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Патент USA US2116899

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May 10, 1938.~
J. KALSEY
2,116,899
SYNCHRONOUS CONVERTER
Filed Feb. 12, 1956
'
5 Sheets-Sheet l
INVENTOR.
MM as)“
A TTORNEYZ
.
May '10, 1938.
_j_ KALSEY
2,116,899
SYNCHRONOUS CONVERTER
Filed Feb. 12, 1936
5 Sheets-Sheet 2
INVENTOR.
A TTORNEY.
May 10, 1938.
J. KALSEY '
2,116,899
SYNCHRONOUS CONVERTER
Filed Feb. 12, 1936
5 Sheets-Sheet 4
INVENTOR.
WWW.
ATTORNEK
May 10, 1938.
J_ KALSEY
'2,116,899
SYNCHRONOUS CONVERTER
Filed Feb. 12, 1936
5 Sheets-Sheet 5
11%- ~20
/30
I IQIXIL/EN TO-R.
BY
761444,. 5.0%.
ATTORNEY.
2,116,899
Patented May 10, 1938
UNITED STATES PATENT OFFICE
2,116,899
.SYNCHRONOUS CONVERTER
John Kalsey, North Palo Alto, Calif.
.Application February 12, 1936, Serial No. 63,573
15 Claims. (Cl. 175—364)
This invention relates to a rotary synchronous
converter for the conversion or recti?cation of
alternating current into direct current.
The object of the present invention is generally
to improve and simplify the construction and op
eration of converters of the character described;
to provide a rotary converter having a main and
an auxiliary commutator with cooperating
brushes to deliver alternating current thereto; to
10 provide means for relieving the brushes on the
main commutator of current load while passing
from one segment to another, or more speci?cally
stated, to provide means for by-passing the cur
rent to the brushes of the auxiliary commutator
15 While the brushes on the main commutator are
passing from one segment to another; to pro
vide means, including a ?xed and a variable re
sistance, for preventing short circuiting be
tween the brushes of the main commutator and
p0 the brushes on the auxiliary commutator; to pro
vide automatic means for maintaining the con
verter in synchronous operation with the gen
erator supplying the A. C. to be converted; to
provide automatic means for selecting a prede
termined current‘ polarity and for maintaining
the D. C. output of the commutator at the se
lected polarity; to provide means for automati
cally breaking the A. C. current supply to the
converter if it fails to operate in synchronism
30 with the A. C. supply; to provide a converter of
high e?iciency; and, further, to provide a con—
verter in which the D. C. output may be regulated
and varied on the A. C. side of the circuit.
The converter is shown by way of illustration
35 in the accompanying drawings, in which—
Fig. 1 is a diagrammatic view showing the con
verter whereby A. C. current is converted into
D. C., said diagram also showing the synchro
nous motor whereby the converter is driven, and,
40 furthermore, showing automatic control appa
ratus for maintaining the driving motor in syn
chronism with the generator supplying the A. C.
current and also for selecting the proper polarity,
_ said diagram, furthermore, disclosing means for
4” automatically breaking the supply of current to
the converter if the driving motor gets out of
phase and, furthermore, showing means for varying the current ?ow to the converter;
/
rent flow in an alternating current supply cir
cuit during one complete cycle of operation;
Fig. 6 is a diagram showing the pulsating D. C.
current produced by the converter during one
cycle of operation;
5
Figs. 7 to 11, inclusive, are diagrams showing
the different positions assumed by the commuta
tor B during one cycle of A. C. input;
Figs. 12 to 15, inclusive, are diagrammatic
views showing one of the collector rings D, the 10
main commutator ring B, and the auxiliary com
mutator ring C, said view showing the relative
positions assumed by the brushes H and H’ when
passing from one segment of the respective com
mutators to the other;
15
Figs. 12“, 13a, 14a and 15a are diagrammatic
views showing how the resistance gradually in
creases and decreases through the brushes H
and H’ while passing from one segment to the
other;
20
Fig. 16 is a longitudinal section through the
converter as actually built;
Fig. 17 is a cross section of the converter
taken on line XVII-—XVII of Fig. 16;
Fig.
18 is
a cross section
taken
on
line 2
XVIII—XVIII of Fig. 16 ;
Fig. 19 is a perspective view showing the rela
tive position of the commutators A, B and C
and the collector rings D and E; and
Fig. 20 is a diagrammatic view showing the 30
automatic control apparatus for maintaining the
driving motor in synchronism with the generator
supplying an A. C. current, also for selecting
the proper polarity.
