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Патент USA US2106100

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Jan. 18, 1938.
2,106,100
B. ‘v‘k'. JONES
CIRCUI T CONTROLLING MEANS
Filed Oct. 8, 1936
33
Inventor;
Bery'nminjov J n66,
I b‘y ?amyd'
H
4/44
is Attorngy.
2,106,100
Patented Jan. 18, 1938
UNITED STATES PATENT OFFICE
2,106,100
CIRCUIT CONTROLLING MEANS
Benjamin W. Jones, Schenectady, N. Y., assign
or to General Electric Company, a corporation
of New York
Application October 8, 1936, Serial No. 104,605
10 Claims. (01. 175-—-294)
My invention relates to circuit controlling
means, more particularly to control means for
circuit controlling switches of the latched closed
type and has for an object the provision of im
5 proved control means of this character.
Circuit controlling switches of the latched
closed type when applied to the control of elec
trical apparatus, such for example as electric
motors, are usually provided with an operating
winding for effecting closure of the switch, with
latch means for latching the switch in its closed
circuit position upon operation thereto, with in
terlock means for interrupting the energizing cir
cuit of operating winding as soon as the switch is
latched closed, and with control means respon
sive to various electrical conditions of the circuit
such as overload or undervoltage conditions for
releasing the latch means automatically to open
the switch.
In order fully to protect the electrical appara
tus against injury due to abnormal circuit con
ditions, the circuit controlling switch is usually
provided not only with undervoltage means and
with instantaneously operable electromagnetic
25 means for releasing the latch, but also with ther
mal overload means responsive to prolonged over
loads of less magnitude than are required to op
erate the electromagnetic overload.
Such ther
mal, overload means are ordinarily incapable of
exerting a mechanical force of very great mag
nitude and accordingly the thermal means, being
incapable of directly releasing the latch mem
ber, may be arranged to control the latch in
directly by controlling the energization of a spe
cial trip device or the deenergization of the un
periodic opening and closing of the circuit con~
trolling switch may result due to the fact that
the energizing circuit for the operating winding
is reestablished through the interlock contacts
each time that the switch opens. Since the latch
is held in its releasing position by the overload
means, the circuit controlling switch will be
caused to open and close periodically as the
circuit for the operating Winding is made and
broken at the interlock contacts.
Furthermore, if the overload means is arranged
to energize a special trip coil, dif?culties may
arise due to the fact that an adequate supply
of energy is necessary to effect operation of the
tripping device. Thus, the circuit voltage may
be too low to eilect operation of the tripping de—
vice and yet too high to e?ect release of the un
dervoltage means. Accordingly, the switch will
remain closed even though a dangerous overload
condition exists in the circuit.
switch having an operating winding energizable 30
to close the switch, means for latching the switch
in its closed position, and means responsive to
closure of the switch for deenergizing the operat
ing winding, control means comprising normally
energized means operable when deenergized to
dervoltage means.
release the latch means, relay means for con
The above arrangement of the thermal over
load means is particularly desirable when the
circuit controlling switch and its control means
are immersed in a body of oil for operation
therein, for in such cases it is desirable substan
tially to isolate the thermal element from the
immersing body of oil, as set forth in my Patent
means so as to release the latch upon the oc
2,051,380 issued August 18, 1936.
Various ar
rangements of the thermal overload means may
advantageously be employed when the operating
winding of the circuit controlling switch is con
trolled by means of a momentary-contact type
control switch. When, however, it is desired to
50 control. the operating winding by means of a
maintaining-contact type switch, for example a
?oat operated or pressure operated switch, con—
siderable difficulty may arise. Thus, if the over
load device is arranged to deenergize the under
voltage means to effect release of the latch, a
. )
It is therefore a further object of my invention
to provide control'means for a circuit controlling
switch of the latched closed type, which control
means is simple and inexpensive and which re
liably effects release of the switch in response
to predetermined overload and undervoltage con
ditions.
In carrying out my invention in one form, I
provide, in connection with a circuit controlling
trolling the normally energized means, and over
load means for energizing the relay means to
e?ect deenergization of the normal energized
currence of predetermined overload conditions.
