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Патент USA US2356166

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Aug. 22, 1944.
2,356,166
‘R. LEE ETAL
PROTECTIVE MEANS FOR ELECTRICAL CONTACTS
Filed Aug. 17, 1942
2 Sheets-Sheet l
FIG- 4
.FIG. 5
IN VEN TORS
R OYAL - LEE
"""D FRED E. BROBERG
BY
ATTORNEY
Aug. 22, 1944.
2,356,166
R. LEE ET AL
PROTECTIVE MEANS FOR ELECTRICAL CONTACTS
2 Sheets-Sheet 2
Filed Aug. 17, 1942
FIG. 11
I 82 -61
[37A
CENTR/FUGAL.
1
84..90
81
SWITCH
15 :{Z
'
A
°‘
lA/VENTORS
ROYAL LEE
"ND FRED EBROBERG
gag/24c
f/fwe
TToR/QEY
A
Patented Aug. 22, 1944
' 2,356,166
UNITED STATES PATENT OFFICE
2,356,166
PROTECTIVE MEANS FOR ELECTRICAL
CONTACTS
Royal Lee, Milwaukee, and Fred E. Broberg,
Racine, Win, assignors to Lee‘ Engineering Re
search Corporation, Milwaukee, Wis., a corpora
tion of Wisconsin
Application August 1'1, 1942, Serial No. 455,076
(Cl. TIL-222)
another modi?ed form of motor speed regulating
system;
17 Claims.
The present invention relates to electrical sys
‘ tems, and more particularly to protective ar
Fig. 10 is a detail view of a governor switch for
rangements for contacts in such systems.
the system of Fig. 9, parts being broken away, and
Switches of the vibratory or periodically oper
Fig. 11 is a diagrammatic representation 01!
ating type have been used in various electrical 5
still another form of motor speed regulating sys
systems, including regulator systems‘for control
tem.
ling the speed of electric motors and the voltage
In that form of the invention shown in Fig. l
of generators. For speed regulation of small
of the drawings, i0 designates an electric motor
electric motors, centrifugal governor switches
have been used to a, considerable extent.
of the series or universal type adapted for opera
tion on either direct current or alternating cur
rent from line conductors i i and i2, the latter .
being provided with a control switch Hi. The mo
tor includes an armature i4 rotatable between
In or
der to protect the switch contacts from damage
by sparking or arcing and to limit induced volt
ages, it has been customary to shunt the switches
with spark suppressing means such as condensers
and resistors.
15 ?eld poles IS, the magnetic structure of the mo
tor being of conventional type.
An object of the invention is to provide an elec
In carrying out the invention, each ?eld pole
trical system, such as a speed regulating system
is provided with a pair of ?eld coils I6 and I‘!
for an electric motor, having improved and sim
which preferably are additive in their magnetiz
pli?ed spark suppressing means vfor electric con
tacts in the system.
_
20 ing e?ect. The corresponding ?eld coils on the
two ?eld poles are here shown to be connected in
Another object of the invention is to provide an
series by conductors i8 and i9, and the adja
electrical system in which inductive windings,
cent terminals of the two coils on one ?eld pole
such as the windings of an electric motor, are so
are connected to each other at 20. The junction
arranged as to form protective means for the
contacts.
25 20 is connected to one of the armature brushes,
and the other armature brush is connected to the
A further object is to provide an improved con
line conductor ii. The terminals of the coils i6
tact protecting electrical system, such as a mo
and IT on the other ?eld pole are connected to
tor speed regulator system, which is capable of
operation on either alternating current or direct ' the contacts 2i and 22 of a speed-regulating gov
current.
30 ernor switch 23, preferably of any well known
' The invention further consists in the several ; centrifugal type, this switch being operated by‘
the motor. The switch contacts may be rotative
features hereinafter described and claimed.
or non-rotative, as is well understood in this art.
