Note: Descriptions are shown in the official language in which they were submitted.
CA 02579626 2007-02-26
CIRCUIT INTERRUPTING DEVICE WITH
AUTOMATIC END OF LIFE TEST
RELAUD APPLICATJ,ON
S The present application is a Continuation-In-Part (CIP) of U.S. Patent
Application Serial
No. 11/362,037, filed on February 27,2006, which claims the priority of U.S.
Provisional Patent
Application Serial No. 60/656,090, filed on February 25,2005, which are herein
incorporated by
reference.
IIWENTION
FIELD OF THE
The present invention relates to a circuit interrupting device, preferably a
ground fault
circuit interrupter (GFCI), which contains a test circuit capable of
automatic.ally
generating a simulated leakage current to detect whether the main components
of the
device are worlcing properly, when the device is properly connected to power
input
terminals (Le., not reversely wired or miswired) and is in a tripped state.
'1'he test circuit
contains an end-of-service-Iife integrated circuit clsip, which is connected
to a switch
which becomes conductive when the device is powered properly and is in a
tripped state.
Thereby, by observing whether the device is capable of being reset, a user can
determine
whether the service life of the device has ended. Optionally, the circuit
interrupting
device contains an indicating light. Thereby, by observing whether a normal
status
indicating light or a problenr status indicating light is turned on and
displayed on the face
of the device, the user can determine whether the service life of the device
has ended.
The circuit interrupting device also possesses a forcible tripping mechanism
through the
operation of the test button to interrupt the power output to the device. The
present
invention also relates to methods for detecting the end of service life of the
circuit
interrupting device.
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BACKGROUND OF THE INVENTION
Circuit interrupting devices, such as ground fault circuit interrupters
("GFCIs") and are
fault circuit interrupters ("AFCIs") have been widely used by consumers since
the 1970s.
Nowadays, due to household safety concerns, there are needs for GFCIs with
extra safety
features. According to new UL standards under UL 943, which are saheduled to
be in effect
starting in July 2006, a GFCI will be required not only to have reverse wiring
protection, but also
to be able to provide a user with indications to alert the user when the GFCI
has reached the end
of its service life and is no longer capable of providing ground fault
protection. That is because
for most of the GFCIs currently available on the market, when their service
life ends, resetting by
pressing the reset button is still possible, which gives the users a false
sense of security that they
are still under proper protection of the GFCI, while in fact the GFCI's
capability of sensing a
ground fault and interrupting the flow of electricity due to a ground fault
may have been
compromised. Thus, when a ground fault occurs, the GFCI may be unable to
provide any
protection, which can result in fatal electric shocks.
In the invention to be presented in the following sections, a newly-designed
GFCI which
is capable of performing an end of life test is provided. The GFCI of the
present invention
allows the user to automatically detect whether the service life of the device
has ended without
operating any parts when a source of electricity has been connected. If the
GFCI can be reset,
the GFCI shows a continuing capability of detecting a ground fault. If the
GFCI cannot be reset,
it means that the end of the service life of the GFCI has been reached, and
that the user should
consider replacing the GFCI.
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SUMMARY OF THE INVENTION
The present invention provides a circuit interrupting device which comprises a
test circuit
which can automatically generate a simulated'leakage current to test the main
components of the
circuit interrupting device. If the circuit interrupting device is properly
connected to the power
source (i.e., not reverse wired or miswired), is in a tripped state, and all
of the main components
of the circuit interrupting device are working properly, the circuit
interrupting device can be
reset. If the circuit interrupting device is powered properly and is in a
tripped state, but at least
one of the main components of the circuit interrupting device is not working
properly, such as
when one or more of the main components is damaged, shorted or opened, the
test circuit does
not permit the circuit interrupting device to be reset. '
The circuit interrupting device can be a ground fault circuit interrupter
("GFCI"), an arc
fault circuit interrupter ("AFCI"), an immersion detection circuit
interrupter, an appliance
leakage circuit interrupter, or a circuit breaker.
The test circuit comprises an end-of-service-life detecting integrated circuit
chip, which
can automatically generate a leakage current when the circuit interrupting
device is powered and
the device is in a tripped state.
The main components of the circuit interrupting device that can be detected by
the test
circuit include, but are not limited to, a differential transfonner (LI), a
leakage detection control
integrated circuit chip (IC 1), an end-of-service-life detecting integrated
circuit chip (IC2), optical
couplers (IC3, IC4), a silicon control rectifier (SCR), a solenoid coil (SOL),
and/or a capacitor.
IC1 is connected to the differential transformer LI. Examples of IC1 include
RV4145
from Fairchild Semiconductor InternationaI and other commercially available
chips such as from
National Semiconductor Co. When a fault is detected, the differential
transformer sends a signal
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to IC I, which in turn sends a signal to the SCR to interrupt electrical
continuity in the circuit
interrupting device.