Referring to the drawings in detail, and par- 35
ticularly Fig. 1, A, B and C indicate a series of
commutator rings and D and E a pair of collec
tor rings.
All of the rings are secured on the
shaft F mounted in suitable bearings and this
is, in turn, driven by a synchronous motor, gen- 40
erally indicated at G, which derives its alternat
ing current from the same source as the alter
nating current to be converted.
An alternating current synchronous motor is
a motor whose speed is governed by the number 45
of cycles in the alternating current energizing the
same. Thus, in the case of a synchronous motor
with a certain number of poles, ‘and connected to
the output of an alternating current generator
Fig. 2 is a cross section of the main commu-t
having the same number of poles, the speed of
tator B;
both machines will be the same and at any given
Fig. 3 is a cross section of the auxiliary com
instant the relative position of both armatures
mutator C;
will be identical. In the case where the num
Fig. 4 is a cross section of the commutator A;
ber of poles on both machines are not the same, 55
55
Fig. 5 is a diagrammatic view showing the cur
2
2,116,899
the resultant motor speed will be an exact ratio
to the speed of the generator.
Taking a two pole A. C. generator, one com
plete revolution of the same will produce one
complete A. C. cycle. During one-half of this
cycle the ?ow of electricity will be in a positive di
rection and during the other half the flow will
be in a negative direction. These one-half cycles
are known as alternations and are diagrammati
cally illustrated in Fig. 5.
Should a two pole A. C. generator revolve at a
speed of sixty revolutions per second, it would
produce a sixty cycle current. By increasing
the poles and reducing the speed proportionately,
15 the current would still be sixty cycles. In other
words a sixty cycle alternating current is a cur
rent which reverses sixty times per second. Tak
ing a two pole synchronous motor operating on
sixty cycles A. (7., its speed will be 3600 R. P. M.
If this motor has four poles the speed will be
1800 R. P. M. The motor’s armature motion is
produced by what is known as a revolving mag
netic ?eld and in this process the armature “locks
in step” with the current cycle,
From the foregoing it should be apparent that
a predetermined point on the shaft of the syn
chronous motor will at all times coincide with a
predetermined point on the A. C. curve; in other
words, if a point on the shaft is in a certain posi
tion and the alternating current at that moment
is in a negative direction and the value of the
same bears a certain relation to the A. C. curve,
when the shaft has made one complete revolu
tion all the current conditions for that particu
35 lar period will be repeated.
For the purpose of description let it be assumed
that the commutator B, in Fig. 1, has four seg
ments insulated from each other and the shaft
F, and that the motor G driving the shaft is a
four pole 1800 R. P. M. sixty cycle synchronous
motor and, further, that segments 1 and 3 of the
commutator B are connected to the collector ring
D while the segments 2 and 4 are connected with
the ring E. In addition thereto, let it be assumed
that the shaft F is rotated in an anti-clockwise
direction and that a sixty cycle alternating cur
rent is impressed on the segments by means of
brushes H and J, which are positioned at a 90°
angle with relation to each other.
Under these conditions with the commutator
revolving, the various forces diagramed in Fig. 5
will be impressed upon the several segments of
the commutator as follows. Assuming that the
motor is running at its proper speed and when at
55 the zero point, or at a’ of Figs. 5 and '7, the
brushes H and J will not be in contact with any
of the segments, at which time there is no cur
rent ?ow in this circuit but when the segments
5 and 2 are moved, just making contact with
60
the brushes H and J, there will be a positive flow
of current starting in the circuit, and further
rotation of the segments, as shown in Fig. 8,
the positive ?ow of current in the circuit will be
at its maximum value. The positive current flow
65
now starts to decrease until it reaches point 19’,
shown in Figs. 5 and 9, (or 1/120 second of time)
where there will be no flow of current and the
brushes are out of contact with the segments,
further rotation of the segments bringing the
segments 4 and I in contact with the brushes H
and J, respectively, and the current flow will be
started in a reverse or negative direction through
the circuit and increase in value until it reaches
75 its maximum negative value, then starts to de
crease until the zero point is reached when one
cycle is completed (or 1/60 second of time).
Under this arrangement the segments l and 3
always receive a positive flow of current and 2
and 4 always receive a negative ?ow of current;
these segments being connected to their respec~
tive rings D and E will rectify the A. C. input
or convert it to a direct current and the cur
rent will be a pulsating one as diagrammatically
illustrated in Fig. 6. Condensers or ?lters of 10
suitable type, not shown, will, however, be placed
in the D. C. line to smooth out the current flow.