In the accompanying drawings, illustrating
In the case of a governor switch with rotatlve
certain embodiments of the invention,
Fig. 1 is a diagrammatic representation of a 35 contacts the current is conducted to the contacts
by the usual brushes and slip rings, the brush
motor speed regulating system arranged in ac
contacts being indicated at 24. The switch con
cordance withthe invention to protect electrical
tact 2i and the connected end of the ?eld coil it
are connected to the line conductor i2, and dur
Fig. 2 is a diagrammatic representation of a
modified form of motor speed regulating system; 40 ing the periods when the governor switch is closed
the end of the associated ?eld coil i1 is also con
Fig. 3 is a detail sectional view of a two-con
, contacts in the system;
.
nected, through the switch. to the line conductor
ductor cable for the ?eld windings of the motor;
i2. During the operation of the motor the ?eld
Fig. 4 is a detail sectional view of a modi?ed
coils l6 remain continuously in circuit, while the
form of two-conductor cable;
Fig. 5 is a transverse sectional view of a part of 45 circuit through the ?eld coils i1 is intermittently
broken at the centrifugal switch. The contacts
a motor ?eld winding having two coils formed
preferably are formed of a resistant metal such
as tungsten, although in some cases other suit
by round wires;
Fig. 6 is a view similar to Fig. 5 but showing
another modi?ed form of two-conductor cable
for the winding;
‘
Fig. 'l is a transverse sectional view of the two
conductor cable of Fig. 6;
Fig. 8 is a transverse sectional view of a further
able metals, such as silver or platinum, may be
50
used.
,
The ?eld coils i8 and ii on each pole piece
are closely coupled, as by forming them in alter
nate layers or sections and preferably by simul
taneously winding two adjacent conductors 25
Fig. 9 is a diagrammatic representation of 55 and 26, Fig. 3, insulated from each other, so as to
modi?ed form of two-conductor cable;
2
2,350,1ee
provide a substantial electrostatic capacity be
tween the conductors. To further enhance the
capacity effect, the conductors are in the form
tacts are adequately protected without normally
requiring the use of auxiliary shunting devices.
of metal ribbons placed face to face and sepa
rated by a thin insulating strip or ?lm 21, as of
varnish or resin, the assembled ribbon conductors
being enclosed by an insulating sheath or cover
and connected as to protect the contacts, these
windings having both a condenser effect and a
resistance effect. In the case of a governor
ing 28, so as to form a ?at cable.
have a protective in?uence on the brush con
as the ?eld windings themselves are so arranged
switch with brush gear, the windings will also
In certain
tacts. The relation of'the motor windings is
cases the two conductors forming the ?eld coils
may be of equal cross-sectional area and resist 10 such that there will be no interference with the
ef?cient operation of the motor on either alter
ance, but in general it is desirable to make the
nating current or direct current. Contact pro
conductors of unequal resistance, the conductor
tection is particularly important on direct cur
25 forming the ?eld windings i6 preferably hav
rent operation because of the tendency of ex
ing the higher resistance, so as to permit opera
tion of the motor over a wide range of speed and 15 cessive sparking to cause transfer of metal
load. The conductors preferably are formed of
a metal with good electrical conductivity, such
as copper or silver or silver-coated copper.
from one contact to the other.
A slight spark
ing is ordinarily unobjectionable and appears
to be useful in aiding contact vibration.
In
some cases the ?eld coils l6 and I‘! may have
In the modi?ed form of motor regulating sys
different numbers of turns and only parts of the 20 tem shown in Fig. 2, the governor switch is in
coils may be closely coupled, these parts being
serted in the conductor is connecting the two
at the switch-connected ends of the coils.
The modi?ed form of two-conductor cable
?eld coils I‘! of the motor [0’.
The system of
Fig. 2 is otherwise the same as that of Fig. l
shown in Fig. 4 comprises a metal ribbon 25'
and operates in the same manner. In the sys
partially or completely enclosed by a metal rib 25 tem of Fig. 2 the ?eld coils I‘! will form choke
bon 26', the inner and outer ribbons being sepa
coils between the governor switch and the line
rated by an insulating strip or ?lm 21’, and the
conductors.
assembly being enclosed by an insulating sheath
In the modi?ed form of ?eld winding shown
or covering 28'. This arrangement of the con
in Figs. 6 and 7, insulated wires 225 and 228
ductors increases the electrostatic capacity. 30 form a two-conductor cable and are ?attened at
The inner ribbon may form either of the ?eld
their adjacent portions to increase the capaci
coils i6 and i1, and the outer ribbon may form
tance effect and to improve the space factor.
either an open or closed loop about the inner
The two wires of the cable are retained in as
ribbon.
sembled relation in any suitable manner as by
In the further modi?cation shown in Fig. 5, 85 an insulating wrapping 228, or merely by ef
a pair of ordinary round insulated wires I25 and
fecting adhesion between the insulated wires.