Connections are also provided by means of which
the overload means short-circuits the normally
energized device to effect release of the latch,
even though the relay means fails to operate.
45
More speci?cally, I provide undervoltage means
for releasing the latch in response to a predeter
mined decrease in the voltage of the circuit con
trolled by the circuit controlling switch and an
auxiliary relay is arranged simultaneously to 50
deenergize the undervoltage means and to inter
rupt the energizing circuit of the operating wind
ing so as to prevent periodic opening and closing
of the circuit controlling switch. The relay
means and the operating winding have a de?nite 55
2
2,106,100
piclnup voltage which is greater than the drop~
out voltage of the undervoltage means and the
additional connections established by the over
load means for short-circuiting the undervoltage
means ensure release of the latch, even though
circuit voltage may be less than the pick-up
voltage of the relay and greater than the drop
out voltage of the under-voltage means.
For a more complete understanding of my in
10 vention, reference should now be had to the
drawinrr in which the single figure is a somewhat
diagrammatic representation of a circuit control
ling switch provided with control means embody
ing my invention.
Referring now to the drawing, I have shown
my invention as applied to a circuit controlling
swite
5c of the latched closed type provided
with circuit controlling‘ contacts H arranged to
latch l5 and operate it to its releasing posit-ion
against the bias of the spring it": upon a prede
termined degree of energization of the winding
30. The winding 30 is energized from a current
transformer 33 so as to be responsive to overload
conditions in the circuit represented by the con
ductors l3 and a heating winding 34 of a suit
able thermal overload device 35 is connected in
series with the current transformer 33
the
winding 36 of the electromagnetic overload de
vice.
As shown, the thermal overload device 35 com
prises in addition to the heating winding 34 a
bi-metallic element 36, the free end of which
carries
contact 31 arranged to engage a sta
tionary contact 38.
In addition to the above described apparatus,
my improved control means includes a pair of
control the connection of a load circuit repre
sented by a pair of conductors I 2 and a supply
circuit represented by a pair of conductors i3.
normally closed push-button switches 31 and 38,
Although I have shown single phase circuits in
order to simplify the drawing, my invention is
obviously applicable as well to three phase sup
ly operated or float operated switch for example,
and an auxiliary relay 4!) having a pair of normal
ly open contacts 4! and a pair of normally closed
contacts 42. Furthermore, in order to energize
ply and load circuits. As shown, the circuit con’
trolling switch i8 is provided with an operating
winding 1'4- arranged when energized to effect
movement of the circuit controlling contacts H
to their closed circuit position, with a pivoted
latch l5 normally biased to its latching position
a control switch 39, which is of the maintaining ii)
contact type, and which may be either manual
the Lmdervoltage means in accordance with the
voltage of the circuit controlled by the switch If},
I provide a potential transformer having a pri—
mary winding 43 connected across the supply cir
cuit represented by the conductors 23 and a sec
by a spring 56 and with suitable interlock con
tacts which comprise a movable contact member
'5 connected to the switch it! by means of a re
silient connection it and arranged to engage a
ondary winding 44 which supplies energy to the
undervoltage means, and likewise supplies control
energy for the operating winding It and the aux~
plurality of stationary contacts 19, 20, and 2|.
The movable contact H is also connected, as
shown, to suitable time delay means 22 represent
With the above description of the principal
elements in mind, it is believed that a complete
understanding of my invention may now be had
from a description of the operation. Upon clo
sure of the control switch 39, either manually or
ed as a conventional dash-pot for delaying oper
ation of the contact I ‘.1 out of engagement with
the stationary contacts 19, 26 and 2! for a pre
determined time after the switch i8 is operated
to its closed circuit position.
iliary relay 40.
