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Патент USA US2125130

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July 26,1938.
'
s. T. scHoFlELD
CONTROL DEVICE FOR CIRCUIT BRÉAKERS
Filed Dec. 31, 1936
2,125,130
Patented July 26, 1938 `
. I
UNITED STATES PATENT OFFICE
l
z,1z5,1so
coN'raoL pEvrcE Eon cmom'r naEAxEas
Stanley T. Schofield, deceased, late of Wilkins
burg, Pa., by Martha M. Schoiield, administra-
'
trix, Wilkinsburg, Pa., assignor to Westinghouse
Electric & Manufacturing Company, East
Pittsburgh, Pa., a corporation of Pennsylvania
Application December 31, 1936, Serial No. 118,577
18 Claims. (Cl. 20o-106)
The invention relates to electric control devices
in general and more particularly to electric con
trol devices for tripping circuit breakers to open
the contacts thereof.
5
-
In medium and high voltage alternating-current power distribution systems, the circuit
breaker and for this reason the circuit breaker
with which the trip device is shown associated in 5
the drawlng'has been illustrated in a diagram
breakers used are relatively large and consider-
matic manner.
able energy is required to r'n'o‘ve‘ the ‘relatively
heavy latch means to trip the breakers. In
AReferring to the drawing, the circuit breaker,
which is illustrated diagrammatically, comprises
10 many instances, auxiliary sources of power are
not available or practical and the practice has
been` to derive the energy for tripping the breaker
from a current transformer associated with the
circuit or line controlled by the breaker. One
15 type of arrangement has been the provision of
an alternating-current electromagnet for tripping the latches of the breaker, the electromagnet being connected in a control circuit which
is energized by a current transformer coupled
20 to the line controlled by the breaker.
The in-
eiiicient useby the electromagnet of the limited
power available makes this arrangement unsatisfactory particularly in view of the use of
larger and heavier circuit breakers.
25
It is accordingly an object of the invention to
provide a novel trip device for tripping large
circuit breakers, which device is operable by a
low energy control circuit.
heretofore known or used,
`
a pair of stationary contacts 3, a movable brush l0
Contact 5 connected to a pair of toggle links 1 and
9 which form a part of the operating mechanism
for closing the-circuit breaker, a releasable latch
means il for restraining the movable brush con
tact 5 in closed circuit position, and a spring l5
means I3 for biasing the movable brush contact
5 to the open circuit position. The latch mem
ber H is pivotally mounted by means of a pivot
Din l5 andiS biased tOlatehing DOSítiOn, eS ShOWn,
by means of a weighted extension I1.
_
20
The trip device comprises in general a sup
Dort I9, a trip lever 2l, a latch 23, a vibratory
energy storing device indicated generally at 25,
an electromagnet 21 for the vibrating device to
store energy therein, and a control circuit 29 for 25
energizing the eleetl`0megnetThe trip lever 2| is pivotally mounted on a
bracket 3| by means of a pivot pin 33.
Another Object; 0f the invention is the provi30 sion of an improved trip device for circuit breakers capable of tripping larger breakers with a,
lower energy control circuit than any trip devices
y
Another object of the invention is to provide
.
It will be understood that the trip device em
bodying the features of the invention is capable
of application to substantially any type of circuit
One end
0f the trip level' 2| Carries a trip projection which,
in the fOl‘m ShOWn, COmDriSeS a Screw 35 which 30
is threaded through the trip lever adjacent its
left-hand end- A 100k 1111i? 37 iS DrOVided for
locking the screw 35 in adjusted position.
The
Opposite end 0f the trip lever Carries the DiVOted
35 a novel low energy alternating-current trip device
for a circuit breaker which is simple, reliable,
latch member 23- The latch member 23 has a 35
depending hOOk-Shaped latch DOftÍOIl 39 and a
and inexpensive to manufacture.
Another object of the invention is the provision of a novel low energy alternating-current
4o trip device for a circuit breaker, which embodies
an adjustable means for varying the time required for tripping the breaker.