I26 form the field coils i6 and II, respectively,
For facility in winding, especially in the case
the two wires being wound in parallel.
The electric motor above described will oper
of small wire sizes, the cable is approximately
circular in cross-section. The cable is conven
ate on either direct current or alternating cur 40 iently formed by a pair of round wires each hav
rent, whichever is available. In operation, the
ing a tough coating 22‘! of insulating enamel,
motor current flows through the armature I4
the two wires being rolled to a ?attened shape
and the series ?eld windings formed by the
and pressed together, preferably in a, simultane
coils i6 and H. A part of the motor current
ous operation. For an electric motor intended
passes through the ?eld coils i1 and centrifugal
to operate within a limited range of speed and
switch contacts 2i and 22 when the latter are
load, the two wires may be of the same size, as
closed, and the other part of the motor current
shown. For some circuits, however, the wires
passes through the ?eld coils i6 and does not '
may be of different size. In certain cases the
pass through the switch contacts. When the
wires may have different conductivity to pro
motor rises to a critical speed the governor 50 vide a difference in resistance.
switch contacts open, thus interrupting the ?ow
In the further modi?ed form of two-con
of current through the ?eld coils ll, the motor
current being then reduced to that ?owing
through the ?eld coils i6. Thereupon the motor
speed drops slightly, causing the switch contacts
to close and restoring the ?ow of current through
?eld coils H. The motor speed then rises
slightly, causing the switch contacts to reopen,
and the cycle of operation is repeated, the re
sult being that the motor speed is maintained 60
within close limits. In practice one or both of
the governor switch contacts vibrate at a rela
ductor cable shown in Fig. 8, a round wire 325
is snugly encased by a metal ribbon or strip 326
insulated therefrom, the wire preferably having
a coating 32'! of insulating enamel and the
ribbon having a similar coating 328. The cable
is approximately circular in cross-section to
facilitate winding. For a, given outside diam
eter, the cable of Fig. 8 will ordinarily have a
greater capacitance effect than the cable of Fig.
1. The outer conductor 326 is shown to form an
open loop about the inner conductor, but in some
instances it may be closed as in Fig. 4.
tively high frequency, say from 50 to 300 cycles
per second, so as to obtain good speed regulation.
In the form of the invention shown in Figs.
If it is desired to have the motor operate at 65 9 and 10, the motor 40 is of a series or universal
different selected speeds, the governor switch
type and is connected to line conductors II and
may be of any suitable adjustable type.
I2, the latter having a control switch i3. The
Heretofore it has been usual to shunt governor
motor is here shown to be of the two-pole type
or regulator switches with protective devices,
and includes an armature 44 rotatable between
such as condensers and resistors, so as to pre
vent deterioration or destruction of the switch
contacts. In some instances it has been neces
sary to provide additional space in or near the
70 pole pieces 45.
'
Each ?eld pole is provided with a ?eld coil 46
and one or more ?eld coils 41, two of the latter
being shown.
The two ?eld coils 46 are con
motor to mount these protective devices. By
nected in parallel, and the parallel combination
means of the present invention the switch con 76 thus formed is connected in series with the
3
2,856,166
armature, the point oi’ connection with the
of Fig. 1, except that the contacts are arranged
armature being indicated at 80. The two ?eld
to close upon an increase of motor speed. The
brush contacts for the switch are indicated at 84.