in response to a predetermined condition if the
switch is ?oat operated or pressure operated, an
predetermined undervoltage conditions, I pro~
energizing circuit is established for the operating
winding M of the switch H), which circuit may
be traced from one side of the secondary winding
vide undervoltage means of the type disclosed
44 of the potential transformer through the con
in my Patent 2,001,494, issued May 14, 1935,
ductors 45 and 46, the push-button switch 37,
the conductors 4'! and 48, the control switch 39,
the conductors 43 and 58, the operating winding~
In order to control the latch 15 in response to
which undervoltage means may be described for
the purposes of the present invention as compris
ing a full wave recti?er 23 which includes a plu
rality of asymmetric conducting units 24 for sup
plying direct cnrrent energy to an energizing
winding 2? of an electromagnetic relay which in
cludes a magnetizable core 28 and a pivoted mag
netizable armature 2i! biased by gravity to its
unattracted position, in which position it effects
the release of the latch 15. As more fully de
scribed in my above referred to Patent 2,001,494,
the armature 2Q, when in its closed circuit posi
tion, provides in conjunction with the magnetiz
(30 able frame :28 a substantially closed magnetic cir
Li
14, a conductor 5!, a pair of interlock contacts
52 carried by the plunger 3| of the electromag
netic overload device, the conductor 53, the co
operating contacts l9, II, and 23, the conductors
54. and 55, the normally closed contacts 42 of
the auxiliary relay 4G and by way of the con
ductors 56 and 5‘! to the opposite side of the sec
ondary winding 44.
Immediately upon cnergization of the operat
ing winding 14, the contacts l l of the circuit con
trolling switch it! are operated to their closed cir
cuit position and an energizing circuit is estab (Ill
lished for the undervoltage means to attract the
pivoted armature 29 and release the latch l5 for
cuit and the full wave recti?er provides a closed
local circuit winding 21', so that upon a decrease
in the voltage supplied to the terminals of the
recti?er, an induced current will flow through
movement to its latching position. This ener
gizing circuit for the undervoltage means extends
the closed local circuit comprising the winding
from the previously energized conductor 49
27 and the legs of the full wave recti?er, which
current tends to prevent decay of ?ux in the
closed magnetic circuit and thus retains the ar
mature in its attracted position for a predeter
mined time after the voltage has decreased.
Adjacent the pivoted latch 15 I also provide an
electromagnetic overload device 25 which com
prises
winding
for moving a magnetizable
plunger l, the upper end of which carries a pro
through a conductor 53, a pair of interlock con
tacts 59 on the switch ID, a conductor 5c, the
recti?er 23, a conductor 8!, a current limiting
jecting ?nger 32 arranged to engage the pivote
5)
resistor 62, the conductors 63 and 64, the cooper
ating interlock contacts 2i, l1, and 20, the con
ductors 54 and 55, the normally closed contacts 42
of the auxiliary relay 4!), and by Way of the con~
duotors 56 and 5'! to the secondary winding M of
the potential transformer.
Operation of the switch I!) to its closed circuit
75
3
2,106,100
position is also effective to stress the resilient
means 58 and accordingly the movable contact
ll tends to move out of engagement with the
?xed contacts is, so, and 2!. The time delay
means 22, however, prevents movement of the
the overload device returns to its normal position.
In order to prevent the plunger 3! of the over
load device 25 from returning to its normal posi~~
tion as soon as the switch It opens, and thereby
reestablishing an energizing circuit for the switch
contact ll‘ until after the under-voltage means
ill, the overload device 25 is preferably provided
has been energized and the latch ‘l5 has moved
to its latching position. As soon as the contact
ll is disengaged ‘from the contacts it), 28, and
10 2!, the energizing circuit for the operating wind
ing Hi is interrupted and accordingly the switch
is thereafter maintained in its closed circuit
position solely by the latch iii. Likewise, dis»
engagement of the contact ill from the contacts
with suitable latch means, shown as a pivoted
Eli and ii is effective to insert a second resistor
dition exists in the circuit represented by the
$5 in the energizing circuit or" the undervoltage
conductors l2 and 53 which induces in the current -
rectifier
and the winding 2“; of the undervolt~
age relay a predetermined amount. The energiz
operate
but which
theisplunger
suirlciently
3! oflarge
the overload
to cause device
the heat
ing winding 34 of the thermal overload relay 35
to generate considerable heat. If this overload
and the contacts ll, 20, and 2!,
So long as normal current conditions exist in
the circuit represented by the conductors i2 and
it, the switch it will remain in its closed circuit
position under the control
the switches 37 and
39. Whenever the switch Sal is open, the energiz
ing circuit for the undervoltage means will be
continues for a predetermined time, the bi
metallic element 36 of the thermal relay 35 will
flex in a- direction to e?ect engagement of the
contacts 3i and 38 and establish an energizing
circuit for the energizing winding of the auxiliary
relay 40.
