Note: Descriptions are shown in the official language in which they were submitted.
1 1 fi25~6
R~SETT~BLE CIRCVIT BREAKE~ FOR USE IN
GROUND FAULT CIRCUIT INTERRUPTERS AND T Æ LIKE
Abstract of the Disclosure
A resettable circuit breaker has a pair of normally
closed contacts through which a load is connected to a power
line and means for opening the contacts in response to a
predetermined change in electrical current flowing to and
from the power line. One of the contacts is mounted on a
rocking member which is maintained between a pivot on the
base of the apparatus and the armature of a latching solenoid
responsive to the predetermined current change by a spring
assembly which causes the rocking member to rotate about the
pivot means thereby opening and closing the contacts depending
on the position of the armature.
Background of the Invention
The danger of electrocution of or serious shock to
an individual coming in contact with an appliance surface
having an electrical potential differing from ground potential
when the individual was also touching a grounded surface
created the need for ground fault circuit interrupters.
Gr~und fault circuit interrupters cut off the supply of
electric current to a "hot" surface immediately upon flow of
electric current to ground through other than the normal return
path of the circuit in which the appliance is connected. Early
ground fault circuit interrupters continuously measured
electrical potential to ground and cut off power to the
monitored appliance in response to a predetermined change in
1387 P/4 CA 1 - ~ ~
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potential, These early devices were inherently faulty in
that it was difficult to obtain a true ground point from which
to measure electrical potential and variations in ground
impedance adversely affected their operation.
Improved ground fault circuit interrupters werP
later developed. Th~se monitored the difference between the
electrical currents flowing into and out of the power line
to which they were connected. Ideally, the supply and return
currents are equal and their difference has a magnitude of
zero. Should an external electrical path from the phase or
hot side of the supply line to ground be completed, the current
at the grounded neutral terminal of the supply line decreases
relative to the current at the phase terminal of the line.
The improved ground fault circuit interrupters employed a
differential transformer which generated a pulse upon the
occurrence of an imbalance between the phase and neutral
currents and this pulse was applied directly to a solenoid
causing the solenoid to actuate thereby opening a set of
contacts between the power line and appliance or load. In
order to function such ground fault circuit interrupters
required very large transformers, too bulky to permit mounting
of the ground fault circuit interrupter in a standard wall
receptacle and highly sensitive solenoids which like the
transformers were very expensive.
Prior art ground fault circuit interrupters were also
prone to tripping due to noise on the power line which created
momentary imbalance between the phase and neutral currents.
#1387 P/4 CA -2-
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Other problems associated with prior art ground fault circuit
interrupters included an inability to cut off powe~ if
inadvertently wired into a circuit in reverse, that is, with
the load terminals connected to the power line and power line
terminals connected to the load. In these devices when the
ground fault circuit interrupter was connected in reverse,
not only was the power continuously supplied to the load
irrespective of actuation of the interrupter, but also in
cases where the opening of the contacts was accomplished
by an electromagnet, current would continue to flow in the
electromagnet after the interrupter was actuated and the coil,
normally designed only for intermittent duty, would burn out.
Another problem found in the prior art ground fault
circuit interrupters was attributable to the use of contact
reset mechanisms which permitted a user to open and reset
the contacts at will. To insure utmost reliability in a
ground fault cîrcuit interrupter, it is desirable that the
contact tripping mechanism be subject to limited duty, i.e.,
only when a ground fault occurs. Prior art ground fault
circuit interrupters permitted a user to open the contacts
manually in the absence of a ground fault thereby offering
the temptation for the user to use the reset mechanism as a
switch for turning an appliance on or off from the power
outlet. Such use often resulted in the deterioration of the
contacts and compromised the reliability of the ground fault
circuit interrupter.