The end-of-service-life detecting integrated circuit chip (IC2), on the other
hand, is
connected to a switch (KRI), which is closed and becomes conductive when the
reset button
(RESET) is in the tripped position, which in turns sends a signal to IC2 to
generate a simulated
leakage current to test the main components of the circuit interrupting
device. If all of the mairi
components in the circuit interrupting device are working properly, IC2 sends
a signal which
allows the reset button (RESET) to be reset; but when at least one of the main
components of the
circuit interrupting device is not working properly, no signal is sent by IC2
and the reset button
(RESET) cannot be reset. If the reset button (RESET) is in a reset state, the
switch is non-
conductive, and no signal can be sent to IC2 to generate the simulated leakage
current to test the
device.
The switch (KRI) comprises a fixed frame and two spring pieces. The two spring
pieces
are connected to pins 2 and 4 of IC2, respectively. When the switch (KR1) is
conductive, and all
of the main components in the circuit interrupting device are working
properly, the device can be
reset, which makes the switch non-conductive. Optionally, IC2 is connected to
a normal status
indicating light or a problem status indicating light through an optical
coupler; iespeetively. If
the device is working properly, the normal status indicating light is turned
on. When at least one
of the components of the circuit interrupting device is not working properly,
the problem status
indicating light is turned on. Preferably, the normal status indicating light
displays a green light
and the problem status indicating light displays a red light or a yellow
light.
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The circuit interrupting device further comprises a manual test circuit, which
generates a
simulated leakage current to trip the circuit interrupting device when the
test button (TEST) is
depressed.
The circuit interrupting device of the present invention can be a ground fault
circuit
interrupter (GFCI). The GFCI contains (a) a housing; (b) a tripping device
positioned in a base
of the housing; (c) a circuit board positioned in the base of the housing,
which contains (1) a first
pair of flexible metal pieces operationally connected to power source input
terminals; one end of
each of the first pair of flexible metal piece passing through a differential
transformer to be
operationally connected to a hot input line or a neutral input line; the other
end of each of the
first pair of flexible metal pieces having a movable contact; (2) a second
pair of flexible-metai
pieces; one end of each of the second pair of flexible metal piece is
operationally connected to a
hot power output terminal or a neutral power output terminal; the other end of
each of the second
pair of the flexible metal pieces has a movable contact point; (3) a pair of
output conductors
positioned in the insulated middle support; each of the output conductors
contains a pair of fixed
contacts. The movable contact of each of the first pair of flexible metal
pieces and the movable
contact of each of the second pair of flexible metal pieces are capable of
connecting/
disconnecting to each of the fixed contacts on the pair of output conductors
to form two groups
of four pairs of power switches (i.e., KR2-l, KR2-2, KR3-l, KR3-2). Also, each
of the pair of
the output conductors has a pair of gripping wing pieces protruding through
the output socket
holes at the front lid of the housing. In addition, each of the movable
contacts of the first pair of
the flexible metal pieces is in a different cross-sectional plane from each of
the movable contacts
of the second pair of flexible metaT pieces. Furthermore, below each of the
first and second pairs
of the flexible metal pieces, there is a position limiting piece.
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The tripping device comprises a tripper, a locking member, a locking spring, a
tripping
lever, and a solenoid coil.
The tripper is positioned underneath a reset button (RESET). The tripper has a
central
through-hole to receive a directional lock which is coupled to the reset
button. The directional
lock has a blunt end and a circular recess. The directional lock is movable in
a vertical direction
in the through-hole. The locking member is L-shaped, containing a horizontal
side extending
into the tripper and through the through-hole and a vertical side having an
inner surface and an
outer surface. The horizontal side of the locking member has a through-hole
therein. The
locking member is movable in a horizontal direction between an aligned
position in which the
through-hole of the locking member allows the blunt end of the directional
lock to pass through
and a misaligned position in which the circular recess of the directional lock
is locked into the
misaligned through-hole of the locking member. The locking spring is located
between a side
wall of the tripping device and the inner surface of the vertical side of the
L-shaped locking
member. The solenoid coil is positioned at the outer surface of the L-shaped
locking member.
The solenoid coil has an iron core. When the solenoid coil is energized, the
iron core moves
towards the outer surface of the vertical side of the locking member, thereby
moving the locking
member into the aligned position; and the tripping lever is connected to a
hole at the horizontal
side of the L-shaped locking membtr.
The tripper comprises a pair of lifting arms positioned below each of said
movable
contacts. Also, the bottom of the tripper is operationally connected to the
circuit board through a
power source switch containing a movable contact located at the bottom of the
tripper and a
fixed contact located at the circuit board; whereby. when the reset button is
depressed, the
movable contact is in contact with the fixed contact so as to close the power
source switch and
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when the reset button is released, the movable contact is detached from the
fixed contact so as to
open the power source switch.
The GFCI further comprises a test button (TEST). The test button has a tail
end which is
extended to an end of the tripping lever. When the test button is depressed,
the tail end of the
test button presses against the tripping lever, which causes the GFCI to
mechanically trip.