This energizing circuit may be traced from the
secondary winding
oi‘ the potential transform
or through the conductors to and lit, the push
interrupted and accordingly the armature of the
undervoltage relay will be released to move the
latch £5 to its releasing position and open the
button switch 31, the conductors
switch Ill.
way of the conductors "5E? and 5? to the other
side of the secondary winding rill. If the voltage
existing on the circuit represented by the con
If the control switch 38 is a pressure
operated or float operated switch, the push
Li
It will now be assumed that an overloaded con
transformer 33 a current which is insuf?cient to
ductors till and
Ii
or (ii in its uppermost position upon operation
thereto. The latch Ma may be withdrawn by 10
pressing a button 3H) to release the plunger 3i
and permit it to drop and close the circuit through
the contacts 52.
cans so as to reduce the energisation of the
ing circuit for the undervoltage means new ex
tends from the conductor
through a con
ductor 6t; and the current limiting resistor 65 to
the conductor 55 rather than through the con
(O
spring pressed latch 31a for retaining the plung~
button switch 3? may be used to open the switch
it at will.
It will now be assumed that with the switch
40 in its closed circuit position, a predetermined
decrease in the voltage or" the circuit represented
by the conductors l2 and i3 occurs. Conse
quently, the magnetic flux in the frame 28 and
the armature 29 of the undervoltage device tends
to decrease, but is maintained for a predeter
mined time by the induced current flowing in the
winding 2'? and. the rectifier 23. If the voltage
does not return to its normal value within a
predetermined time, the armature 229 will be re
leased and will move to the position shown in
the drawing to release the latch and open the
and.
contacts 3? and 38, the conductors ‘.38 and lit,
the winding of the auxiliary relay 4E, and. by
ductors i2 and i3 is su?iciently high to induce
in the secondary winding {ill of the potential
transformer a control voltage which is above
the pick-up voltage of the relay r’lil, the relay
will immediately be operated to interrupt at the
contacts
both the energizing circuit for the
undervoltage means and the energizing circuit
for the operating winding l4. Consequently, the
armature 29 of the undervoltage relay will opera
switch ill. Although the energizing circuit for
the operating winding Hl will be reestablished as
soon as the movable contact ll reengages the
not reclose.
device.
As soon as the voltage returns to nor
4 .3
ate with a slight time delay to the position. shown
in the drawing to release the latch l5, whereupon
the circuit controlling switch M is immediately
opened. As hereinbefore mentioned, the ener
gizing circuit for the operating winding M is 11126wise interrupted at the relay contacts 42 and
accordingly the circuit controlling switch it does
contacts l9 and 28, the switch it‘ will not be
Cl Ur operated to its closed circuit position until the
voltage returns to normal, because the pick-up
voltage of the switch it is considerably greater
than the drop-out voltage of the undervoltage
Li;
, the
.71)
Consequent to operation of the relay 49 to its
uppermost position, a holding circuit is estab~
lished for the energizing winding of the relay
is, which circuit may be traced from the second
ary winding 45 of the potential te‘ansforrner
through conductors t5 and ‘ii, ‘the push-button
UL)
switch 38, a conductor T2, the contacts M of
the undervoltage device energized to attract its _ relay M, a conductor 13, and by way of the en
armature 29 and permit the latch id to move to ergizing winding for the relay M and the con—
its latching position.
Thus,
ductorsit ‘illwill
andbe5?seen
to the
‘thatsecondary
the relaywinding
4e will be
(S0 mal, however, the switch will again be closed and
If a severe overload occurs in the circuit repre~
sented by the conductors l2 and i3, a current
will be induced in the current transformer 33
which will energize the winding 36 of the electro—
magnetic overload device 25 sui?ciently to move
the plunger 3! upwardly and operate the latch [5
Since the energizing
circuit for the operating winding N3 of the switch
it? is interrupted at the contacts 52 upon opera
tion of the plunger ill, the switch iii will not be
7 O to its releasing position.
reclosed, even though the contact i7 reengages
75 the contacts Ill and 29 until the plunger 3| of
maintained in its operating position to prevent
(3.3
reestablishment of an energizing circuit for the
operating winding ill until such time as the push
button switch 33 is operated to decnergize the re~
lay at and reestablish energizing circuits for the
operating winding
l5! and the
undervoltagc '
means.