The contact 8| and the connected end of the ?eld
coil ‘II are connected to the line conductor 12,
and during the periods when the governor switch
is closed the end of the ?eld coil 11 is also con
coils 41 on each ?eld pole are connected in par
allel and are closely associated with the corre
sponding ?eld coil 46, as by simultaneously wind
ing two conductors in any one of the various
ways shown in Figs. 3 to 8. In the case of two
coils 41, one of them is coextensive with one half
nected, through the switch, to the line conductor
of the coil 46 and the other is coextensive with
12. The shunt ?eld coils ‘l8 and 11 are prefer
the other half of the coil 48. The corresponding 10 ably !ormed by two conductors wound as in the
terminals of the four ?eld coils 41 have a Junc
system 01’ Fig. 1. If desired, the motor also may
tion at 5! withthe line conductor [2 and termi
be provided with series ?eld windings 90 to limit
nals of the ?eld coils 46. The other terminals of
the starting current and to increase the starting
torque.
each pair of ?eld coils 41 are connected to the
armature junction 50through a‘ centrifugal gov
ernor switch 53 driven by the motor, one suitable
form of switch being shown in Fig. 10. This
governor switch has two sets of contacts 55, 56
and 51, 58 with the same speed setting, there
being one set of contacts for each pair 01' ?eld
coils 41.
In the operation of the motor of Fig. 11, the
governor switch contacts engage when the motor
speed rises to a critical value, thus permitting
current to ?ow through the shunt ?eld coils 11.
Because of the increased ?eld ?ux, the motor
speed drops slightly and the switch contacts then
.
The switch shown in Fig. 10 has a rotatable
insulating disk 59 adapted to be mounted on the
motor shaft. The contacts are carried by re
spective leaf springs 60 secured to brackets 8| on
one side of the disk, and the other side of the
disk has three collector rings 62, the brush con
tacts being indicated at 54 in Fig. 9. The speed
setting of the two switch units is varied by ad
justing devices 63 carried on the disk 59. The 30
contacts 55 and 51 are vibratory, while the con
tacts 56 and 58 are non-vibratory but are dis
tacts 55 and 51 are connected in common to the
lector ring, and the contacts 56 and 58 are con
nected to the respective sets of ?eld coils 41 by
way of the two inner collector rings.
ing to maintain the motor speed within close
limits.
'
The shunt ?eld windings are so arranged and
connected as to have a protective action on the
contacts, similar to that in the system of Fig. 1.
While the invention is particularly adapted for
use in protecting electrical contacts in motor
speed regulating systems, it is also applicable to
the protection of contacts in other electrical sys
tems.
What we claim as new and desire to secure by
placeable by the adjusting devices 63. The con
armature junction 50 by way of the outer col
reopen. The motor speed then rises slightly and
the cycle of operation is repeated, the result be
Letters Patent is:
35
,
1. In an electrical system, a circuit having a
pair of coil-forming conductors arranged in par
allel and adapted to be traversed by electric cur
rent, and means for regulating the ?ow of 'cur
During the operation of the motor of Fig. 9,
rent in said circuit comprising a switch in series
the ?eld coils 46 remain continuously in circuit 40 with one of said conductors for interrupting the
while the circuit through the two sets of ?eld
?ow of current through said conductor while the
coils 41 is intermittently broken at the two sets
other conductor is in circuit, said conductors be
of swich contacts. As in the system of Fig. 1,
ing connected'together at a distance therealong
the operation of the governor switch will main
from said switch and beingv in close proximity
tain the motor speed within close limits. The 45 along a. substantial portion of their length to have
two switch units preferably operate synchro
a capacitance e?ect, said associated conductors
nously, but asynchronous operation is also pos
forming a spark suppressor for said switch.
sible as the switch units control separate circuits.
