U.S. patent number 3,806,845 [Application Number 05/310,571] was granted by the patent office on 1974-04-23 for ground fault interrupter.
This patent grant is currently assigned to ITE Imperial Corporation. Invention is credited to John B. Cataldo, Martin V. Zubaty.
United States Patent |
3,806,845 |
Zubaty , et al. |
April 23, 1974 |
GROUND FAULT INTERRUPTER
Abstract
A ground fault interrupter is constructed with a single housing
divided into two compartments. One compartment houses an automatic
circuit breaker that is manually operable by successive depressions
of a slidable operating member, and the other compartment houses a
ground fault detector and an electromagnet that is actuated when a
ground fault is detected. A lost motion means connects the
electromagnet armature to the armature of the magnetic overload
trip means of the circuit breaker in a manner such that movement of
the electromagnet armature moves the overload armature to trip the
circuit breaker, but movement of the overload armature will not
move the electromagnet armature. In another embodiment a common
magnetic frame and armature are used for the magnets in both
compartments, and a permanent magnet is utilized to provide
pre-excitation to the electromagnet structure.
Inventors: |
Zubaty; Martin V.
(Bellefontaine, NJ), Cataldo; John B. (Moorestown, NJ) |
Assignee: |
ITE Imperial Corporation
(Philadelphia, PA)
|
Family
ID: |
23203134 |
Appl.
No.: |
05/310,571 |
Filed: |
November 29, 1972 |
Current U.S.
Class: |
335/18; 361/102;
361/45; 361/115 |
Current CPC
Class: |
H01H
83/226 (20130101); H01H 71/32 (20130101) |
Current International
Class: |
H01H
83/00 (20060101); H01H 71/32 (20060101); H01H
83/22 (20060101); H01H 71/12 (20060101); H01h
073/00 () |
Field of
Search: |
;335/18 ;317/18D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Broome; Harold
Attorney, Agent or Firm: Ostrolenk, Faber, Gerb &
Soffen
Claims
The embodiments of the invention in which an exclusive privilege or
property is claimed are defined as follows.
1. A ground fault protective device including a single housing
having a partition separating first and second side-by-side
compartments within said housing; an automatic circuit breaker
within said first compartment; a ground fault detector in said
second compartment; said circuit breaker including a stationary
contact, a movable contact means, latch means for maintaining said
movable contact means in an operating position, automatic trip
means to release said latch upon predetermined overload conditions
in the circuit being protected by said circuit breaker, an
operating means for moving said movable contact means to a circuit
breaker closed position when said movable contact means is in said
operating position and for moving said movable contact means to a
circuit breaker open position when said latch means releases said
movable contact means; said operating means including an operating
member biased to normally protrude outward from said first
compartment; said operating member being mounted for linear
movement and being manually depressible so that upon successive
manual operations thereof in the same direction, said operating
member will actuate said operating means to alternately open and
close said circuit breaker; said ground fault detector including a
releasing portion connected to said circuit breaker to release said
latch means when a ground fault is detected by said ground fault
detector; said automatic trip means including a first electromagnet
having a first armature and the releasing portion of the ground
fault detector including a second electromagnet having a second
armature connected to said first armature for moving the latter to
release said latch means when said second electromagnet is
energized; a link interconnecting the armatures and movable
linearly in a plane generally parallel to said partition and
generally parallel to movement of said operating member.
2. A device as set forth in claim 1 in which there is a lost motion
connection between said first and second armatures whereby movement
of said second armature is effective to move said first armature
and movement of said first armature is ineffective to move said
second armature.
3. A device as set forth in claim 1 in which the link is adjacent
the partition.