As will be well understood by those skilled in
the art, certain types of overloads may cause a
considerable decrease in the voltage of the cir
cult and I have found in actual practice that over
4
2,106,100
load conditions will often arise in which the
voltage of the circuit represented by the conduc
tors l2 and 13 may be of such a value that the
control voltage induced in the secondary wind
ing 44 of the potential transformer will be less
than the pick-up value of the relay 40 and greater
than the drop-out value of the undervoltage
lieans. Under such voltage conditions, closure
of the contacts 3'! and 38 does not effect opera
tion of the auxiliary relay 4!! and since the con
trol voltage is of suf?cient magnitude to main
tain the undervoltage device in its energized posi
tion, the circuit controlling switch in will not be
opened, even though a dangerous overload con—
dition exists in the circuit represented by the
conductors l2 and i3.
In order to provide for operation of the switch
its open circuit position under such condi
tions, the contacts 3'! and 38 controlled by the
overload relay 35 are arranged upon closure to
short-circuit the undervoltage means and there
by ensure release of the latch l5, even though
the auxiliary relay 43 does not pick up. This
short-circuit extends from the conductor 4'! in
the energizing circuit of the undervoltage means
through the conductor 2’, the contacts 31 and
and the conductors 6B and 14 to a midpoint
on the current limiting resistor 65. As soon as
this short-circuit is completed, the undervoltage
means will be substantially deenergized and the
latch it will be released to open the switch ll
Under these conditions, it is not necessary to in
terrupt the energizing circuit of the operating
winding M since the control voltage available is
below the pick-up voltage of the switch 10 and
accordingly a periodic opening and closing of
the switch 153 cannot occur.
It will thus be seen that I have provided im
for deenergizing the operating winding, said con~
trol means comprising means normally energized
from the circuit controlled by said switch and
operable when deenergized to release said latch
means, relay means energizable from said circuit
for controlling the energization of said normally
energized means, overload means responsive to
predetermined overload conditions for energizing
said relay means to effect deenergization of said
normally energized means and thereby release
said latch means, and connections controlled by
said overload means for short-circuiting said nor
mally energized means to effect release of said
latch means even though the voltage of said cir
cuit is insuf?cient to effect operation of said relay
means.
3. Control
means for
a
circuit
controlling
switch having an operating winding energizable
to close the switch, means for latching the switch
in its closed circuit position upon operation there~
to and means responsive to closure of the switch
for deenergizing the operating winding, said con
trol means comprising means normally energized
from the circuit controlled by said switch and
operable when deenergized to release said latch '
means, relay means energizable from said circuit
for controlling the energization of said normally
energized means, overload means responsive to
prcdet rrnined overload conditions for energizing
said relay means to e?'ect deenergization of said
normally energized means and thereby release
said latch means, means controlled by said relay
means for preventing reenerglzation of said oper
ating winding upon movement of said switch
means to its open circuit position, and connec
tions established by said overload means for
short-circuiting said normally energized means to
effect release of said latch means even though
proved control means which will reliably effect
the voltage of said circuit is insu?icient to oper
operation of the switch ill to its open circuit
position under all dangerous conditions of over
load or undervoltage.
While I have shown a particular embodiment
of my invention, it will be understood, of course,
that I do not wish to be limited thereto since
many modi?cations may be made and I, there
ate said relay means.
4-. Control means for a
fore, contemplate by the appended claims to cover
any such modi?cations as fall within the true
spirit and scope of my invention.
What I claim as new and desire to secure by
Letters Patent of the United States, is:
1. Control means for a circuit controlling switch
having an operating winding energizable to close
the switch, means for latching the switch in its
closed circuit position upon operation thereto a. d
means responsive to closure of the switch for de
energizing the operating winding, said control
means comprising normally energized means op
erable upon deenergization thereof to release said
latch means, relay means for controlling said
normally energized means, overload means for
energizing said relay means to effect deenergiza
tion of said normally energized means and there
by release said latch means upon the occurrence
of predetermined overload conditions, and con—
nections controlled by said overload lncans for
short-circuiting said normally energized means to
effect release of said latch means upon the oc
currence of said overload conditions even though
said relay means fails to operate.