It should be evident that the commutator itself
does not consume any energy and will convert
one hundred percent of the current input. It
should also be evident that the amount of energy
and the pressure behind the same can be altered
without changing the general arrangement as a
variable transformer may be placed on the A. C.
side of the circuit to vary the amount of energy
and pressure. The synchronous motor G driv
ing the commutator need only be large enough
to provide the desired rotation and inasmuch as
there is no electrical connection between the two
it can be operated on the conventional 110 volt~
age. It should be evident that the variations
impressed or converted will not change the load
on the motor. The only requisite is that both
currents have identical periods and cycles. Inas
much as the supply is derived from one generat
30
ing system this is a practically assured condi~
tion.
The consumption of energy by the synchronous
motor driving the converter is constant, hence
the cost of conversion depends upon the amount
of energy converted. The motor driving the con-w
verter in operation in my laboratory at the pres
ent time consumes about 200 watts per hour and
my average use of D. C. approximates 10,000
watts. In this particular instance the efficiency of 40
the converter is 98%. Regulation of D. C. voltage
after delivery to a consumer is a complicated
matter and in most cases is accompanied by the
loss of considerable energy. Compared to this
the regulation of A. C. supply is a simple matter
consuming very little energy in the process.
With the use of my converter the desired D. C.
values are regulated at the A. C. side by means
of the variable transformer shown, or the like.
The converter so far described would seem‘
perfect.
This, however, is far from being the
case and I shall try to describe some of the faulty
conditions. Referring to the diagram shown in
Fig. 5, if the alternating current were in perfect
phase with the generator and the resultant curve ‘F'
were regular, then at the points‘ a’, b’, c’, where
the flow reverses, there would be no voltage and
hence no current. Thus if the brushes H or J
had only the thickness of the imaginary zero
line it could pass from one segment to the other
at the time when the circuit is dead. However, a
practical brush must have thickness and thus
at some period the brush must contact both seg
ments at the same time and though the energy
at that instant would be very small there would
be a momentary short circuit. Now, if the thick
ness of the insulation be increased a width slight
ly wider than the width of the brush this defect
would be overcome but another condition would
70
appear; that is, as the trailing edge of the seg
ment pulls away from the brush there would be
a momentary break in the circuit. The tendency
for an interrupted current is to continue contact
after a break and this condition is carried on 75
3
2,116,899"
“ through space, the result is a: disagreeable spark
ing which‘ quickly pits‘ bothv the copper and brush
which, in turn, intensi?es this’ phenomena until
?nally the device becomes useless.
In‘ practice it is never possible to obtain an
alternating current free from imperfections and
position‘, Fig. 113, the: brush‘ H has partially left
the segment I1 and is entirely bearing on the high
resistance tip 6. Under this condition the H
brush- can only deliver a fraction of the total
we seldom have currents where all‘ conditions are
in phase. Thus, the zero line of the alternating
current curve, see Fig. 5‘, or rather the relation‘ of
10 the same with respect to-the curve is never‘ con
stant and hence there maybe considerable cur
rent in the circuit at the time? the brushes cross
the joint. The result is sparking, pitting and
scoring which, in turn, causesfaulty contact and
load, meanwhile, the auxiliary brush H’ is bear CH
ing directly on the load transfer segment ‘I and
the main load2 or current is delivered from brush
H through the special resistance, to be described,
to H’ then to segment I» through wire 8 to seg
ment I5 and: ?nally through wire‘ l4‘ tov the col 10
lector ring D. In this'p'osition the main load is
delivered by the auxiliary segment.
As motion‘ progresses brush H has diminishing
contact with‘ the resistance tip 6 of segment I
irregular commutation. Thus, in the case of a
narrow joint we have short circuits, in wider
joints we have sparking and ?ashing.
To overcome this defect I have developed a
system whereby the load carried by the segments
20' is- gradually reduced as the‘ joint comes under
the brush and entirely ceases at the moment the
trailing edge of the segment leaves the brush.