4. A ground fault protective device including housing means
defining first and second side-by-side compartments; an automatic
circuit breaker within said first compartment; a ground fault
detector in said second compartment; said circuit breaker including
a stationary contact, a movable contact means, latch means for
maintaining said movable contact means in an operating position,
automatic trip means to release said latch upon predetermined
overload conditions in the circuit being protected by said circuit
breaker, an operating means for moving said movable contact means
to a circuit breaker closed position when said movable contact
means is in said operating position and for moving said movable
contact means to a circuit breaker open position when said latch
means releases said movable contact means; said operating means
including an operating member biased to normally protrude outward
from said first compartment; said operating member being mounted
for linear movement and being manually depressible so that upon
successive manual operations thereof in the same direction, said
operating member will actuate said operating means to alternately
open and close said circuit breaker; said ground fault detector
including a releasing portion connected to said circuit breaker to
release said latch means when a ground fault is detected by said
ground fault detector; said first and second armatures constituting
different portions of a single armature member; said first and
second electromagnets including a common stationary frame to which
said armature member is mounted; said first and second
electromagnets including respective first and second operating
coils mounted to said stationary frame and arranged so that aiding
fluxes are generated in said frame by currents flowing in said
operating coils.
5. A device as set forth in claim 4 in which there is a permanent
magnet means positioned to generate flux in said core to said those
fluxes generated by currents flowing in said operating coils of
said electromagnets.
6. A ground fault protective device including housing means
defining first and second side-by-side compartments; an automatic
circuit breaker within said first compartment; a ground fault
detector in said second compartment; said circuit breaker including
a stationary contact, a movable contact, latch means for
maintaining said movable contact means in an operating position,
automatic trip means to release said latch upon the occurrence of
predetermined overload conditions in the circuit being protected by
said circuit breaker, an operating means for moving said movable
contact means to a circuit breaker closed position when said
movable contact means is in said operating position and for moving
said movable contact to a circuit breaker open position when said
latch means releases said movable contact means; said operating
means including an operating member pretruding outward from said
first compartment; said operating member being manually operable so
that successive manual operations of said operating member will
actuate said operating means to alternately open and close said
circuit breaker; said ground fault detector including a portion
connected to said circuit breaker to release said latch means when
a ground fault is detected by said ground fault detector; said
automatic trip means including a first electromagnet having a first
armature and the portion of the ground fault detector including a
second electromagnet having a second armature connected to said
first armature for moving the latter to release said latch means
when said second electromagnet is energized; said first and second
armatures constituting different portions of a single armature
member; said first and second electromagnets including a common
stationary frame to which said armature member is mounted; said
first and second electromagnets including respective first and
second operating coils mounted to said stationary frame and
arranged so that aiding fluxes are generated in said frame by
current flow in said operating coils.
7. A device as set forth in claim 6 in which there is an adjustable
permanent magnet means positioned to generate flux in said core to
aid those fluxes generated by currents flowing in said operating
coils and thereby control sensitivity.
Description
Conventional circuit breakers for home and light industrial
applications usually have thermal and magnetic fault responsive
trip means to automatically open the main contacts of the circuit
breaker when excessively high current flows through the main
contacts. The protection afforded prevents damage to load wiring
and to the load. However, this does not insure that low magnitude
fault currents caused by high resistance faults to ground will not
result in injury to personnel or start fires.
In order to obtain protection against the aforesaid low magnitude
faults, so-called ground fault interrupters have been provided to
extend the protection afforded by conventional circuit breakers. A
typical ground fault interrupter is described in U.S. Pat. No.
3,473,091, issued Oct. 14, 1959, to A. R. Morris et al. for a
"Ground Leakage Differential Protective Apparatus."
In accordance with the instant invention, an insulated housing is
divided into two compartments, one of which contains a conventional
push-push type single-pole circuit breaker having thermal and
magnetic means for automatic tripping under high current fault
conditions. The other compartment houses the elements for detecting
ground faults and generating a mechanical force to trip the circuit
breaker when relatively low current ground faults are present. In
one embodiment of the instant invention, the ground fault unit
includes an electromagnet with an armature that is connected by an
insulating link to the armature of the circuit breaker magnetic
trip. This link provides a lost-motion connection constructed so
that operation of the ground fault magnet moves the armature of the
circuit breaker trip magnet, but energization of the trip magnet is
ineffective to move the armature of the ground fault magnet so that
calibration of the magnetic overload trip device is not effected by
the ground tripping device.
In another embodiment of the instant invention the ground fault and
circuit breaker magnet coils are mounted on a common magnetic frame
extending into both compartments, with this frame including a
single movable armature. The coils of the ground fault and overload
magnets are wound so that the fluxes generated thereby are in
aiding relationship. As an optional feature, one or more permanent
magnets may be provided to aid the magnet fluxes.