The present invention also provides a method for detecting whether the service
life of the
circuit interrupting device has ended. The first method requires that the user
(1) power the
circuit interrupting device properly (i.e., without reverse wiring or
miswiring); (2) make sure that
the device is in a tripped state (if not, the user can depress the test button
to manually trip the
device); and (3) observe whether the circuit interrupting device can be reset.
If the circuit =
interrupting device can be reset, the service life of the circuit interrupting
device has not ended.
If the circuit interrupting device cannot be reset, the service life of the
circuit interrupting device
has ended, and the user should consider replacing the device with a new one.
The tripped state
can be induced by a ground fault, a simulated leakage current, or by
mechanical tripping
mechanism. In most occasions, a GFCI manufactured by a factory is generally
delivered in a
tripped state before being installed.
Optionally, the user can observe whether a normal status indicating light or a
problem
status indicating light is lighted on the face of the receptacle to determine
whether the device has
reached the end of the service life or not. If the normal status indicating
light is turned on, the
circuit interrupting device is still working properly; if the problem status
indicating light is
turned on, the service life of the circuit interrupting device has ended.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a cutaway oblique view illustrating the structure of the present
invention.
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Figure 2 is the front view of the present invention.
Figure 3 is the front view of the present invention with the top cover
removed.
Figure 4 is a diagram illustrating the positional relationship of each part on
the circuit
board in the present invention.
Figure 5-1 is a partial cross-section along C-C in Figure 3, illustrating the
initial =state of
the GFCI.
. Figure 5-2 is a partial cross-section along C-C in Figure 3, illustrating
the normal
working state of the GFCI.
Figure 5-3 is a partial cross-section along C-C in Figure 3; illustrating the
state when the
receptacle trips as the test button is depressed.
Figure 5-4 is a partial cross-section along GC in Figure 3, illustrating the
state when the
receptacle is forcibly tripped by depressing the test button.
Figure 6-1 is a partial cross-section along A-A in Figure 3, illustrating the
tripping state
of the receptacle.
Figure 6-2 is a partial cross-section along A-A in Figure 3, illustrating the
reset state of
the receptacle.
Figure 7 is a logic closed-loop block diagram of the control circuits used in
the present
invention.
Figure 8 is a detailed circuit diagram of the control circuit used in the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
As shown in Figure 1, the circuit interrupting device, such as a ground fault
circuit
interrupter, as disclosed in the present invention, mainly comprises a housing
and a circuit board
18, which is installed within the housing. The circuit board 18 not only can
control the GFCI to
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CA 02579626 2007-02-26
have or not to have power output but also can automatically test whether the
service life of the
GFCI has ended, that is, whether the circuit still has the electrical leakage
or ground fault
protection function and can display the test result without operating any
parts of the device.
In the housing, there are a front lid 2, an insulated middle support 3 and a
base 4. A
metal mounting strap 1 is installed between the front lid 2 and the insulated
middle support 3.
Circuit board 18 is installed between the insulated middle support 3, and the
base 4.
As shown in Figures 1 and 2, power output sockets 5, 6, reset button hole 8-A,
test button
hole 7-A, and status indicating light hole 30-A are found on front lid 2.
Reset button (RESET) 8
and test button (TEST) 7 are installed in reset button hole 8-A and test
button hole 7-A,
respectively. Reset button 8 and test button 7 penetrate through metal
mounting strap 1 and
insulated middle support 3 to make contact with the parts on circuit board 18.
Four hooks 2-A
are arranged on the side of front lid 2 to hook in the slot 4-B on base 4.
Metal mounting strap 1 is grounded through grounding screw 13-A (as shown in
Figures
1-2) and wires. Grounding pieces 11,12 are arranged on metal mounting strap 1
at places
corresponding to the grounding holes of power output sockets 5, 6 of front lid
2.
As shown in Figures 1 and 3, a hot power output conductor 14 and a neutral
power output
.... .
conductor 13 are installed on the two sides of the insulated middle support 3.
At the two ends of
power output conductors 13, 14, gripping wing pieces 60, 61, 62, 63 are
arranged at the places
corresponding to the hot and neutral holes of power output sockets 5, 6 on the
front lid 2. Fixed
contacts 15, 52 and 16, 53 are arranged on power output conductors 13, 14,
respectively, to form
two pairs of fixed contacts 15, 16 and 52, 53.
As shown in Figure 1, base 4 is used to accommodate insulated middle support 3
and
circuit board 18. A pair of hot and neutral power input wiring screws 9, 10
and a pair of hot and
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neutral power output wiring screws 109, 110 are installed symmetrically on the
two sides of base
4.
The key part ofthe present ixvention is the circuit board 18, which is
installed in the
housing. The circuit board 18 supplies power to or cuts power from the power
output sockets 5,
6 of front lid 2 and the power output wiring screws 109, 110 on the two sides
of base 4 and has
the capability of automatically detecting whether the service life of the GFCI
has ended.