#1387 P/4 ~ _3
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_ mmary of the Invention
The previously mentioned problems associated with
ground fault circuit interrupters of the prior art are
overcome by the instant invention which includes a resettable
circuit breaker having normally closed main contacts, means
for connecting a load to one side of said contacts, means
for connecting a power line to the other of said contacts,
means for interrupting the connection be~ween the load and
power line by opening the contacts in response to a predetermined
change in ~he current in the power line and means for resetting
(closing) the contacts in the absence of the predetermined
change in current. Ground fault circuit interrupters embodying
the invention may include a differential transformer for sensing
a current imbalance between the phase and neutral power lines
to which the ground fault circuit interrupter is connected,
sensor circuitry for providing an output signal when the
current imbalance exists for a predetermined time at a
predetermined magnitude, and a SCR responsive to the output of
the sensor circuitry. The SCR is in circuit ~ith the coil of
a latching relay according to the invention to cause the
contacts to open when the SCR conducts in response to a current
imbalance. Auxiliary contacts responsive to the main contacts
are provided for preventing application of current to the relay
coil after occurrence of a ground fault irrespective of whether
the ground fault circuit interrupter is properly wired in
circuit.
The relay includes an armature slidably and pivotally
#1387 P/4 CA _4_
~ 1 62S76
mounted within a frame and connected to a coil spring. A
separate spring assembly connects the arm~ture to a rocking
member on which one of the contacts is mounted, the rocking
member being pivotal with respect to the chassis of the
S ground fault circuit inter~upter to rotate in one direction
t~ open the contacts when the armature of the relay is unlatched
upon energization of the coil and to rotate in the opposite
direction to close the contacts when the armature of the relay
is depressed and ~eld in a latched position under the tension
of the coil spring.
In accordance with a broad aspect of the invention,
switching apparatus for selectively completing or interrupting
an electrical connection between an input and an output
conductor includes a magnetizable armature movable between
first and second positions, and an electromagnet adapted, when
energized, to move said armature from the first ~osition to the
second position, the armature being unresponsive to the
electromagnet when in its second position. The apparatus further
includes an input contact connected to the input conductor, and
an output contact connected to the output conductor, with
rocking means rotata~le in response to movement of said armature.
One of the contacts is mounted on the rocking means and is rotatable
therewith into engagement with the other of the contacts when
the armature is moved from its second position to its first
position, and out of engagement with said other of the input and
output contacts when said armature is moved from its first
-- 5 --
1387 P/4 CA
1 J 62576
posîtion to its second position. The apparatus still further
includes a member movable under the influence of pressure
connected to the armature for moving the armatule to its first
position from its second position when operability is desired,
with the armature being inoperable in response to teasing
pressure when in its first position.
It is, therefore, an object of the invention to provide
a resettable circuit breaker for use in a ground fault circuit
interrupter wherein current flow is immediately interrupted
upon completion of a circuit between ground and either the
phase or neutral connections to a load.
Another object of the invention is to providP ~ ground
fault circuit interrupter which can be conveniently packaged
for installation in a standard wall outlet receptacle.
Still another object of the invention is to provide a
ground fault circuit interrupter which actuates in response
to the magnitude of current flow in an unwanted external
circuitand the time during which external current flow occurs.
A further object of the invention is to provide a
ground fault circuit interrupter immune to coil burn-out
when installed in reverse.
A still further object of the invention is to provide
a ground fault circuit interrupter with a compact yet positive
#1387 P/4 CA - 5a -
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resettable latchin~ relay for permitting current flow from
a power line to a load only in the absence of ground faults.
An additional object of the invention is to provide
a tease-proof ~round fault circuit interrupter which, once
5 reset into a conducting condition, cannot be rendered non-
conducting absent the occurrence of a ground fault.
Other and further objects of the invention will be
apparent from the following drawings and description of a
preferred embodiment of the invention in which like reference
10 numerals are ~sed to indicate like parts in the various views.