At the same time the load is transferred to an
auxiliary brush which continues to deliver thev
25 load to the circuit until‘ the main brush has
traveled across the insulated joint. This system
is of prime importance for it allows a continuous
delivery of energy and hence eliminates all spark
ing. The manner in which this is accomplished
is, best illustrated? in Figs. 12 to 15, which are
diagrams showing the relationship between the
segments, brushes and current values at or near
the A. C. zero line, said diagram indicating four
different conditions while the brushes are cross
until ?nally the segment becomes non-conductive
until it reaches the‘ position shown in Fig. 14
where'the‘ flow through the segment has entirely
ceasedi Meanwhile the load is being delivered.
through’ the brush H’ but at this moment this
brush begins to contact the resistance tip 9 of
segment ‘I and as motion continues and resist
ance offered by the segment becomes greater a
small fraction of time after this condition and in
the fourth position, see Fig. 15, brush H has con
tacted segment 2 and brush H’ has ceased to 25
deliver current‘. Meanwhile the current has re
versed so that the brush H is delivering current
ing the joint between‘ segments.
In these'diagrams D'represents one of' the col
lector rings which delivers the converted or direct
current‘to the'direct current side of the converter,
B the main‘commutator, and IIandZ the segments
thereoniwhich receive the alternating current to
be converted, said current being introduced by
the brush‘ H. In this case the insulation between
the segments has been widened, the'width being
slightly in excess of' that of the brush. In addi
tion, the trailing edge of‘ each segment is con
structed of material 6', such as nichrome, or the
like, having a high‘ resistance to the passing of
the'current. C indicates an auxiliary commuta
tor containing conducting segments 1' positioned
' directly over the zero‘line; or‘ their position occu
pies the corresponding space of the insulation
between the segments I andZ. The segments 1
shown in‘ the diagram are insulated from the
rest of the commutator but are'in electrical con
nection with segment I through wire 8. The seg
ments‘! also have a trailing edge 9 of high’ re
sistance material.‘ The brush H’, which will be
referred tov as the auxiliary brush; is only one
half the width of the brush H.- In these diagrams
60 the auxiliary segment ‘I- and segment I' are directly
connected by the wire 8. The brush H’ is con
nected to brush H by means of a special resistance
hereinafter to be described.
Assuming‘ the‘converter‘v is in rotation and in
the direction'of arrow is, and‘ again referring to
Figs. 12 to 15', the diagrams show'four different
positions of 'the commutatorv segments under the
brushes and‘each-position' indicates on the load
transfer diagram depicted at‘ the right just how
the load is distributed; In the ?rst position, Fig.‘
12, all‘ofth'e load or current is delivered by the
brush‘H to segment I'andl‘ thence to the collector‘
ring'D by means of the‘wir'e' M‘. The auxiliary
brush: at this? moment is inactive. In the second
to segment 2 which is connected‘ to the negative
side of the system. In the fourth position before
brush H’ has left the auxiliary segment the brush
H has contacted segment 2 and also the current
?ow has been reversed. The condition of dual
contact maintains only for a small fraction of
time, the facts are that for that period, current 35
is being delivered'by one leg‘ to both sides of the
circuit. Though the actual short-circuit is
through resistance, the value of the current may
be such as tonullify the advantages of the re
sistance‘tip of the auxiliary segment ‘I.
To overcome this condition I have designed an
automatically controlled variable resistance. Its
function is to render brush-H’ conductive in pro
portion to‘ the total value of the‘entire load im
pressed upon the system. By calculation and 45
tests, the‘ energy transferred to the brush H’
should: be one-half? of one percent of the total
energy going through the converter. Inasmuch
as the total‘ energy varies according to the de
mand, an arrangement whereby the energy pass
50
ing through brush H’ shouldv at all’ times be in
the proper proportion is necessary.
'
Fig. 1 depicts the two brushes H and H’ with
a ?xed resistance l5 between'them. This resist
ance is permanently adjusted to‘ta-ke care of a 55
minimum requirement. In addition there is a
variable resistance 16 in shunt with this arrange
ment. This resistance consists of'a unit plunger
I‘I'mounted within'the coil l8 of a solenoid. The
coil in‘the solenoid is fed'with D. C. current from 60
the wires 19 and 20 and the amount of current
passing through the same'governs the position of
acontact arm 2|.
The contact arm travels over
the resistance coil [6» and hence controls the
amount of current‘ capable of passing.
In many D. C. uses itis' of the utmost impor
tance that the ?ow'of current is always in a pre
determined‘direction therein; in other words, that
the polarity is never reversedl
Inasmuch as the
synchronous motor may “lock in step” with either
the top ‘or the bottom half'of the‘A. C. wave when
started‘, or‘ after interruption of- service, a con
trolling devicev to force the commutator to deliver
D. C. with the desired polarity is essential. This
control is'shownin Figs. Land-520'. In these ?g 75
4
2,116,899
ures, G indicated the synchronous motor whereby
the converter as a whole is driven. Rotating with
the converter is the commutator A. A section of
this commutator is shown in Fig. 4. In this case
it will be noted that there are two segments 23
and 2G oppositely disposed with relation to each
other but electrically connected. Between them
are disposed two insulating segments 25 and 26.