As shown in Figures 1 and 4, two resilient power input metal pieces 50, 51 are
arranged
on circuit board 18. One end of the flexible power input metal pieces 50, 51
is bent downward at
a 90 angle, penetrates through differential transformer 19, and is soldered
onto circuit board 18,
and is connected to hot and neutral power input =wiring screws 9, 10 via input
wiring pieces 24,
25. Neutral power input wiring screw 9 is connected to the neutral wire of the
power supply
inside the wall via a conductive wire. Hot power input wiring screw 10 is
connected to the hot
wire of the power supply inside the wall via a conductive wire. Movable
contacts 54, 55-are
arranged at the other end of flexible power input metal pieces 50, 51. The
movable contacts 54,
55 correspond to the fixed contacts 52, 53 (as shown in Figure 3) on the power
output conductors
13, 14, respectively, which are arranged on insulated middle support 3. Two
texible metal
output pieces 20, 21 are an-anged on two sides above circuit board 18. One end
of the flexible
metal output pieces 20, 21 is soldered together with the metal pieces 80, 81
onto the printed-
circuit board and is connected to the power output wiring screws 109, 110 oii
the two sides -of
base 4. Movable contacts 22, 23 are arranged at the other end of the flexible
metal output pieces
20, 21. The movable contacts 22, 23 correspond to the fixed contacts 15, 16 on
power output
conductors 13, 14 (as shown in Figure 3). As shown in Figure 8, the movable
contact 55 on the
hot power input metal piece 51 and the fixed contact 53 on hot power output
conductor 14 form a
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CA 02579626 2007-02-26
pair of switches KR2-1. The movable contact 54 on neutral power input metal
piece 50 and the
fixed contact 52 on neutral power output conductor 13 form a pair of switches
KR2-2. The fixed
contact 16 on hot power output conductor 14 and the movable contact 23 on
flexible metal piece
21 form a pair of switches KR3-1. The fixed contact 15 on neutral power output
conductor 13
and the movable contact 22 on flexible metal piece 20 form a pair of switches
KR3-2. The
movable contacts and fixed contacts on the power input metal pieces 50, 51,
power output
conductors 13, 14, and flexible metal output pieces 20, 21 form two groups of
four pairs of
power switches KR2-l, KR2-2, KK3-1, KR3-2. -
As shown in Figures 1, 4, and 5-1, a tripping device, which can effect power
connection/disconnection between flexible power input metal pieces 50, 51 and
power output
conductors 13, 14 and can supply or interrupt electric power to or from
flexible metal output
pieces 20, 21 through power output conductors 13, 14 to effect power
connection/disconnection
with respect to power output conductors 80, 81, is also arranged on circuit
board 18. This
tripping device includes tripper 28, locking.member 30, locking spring 34,
tripping lever 37, and
solenoid coil 26.
The tripper 28 is located below reset button 8 and has a cylindrical shape.
Its left and
right sides extend outwardly to form lifting arms. The flexible power input
metal pieces 50, 51
and flexible metal output pieces 20, 21 are located above the left and right
lifting arms and can
move up and down along with tripper 28. Also, as shown in Figure 4, the
movable contact 54 on
power input metal piece 50 and the movable contact 22 on flexible metal output
piece 20 cross
each other at a position above the side lifting arm of tripper 28. Similarly,
the movable contact
55 on power input metal piece 51 and the movable contact 23 on flexible metal
output piece 21
also cross each other at a position above the side lifting arm of tripper 28.
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A longitudinal central through-hole 29 is formed at the top of tripper 28.
Reset
directional lock 35 equipped with reset spring 91 and embedded in the bottom
of reset button 8
can move up and down along central hole 29. The reset directional lock has a
blunt end. The
directional lock is movable in a vertical direction in the central through-
hole. A circular recessed
locking slot 36 is formed in the lower part of reset directional lock 35 close
to the bottom of the
directional lock to form a groove. A movable "L"-shaped locking member 30 made
of a metal
material is ananged in the lower part of tripper 28 and penetrates through
tripper 28. A through-
hole 31 is formed in the horizontal side of locking member 30. The locking
member 30 is
movable through the through-hole in a horizontal direction between an aligned
position in which
the through-hole of the locking member 30 is aligned with the blunt end of the
directional lock
35 to allow the directional lock to pass through and a misaligned position in
which the circular
recess of the directional lock 35 is locked into the through-hole of the
locking member 30. A
circular slot 33 is formed between the side wall of tripper 28 and the inner
side of locking
member 30. A locking spring 34 is arranged in the circular slot. A solenoid
coil 26 with a
movable iron core 42 arranged inside is arranged outside the side wall of
locking member 30.
The movable iron core 42 inside solenoid coil 26 faces the side wall of
locking member 30. A
protective cover 41 is ansanged above solenoid coil 26. One end of the
insulated middle support
presses against the protective cover 41.
A hole 32 is formed at one end on the top surface of locking member 30. A"7"-
shaped
tripping lever 37 penetrates through-hole 32. Tripping lever 37 is located
directly underneath the
test button 7. A pivot 28-A is arranged on the side wall of tripper 28 close
to tripping lever 37.