2. Control means for a circuit controlling
switch having an Operating winding energizable
to close the switch, means for latching the switch
in its closed circuit position upon operation there
to and means responsive to closure of the switch
circuit
controlling
switch having an operating winding energizable
to close the switch, means for latching the switch
in its closed circuit position upon operation
thereto and means responsive to closure of the 45
switch for decnergizlng the operating winding,
said control means comprising undervoltage
means energizable from the circuit controlled by
said switch for releasing said latch means upon a
predetermined decrease in the voltage of said
circuit, an auxiliary relay energizable from said
circuit,
means responsive to predeter
mined overload conditions for establishing an
energizing circuit for said relay, means respon
sive to operation of said relay for cleenergizing
said undervoltage means to release said latch
means and for preventing reenergization of said
operating winding upon operation of said switch
to its open circuit position, and connections es
tablished
said overload means for short-cir
cuiting said undervoltage means to release said
latch means even though the voltage of said cir
cuit is insunicicnt to operate said relay.
5. Control means for a circuit controlling
switch havinrr an operating winding energizable
to close the switch, means for latching the switch
in its closed circuit 1 osition upon operation there
to and means responsive to closure of the switch
for deenergizing the operating winding, said con
trol means comprising undervoltage means on
irgizable from the circuit controlled by said
switch for rel-easing said latch means upon a pre»
determined decrease in the voltage of said circuit,
an auxiliary relay energizab-le from said circuit,
overload means responsive to predetermined over
50
55
60
65
5
2,106,100
load conditions for establishing an energizing
circuit for said auxiliary relay, means responsive
to operation of said relay for deenergizing said
said control means comprising means for dcriv~
undervoltage means to release said latch means
circuit, undervoltage means energizable in ac
and for preventing recnergization of said oper
ating winding upon operation of said switch to
its open circuit position, said switch and said
cordance with said control voltage for releasing
relay having a pick-up voltage greater than the
overload means for releasing said latch means
drop-out voltage of said underroltage means, and
10 connections established by said overload means
for short~circuiting said undervoltage means to
release said latch even though the voltage of said
circuit is greater ‘than said drop-out voltage and
less than said pick-up voltage.
6. Control means for
,uit controlling
switch having an operating
energizablc
to close the switch, means for latching the switch
in its closed circuit position upon o1 ration. therc~
to and means responsive to closure oi.’ the switch
20 for deenergizing the operating winding, said con.“
ing from the circuit controlled by said switch a
control voltage proportional to the voltage of said
said latch means upon a predetermined decrease
in the voltage of said circuit, electromagnetic
substantially instantaneously in response to
overload currents of predetermined magnitude, 10
an auxiliary relay, thermal overload means re»
lsponsive to prolonged overload currents of less
than said predetermined magnitude for ener
giz'ng said auxiliary relay from said current de-I
riving
means responsive to operation of 15
said relay for deenergizing said undervoltage
means to release said latch means and for pre
venting reenergization of said operating winding
upon operation of said switch to its open circuit
position, said switch and said relay having an 20
trol means comprising means for deriving from
the circuit controlled by said switch a control
eiiective pick-up voltage greater than the drop
voltage proportional to the voltage of said circuit,
nections established upon operation or said then
mal overload means for short~circuiting said
undervoitage means energizablc in accordance
with said control voltage for releasing
latch
Inca
upon a predetermined decrease in the
out voltage of said undervolt
means,
con’
undervoltage means to insure release of
25
latch means even though said control voltage is
less than said pick-up voltage and greater than
voltage of said circuit, an auxiliary relay, overload means i ‘sponsive to predetermined overload
said drop-out voltage.
iron;
conditions
said volts
for one
deriving
‘wing means,
said auxiliary
means respon
switch having an operating winding energizable
s'
to close the switch, means for latching the switch
in its closed circuit position upon operation
thereto and means respcrsive to closure
the
switch for deenergizing the
winding,
to operation of said relay for deenergizing
said ruidervoltage means to release said latch
means
op-oi‘" and [or
'
preve
' upon operation
r-oonergization
of said of
switch
ting vindl
to its open circuit position,
switch and said
relay hav' ;
pickmup voltage greater than the
dropout '
c of said undervoltage means, and
blished by said overload means
for s.=:
iii-lg
undervoltage met.
to
release said atch means even though
con
trol voltage i greater than. said drop-out voltage
and less Ji'litll said picky-up voltage.