Description of the Drawin~s
Fig. 1 is an electrical circuit schematic diagram
of the apparatus of the invention;
Fig. 2 is a front view of the ground fault circuit
interrupter ofthe invention;
Fig. 3 is a sectional view of the apparatus of the
invention, showing the apparatus of the invention in one
state of operation in its intended environment;
Fig. 4 is a sectional view similar to the view of
Fig. 3 of a part of the apparatus during transition to
another state of operation in its intended environment; and
Fig. 5 is a view similar to Fig. 3 showing the
apparatus after the completion of transition to its other
state.
Description of the Preferred Embodiments
Referring now to the circuit schematic wiring diagram
of Fig. 1 of the drawings, there are shown input terminals 1
#1387 P/4 CA -6-
1 1 6257G
and 3 which are respectively connected to the phase and
neutral wires of a 60 cycle a.c. power line as, for example,
an electrical supply circuit leading from a fuse box in a
residence or commercial building. The neutral terminal 3 is
connected by a lead 5 to the outer conductor of a coaxial
cable 7 at the line end of the cable. The outer conductor
of the cable 7 can be a rigid conducting hollow cylindrical
conduit. The center conductor or phase lead 9 of the cable
.7 is connected to the phase terminal 1 at its line end and
to a contact 11 of a relay actuated switch 13 at its load end. A
conductor 15 is connected at its line end to the load end of
the outer conductor of the cable 7 and at its load end to a
contact 17 of a switch 19 which is structurally combined
with the switch 13 for joint actuation with it as will later
be described.
Load terminals 21 and 23 are respectively connected
to a load phase wire 25 and a load neutral wire 27. The load
phase wire 25 and load neutral wire 27 are respectively connected
to contact 31 of the switch 13 and contact 29 of the switch 19.
The switches 13 and 19 are normally closed providing electrical
continuity between input terminal 1 and output terminal 21 and
between input terminal 3 and output terminal 23. Upon
occurrence of a ground fault, the switches 13 and 19 are
opened interrupting the flow of current between contacts 17 and
29 and between contacts 11 and 13 as will subsequently be
explained.
A differential transformer 33 has a core circumscribing
#1387 P/4 CA _7_
5 ~ 6
the neutral wire 5 and hot wire 9 which serve as the
transformer pri~aries and a secondary winding having output
leads 35 and 37 which are connected to the input of a ground
fault circuit interrupter sensing circuit 39. Capacitor
44 provides the necessary feedback for the integrator portion
of the circuit 39. The circuit 39 as shown in Fig. 1 can be
a Motorola MC3426 which is commercially avail,able. National
Semi Conductor Inc. (NSI) makes and sells an integrated
circuit LM1850 functionally similar to the Motorola circuit
which can also be purchased and used in a circuit similar to
that of Fig. 5 but modified slightly in accordance with known
requirements of the NSI circuit.
' Noise suppression for the circuit 39 is provided by
resistor 4Z and capacitor 46. Capacitor 48 provides filtration
for the circuit 39. The output of the circuit 39 is applied
via lead 41 to the gating stage 43 of a silicon controlled
rectifier (SCR) 45 having an anode 47 and a cathode 49.
Capacitor 51 connected in parallel with the SCR 45 provides
noise suppression for the SCR 45.
A difference in the respective currents flowing
throu~h the primaries of the transformer 33 induces a voltage
pulse in the secondary winding which appears across leads 35
and 37 and is applied to the circuit 39 where it is integrated,
and if the pulse is of sufficient magnitude and duration, a
pulse is generated at the output of the circuit 39 on line 41
and applied to the gating stage 43 to render the SCR 45
conducting.
#1387 P/4 CA -8-
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The coil 61 of an electromagnet is connected
between the anode 47 of the SCR 45 and an auxiliary
contact 63 which is connectable to the contact 31 by
a plunger actuated switch 65. The switch 65 is
mechanically coupled with switches 13 and 19 in a manner
to be described so that switches 13, 19 and 65 all open
when coil 61 is ener~ized and all close when the coil 61
is de-energized and the contacts are reset as will later
be described. When the SCR 45 is rendered conductinO in
response to a current imbalance in the leads 5 and 9, it
causes switches 19, 13 and 65 respectively connected
between contacts 17 and 29, contacts 11 and 31, and contacts
31 and 63 to open and remain open,irrespective of whether
the coil 61 remains energized or is de-energized, until the
switches 19, 13 and 65 are manually reset.
