SCR) that is connected to the solenoid coil on the electric circuit
board.
A test resistor is located underneath the test button with one end series
connected to a
white line of the electric input wire.
In another exemplary embodiment, a reset apparatus for a circuit interrupting
device
including a line side connection capable of being electrically connected to a
source of
electricity; a load side connection capable of being electrically connected to
a load side
conductor, is provided. The reset apparatus comprises a reset button having a
depressed and
a relaxed position. A resilient element biases the reset button into the
relaxed position. A
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directional lock is coupled to the reset button and has a bottom surface. A
bias member is
arranged under the reset button, the reset bias member defines a central
aperture therein
receiving the directional lock. The directional lock is moveable in a vertical
direction in the
aperture. A first pair of electric contacts is provided for making an electric
connection
between the line side connection and the load side connection. A latch extends
into the bias
member and through the aperture, the latch defines an opening therein and is
movable
through the aperture in a horizontal direction between an aligned position in
which the
opening is aligned with the bottom surface of the directional lock and a
misaligned position
in which the opening is misaligned with the bottom surface of the directional
lock. The latch
is adapted to engage the directional lock such that movement of the reset
button to the relaxed
state causes the bias member to close the first pair electric contacts.
In another exemplary embodiment the circuit interrupting device comprises a
line side
connection capable of being electrically connected to a source of electricity.
A load side
connection capable of being electrically connected to a load side conductor
for providing
electricity to a load side. A user load connection capable of conducting
electricity to at least
one load for providing an electrical connection to the source of electricity.
A first conductive
path provides an electrical connection between the line side connection and
the user load
connection. A second conductive path provides an electrical connection between
the line side
connection and the load side connection. A reset mechanism for establishing an
electrical
connection. First means for detecting a fault condition and second means,
separate from the
first means, for testing for a reverse wiring condition when the reset
mechanism is actuated
are also provided. Means interrupt at least one of the first conductive path
or the second
conductive path when a reverse wiring condition or a fault is detected.
According to another embodiment, the circuit interrupting device comprises a
first
conductor and a second conductor. A first pair of contacts is provided with
each contact
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coupled to one of the first and second conductors. A second pair of contacts
is moveable to a
closed position via a reset button. A plunger is disposed in a solenoid. The
plunger is
moveable between a first position and second position when the solenoid is
energized and de-
energized, respectively. A current controller is coupled to the solenoid and
to at least one of
the first and second conductors via the second pair of contacts. The current
controller
prevents current flow through the solenoid to de-energize the solenoid when
the first and
second conductors are reverse wired and allows current flow to energize the
solenoid when
the first and second conductors are wired correctly. A fault detection circuit
energizes the
solenoid when a fault is detected. When the solenoid is energized via the
current controller,
the plunger initiates closing of the first pair of contacts to complete a
circuit between the first
and second conductors and when the solenoid is energized via the fault
detection circuit the
plunger initiates opening of the first pair of contacts to interrupt the
circuit between the first
and second conductors.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a three-dimensional exploded view of the circuit interrupting
device of the
present invention.
Figure 2 is a perspective view of the circuit interrupting device of an
embodiment of
the present invention.
Figure 3 is a perspective view of the circuit interrupting device of an
embodiment of
the present invention without the upper cover.
Figure 4 is a view of the components on the electric circuit board placed
inside the
base of the circuit interrupting device of an embodiment of the present
invention.
Figure 5A is a sectional view of Figure 3 following line A-A, schematically
showing
an interruption of the electric connection between the electric input end and
the electric
output end in the circuit interrupting device of an embodiment of the present
invention.
Figure 5B is a sectional view of Figure 3 following line B-B, schematically
showing
an interruption of the electric connection between the electric input end and
the electric
output end in the circuit interrupting device of an embodiment of the present
invention.
Figure 6A is a sectional view of Figure 3 following line A-A, schematically
showing
the electric connection between the electric input end and the electric output
end in the circuit
interrupting device of an embodiment of the present invention.
Figure 6B is a sectional view of Figure 3 following line B-B, schematically
showing
the electric connection between the electric input end and the electric output
end in the circuit
interrupting device of an embodiment of the present invention.
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Figure 7A is a sectional view of Figure 3 following line A-A, schematically
showing
the interruption of the electric connection between the electric input end and
the electric
output end in the circuit interrupting device of an embodiment of the present
invention.
Figure 7B is a sectional view of Figure 3 following line B-B, schematically
showing
the interruption of the electric connection between the electric input end and
the electric
output end in the circuit interrupting device of an embodiment of the present
invention.