Accordingly, a primary object of the instant invention is to
provide a novel construction for a combination circuit breaker and
ground fault protective device.
Another object is to provide a combination unit of this type in
which the circuit breaker handle is of the push-push type.
Still another object is to provide a combination unit of this type
having a lost motion connection between the overload magnet
armature and the armature of the ground fault tripping magnet.
A further object is to provide a combination unit of this type in
which there is a common magnetic frame and including a common
armature for the overload tripping magnet and the ground fault
magnet.
These objects as well as other objects of this invention will
become readily apparent after reading the following description of
the accompanying drawings in which:
FIG. 1 is a side elevation of a combination circuit breaker-ground
fault detector constructed in accordance with teachings of the
instant invention.
FIG. 2 is a plan view of the combination unit of FIG. 1.
FIG. 3 is a cross-section taken through line 3--3 of FIG. 2,
looking in the direction of arrows 3--3.
FIG. 4 is a cross-section taken through line 4--4 of FIG. 3,
looking in the direction of arrows 4--4.
FIG. 5 is a plan view of the armature for the ground fault tripping
magnet.
FIG. 6 is an end view of the armature of FIG. 5, looking in the
direction of arrows 6--6.
FIG. 7 is a plan view of the insulating link interconnecting the
ground fault and overload current tripping armatures.
FIG. 8 is an end view link of FIG. 7, looking in the direction of
arrows 8--8.
FIG. 9 is a plan view of the overload current armature.
FIG. 10 is an end view of the armature of FIG. 9, looking in the
direction of arrows 10--10.
FIG. 11 is an electrical schematic showing the combination unit of
FIG. 1, connected in circuit between a load and a source of
electrical power.
FIG. 12 is a view similar to FIG. 3, illustrating another
embodiment of the instant invention in which a common magnetic
frame supports the operating coils for both the overload current
and ground fault tripping electromagnets.
FIG. 13 is a side elevation of the electromagnets of FIG. 12,
looking in the direction of arrows 13--13 of FIG. 12.
Now referring to the figures. Combination circuit breaker ground
fault detector 20, often referred to as a ground fault interrupter,
includes molded housing 21 having a rear opening covered by
insulating sheet 22 and metal plate 23 having mounting gears 24, 25
integrally formed therewith. Fasteners 26 received in three housing
formations 27 fixedly secure sheet 22 and plate 23 to the rear of
housing 21. Centrally located internal partition 28 divides housing
21 into side-by-side compartments. The left one of these
compartments, as viewed in FIG. 3, contains the elements of a
single pole so-called "push-push circuit breaker" constructed
essentially the same as each pole of the circuit breaker
illustrated in U.S. Pat. No. 3,075,058 issued Jan. 22, 1963, to E.
P. Platz et al. for a "Push-Push Circuit Breaker." The right-hand
compartment of housing 21, as viewed in FIG. 3, contains the
elements of a ground fault protector. These elements (not shown)
are mounted to printed circuit board 29 and are arranged, for
example, in a circuit of the type illustrated in the aforesaid
Morris et al. U.S. Pat. No. 3,473,091. Also mounted within the
right-hand compartment is ground fault tripping magnet 30 that is
actuated by signals generated in secondary winding 32 and fed
through amplifier 35 of the ground fault detector.
Secondary winding 32 is part of transformer 31 which also includes
identical primary windings 33, 34 connected in series with the
neutral 37 and hot wires 38, respectively, connecting a.c. source
36 to electrical load 39. Primary 33 is connected through lead 41
to neutral line 37 that is grounded near source 36. The other end
of primary 33 is connected through lead 42 and line 43 to one
terminal of load 39. The other terminal of load 39 is connected
through line 44 to circuit breaker load terminal 45. Hot line 38 is
connected directly from source 36 to circuit breaker line terminal
46. The path between terminals 45, 46 internal of housing 21
includes load terminal 45 connected to one end of coil 47 of
overload tripping magnet 50, through coil 47 and primary 34 to one
end of overload tripping bimetal 58, through bimetal 58 and movable
contact arm 48 engaged with stationary contact 49 mounted to line
terminal 46 at a point thereof internal of housing 21.