A normally open plunger actuated test switch 71 i~
provided between a contact 73 which is connected by line 75
to the load phase wire 27 and a contact 77 which is connected
through a resistor 79 to the line neutral lead 5. Closing of
the switch 71 provides a path for current to flow from the
phase wire 25 to ground through the neutral lead 5 bypassing
the transfo~mer 33. A current imbalance then exists between
the current flowing in the outer conductor 7 and the current
flowing in the inner conductor 9. This current imbalance is
sensed by the differential transformer 33 which causes the
contacts associated with switches 13, 19 and 65 to open as
previously described.
The series combination of a light-emitting diode 81,
. a resistor 83 and diode 85 is connected in parallel with the
#1387 P/4 CA -9-
1 1 6257G
load terminals 21 and 23 and is llt when the switches 13
and 19 are closed and power is applied to the line terminals
1 and 3 of the ground fault circuit interrupter, The lit
LED 81 provides a visual indication that the circuit in
which the ground fault circuit interrupter is installed is
operating normally, i.e., without any ground fault. Upon
occurrence of a ground fault which causes the switches 13,
19 and 65 to open power to the LED 81 is cut off and the
light is extinguished. An extinguished LED provides a visual
indication that a fault exists in the circuit.
The LED can also be used to test for reverse
installation of the ground fault circuit interrupter. Should
the load terminals 21 and 23 be inadvertently connected to
the power line and the line leads 1 and 3 mistaken for the
load leads, the LED 81 will remain lit at all times, even
after the test button 71 is actuated since power will be
continuously applied to the terminals 2l and 23 across the
light-emitting diode circuit.
The disclosed circuit, by employing auxiliary switch
65 between the contacts 31 and 63 to selectively connect the
relay coil 61 to the load phase wire 25, prevents burn-out
of the coil 61 upon an inadvertent reversed connection of
the ground fault circuit interrupter. If the load side of
the coil 61 were permanently connected to load phase wire 25,
inadvertent reverse connection of the ground fault circuit
interrupter, whereby the load terminals 21 and 23 would be
connected directly to the power line, would result in a
#1387 P/4 CA -10-
1 1 625~6
continuous flow of current through the coil 61, even ater
the contact switches 13 and 19 were tripped. This would
likely result in burn-out of the coil 61 which is intended
only for intermittent duty. Under the arrangement shown in
Fig. 1, even if power is supplied directly to the load
terminals 21 and 23, once the interrupter trips opening
switches 13 and 19, mechanically coupled switch 65 also opens
thereby preventing current flow to the coil 61 and, hence,
avoiding its burning out.
A power transformer 91 axially displaced from the
transformer 33 also circumscribes the outer and inner
conductors 7 and 9 for detecting the completion of a neutral
to ground circuit at the load. Such an occurrence can
result in current flow from the ground to which the line
side of the neutral wire 5 is connected, to the line side
of the neutral ~, to the load side of the neutral 5, to the
unwanted external ground, and back to the original ground to
which the line side of the neutral wire 5 is connected. The
primary winding of transformer 91 is connected between load
phase wire contact 31 through auxiliary switch 65, and load
neutral contact 29 through switch 19. The primary winding
of the transformer 91 is connected in series with a capacitor
76 and a metal oxide varistor 74 is connected in parallel
with the load for voltage transient suppression. When a
ground to neutral circuit is completed, current flows in it
induced by the inductively coupled transformer 91. The flow
of current causes an imbalance between the currents in the
~1387 P/4 CA
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neutral and phase conductors adjacent transformer 33 and is
sensed in the same manner as a ground fault as previously
described.