Tripper lever 37 can rotate around the pivot 28-A on the side waII of tripper
28.
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CA 02579626 2007-02-26
Tripper 28, locking member 30, locking spring 34, and tripping lever 37 are
connected to
each other to form an integral body that can move freely.
According to the present invention, the=movabEe iron core 42 located within
the solenoid
coil 26 can be moved toward and push locking member 30 when the solenoid coil
is energized.
As a result, reset directional lock 35 embedded in the bottom of reset button
(RESET) 8 can
move up and down along central through-hole 29 of tripper 28 and the locking
member hole 31
of locking member 30 to reset or trip reset button 8 to ensure whether or not
the GFCI has or
does not has power output. In other words, in the present invention, reset
button 8 is reset or
tripped through the tripping device so that the GFCI may or may not have power
output.
As shown in Figures 4 and 8, there is also a differential transformer 19
(coils LI, L2 in
Figure 8), which is used for detecting leakage current on circuit board 18.
Hot wire HOT and
neutral wire WHITE penetrate the differential transformer. When ground fault
occurs in the
power- supply circuit, the differential transformer will output a voltage
signal to leakage current
detection control chip IC I (such as model RV4145). Pin 5 of chip IC I will
output a control
signal to turn on silicon-controlled rectifier (SCR) V13 to trip the device on
circuit board 18 so
as to interrupt the power output.
As shown in Figure 4, circuit board 18 has two indicating lights used for
indicating
whether or not the service life of the GFCI has ended. One of the lights is
nonnal status
indicating light V17, while the other is problem status indicating light V l
0. As shown in Figures
6-1 and 6-2, light-guiding tube LEDI arranged in the longitudinal direction is
set on the
indicating lights V 17 and V 10. The top of light-guiding tube LED I is
located below the
indicating light hole 30-A on the surface of front lid 2. The light emitted
from the two indicating
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CA 02579626 2007-02-26
lights V 17, V 10 is refracted through light-guiding tube LED 1 to the surface
of the ground fault
circuit interrupter.
As shown in Figures 6-1, 6-2, 8, the present invention also utlilizes a switch
KR1, which
opens (i.e., non-conductive) and closes (i.e., conductive) in connection with
reset button 8
(RESET). The switch KR I comprises fixing frame 101 and two spring pieces 102,
103. Spring
piece 102 is connected to pin 2 of end-of-service-life detecting integrated
circuit chip IC2, with a
model no. of ZQC.051208, through resistors R7, R3 and capacitor Cl. Spring
piece.103 is
connected to pin 4 of end-of-service-life detecting integrated circuit chip
IC2. When the reset
button is in the tripped state, the spring piece 102 of switch KR1 is in
contact with spring piece
103 due to the inclined side surface of the reset button to enter the
conductive state (Figure 6-1).
When the reset button is at the reset state, since the inclined side surface
of the reset button
moves downwards, spring piece 102 restores the original shape and is separated
from spring
piece 103 to enter the non-conductive state (Figure 6-2). Therefore, in
connection with the state
of the reset button (RESET) 8 (i.e., in a tripped state or a reset state), the
switch KRl is capable
of sending a signal to end-of-service-life detecting integrated circuit chip
IC2 to test the main
components of the GFCI.
As shown in Figures 5-1 and 8, there is a power source switch KR4 made of a
flexible
metal material between the bottom of tripper 28 and circuit board 18. Power
source switch KR4
comprises two spring pieces 67, 68. Spring piece 67 is connected to pin 5 of
leakage detection
control chip IC 1, while spring piece 68 is connected to pin I of end-of-life
detecting chip -IC2
through resistor RIO. The power source switch KR4 also interacts with reset
button (RESET) 8.
When reset button RESET. is pressed down, power source switch KR4 is closed.
When reset
button (RESET') 8 is released, power source switch KR4 is opened.
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The IC power supply mode used in the present invention is a half-wave
rectifier with a
capacitor filter and a half-wave rectifier with a serial constant-voltage
filter. For example, V3,
R7, C6 are VCCI; V2, R8, V3, C7 are VCC2.
Figure 7 is the logic principle block diagram used by the control circuit in
the present
invention for realizing the leakage protection and the end-of-service-life
detecting function.
There are 8 circuits in the GFCI, namely U1, U2, U3, U4, U5, U6, U7, and U8.
As shown in
Figure 7, main circuit U I is used for detecting leakage current and
resetting/tripping of the reset
button; circuit U2 is used for generating a simulated leakage and displaying
the status of the
GFCI; circuit U3 is used for identifying the reset/trip state of the reset
button; circuit U4 is the
simulated testing and feedback circuit; circuit U5 is used for resetting a
voltage output; U6 is the
end-of-service-life detecting circuit; U7 is the manual testing circuit; and
U8 is used for
providing output voltage to the receptacle display. A test circuit which is
capable of generating a
simulated leakage current/ground fault to test the main components of the
GFCI.contains certain
portions of circuits U2, U3, U4, U5, and U6. Optionally, a certain portion of
circuit U8 can -be
included. The detailed circuitry as depicted in Figure 7 is for illustration
only. An artisan with
ordinary skill in the field would know which portions of the circuits are
required to construct the
test circuit.