\
'I'he novel features that areconsidered characteristic of the invention are set forth in par45 ticular in the appended claims. The invention
itself, however, both as to structure and operation, together with additional objects and advantages thereof, will best be understood from the
following detailed description oi an embodiment
50 of the invention when read in connection with the
accompanying drawing, in which:
The single, partly diagrammatic, figure shows
the trip device embodying the features of in-
weighted extension 4|. The latch member 23 is
piVOlJellY mounted 0n the right-hand end 0f the
trip lever by means of a pivot pin 43 and is biased
in a clockwise direction about the pivot pin 43 40
by means of the weighted extension 4l. A stop
pin 45 is mounted on the trip lever 2| for limiting
clockwise rotation of the latch member 23.
The vibratory energy storing device comprises
a spring 4l and a weight member 49. One end 45
of the spring 41 is bent over and secured tó the
support I9 by means of a holding screw 5|. The
weight member 49 is secured to the opposite or
free end of the spring 4l in any suitable manner.
The upper end of the weight member 49 is pro- 50
vided with a latch engaging projection 53 which
vention, .in side elevation; the circuit breaker
55 being shown in diagrammatic form.
is adapted to be latched into engagement with
the hook-shaped end 39 of the latch member 23
when the weight member attains a predeter
mined amplitude of vibration.
55
Z
2,125,130
The alternating-current electromagnet 21 is
mounted adjacent the central portion of the
its latching position. The control circuit 29 is
deenergized by the opening of the movable con
spring 41 by means of an angle-shaped bracket
tact 5. The parts of the trip_device are thus
restored to their normal position ready for a
55. The vertical leg of the bracket is provided
with an adjusting slot 51, and is secured to the
support I9 by means of a bolt 59 and a nut 6I.
The body portion of the bolt. 59 passes through
an opening in the support I5, through the slot
and the latch means I I reengages the toggle link
age 1-9 to latch the breaker in closed circuit
51 of the bracket 55, and a lock washer 63 is
position.
positioned between the vertical leg of the bracket
55 and the nut 6I. This arrangement provides
an adjustable mounting means for the electro
magnet 21, whereby the air gap between the
core of the electromagnet and the spring 41 may
be adjusted in order to vary the time required
for the weight member to attain a predetermined
amplitude of vibration. The electromagnet 21
is connected in a control circuit 29 which, in the
embodiment shown, receives its energy from a.
current transformer 65 which is coupled to the
line LI controlled by the breaker. A control
switch 61 is interposed in the circuit 29 for con
trolling energization of the electromagnet 21.
The spring 41 is composed of magnetic ma
terial so as to be influenced by the pull of the
electromagnet. If desired, the spring 41 may be
provided with an armature 69 secured to the
spring at a point above the core of the electro
magnet 21. The spring 41 and the weight mem
30 ber 49 are so proportioned that the natural or
inherent frequency of vibration of these connect
ed members corresponds to-the frequency of the
alternating pull of the electromagnet 21 or to
the frequency of the control circuit 29 so that
when the control circuit is closed by the switch
G1, the electromagnet causes the spring 41 and
the connected weight member 49 to vibrate with
increasing amplitude to store energy in said
Weight.
40
subsequent operation. The circuit breaker is
closed by the operating mechanism (not shown),
'
The operation of the device is as follows: With
the parts in the position shown in the drawing,
let it be assumed that it is Idesired to trip the
breaker. Control switch 61 is closed either man
ually or by means of a relay to effect energization
of the electromagnet 21 by means of the control
circuit 29. The energization of the electromag
net 21 causes the spring 41j'and connected weight
member 49 to vibrate with increasing amplitude.
After a predetermined time, the amplitude of vi
50 bration of the spring 41 and connected weight
member 49 is increased to such an extent that
the upper end of the weight member 49 engages
the weighted extension 4I of the latch 23 to ef
fect partial counter-clockwise rotation of the
latch. The partial counter-clockwise rotation of
the latch 23 causes the hook-shaped latch por
tion 39 to engage under the latch projection 53
of the weight member 49. The downward move
ment of the weight member, in which consider
60 able energy has been stored, eii'ects clockwise ro
tation of the trip lever 2l about its pivot pin 33
and causes the screw 35 to engage and move
latch means II in a clockwise direction to effect
release of the toggle linkage 1-9. The release
of the toggle linkage 1-9 permits the biasing
spring means I3 to move the toggle links to col
lapsed position which eiîects movement- of the
movable brush contact 5 to its open circuit posi
tion.
