Note: Descriptions are shown in the official language in which they were submitted.
1058739
Background o~ the Invention
In order to comply with certai~ industry standards and
safety provisions, ground fault interrupters often include an
under voltage relay. Prior devices have included two trip coils,
one to interrupt the circuit on occurrence of a ground rault and
the other to do so on occurrence of an under voltage condit~on.
This invention enables one trip coil to perform both
functions thus reducing cost and the space required for an ~ ~ -
extra coil.
According to one aspect of the present invention~ a
ground fault power circuit interrupter ~or use in a power cir
cuit having ground fault sensing means for sensing the occur-
rence of a ground fault above a preselected magnitude, compris-
es a single magnetic core and coil, armature means operatively
associated with and normally attracted to sald magnetic core
ln response to energization of sald coil by a current above a
predetermined value, power clrcuit contact means including a
movable carrier member carrying a contact and controlled by
said armature means ror extending said power clrcuit through
said contact ln response to ~he energl~ion of said coil by
said current above said predetermined value, mechanical biasing
means to bias said armature ~rom said magnetic core and movlng
said carrier member and contact to interrupt sald power circuit
in respon~e to the current in sald magnetic coil falling below
said predetermined Yalue~ control circuit means including
rectifier supply means connected to sald power circuit, first ~-
switch means ln said control circuit in a normally conducting
state when said co~trol circuit is powered by sald rectifier
supply means for energizlng said coil, a second switch con-
trolled in response to the sensing of a ground ~ault above
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said preselected magnltude, threshold switch actuating means
having lnternal circuit responsive variable resistance
characteristics for controlllng said first switch means to
render said first switch means non-conducting and thereby
interrupt current in sald coil in response to the control of
said second switch by said ground fault current above said
preselected magnitude, said armature, carrier and contact moved
by said biasing means ~n response to said coil being energized
by a current below said predeterm~ned value'for interrupting
said power circuit, a first conductor e~ndlng between sald ~.
rectifier supply means and said second switch mean~, a second
conductor connected at one end to said first conductor at a r~
~unction point thereon between said rectifier supply means
and said second switch means and at the other end to sald
first switch means, sald threshold switch actuating .means
being connected in series ln said second conductor between said
~unction point and said first switch means, and a manually
movable reset member engaged with said carrier for moving sald
carrier and contact against sa~d blas to move said armature
toward said core for enabling said armature to control said
contact ~or extending said power circult in response to the
current ln sald power circult being above sald predetermined :
value and moved by sald carr~er in response to said coil being
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energized by a current below said predetermined value. ; :
The inventlon will be more clearly understood after
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re~erence to the following detailed speci~ication read in .:
con~unctlon with the drawings wherein:
Fig. 1 is a side elevation view of a ground fault
circuit interrupter in accordance withthis invention, wlth
oertain parts in section and others broken away, showin~
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the contacts in clo~ed position;
Flg. 2 is a side elevation view of the device of Fig.
1 showing the contacts in open position;
Fig. 3 is an end elevation of a main spring and arm~
ature bias spring taken on line 3-3 of Fig. l; ,
and
Fig. 4 is a schematic drawing illustratlng a clrcuit
and components for use in the ground fault interrupter o~
this invention.
A ground fault circuit lnterrupter in accord with
this invention includes trip coil 1 wound on magnetic core ~ :
having a pro~ecting pole face 3. The coil ls mounted on
frame 4 with pole face 3 in position to attract armature 5
which is mounted to rotate on armature pivot 6 between a posi-
tion in contact with and out of contact with pole race 5.
Bias coil spring 7 is mounted on lateral shaft 8, with movable
spring end 9 secured to armature 5 and retained spring end 10
abutting the coil-facing side 11 o~ spring retaining ledge 12.
Bias coil spring 7 thus provides a bias to urge armature 5
away ~rom pole race 3.
Main coil ~pring 13 ls also mounted on lateral sha~t
8, having retained end 14 abutking the contact-raalng side
15 of spring retaining ledge 12 and having a center span 16
~ positioned to cradle contact carrler member 17 between
.l lever arms 18 with cross arm 19 seating in lateral groove
20 o~ carrier member 17. Main coil spring 13 thus pro-
vides a bias to urge khe body 21 o~ carrier member 17
against contact pivot 22 thereby moving carrier contact 23
away ~rom stationary contact 24 to open the circuit
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lOS8739
1 ~ protecte y the ground fault interrupter
2 ~ Contact 23 and 24 open and close a power circuit protected
3 ll by the interrupter. i
4I Carrier member 17 includes a transverse lip 25 projecting
5li rearward therefrom for engagement with forwardly extending .