The use of two sets of contacts also increases the
2. In an electrical system, a circuit having a
pair of coil-forming conductors arranged in par
current-carrying capacity of the switch. The 50 allel and adapted to be traversed by electric cur
arrangement of Figl 9 is particularly suitable for
rent, said conductors being formed of metal rib
low voltage motors, for example 12-volt motors,
bons insulated from each other along their length
and also for high voltage heavy duty motors,
but lying close together iace-to-face, and means
such as 110-volt motors, as it permits an increase
for regulating the flow of current in said cir
in the number of turns in the ?eld coils to en 55 cuit comprising a switch in series with one of
hance the capacitance effect and incidentally
said conductors for interrupting the ?ow of cur
permits the use of smaller wire sizes to facilitate
rent through said conductor while the other con
winding of the coils.
ductor is in circuit, said conductors being con
In the form of the invention shown in Fig. 11,
nected together at a distance therealong from
the numeral 10 designates a direct current motor 60 said switch and having a capacitance effect, and
of the shunt ?eld type. The motor is supplied
said associated conductors forming a spark sup
with current from line conductors II and I2 and
pressor for said switch.“
7
r
includes an armature 14‘ rotatable between pole
3. In an electrical system, a circuit having a
pieces 15. Shunt ?eld coils ‘I6 and 11 are car
pair of coil-forming conductors arranged in par
ried on each of the ?eld poles of the motor. The 65 allel and adapted to be traversed by electric cur
corresponding ?eld coils on the two ?eld poles
rent, one of said conductorsbeing encased in
are connected in series by conductors ‘I8 and 19,
the other and being in close proximity thereto
and the adjacent terminals of the two coils are
to have a capacitance e?ect, and a'switch in
connected to each other at '80. The junction
series with one of said conductors for inter
80 is connected to one of the armature brushes
rupting the ?ow of current through said con
and to the line conductor II, and the terminals
ductor while the other conductor is in circuit, said
of the ?eld coils ‘l5 and 11 on the other ?eld pole
conductors being connected together at a dis
are connected to the contact 8| and 82 of a speed
tance therealong from said switch, and said asso- ,
regulating governor switch 83 operated by the
ciated conductors forming a spark suppressor for
motor. The governor switch 83 is similar to that 75 said switch. ‘
4
2,856,186
4. In an electrical system, a magnetic struc
cased in the other and being in close proximity
ture having coil means including a plurality of
coils arranged in parallel and with their con
ductors in close proximity along a substantial
thereto to have a capacitance effect, and means
for interrupting the ?ow of current through one
of said conductors while the other conductor is
in circuit, said associated conductors forming a
spark suppressor for said current-interrupting
portion of their length to provide a capacitance
effect, and switch means connected in series with
one of said coils for interrupting the flow of cur
rent through said coil while the rest of said coil
means remains in connected relation in said cir
means.
11. In an electrical system, a pair of conduc
tors arranged in parallel and adapted to be trav
cuit, said coils forming a spark suppressing 10 ersed by electric current ?owing in the same di
means for said switch means.
rection, each of said conductors being of rounded
5. In an electrical system, a circuit having a
oblong cross-section with a ?attened side, the
pair of conductors both adapted to be traversed
flattened portions 01' said conductors being in
by electric current ?owing in the same direction,
facing relation to provide a capacitance effect,
said conductors being additive in their magnetic 15 and the assembled pair of conductors forming a
effect and being in close proximity along a sub
cable of generally circular shape in cross-section,
stantial portion of their length to have a. capaci
and means for interrupting the flow of’ current
tance effect, and cooperating separable contacts
through one or said conductors while the other
for interrupting the flow of current through one
conductor is in circuit, said associated conduc
of said conductors while the other conductor is 20 tors forming a spark suppressor for the current
in connected relation in the circuit, said asso
interrupting means.
ciated conductors forming a spark suppressor for
the separable contacts.
12. In an electrical system, an electric motor
having a ?eld winding comprising a pair of field
coils arranged in parallel and additive in their
6. In an electrical system, a circuit having a
pair of conductors both adapted to be traversed
magnetizing effect, said coils comprising a pair of
by electric current ?owing in the same direction,
conductors lying in close proximity over a sub
said conductors forming a pair of coils additive
stantial portion of their length to have a capaci
in their magnetic effect and being in close prox
tance effect, and speed-responsive switch means
imity along a substantial portion of their length
for interrupting the current through one of said
to have a capacitance effect, and cooperating 30 ?eld coils while the other field coil is in circuit,
separable contacts for interrupting the flow of
said associated ?eld coils forming a spark-sup
current through one of said coils while the other
pressing means for said switch means.
coil is in connected relation in the circuit, said
13. In anelectrical system, an electric motor
associated coil-forming conductors forming a
having two sets of field coils arranged in parallel,
35 each set of coils comprising a pair of conductors
spark suppressor for the separable contacts.