At a predetermined point in the downward
movement of the weight member 49, the latch
23 releases the trip lever 2| from its connection
with the weight member 49. The trip lever 2l
is returned to the normal position shown by the
76 return movement of the biased latch means II to
-
It will thus be seen that even though the power 410
available in_the control circuit 29 is low, the im
proved- trip device provides an arrangement for
tripping extremely heavy breakers by the energy
derived from the low power control circuit. This
is rendered possible by reason of the fact that 15
the energy derived from the control circuit is
stored in the vibratory device comprising the
spring 41 and the weight member 49, over a. pe
riod of time. Thus enough energy can be stored
in the weight member 49 to trip large heavy 20
breakers.
'I'he trip device described may also be utilized
as a time delay overload trip device by providing
a means for closing the switch 61 in response
to overload conditions in any well known man 25
ner. In such case, the time delay between the
energization of the control circuit 29 and the
tripping of. the breaker can be varied by adjust
ing the position of the electromagnet 21 by means
of the slot 51, the bolt 59, and the nut 6 I; to vary 30
the air gap between the core of the electromag
net and the spring 41. By increasing the air gap,
the. weight member 49 will be influenced less by
the electromagnet and thus require a longer time
to build up to the required amplitude of vibra 35
tion to trip the breaker.
The trip device may also be used as an over
voltage or under-voltage trip means by making
the control switch 61 responsive to over~voltage
or under-voltage conditions.
40
It is obvious that the trip device described is
applicable to various types of circuit breakers.
For example, in the case of a three-pole circuit
breaker, the trip lever ZI would be arranged to
engage and move the trip bar of the breaker to
tripping position when the weight member 49
attains a predeterminedY amplitude of vibration.
Likewise, the trip device is applicable to other
forms of circuit breakers involving diñ'erent types_
of latch means and operating mechanisms.
50
It will thus be seen that the invention provides
a novel and improved trip device for circuit
breakers which is simpler, more reliable, and
less expensive to manufacture than trip devices
that have heretofore been known or used. The 55
invention also provides an alternating-current
trip device for circuit breakers which is capable
of tripping larger breakers with a lower energy
control circuit than has heretofore been con
sidered possible.
.
60
While the invention has been disclosed in
accordance with the provisions of the patent
statutes, it is to be understood that various
changes in details of structure may be made
without departing from the spirit of the inven
tion. It is desired, therefore, that the inven
tion be limited only by the reasonable construc- '
tion of the appended claims, and by the prior art.
The invention claimed is as follows:
1. In a circuit breaker having relatively mov
able contacts biased to open circuit position and
means for releasably holding said contacts in
closed circuit position, the combination of a trip
device comprising a vibratory mass, electromag
netic means for vibrating said mass with increas 75
2,125,180
ring amplitude, said mass'being operable upon
the attainment of a predetermined amplitude
3..
tion oi' said spring and connected weight corre
sponding to the frequency of the control'circuit
so that said spring and weight are vibrated with
of vibration to ei'fect release oi' said holding
means to permit opening of said contacts.
increasing amplitude during energization of said
2. In a control device, the combination of a
vibratory member, an electromagnetic means for
spring and weight attain a predetermined am
vibrating said member with increasing ampli
tude and means operated by said member when
it attains a predetermined amplitude of vibra
tion for eiïecting actuation of said control device.
'3. In a circuit breaker having relatively mov
able contacts, means biasing _said contacts to
open circuit position, releasable latch means for
holding said contacts closed, a trip device com
15 prising a vibratory member, an electromagnetic
means for vibrating said member with increas
ing amplitude, said member being operable upon
the attainment ot a predetermined amplitude
of vibration to release said latch means to allow
.20 said contacts to be opened by said biasing means.
'4. In a control device, a vibratory mass, an
alternating-current electromagnet for vibrating
said mass, a low energy alternating-current con
trol circuit for said electromagnet, the energiza
25 tion of said circuit causing said electromagnet
to vibrate said mass with increasing amplitude,
said mass being operable upon the attainment
of a predetermined amplitude of vibration to
effect operation of said device.