6 il armature flange 26 when armature 5 is in contact with pole. ~ace
7 il 3 during normal operating energization of coil 1. Reset button
81~ 27 is depressable manually to bear against a portion of carrier i,
. 9'1 body 21 oppositely of and slightly forward of lateral groove 20
101~ in which cross arm 19 of main spring I3 seats to apply a bias
opposing the thrust of reset button 27 against.carrier body 21.
12 il When reset button 27 is manually depressed to bear against
13l carrier body 21, carrier member 17 moves against the tension
.14~ of main spring 13 from a contact open position to a contact
15~ closed posi~lon whereupon transverse lip 25 projecting rearward 1, .
16j from carrier 17 i.s engaged by armature fl.ange 26 to l.ock carrier
17 ~! member 17 in~contact closed position. The contacts 23 and 24 are
18-i held together;in;closed position until the voltage on coil 1
1 19 , drops below a pre-selected amplitudej enabling bias coil spring
20 i 7 to overcome the magnetlc attractlon force of pole ~ace 3 and :
21,1 urge armature 5 away from contact therewith, ~s armature 5 is
. 22~ urged away from pole ~ace 3 it rotates on pivot 6 causing
23'i~ armature flange 26 to disengage from transverse lip 25 of
24~ carrier member 17. The biasing cross arm 19 of maln spring 13
251 is thereupon free to move carrier member 17 in the direction
26 ll which causes carrier 17 to engage contact pivot 22 causing
27, . carrier member 17 to pivot to a contact open position, se~arating
28'l carrier contact 23 from stationary contact 24. The protected
29 circuit is thereby interrupted as a result of the said drop in
30. voltage on~trip coil 1 below a pre-selected amplitude, which
31j occurs on appearance of a ground fault or an under voltage
32~¦ condition in the protected circui.t.
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1¦Fig. 4 illustrat.es schematically a control circuit which
2 causes a drop in voltage to occur in trip coil 1 on appearance
of a ground ~ault or under voltage condition. A dif~erential ~.
4 transformer 28 encompasses power lines ~1 and L2 to detect a
5¦ ground fault on appearance in said lines, which causes ampli~ler
6l 29 to provide an input to silicon-controlled rectifier 30 which ~:
71 then conducts. ~ . .
81~ During normal circuit conditions, when power line Ll is
91¦ positive with respect to L2, current flows from Ll through diode :
10ll 33, trip coil 1, n-p-n transistor 31 and diode 34 to L2. When
~ L2 becomes positlve with respect to Ll, current ~low is ~rom L2 .
121~ through diode 35, trip coil 1, n-p-n transistor 31 and diode 32
1311 to Ll. Diodes 32, 33, 34 and 35 are thus connected to provide a .
141~ ~ull wave recti~ier circuit between transistor 31 and power lines
15 j! Ll and L2, l
16il When a ground ~ault is detected by differential trans~ormer .
17 1l 28 causing an input to SCR 30, the SCR 30 conducts resulting in
18~:,¦ a low voltage at Junction X. A zener diode 36 prevents current :
19 from flowing in: the base o~ transistor 31 and the transi.stor 31 .
20l goes into a non-conducting or "of~" state. The current in trip . ~
2111 coil 1 is thereby interrupted, whereupon the bias spring 7 over- :
22 1l comes the magnetic attractlon force o~ pole ~ace 3 and urges
23j armature 5 away therefrom causing the protected circuit to be .
24l interrupted as armature~flange 26 disengages ~rom transverse lip . :.
25 1l 25 permittlng contacts 23 and 25 to open, .
26 1 Similarly, when line voltage drops to a pre-determined level
27i', or in the event one of the power lines L1 or L2 is severed, the I ..
28~ trip coil 1 releases the biased armature 5 and interrupts the
29l protected circuit in the manner described.
301 Reset button 27 is mounted ~or reciprocal movement throug~
31~l frame 4 or other support to engage the body 21 Or carri.er member I .
32~ 17 adjacent oontact pivot 22. After carrier member 17 has been 11
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l rotated to a contact open position as shown in Flg. 2, the J
2 interrupter is reset by depressing re-set button 27 whi.ch urges
3 carrier member 17 against the bias of main coil spring 13 to a
4 contact closed position as shown in Fig. l, I~ the`fault current ;
5 l or under voltage condition is no longer present, trip coil l j-
61 again is energized attracting armature 5 to pole face 3 and ~`
7 positioning armature flange 26 to engage transverse lip 2$ of ~
~ 8 contact carrier member 17. When so engaged, contacts 23 and 24 ~.
I 9 are closed and maintained in releasably locked position until a ~ . ~:
ll ~ault current or~under voltage oonditlon again occurs, ~
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27
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29
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