The test circuit contains an end-of-service life detecting chip (IC2); which
is located in
circuit U6. IC2 is given a model no. ZQC-051208 by the inventors. IC2 has 8
pins, including
two pins, i.e., pins 7 and 8, which are currently reserved for other purposes
in the future. Pin I of
IC2 is for outputting a voltage signal to reset a circuit interrupting device.
Pin 2 of IC2 is for
receiving a signal from switch KR1 to detect the state of the device (i.e., in
a tripped state or a
reset state). Pin 3 of IC2 is for sending a signal to U2 to generate a
simulated leakage current.
DCDOCS/656301.1 15
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Pin 4 of IC2 is for receiving power for IC2. Pin 5 of IC2 is for receiving a
feedback signal. Pin
6 of IC2 is a grounding pin.
When the power input terminals LM, NIN of the GFCI are properly connected to
the hot
and neutral wires of the power sources inside the wall, i.e., without reverse
wiring or miswiring,
the device is powered. For most of the new device, the GFCI is in the tripped
state. Switch
KR1, which is a part of circuit U3 and whose two spring pieces are in
connection with the reset
button (RESET), recognizes the tripped state of the device and becomes
conductive (i.e., in a
closed condition). The closing of switch KRI produces a signal which is sent
through U3 to pin
2 of the end-of-service life detecting chip (IC2) in circuit U6, which in turn
sends a signal from
pin 3 to circuit U2 to generate a simulated leakage current. The simulated
leakage current passes
through circuits U I and U4. When the GFCI is working properly, circuit U4
sends a signal
denoting that a normal condition has been reached to the feedback signal
receiving pin 5 of IC2,
which in turn keeps pin 1 of IC2 at a high voltage level and sends a signal to
circuit U5 to allow
the device to be reset. Optionally, the elevated voltage level of pin 1 of IC2
can send a signal to
activate the normal status indicating light Vl7in circuit U8 through optical
coupler IC4. As a
result, the normal status indicating light on the face of the receptacle is
lighted, preferably in
green. At the same time, pin 3 of IC2 is changed to a low voltage level, and
as a result, the
simulated leakage current generated by circuit U2 is stopped. At this time, if
the reset button
(RESE'I) is depressed, the GFCI can be reset and function properly. Due to the
mechanical
interaction between the reset button (RESET) and switch KR1, switch KRI is
opened and
becomes non-conductive.
If any main components in the GFCI are defective, i. e., if the service life
of the device
has ended, circuit U4 is incapable of sending a normal state signal to pin 5
of IC2 to allow pin I
ocnoc8re5o301.1 16
CA 02579626 2007-02-26
of IC2 to elevate to a high voltage level. As a result, pin i of IC2 is at a
low voltage level so that
no signal can be output to U5 and the device is incapable of being reset.
Optionally, since pin 3
of 1C2 continues to have a high voltage output, the problem status indicating
light V 10 of circuit
U2 through optical coupler IC3 is tumed on and displayed on the face of the
receptacle. The
lighting of the problem status indicating light reminds the users that the
GFCI has reached the
end of the service life and should be replaced. The problem status indicating
light is preferably
to be red or yellow.
Besides the automatic generation of a simulated leakage current through
circuit U2, which
is capable of checking whether the circuit interrupting device still has the
electrical leakage
protection function after being powered, the receptacle disclosed in the
present invention can
also generate a simulated leakage current through a manual test circuit U7
when the user presses
test button (TEST) 7 to trip the device.
Figure 8 is a detailed circuit diagram of the control circuit used in the
present invention.
The main components include, but are not limited to, differential transformer
L1, L2 used for
detecting leakage current, leakage detection control chip ICI, end-of-service-
life detecting
integrated circuit chip IC2, optical couplers 1C3,1C4, a silicon control
rectifier, and a solenwid
coil. The circuit for automatically generating a simulated leakage current in
the receptacle of the
present invention contains serially connected resistor R2 and rectifier/diode
bridge V6-V9. One
end of resistor R2 is connected to hot wire LIN of the power input terminal,
while the other end is
connected to neural wire NIN of the power input terminal through
rectifier/diode bridge V6-V9.
When the GFCI is powered, and is in the tripped state, the serially connected
resistor R2 and
rectifier/diode bridge V6-V9 automatically short-circuit the hot and neutral
wires to generate a
simulated leakage current/ground fault.