5. In a circuit breaker having relatively mov
able contacts biased to open circuit position, re
leasable means for holding said contacts closed,
an energy storing device, means including anV
electromagnet and a low energy control circuit
35 for storing energy in said device at a certain
30
rate, said device being operable upon the attain
ment of a predetermined amount of energy to
eiIect release of said holding means to permit
said contacts to open.
6. In a circuit controlling device, the combina
40
tion of a spring suspended vibratory mass, an
alternating-current electromagnet, a low energy
alternating control circuit for energizing said
electromagnet, said spring suspended mass hav
45 ing a natural frequency of vibration correspond
ing to the frequency of the alternating pull of
said electromagnet so that said spring suspended
mass is vibrated with increasing amplitude by
said electromagnet, and means operab‘le by said
50 mass when it attains a predetermined amplitude
of vibration for effecting operation of said device.
'7. In a circuit breaker, relatively movable con
tacts, means biasing said contacts to open cir
cuit position, releasable means for holding said
55 contacts closed, a trip device comprising an en
ergy storing vibratory member, an alternating
current electromagnet for vibrating said mem
ber to store energy therein, a low energy control
circuit for energizing said electromagnet, the
60 natural frequency of vibration of said member
corresponding to the alternating pull of said elec
tromagnet so that said member is vibrated with
increasing amplitude as energy is stored therein,
means operable by said member when a predeter
65 mined amount of energy is stored therein'to re
lase said holding means to permit said contacts
to open.
8. In combination, a circuit'controlling device,
a spring secured to a support at one end, a Weight
70 secured to the free end of said spring, an alter
mating-current electromagnet mounted adjacent
said spring for vibrating the same when said
electromagnet is energized, a low energy alter
nating-current control circuit for energizing said
75 electromagnet, the natural frequency of vibra
circuit, means operable by said weight when said
plitude of vibration fo;‘_ eiïecting actuation of
said circuit lcontrolling device.
9. In a circuit breaker, relatively movable con
tacts biased to open circuit position, a releasable 10
latch means'for holding said contacts closed, a
trip devicecomprising a vibratory member, an
alternating-current electromagnet for vibrating
said member, a low energy control circuit for
energizing said electromagnet, the proportions 15
of said member being such that its natural fre
quency of vibration corresponds to the frequency
of pull of said electromagnet so that the ampli
tude of vibration of said member increases at a
certain rate, means operable by said member 20
when it attains a predetermined amplitude of
vibration for moving said latch means to cause
said contacts to open.
l0. A circuit controlling device, control means
for said device comprising a vibratory member, 25
an alternating-current electromagnet for vibrat
ing said member, a low energy control circuit -for
energizing said electromagnet, the proportions of
said member being such that its natural fre
quency of vibration corresponds to the frequency 30
of pull of said electromagnet so that the amplitude
of vibration of said member increases at a cer
tain rate, means operable by said member when
it attains a predetermined amplitude of vibra
tion for effecting operation of said device, and
means for varying the rate of increase of ampli
tude of vibration of said member to vary the time
required for said member to eifect operation of
said device.
11. In a control device, means for actuating 40
said device comprising a vibratory member, an
alternating-current electromagnet for vibrating
said member, a low energy control circuit for
energizing said electromagnet, said electromagnet
When energized causing said member to vibrate 45
with increasing amplitude, said member when it
attains a predetermined amplitude of vibration
effecting actuation of said device, and means for
varying the time required for said member to
attain said predetermined amplitude.
50
12. In a circuit breaker, stationary Contact
means, a switch vmember movable to open or to
closed circuit position to open or to close the
circuit, means biasing said switch member to
open circuit position, releasable latch means for 55
holding said switch member in closed circuit
position, a trip device for releasing said latch
means comprising a vibratory spring supported
weight means,»said Weight means being operable
upon the attainment of- a predetermined ampli 60
tude of Vibration to release said latch means to
allow said switch member to move to open circuit
position, an alternating-current electromagnet
for vibrating said weight means to store energy
therein, and a low energy alternating-current 65
control circuit for energizing said electromagnet,
the natural frequency of vibration of said spring
supported weight means corresponding to the fre
quency of said control circuit so that said Weight
means is vibrated with increasing amplitude dur
ing energization of said circuit.