'7. In an electrical system, a dynamo-electric
lying in close proximity to have a capacitance
machine having a magnetic structure with two
effect, and speed-responsive switch means hav
pairs of ?eld coils additive in their magnetic ef
ing two switch units for the respective sets of
fect, each pair comprising two conductors ar
field
coils and for interrupting the current
ranged in close proximity along a substantial por 40 through one of the coils in each set while the
tion of their length to have a capacitance effect,
other coil in each set is in circuit, said associated
the corresponding coils of said pairs being con
?eld coils forming a spark suppressor for said
nected in series, and current-interrupting means
switch units.
connected between two of said series-connected
14. In an electrical system, an electric motor
coils for varying the energization of the magnetic r having a plurality of more than two field coils
structure, said associated coils forming a spark
arranged in parallel and in additive magnetic
suppressing means for said current-interrupting
relation, said coils comprising a plurality of con
means.
ductors lying in close proximity to have a capaci
8. In an electrical system, an electric motor
tance effect, at least two of said conductors par
50
having a series ?eld winding comprising a pair of
alleling different parts of another of said con
?eld coils arranged in parallel and additive in
ductors and forming ?eld coils of fewer turns
their magnetizing effect, said coils comprising a
than said last-named conductor, and speed-re~
pair of conductors lying in close proximity over
sponsive switch means for interrupting the cur
a substantial portion of their length to have a
rent only through the coils of fewer turns, said
capacitance effect, and speed~responsive switch 55 associated ?eld coils forming a spark suppressor
means for interrupting the current through one
. of said ?eld coils while the other ?eld coil is
in circuit, said associated ?eld coils forming a
for said switch means.
15. In an electrical system, a circuit having
a plurality of more than two coils arranged in
parallel and in additive magnetic relation and
spark-suppressing means for said switch means.
9. In an electrical system, an electric motor 60 adapted to be traversed by electric current, said
having a series ?eld winding comprising a pair
coils comprising a plurality of conductors lying
of ?eld coils arranged in parallel and additive in
in close proximity to have a capacitance effect,
their magnetizing effect, said coils comprising a
at least two of said conductors paralleling dif
pair of conductors lying in close proximity over
ferent parts of another of said conductors and
65
a substantial portion of their length to have a
forming coils of fewer turns than said last-named
capacitance effect, one of said coils having a
conductor, and means for interrupting the cur
lower resistance than the other, and speed-re
rent through at least one but less than all of said
sponsive switch means for interrupting the cur
coils, said associated conductors forming a spark
rent through the coil of lower resistance while the
70 suppressor for said current-interrupting means.
other ?eld coil is in circuit.
16. In an electrical system, a circuit having
10. In an electrical system, a pair of coil-form
coil means consisting of a plurality of more than
ing conductors arranged in parallel and adapted
two coils arranged in parallel and adapted to be
to be traversed by electric current flowing in the
traversed by electric current, said coils compris
same direction, one of said conductors being en 75 ing a plurality of conductors lying in close prox
a
2,868,166
imity to have a capacitance ei'iect, at least two
of said conductors paralleling different parts of
another of said conductor and forming coils of
fewer turns than said last-named conductor. and
means for interrupting the current through the
coils having the fewer turns while the rest of the
coil means is in circuit, said associated conduc
5
comprising a pair 01' conductors lying in close
proximity along a substantial portion of their
length to have a capacitance effect, and speed
responsive switch means for interrupting the cur
rent through one of said coils to govern the
speed of the motor, the other field coil being in
circuit during the current interruption, said as
sociated ?eld conductors forming a spark sup
tors forming a spark suppressor for said current
pressor for said switch means.
interrupting means.
17. In an electrical system, an electric motor 10
ROYAL LEE.
having a pair of shunt ?eld coils arranged in
parallel and in additive magnetic relation and
map E. BROBERG.
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