DCOOCS/656301.1 17
CA 02579626 2007-02-26
If the GFCI is working properly and when a leakage current occurs in the
circuit, the
differential transformers immediately sense a voltage signal at a certain
level and send it to
signal input pins 1 and 2 of leakage detection control chip IC i. Pin 5 of
chip IC t then outputs a
signal to the gate of SCR V13 to trigger and turn on SCR V13. As a result, the
solenoid coil
(SOL) in the tripping device is powered, and the iron core inside the SOL
moves to trip the
tripping device so as to interrupt the power output. After the GFCI is
tripped,'because the reset
button (RESET) is in the tripped state, switch KRl in circuit U3 is closed and
becomes
conductive due to interaction with the reset button (RESE'I'), which causes
the GFCI to
automatically generate a simulated leakage current to test the device again.
Also, if the GFCI is working properly, the voltage level at pin 1 of the end-
of-service-life
detecting chip IC2 in U6 is elevated and outputs an elevated voltage level to
U5 to allow the
device to be reset. Optionally, the output signal of pin 1 of IC2 can also be
connected to circuit
U8 to enable optical coupler IC4 in U8 to function. U8 contains a normal
status indicating light
which, when activated, can be output to light up the normal status indicating
light on the face of
the receptable. As a result, silicon-controlled rectifier (SCR) V 18 becomes
conductive, and
normal status indicating light V 17 is turned on.
On the other hand, if any of the main components in the GFCI are damaged or
defective,
i.e., when the service life of the GFCI has ended, pin I of the end-of-service
life detecting chip
IC2 in U6 does not send a signal to U5 to activate the reset mode to allow the
GFCI to reset. As
a result, the GFCI cannot be reset, and the voltage level at pin 3 of IC2 is
elevated to enable
optical coupler IC3 in U2 to function. Silicon-controlled rectifier (SCR) V11
therefore becomes
conductive, and problem status indicating light V 10 is turned on to remind
the user to replace the
DCGOCS1656341.1 18
CA 02579626 2007-02-26
device with a new one. The problem status indicating light V 10 is preferably
to be either a red or
a yellow light.
If the GFCI is working properly, when a ground fault or a leakage current is
detected, the
differential transformers sense a certain volume of imbalance voltage passing
through and send a
signal to input pins I and 2 of the leakage current detecting chip IC 1, which
outputs a control
signal from pin 5 of IC 1 to the gate of SCR V 13 to activate SCR V 13. After
SCR V 13 becomes
conductive, it energizes the solenoid coil* (SOL) of the tripping device, and
causes the movable
iron core within the SOL to plunge the tripping device so as to trip the GFCI
and interrupt the
power output. Due to the tripping of the reset button (RESET), switch KRI,
which interacts with
the reset button (RESET), is pushed to close, which sends a signal to the test
circuit and activates
the testing of the GFCI. At this tiine, if all of the main components of the
GFCI still function
properly, pin 1 of IC2 in circuit U6 is changed to a high voltage level, which
sends a signal to U5
to allow the reset button (RESET) to reset or optionally sends a signal to the
optical coupler IC4
in circuit U8 to activate SCR V 18. Once SCR V 18 becomes conductive, the
normal status
indicating light V 17 is turned on.
On the other hand, if any of the main components in the GFCI are damaged or
defective,
i.e., if the service life of the GFCI has ended, pin 1 of IC2 in circuit U6
shows a lower voltage
level. As a result, no signal can be sent to U5, so that reset button (RESET)
cannot be reset. At
the same time, pin 3 of IC2 outputs an elevated voltage level, which sends a
signal to optical
coupler IC3 to activate SCR V 11. Once SCR V 1 I becomes conductive, the
problem status
indicating light is turned on, which reminds a user that the service life of
the GFCI has ended,
and that he/she should replace the GFCI.
DCD0CSI656301.1 19
CA 02579626 2007-02-26
As shown in Figure 8, once the automatic testing of the end of service life of
the device
has been completed, and the device is found to be working normally and is able
to provide
electrical leakage or ground fault protection, the voltage level at pin I of
the end-of-service-life
detecting chip 1C2 is elevated. When the user presses the reset button
(RESET), since switch
KR4 interacts with the reset button (RESET), switch KR4 is closed at the same
time when reset
button (RESET) is pressed down. SCR V 13 is triggered to become conductive.
Solenoid coil
(SOL) is powered so that current flows through it to generate a magnetic
field. The iron core=
inside the coil moves to push locking member 30 of the tripping device of the
GFCI to move. As
shown in Figure 5-2, the lock slot 36 of reset directional lock 35 embedded at
the bottom of the
reset button (RESET) is seized in the lock hole 31 of locking member 30. Reset
button (RESET)
is released, driving tripper 28 to move up to elevate the flexible metal
pieces 50, 51, 20, 21
located above the lifting arms on the two sides of tripper 28. As a result,
the movable contacts
54, 55 on flexible power input metal pieces 50, 51 make contaot with the fixed
contacts 52, 53 on
power output conductors 13, 14 to power up output conductors 13,14. This
allows the flow of
electricity to the power output sockets 5, 6 on the face of the GFCI. Also,
the movable contacts
22, 23 on flexible metal pieces 20, 21 make contact with the fixed contacts
15,16 on power
output conductors 13, 14 to power the flexible metal pieces 20, 21, which are
in contact with
power output terminals 80, 81. This allows electricity to be output to power
output terminals 80,
81 of the GFCI and to the power output sockets 5, 6 on the face of the
receptacle, and thereby the
GFCI operates normally.