13. In a circuit breaker, stationary contact
means, a switch member movable to open or to
closed circuit position to open or to close the cir
cuit, means biasing said switch member to open
4
2,125,130
circuit position, releasable latch means for hold
_ ing said switch member in closed circuit position,
quired for said spring and weight to attain said
predetermined amplitude of vibration:
a trip device for releasing said latch means com-'-~
prising a vibratory spring supported weight
16. In a circuit controlling device, means for
actuating said device comprising a spring secured
means, said weight means being operable upon
the attainment of a predetermined amplitude of
to a support at one end, a Weight secured to the
free end of said spring, an alternating-current
vibration to release said latch means to allow
electromagnet mounted adjacent said spring for
said switch member to move to open circuit posi
tion, an alternating-current electromagnet for
10 vibrating said weight means, a low energy alter
vibrating the same when said electromagnet is
energized, a low energy alternating-current con
nating-current control circuit for energizing said
electromagnet, the natural frequency of vibra
natural frequency of vibration of said spring and
connected weight corresponding to the frequency
tion of said spring supported weight means cor
responding to the frequency of said control cir
trol circuit for energizing said electromagnet, the
of the control circuit so that said spring and
Weight are vibrated with increasing amplitude
15 cuit so that said weight means is vibrated with - during energization of said circuit, said weight
increasing amplitude during energization of said \and spring upon the attainment of a predeter
circuit, and means for varying the time required mined amplitude of vibration effecting actuation
for said weight means to attain said predeter
mined amplitude.
14. In a circuit controlling device, means for
20
vactuating said device, comprising a vibratory
spring supported weight means, said Weight
means being operable upon the attainment of a
predetermined amplitude of vibration to effect
25 actuation of said device, an alternating-current
electromagnet for vibrating said weight means, a
low energy alternating-current control circuit
for energizing said electromagnet, the natural
frequency of vibration of said spring supported
30 weight means corresponding to the frequency of
said control circuit so that said Weight means is
vibrated with increasing amplitude during ener
gization of said circuit, and means for adjusting
the position of said electromagnet to vary the time
35 required for said weight means to attain said pre
determined amplitude.
15. In a circuit breaker, relatively mova_ble
contacts, means biasing said contacts to open
circuit position, releasable latch means for hold
40 ing said contacts closed, a trip device comprising
a spring secured to a support at one end, a Weight
secured to the free end of said spring, an alter
hating-current electromagnet mounted adjacent
said spring for vibrating the same when said elec
45 tromagnet is energized, a low energy alternating
current control circuit for energizing said electro
magnet, the natural frequency of vibration of said
spring and connected weight corresponding to
the frequency of the control circuit so that said
50 spring and weight are vibrated with increasing
amplitude during energization of said circuit,
means operable by said Weight when said spring
and weight attain a predetermined amplitude
of vibration for effecting release of said latch
55 means to allow said biasing means to open said
contacts, and means for varying the time re
of said device, and means for adjusting the posi
tion of said electromagnet relative to said spring
for varying the time required for said spring and
Weight to attain said predetermined amplitude of
vibration.
‘
17. In a circuit breaker, relatively movable
contacts, means biasing said contacts to open cir
cuit position, releasable means for holding said
contacts closed, a trip device comprising an
energy storing vibratory member, an alternating
current electromagnet for vibrating said member
to store energy therein, a low energy control cir
cuit for energizing said electromagnet, the natural „
frequency of vibration of said member corre
sponding to the alternating pull of said electro
magnet so that said member is vibrated with in
creasing amplitude as energy is stored therein,
means operable by said member when a predeter
mined amount of energy is stored therein to
release said holding means to permit said contacts
to open, and means for varying the time required
for said vibratory member to eiîect release of said
holding means.
40
18. In a circuit breaker having relatively mov
able contacts biased to open circuit position, re
leasable means for holding said contacts. closed,
an energy storing device, means including an
electromagnet and a low energy control circuit
for storing energy in said device at a certain rate, 45
said device being operable upon the attainment
of a predetermined amount of energy to effect
release of said holding means to permit said con
tacts to open, and means for varying the time
interval between energization of said circuit and 50
the release of said holding means.
MAR'I‘HA M. SCHOFIELD,
Administratrz'x of the Estate of Stanley T. Scho
field, lDeceased.
55
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