The mechanical operation of a ground fault circuit
5 interrupter according to the invention will now be described
with reference to Figs. 2, 3, 4 and 5.
Referring to Fig. 2, there is shown the face or outlet
side of an electrical outlet or receptacle adapted to receive
two a.c. grounding plugs each of which is connected to an
10 appliance or load. The outlet also has a reset button 101
which, when depressed, closes the mechanically coupled switches
13, 19 and 65. The test button 71 is also accessible from the
face of the outlet for causing an intentional ground fault for
testing the interrupter as previously explained. The light-
emitting diode 81 can be seen on the face of the outlet paneland will normally be lit when the interrupter is in a reset
condition, that is, when the reset button 101 has been depressed
and there has been no subsequent ground fault, and will be
extinguished when and after a ground fault occurs. To test
the unit when it is in a reset condition, the test button 71
is pressed at which time, if the unit is properly installed,
the light-emitting diode 81 should change from a lit to an
extinguished state. Pressing the reset button 101 should
restore the terminated po~er to the outlet and cause the LED
81 to be lit again.
Referring now to Fig. 3, the ground fault circuit
interrupter of the invention is contained in a lower housing
#1387 P/4 CA -12-
1 1 625~i
103 and an upper housing 105 which n~tes wlth the lower
housing 103 to form a-substantially enclosed casing for the
mechanical and electronic components of the ground fault
circuit interrupter.
The reset button 101 has an upper surface 106 which
is adapted to have applied to it finger pressure to close the
swi~ches 13, 19 and 65. A metal frame 107 has a floor 109 and
two vertical sp~ced parallel side planar members 111 extending
transversely fro~ opposite edges of the floor 109. The side
planar members 111 of the frame 107 each have a symmetric slot
113 with the uppermost edge of each of the slots 113 having
an inclined region 115 and a horizontal region 117 laterally
displaced from the inclined region 115. The laterally
displaced edge regions 115 and 117 of the slot 113 are separated
by a shoulder 119. The slot 113 tapers along the downward
inclination of the edge region 115 toward the shoulder 119
and then abruptly widens at the shoulder 119 where the edge
region 117 of the slot 113 is vertically displaced from the
edge region 115.
An armature 116 is pivotally connected at one of its
ends to the reset button or plunger 101 and has the other of
its ends slidably disposed in each slot 113 of the frame 107.
The armature 116 is substantially rectan~ular in shape with
four ears projecting outwardly in parallel directions from
each of the four corners of the armature 116. Opposite ears
121 are rotatably disposed in circular apertures 123 formed in
the side walls of the reset button 101 and opposite ears 125
are slidably disposed in the slots 113 of the frame 107. The
#1387 P/4 CA -13-
1 1 62~76
edge of the arm~ture 116 between the ears 125 is provided
with a hook-like member which may be formed by notching and
bending a portion of the armature material to receive one
end 127 of a coil spring 129. The other end 131 of the coil
spring 129 is hooked over a notched member 133 which is
formed of one of two inward-directed frame portions 135 which
are connected to the frame vertical members 107 and which are
in parallel spaced relationship to the floor 109 of the frame
107. The coil spring 129 is disposed in a space between the
mutually inwardly-directed frame members 135 and when tensioned
by stretching urges the edge of the armature from which the
ears 125 project in an oblique direction toward the outlet side
of the ground fault circuit interrupter and away from the floor
109 of the frame 107.