Figure 8 is a schematic diagram of the electric circuit of the circuit
interrupting device
of an embodiment of the present invention.
DETAILED DESCRIPTION OF INVENTION
As shown in Figures 1-4, a circuit interrupting device, for example a GFCI, an
AFCI,
or other device, according to an exemplary embodiment of the present invention
mainly
comprises an upper cover 2, an intermediate support 3, and a base 4 assembled
together. As
shown in Figure 2, on the upper cover 2, there are two electric output plugs 5
and 6, a test
button (TEST) 7, and a reset button (RESET) 8.
A mounting strap 1 is installed between the upper cover 2 and the intermediate
support 3. The mounting strap 1 has ground points 11, 12 that are connected to
ground
receptacles of the electric output plugs 5, 6 through openings in the upper
cover 2. An
electric circuit board 18 is installed between the intermediate support 3 and
the base 4.
As shown in Figure 3, the intermediate support 3 includes a pair of output
conductors
13, 14 that are made from conductive materials. The output conductors 13, 14
are disposed
on either side of the support 3. The two output conductors 13 and 14 have
conductive
members 60, 61, 62, and 63 corresponding to the hot receptacles and white
receptacles of the
electric output plugs 5, 6 in the upper cover 2. Additionally, the output
conductors 13, 14
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also comprise, respectively, electric contacts 15 and 16. A test button switch
piece 40 is
located between one of the output conductors 13, 14 and the test button 7.
As shown in Figure 1, the base 4 is used as a housing to enclose the
intermediate
support 3 and the electric circuit board 18. Both sides of the base 4
comprise, respectively, a
pair of electric input connection screws 9 (HOT) and 10 (WHITE) and a pair of
electric
output connection screws 109 (HOT) and 110 (WHITE), coupled in parallel.
Inside the base
4, there are a pair of electric output leads 81 and 80 connected to the
electric output
connection screws 109 (HOT) and 110 (WHITE) respectively. The electric output
leads 80
and 81 have two electric contacts 52 and 53, respectively.
As shown in Figures 4 and 5A, inside the base 4, the electric circuit board 18
comprises a pair of electrically conducting flexible input components 95, 96
having four
flexible input fingers 20, 21, 50, and 51, a differential transformer 19 for
testing for leakage
of electric current, a solenoid coil 26 having a plunger 42 therein, a reset
button bias member
28, and a flexible switch 37.
The flexible input fingers 20, 21, 50 and 51 at one end of the flexible input
components 95, 96 have electric contacts 22, 23, 55 and 54. The other ends of
the flexible
input components 95, 96 pass through the differential transformer 19 to
connect via input
leads 24 and 25 to the electric input connection screws 9 and 10. The electric
contacts 22 and
23 on the flexible input fingers 20, 21 correspond to the electric contacts 15
and 16 on the
output conductors 13, 14 in the intermediate support 3. The electric contacts
54 and 55 on
the flexible input fingers 50, 51 correspond to the electric contacts 52 and
53 on the electric
output leads 80 and 81 in the base 4.
Also included on the electric circuit board 18 is a solenoid coil 26, with a
plunger 42
placed inside. A test resistor 27 is located underneath the test button 7 on
the upper cover 2,
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with one end of the test resistor 27 connected to the input connection screw
10 (WHITE) (See
Figure 8).
Referring now to Figures 5A and 5B, the reset button bias member 28 on the
electric
circuit board 18 is located underneath the reset button 8. A housing 100 may
be provided to
support the reset button bias member (See Figure 1). A portion of the bias
member 28 is
arranged below the flexible input fingers 20, 21, 50 and 51, as best seen in
Figure 5B. A
central opening 29 is provided in the top of the reset button bias member 28,
and a movable
L-shaped latch 30 is arranged at the bottom of the reset button bias member
28. The latch
component 30 includes an opening 31. The latch 30 has a first leg that extends
into bias
member 28 and through the central opening 29. The latch 30 is preferably
movable in a
horizontal direction through the bias member 28. A second leg of the latch 30
is disposed
along side of the bias member 28. A circular groove 33 is provided between one
side of the
reset button bias member 28 and the second leg of the latch 30. The circular
groove 33 has a
spring 34 fit therein. The spring 34 is biased against the second leg of the
latch 30. A
directional lock 35 is located inside the reset button bias member 28 and
vertically passes
through the central opening 29. The directional lock 35 has a bottom surface
41. A locking
groove 36 is provided on the directional lock 35, near the bottom surface 41.