Ground fault trip magnet 30 includes ground fault trip coil 84 and
movable armature 52. The latter is connected by insulating link 53
to movable armature 51 of circuit breaker magnet 50 in a manner
such that movement of armature 52 is transmitted by link 53 to
cause movement of armature 51 downward with respect to FIG. 3, or
in tripping direction, thereby moving armature latch formation 54
below and clear of latch tip 55 on movable contact arm 48 so that
main operating spring 56 is effective to move contact arm 48 about
its pivot pin 57, thereby separating the lower end of movable
contact arm 48 from stationary contact 49. The circuit breaker
automatic trip means also includes bimetal 58 which upon heating
deflects downward with respect to FIG. 3, engaging insulating
button 59 mounted to circuit breaker armature 51, causing the
latter to move downward to unlatching position.
As fully explained in the aforesaid U.S. Pat. No. 3,075,058,
operating button 61, slidably mounted to housing 21, is manually
depressible and is constructed so that the circuit breaker main
contacts 48, 49 will alternately open and close with successive
depressing operations of button 61. In a manner well known to the
art, button 62, upon being depressed, causes the engagement of
spring contact 63 with spring contact 64 to generate a tripping
signal in secondary winding 32 of transformer 31.
As best seen in FIGS. 7 and 8, insulating link 53 is a thin
elongated member having rectangular cutouts 66, 67, with the latter
being noticeably elongated in the direction of the longitudinal
axis of link 53. Ground fault tripping armature 52 (FIG. 5) along
one edge thereof is provided with spaced pivot extensions 71.
Lateral extension 72 of armature 52 extends into the smaller
aperture 66 of link 53. Elongated aperture 67 of link 53 receives
lateral extension 73 of circuit breaker magnet armature 51 (FIG.
9). The latter is provided with pivot extensions 74 projecting from
the edge thereof opposite plastic button 59. Thus, when coil 84 of
ground fault magnet 30 is energized, the rear of armature 52 is
moved downward against the force of coil spring 81, with armature
extension 72 moving link 53 longitudinally downward. This causes
the upper boundary wall of elongated aperture 67 to engage circuit
breaker armature extension 73 thereby moving the rear end of
armature 51 downward against the force of its coil biasing spring
82 to release latch tip 55 of movable contact arm 48. It is noted
that energization of circuit breaker magnet 50 is ineffective to
move ground fault armature 52 in that upon energization of magnet
50 causing downward movement of armature 51, extension 73 thereof
is free to travel downward in elongated aperture 67 without causing
movement of link 53. Thus, it is seen that ground fault armature
biasing spring 81 does not influence the calibration of the
magnetic trip for the circuit breaker section.
The first (FIGS. 1-10) and second (FIGS. 12 and 13) embodiments of
this invention differ in that in the latter both circuit breaker
trip coil 47, ground fault trip coil 84, and the magnetic cores for
each are mounted to a common magnetic frame 85 which extends across
both compartments of housing 86 for ground fault interrupter 100,
and a common armature 87 extending across both compartments of
housing 86 is utilized so that link 83 is eliminated. Naturally,
because of the raised location of ground fault trip coil 84 in FIG.
12 as compared to the position thereof in FIG. 3, printed circuit
board 88, carrying the electrical components (not shown)
constituting the ground fault detector is of a different
construction than printed circuit board 29, and most of the
components mounted to board 88 are disposed below magnet coil 84.
In the embodiment of FIGS. 12 and 13, since coils 47 and 84 are
mounted to common frame 85, circuit breaker current flowing through
coil 47 premagnetizes frame 85 to achieve very fast operation of
armature 87 when coil 84 is energized. The magnetic fluxes
generated by currents flowing in both coils 47 and 84 act in series
on common armature 87. To accomplish even higher sensitivity and
narrow the pickup range, additional magnetic flux is provided by
permanent magnet 89 mounted to the vertical leg of magnetic frame
85. One or both of the cores for coils 47 and 84 may have permanent
magnets. Any of the permanent magnets may be adjustable, by
repositioning or otherwise, to control electromagnet
sensitivity.
Although there have been described preferred embodiments of this
novel invention, many variations and modifications will now become
apparent to those skilled in the art. Therefore, this invention is
to be limited not by the specific disclosure herein, but only by
the appending claims.
* * * * *