As a result of the angular relationship between the
axis of-the spring 135 and the plane of the armature 116, the
force exerted by the tensioned spring 135 on the armature 116
has two vector components, one parallel to the planP of the
armature 116 and the other transverse to that plane. The
parallel vector component urges the armature and reset button
or plunger 101 in a direction to move the reset button 101
into a raised position projecting beyond the outer side of
the ground fault circuit interrupter receptacle while the
transverse vector component urges the ears 125 against the
edge regions 115 or 117 of the slot 113 depending upon the
degree of depression of the armature 116. As the reset button
101 is pressed inwardly from the face or outlet side of the
ground fault circuit interrupter, the armature 116 is also
#1387 P/4 CA -14-
~ 5~6
forced inwardly and each ear 125 moves along a respective
edge region 115 of a slot 113 until it passes a shoulder ll9
at which point it is abruptly pulled against corresponding
edge region 117 of the slot 113 where it is held by the force
of the spring 135 against respective shoulder 119, the
shoulder 119 serving as a latch point for the latching ears 125.
In order ~or the latching ears 125 to be freed from
the latch points at the shoulders 119, they must be moved in a
direction transverse to the planeof the armature, that is,
the armature must be pivoted about pivot ears 121 in apertures
123 toward the frame floor member 109. An electromagnet including
coil 61 wound about a cylindrical core 62 is
affixed to the frame floor member 109 bymeans of a rivet 141
with the axis of the electromagnet being vertical and
substantially transverse to the variable plane of the movable
armature 116. The coil 61 is normally de-energized as
previously explained with reference to Fig. 1 and when energized,
exerts an attractive force on the armature 116 which is made of
a magnetizable metal.
The armature 116 is placed in a latched position by
depressing the reset button lOl which thereby forces the latching
ears 125 passed the shoulder ll9 to latch adjacent side edge
regions 117 under the force of the spring 135 which becomes
tensioned as the armature moves inwardly. When the coil 61
is energized, the armature 116 is attracted to the core 62.
The armature 116 pivots on ears 121 in apertures 123 until the
ears 125 clear the shoulder 119 at which time the armature 116
and reset button 101 move abruptly outward with the reset
#1387 P/4 CA -15-
~ 3 6~576
button 101 then projec~ing beyond the face of the receptacle
and the ears 125 being contained against respective vertical
edges 143 of the slots 113.
When the armature is depressed by applying pressure
to the surface 105 of the reset button 101, the edge of the
armature 116 between ears 125 engages two outwardly extending
prongs 151 (in the drawings one prong 151 is hidden by the
other) of a leaf spring 153. The leaf spring 153 has a surface
parallel and proximate to the face of the receptacle which is
substantially H-shaped with downwardly extending prongs 151
comprising two spaced lower parallel legs of the H and opposite
upwardly extending legs 155 entrapped under tension behind either
side of the lip 159 of a support member 157 which is mounted on
a vertical wall 160 which is fixedly connected to the lower
housing 103. The lip 159 cooperates with two inward extending
proJections at the distal ends of the legs 155 of the leaf
spring 153 to partially tension the leaf spring 153 and keep
the legs 155 trapped beneath the lip 159. Another prong 161 of
the leaf spring 153 projects from the crossbar of the H-shaped
leaf spring first towards the legs 151 and then bends under
and back towards the legs 155 and is urged against the wall 160.
The crossbar of the H-shaped spring 153 is apertured
at 163 to receive one end of a substantially V-shaped wire
spring 165. The other end of the spring 165 is disposed in
a notch 167 formed in a projection 168 extending from the
middle of a rocking member 169 which supports line contacts
ll (visible in Figs. 3 and 5) and 17 (hidden in Figs. 3 and 5).
#1387 P/4 CA -16-
1 1 52576
The rocking member 169 is substantially L-shaped at either
of its ends ~the face of one end being visible in Figs. 3
and 5) and deep enough to permit mounting of two rivets 170
on opposite sides of projection 168 each of which affixes
one leg of a respective L-shaped conductor to a parallel
face of the rocking member 169, the conductors suppor~ing
contacts 11 and 17 on their transverse legs. When the ground
fault circuit interrupter is in a latched condition with the
reset button 101 depressed and ears 125 of the armature 116
entrapped at the catch points 119 in the slots 113, the
armature 116 exerts an inward pressure on the legs 151 of the
H-shaped spring 153 thereby tilting the attached end of the
wire spring 165 downwardly so that its other end urges the
notched portion 167 of the rocking member 169 upwardly. The
rocking member 169 is urged, at all times, against a pivot
member 171 which is affixed to the wall 160 in spaced
relationship to the support member 157 and which has a downward
extending lip 172 which overhangs an upwardly extending lip 174
on the middle portion of the L-shaped rocking member 169. The
rocking member 169 is, as a result of the dispositions of the
support member 157 and pivot member 171 confined by the -
tension in the spring 165 between the members 169 and 171.