7. Control
means for
a
circuit
controlling
9. Control
means
said switch for releasing
predetermined r. enitudc for controlling the en
crgizatlon of said relay, means responsive to
operation of
relay for deenergizing said
on
‘voltage means to release said latch and
for preventing reenergization of said operating
winding upon operation of said switch to its open
circuit position, and connections established
upon operation of said thermal overload means
for short~circuiting said undervoltage means to
release said latch independently of said auxiliary
relay.
Control
means
for a circuit controlling
ch having an operating winding energizable
'
~
,
release said latch means
~
mama
foo",
f ~"' 12 of said oper
ating winding upon operat'co of said switch to its
open circuit position, additional means responsive
to operation of said relay for completing a hold
ing circuit therefor, manual means for inter»
rupting said holding circuit to deenergize
re~ 50
lay to permit reenergization of said operating
winding and said undervoltage means, and con
nections established upon operation of said over
load means for short-circuiting said undervolt
age means to release said latch means even
though the voltage of said circuit is insu?icient
to effect operation of said relay.
10. Control means for a circuit controlling
switch having an operating windi
energizable
to close the switch, means for latching the switch
in its closed circuit position upon operation
thereto and
responsive to closure of the
switch for deenergizing the operating winding,
said control
comprising
for de
riving from the circuit controlled by said switch
a control voltage proportional to the voltage of
said circuit, means for energizing said operating
winding from said voltage deriving means, under~
voltage means energizable in accordance with
said control voltage for releasing said latch 70
means upon a predetermined decrease in the
voltage oi": said circuit, electromagnetic overload
in its closed circuit position upon operation
thereto and means responsive to closure of the
75 switch for deenergizing the operating winding,
40
ergizing circuit for said relay, means responsive
to operation of said relay for deenergizing said
and for prover
circuit, electroi i'netic means for releasing said
latch substantially instantaneously in response
to overload currents of predetermined magni
tude, an auxiliary relay energizable from said
circuit, thermal overload means responsive to
prolonged overload currents of less than said
.
mined
circuit, overload
overloadconditions
means respcn
for completing
e to , an on
undervoltage meam
said switch for releasing said latch means upon
a predetermined decrease in the voltage of said
latch mean; in.
circuit,
a predetermined
an auxiliary
decrease
relay in
enereirable
the voltage
from
of said
to close the switch, means for latching the switch
in its closed circuit position upon operation
thereto and means responsive to closure of the
said control means comprising undervoltage
means energizable from the circuit controlled by
05
said
meanscontrol
energizable
means
fromcomprising
the circuit controlle
undervclt
switch having an operating winding energizable
switch for rcenergizing the operating winding,
a circuit controlling
means for releasing said latch means substan~
tially instantaneously in response to overload
currents of predetermined magnitude, a relay,
6
2,106,100
thermal overload means responsive to prolonged
overload currents of less than said predetermined
magnitude for energizing said relay from said
current deriving means, means responsive to op
eration of said relay for deenergizing said un
dervoltage means to release said latch means
and for preventing reenergization of said operat
ing Winding upon operation of said switch to its
said relay to permit reenergization of said op
erating winding and said undervoltage means,
said switch and said relay having an effective
pick-up voltage greater than the drop-out volt
age of said undervoltage means, and connections
established upon operation of said thermal over
load means for short-circuiting said undervolt
age means to insure release of said latch means
open circuit position, additional means controlled
even though said control voltage is less than said
by said relay for establishing a holding circuit
therefor, manually operable means for interrupt
ing said holding circuit to e?ect deenergization of
pick-up voltage and greater than said drop-out 10
voltage.
BENJAMIN W. JONES.
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