A spring 91 is
provided to the top of the directional lock 35, beneath the reset button 8.
As shown in Figures 5A and 8, the flexible switch 37, made of a flexible
conductive
material, is located between the reset button bias member 28 and the electric
circuit board 18.
A first end of the flexible switch 37 is connected to the electric circuit
board 18. A second
end of the flexible switch 37 is moveable and has a protruding pinpoint
contact 39 that
corresponds to a contact 38 disposed on the circuit board 18 underneath
contact 39. The first
end of the flexible switch 37 is connected to a rectifier circuit 120, and the
second end of the
flexible switch is connected to a gate trigger 121 of a SCR (See Figure 8).
The flexible
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switch 37 and the SCR are used to test for and to guard against reverse
wiring, i.e. to prevent
an error in connecting the electric input wiring and the electric output
wiring of the circuit
interrupting device, as is described in more detail below.
Figures 5A-6B indicate an example of a scheme under which the circuit
interrupting
device of an exemplary embodiment of the present invention works to prevent
leakage of
electric current and to interrupt an electric connection between the input and
the output.
Figures 5A and 5B illustrate an exemplary circuit interrupting device with the
circuit
interrupted, that is, there in no connection between contacts 15, 16, 52, 53
and contacts 20,
21, 50, 51, respectively. In Figures 5A and 5B, the reset button 8 is
depressed to reset the
circuit interrupting device to a conducting state. When the reset button 8 is
depressed, the
directional lock 35 moves downward. As can be seen in Figure 5A, the opening
31 in latch
30 is misaligned, that is, offset, with the bottom surface 41 of the
directional lock 35. Thus
the bottom surface 41 cannot pass through the opening 31 and is pressed
against the surface
of the latch 30. The downward action of the directional lock 35 against the
latch 30 causes
the bias member 28 to move downward. Because of the downward movement of the
reset
button bias member 28, the pinpoint contact 39 on the flexible switch 37 is
moved downward
and connected to contact 38 as shown in Figures 5A and 5B.
As shown in Figure 8, the flexible switch 37 is connected at one end to
resistor 27,
which in turn is connected to an anode 120 of a rectifier circuit. The other
end of the flexible
switch 37 is connected through the contact 38 to a trigger gate 121 of the
SCR. An electric
connection between contacts 38 and 39 completes a circuit between gate 121 and
anode 120.
When the electric input and output wiring is connected to the circuit
interrupting device
properly, i.e. no reverse wiring, a positive voltage is provided at anode 120.
This voltage
should bias the SCR into a conducting state, allowing current to flow through
the solenoid
coil 26. The solenoid coil 26 is thus charged with electricity and yields a
magnetic field,
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which draws the plunger 42 inward to hit on the latch 30. The latch 30 moves
with the
plunger 42 against the force of spring 34, to the left in Figure 5A. The
movement of latch 30
aligns the opening 31 with the bottom surface 41 of the directional lock 35
such that the
bottom surface 41 of the directional lock 35 passes through the opening 31, as
shown in
Figures 6A and 6B.
Figures 6A and 6B illustrate the state of the circuit interrupting device
after the reset
button 8 is released. When the reset button 8 is released, the pinpoint
contact 39 and the
contact 38 of the flexible switch 37 are disconnected. A voltage is no longer
present at gate
121 and the SCR is no longer biased into a conducting state. Thus, the
electric current no
longer flows through solenoid coil 26 and the solenoid coil 26 no longer
produces the
magnetic field. In turn, the plunger 42 no longer acts on the latch 30. The
spring 34 between
the latch 30 and the reset button bias member 28 causes the latch 30 to move
back towards its
misaligned position, to the right in Figures 5A and 6A. However, since the
directional lock 35
is now positioned in opening 31, the latch 30 cannot move completely back to
the misaligned
position. Instead, the opening 31 of the latch 30 slides into the locking
groove 36 of the
directional lock 35. Due to the force of spring 34, the directional lock 35
and the latch 30 are
engaged with each other as shown in Figure 6A.
At substantially the same time the connection between contacts 38 and 39 is
broken,
the release of the reset button 8 allows the spring 91 near the top of the
directional lock 35 to
move the reset button 8 and the directional lock 35 upward. Due to the
engagement of the
directional lock 35 with the latch 30, via the locking groove 36 and opening
31 as described
above, the reset button bias member 28 also moves upward. The bias member 28,
in turn,
lifts the contacts 22, 23, 55, and 54 on the flexible input fingers 20, 21,
50, and 51 upward to
connect to the contacts 15 and 16 of the output conductors 13, 14 and to the
contacts 52 and
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53 of the electric output leads 80 and 81, so that the input and output are
electrically
connected (Figures 6A and 6B).