The lip 174 of the rocking member 169 intermediate the contac~s
11 and 17 is shortened and abuts against a corner of the pivot
member 171 to form a pivot region 173 about which the rocking
member 169 can be rotated relative to the pivot member 171.
Rotation of the rocking member 169 is limited in one direction
#1387 P/4 CA -17-
~ 1 625~B
by the support mem~er 157 and in the other direction at least
initially by the engagement of the respective contacts. The
~ire spring 165 urges the rocking member 169 towards the pivot
member 171 and, when the legs 151 of the H-shaped spring 153
5 are depressed by the armature 116, urges the rocking member
169 to pivot away from the supporting member 157 thereby
causing the contacts 11 and 17 to rotate toward load contacts
31 and 29 (behind 31 in Figs. 3 and 5) to complete a circuit
between the line and load terminals of the ground fault
lo circuit interrupter.
A spring loaded plunger 181 is disposed beneath one
of~`ithe legs 155 of the H-shaped spring 153 so that when the
legs 151 of the H-shaped spring 153 are under pressure of the
armature 116, the plunger 181 is depressed thereby causing a
15 resilient conductor 183 which is connected to the contact
31 to engage contact 63 thereby closing the auxiliary contacts
which connect the relay coil 61 to the load side of the phase
wire 25.
Upon occurrence of a ground fault, the coil 61 is
20 energized as previously described and the armature 116 is
a ~racted to it. The armature begins to rotate until the
ears 125 clear the latch point on the shoulder 119 in the
frame 107 at which time the armature 116 begins to move
longitudinally toward the face of the receptacle urged by
the spring 135, as shown in Fig. 4. Linear motion of the
armature continues until the ears 125 engage edge 143 of the
slo~ 113 in the frame 107 as shown in Fig. 5.
#1387 P/4 CA -18-
7 6
With the armature 116 in a raised position, pressure
on the arms 151 is reduced and the H-shaped spring 153 rotates
upwardly about a fulcrum formed between the legs 155 of the
H-shaped spring and the support member 157. Pressure on the
auxiliary contact button 181 is then relieved and the spring
loaded plunger 181 moves longitudinally permitting the biased
contact arm 183 to separate from the auxiliary-contact 63
thereby breaking the electrical connection between auxiliary
contacts 31 and 63.
As the H-shaped spring 153 rota~es upwardly the wire
spring 165 is tilted so that the notched end portion of the
rocking member 169 is urged inwardly thereby pivoting about
the pivo~ member 171 and causing the main contacts 11 and 31,
and 17 and 29 to open. Switches 13 and 19 which were referred
to in connection with the discussion of the schematic diagram
of Fig. 1 comprise the rocking member 169, pivot member 171,
support member 157, springs 153, 165 and 135, armature 116,
frame 107 and reset button 101. Switch 65 comprises the
foregoing in combination with plu~ger 181 and flexible
20 bias contact arm 183.
It will be appreciated that the previous~y described
circuit interrupting mechanism although illustrated in the
environment of a ground fault circuit interrupter can be
utilized with or without the sensors 33 and 91 in other
25 environments including circuit breakers intended to trip upon
circuit overload. It will further be appreciated that the
foregoing description is of one preferred embodiment of the
invention which can be applied in other embodiments and which
is to be limited only by the following claims.
#1387 P/4 CA -19-