As shown in Figures 8, and 5-3, when test button (TEST) is pressed down, a
simulated
leakage current is generated. After differential transformers L1, L2
(differential transformers 19)
detect the leakage current, they output a voltage signal to leakage current
control chip IC1, which
DcnocBlB56801.1 20
CA 02579626 2007-02-26
elevates the voltage at pin 5 of chip IC 1, which in turn makes SCR V 13
conductive. A current
flows through solenoid coil 26 (SOL) to generate an electromagnetic field,
which pulls in iron
core 42 to push locking member 30 to move, as shown in Figure 5-3. The bottom
part of lock
slot 36 of reset directional lock 35 penetrates central hole 31 of locking
member 30. Reset
button 8 is tripped, and allows tripper 28 to drop. The flexible power input
metal pieces 50, 51,
20, 211ocated above the two lifting arms of tripper 28 drop as well to
disconnect the movable
contacts 54, 55 on flexible power input metal pieces 50, 51 from the fixed
contacts 52, 53 on
power output conductors 13, 14. The fixed contacts 15, 16 on power output
conductors 13, 14
are disconnected from the movable contacts 22, 23 on flexible metal pieces 20,
21 so that neither
power output conductors 13, 14 nor flexible metal pieces 20, 21 are powered.
As a result, there
is no power output to the power output terminals 80, 81 of the GFCI or to the
power output
sockets 5,6 on the face of the front lid 2 of the GFCI, so that the entire
power output of the GFCI
is interrupted.
The present invention also allows the user to forcibly and mechanically trip
reset button
(RESET) 8 by pressing test button (TEST) 7 to interrupt the power output of
the GFCI. As
shown in Figure 5-4, test button (TEST) 7 has a tail end which penetrates
through insulated
middle support 3, which touches upon the end of tripping lever 37. When the
service life of the
GFCI has ended and the reset button (RESET) cannot be tripped by using
simulated leakage
current, the user can further press down test button (TEST) 7 to forcibly trip
the device. This tail
end has a slipped over spring 40. If the user wants to detect whether the
mechanical operation of
the GFCI is operational and reliable, he/she can depress test button (TEST) 7.
The tail end of
test button 7 pushes the end of tripping lever 37 to move downwards to pull
locking member 30.
Locking spring 34 on the other side of the locking member is compressed. The
lock slot 36 on
DCDOCS1666301.1 21
CA 02579626 2007-02-26
directional lock 35 jumps out of locking hole 31 on locking member 30. Tripper
28 falls, and
flexible power input metal pieces 50, 51 fall as well. The movable contacts on
the flexible
power input metal pieces are disconnected from the fixed contacts on power
output conductors
13, 14. As a result, power output conductors 13, 14 are not electrified. The
flexible metal pieces
20, 21 connected to power output terminals 80, 81 are not electrified, either.
Since neither power
output conductors 13, 14 nor power output terminals 80, 81 are electrified, no
power is output to
the load terminals, that is, power output terminals 80, 81 of the GFCI or to
the power output
sockets 5, 6 on the face of the GFCI front lid 2.
-As shown in Figure 4, two pairs of position limiting pieces 43, 44 and 73, 74
are anmged
on the coil frame 41 of solenoid coil 26 below the movable contacts of
flexible power input
metal pieces 50, 51 and below flexible metal pieces 20,21.
As described above, the present invention not only provides electrical leakage
or ground
fault protection but also can automatically check whether the service life of
the GFCI has ended
and display the test result by means of the indicating lights after the device
of the present
invention is connected to the hot and neutral wires of the power line inside
the wall. If the GFCI
still has electrical leakage or ground fault protection, the reset button can
be reset normally, aiid
the normal status indicating light is turned on, which indicates that the GFCI
is working properly
and there is power output from the device. If the service life of the GFCI has
ended, the end-of-
service-life detection control chip IC2 prohibits the resetting of the reset
button, so that no power
is output to the power output sockets on the face of the front lid 2 or load
output terminals of the
GFCI. This provides a signal to the user that the GFCI should be replaced. In
addition, when a
certain component in the GFCI becomes defective, for example, when the
solenoid coil is unable
to work properly, it is possible to forcibly interrupt the power output of the
receptacle in a
Dcoocsl656301.1 22
CA 02579626 2007-02-26
mechanical manner by pressing the test button. This invention has powerful
functions and
provides good safety. It can be used to guarantee the safety of the user and
to protect electrical
appliances.
While the invention has been described by way of examples and in ternrnns' of
the preferred
embodiments, it is to be understood that the invention is not limited to the
disclosed
embodiments. On the contrary, it is intended to cover various modifications as
would be
apparent to those skilled in the art. Therefore, the scope of the appended
claims should be
accorded the broadest interpretation so as to encompass all such
modifications.
DCO0C8/656904.1 23