Figures 5A, 5B, and 8 also illustrate an exemplary scheme of protection to
interrupt
the electric connection of the electric input and the electric output on the
circuit interrupting
device of an exemplary embodiment the present invention when the electric
input is
mistakenly reverse-wired to the electric output on the circuit interrupting
device. When the
circuit interrupting device is reverse-wired, the pair of electric input wires
are connected to
the electric output screws 109, 110 and the electric output wires are
connected to the electric
input screws 9, 10. As indicated in Figure 8, although the circuit
interrupting device itself is
intact, when the reset button 8 is pressed down so that the two contacts 39
and 38 of the
flexible switch 37 are connected, due to the reverse wiring, there is no
electric voltage at the
trigger gate of the SCR. Thus, the SCR is in a non-conducting state so that no
electric current
can pass through the solenoid coil 26. As a result, the plunger 42 does not
move inward into
the solenoid 26 and does not hit on the latch component 30. The opening 31 in
latch 30
remains misaligned with the bottom surface 41 of the directional lock 35. The
directional
lock 35 cannot pass through opening 31 and the bottom surface 41 of the
directional lock 35
stays pressed against the surface the latch component 30.
Consequently, when the reset button is released, bias member 28 does not move
upward. Therefore, the contacts 22, 23, 55, and 54 of the flexible input
fingers 20, 21, 50,
and 51 are not connected to the contacts 15 and 16 of the output conductors 13
and 14 and the
contacts 52 and 53 of the electric output leads 80 and 81, as is shown in
Figures 7A and 7B.
Consequently, there is no electric connection between the electric input and
the electric
output.
Figures 7A, 7B and 8 also illustrate the state of an exemplary circuit
interrupting
device when a fault has been detected. Initially, the circuit interrupting
device is in the
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position illustrated in Figures 6A and 6B, with the contacts closed. When the
differential
transformer 19 of the circuit interrupting device of an exemplary embodiment
the present
invention detects a leakage electric current, a signal is provided to the IC
(Figure 8). The IC
generates a signal that biases the SCR into conducting state so that the
solenoid coil 26 has
electric current flowing therein, which produces a magnetic field. The plunger
42 is drawn
into the solenoid coil 26 by the magnetic field and hits on the latch 30,
which pushes the latch
30 against the force of spring 34. The latch 30 is thus moved to its aligned
position. The
locking groove 36 on the directional lock 35 slides out of engagement with the
opening 31 of
the latch 30. The directional lock 35 is now free to move through opening 31.
The reset
button 8 moves up due to the force of the spring 91 and pulls the directional
lock 35 upwards.
The reset button bias member 28 slides downward when pushed by flexible input
fingers 20,
21, 50, and 51. In turn, the contacts 22, 23, 55, 54 of the flexible input
fingers 20, 21, 50, and
51 separate from the contacts 15 and 16 of the output conductors 13 and 14 and
the contacts
52 and 53 of the electric output leads 80 and 81. Thus, the electric
connection between the
electric input and the electric output is interrupted, as shown in Figures 7A
and 7B.
When the user wants to disconnect the electric connection between the electric
input
and the electric output of the circuit interrupting device, the test button 7
is depressed so that
the test button switch 40 is connected to the test resistor 27. When the
differential
transformer 19 detects a test leakage electric current, the SCR becomes
conducting.
Consequently, the solenoid coil 26 has electric current flowing therein, which
produces a
magnetic field. The magnetic field draws the plunger 42 inward so that it hits
on the latch 30,
which pushes the latch 30 against the force of spring 34. The latch 30 is thus
moved to the
aligned position. The locking groove 36 on the directional lock 35 thus slides
out of the
opening 31 of the latch component 30, see Figure 7A. The reset button 8 moves
upward
because of the force of spring 91 at the top of the directional lock 35 and
the reset button bias
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member 28 moves downward due to the flexible input fingers 20, 21,50, and 51.
As a result,
the contacts 22, 23, 55, and 54 on the flexible input fingers 20, 21, 50, and
51 are
disconnected from the contacts 15 and 16 of the output conductors 13 and 14
and the contacts
52 and 53 on the electric output leads 80 and 81. Thus, the electric
connection between the
electric input and the electric output is interrupted.
The above detailed description is illustrative, but not limiting the scope of
the present
invention. Reasonable variations, such as those occur to reasonable artisan,
can be made
herein without departing from the scope of the present invention.