Two brushes 2? and 28 make contact and the cur
rent supply is taken directly from the A. C. feed
line indicated by the numerals 3i! and 3!; the
current value being controlled by the transformer
M.
The action is such that when a commutator
is in the position shown, it will allow current to
15 pass through. When the commutator makes one
quarter of a revolution no current can pass.
In
asmuch as the commutator A is synchronous with
20
the motor G, the resultant current flow through
the commutator is a direct half-wave pulsating
current. The numeral 33 indicates an evacuated
tube containing a metallic dome electrode M. In
addition thereto, there is a ring-shaped electrode
35, the lower portion of which is shielded with
a non-conducting material as shown at 36.
A
25 third electrode Si is also employed. It consists
of a small concave disc, the concave side of which
is covered with a photoelectric sensitive material.
The tube contains a very small amount of inert
gas, such as neon. The phenomenon here is that
30
all surfaces within the evacuated tube will attract
this gas and following certain physical laws will
spread evenly over the surfaces. The amount of
gas introduced is slightly more than what is nec~
35
essary to effect this covering, making the space
between the electrodes slightly conductive for
small electric charges. The conduction of the
electrical charge in this tube is brought about
by the movement of electrons. These electrons
can only move from a negative surface to a posi
40 tive surface. The amount of energy actuating
the two electrodes 34 and 35 is just enough to
allow electronic movement between them. As the
electrons impinge upon either of the electrodes
the gas deposited will emit a glow on the surface
of the dome. Should the ?ow be from the ring
to the dome 34 the top interior surface will glow.
Should the ?ow be from the dome to the ring,
the ring surface will glow. In the ?rst case the
glow would be transmitted to the disc 37. In the
second case any downward glow from the ring
would be stopped by the ring shield 36 and the
upward glow toward the dome would be insuf?~
cient to cause any re?ection from the dome, thus
whether the disc 31 would be energized or not
would depend upon the direction of current flow
passed by the commutator. The disc 31 is in cir
cuit with a relay magnet 38 which, if energized,
will cause the two contacts 39 and 4|] to separate
(50 and hence will break the current to the synchro
nous motor G.
Assume when the motor G is started that the
commutator will pass the current in such a direc
tion as to cause the dome interior 34 to glow.
If that is the case it will energize the photo
electric disc 31 and cause the current to flow
through the transformer N and the relay 38 and
break the motor contacts 39 and 40 and thereby
slow the motor down. When the motor has
slowed down one-quarter of a revolution the rela~
tive position of the commutator has been changed
and will now pass the current in the opposite
direction. This will keep the dome’s interior dark
and the motor will remain locked in the desired
75. position. One important feature of the control
system just described is that it operates entirely
on the same circuit as the motor G making it
independent of the energy passing through the
converter.
If for any reason the synchronous motor should CR
not function in synchronization with the current
to be converted and while the D. C. current is
in use, the result would be an introduction of
A. C. current into the D. C. system and the rela
tionship between the A. C. converter and the 10
D. C. would be upset; also the current ratio for
the auxiliary brushes would be destroyed which
might result in damage or total destruction of
the converter. To prevent this a circuit breaking
relay has been developed. This is shown in Fig. 1
and presents a system of passing a current to any
standard circuit breaker only when the motor is
out of synchronization with the alternating cur
rent. This system, furthermore, allows the same
current actuating motor G to operate the relay 20
and also the breaker, thus making the entire con
trol independent of the energy across the con
verter. The circuit connected to the breaker
magnet 45 is open at the contact points (22, the
current entering the magnet 43 passes through
the commutator A and also through a condenser
44. The principle here is that a direct current
will not pass through a condenser whereas an
alternating current will.
Now as long as the commutator passes direct 30
current the contact points 42 will remain open
but as soon as the motor G is out of step the
commutator A will pass alternating current,
thereby energizing the relay 43 and permitting
the current to pass through the contacts 42 and
the breaker magnet 45, causing the same to open
the circuit breaker 46.
The break in the circuit feeding the converter
is, of course, only momentary as the tube 33 per
forms two functions ?rst that of selecting the ‘i
proper polarity and, secondly, that of maintain
ing the motor G in synchronism with the A. C.
generator supplying the system.
That is, if the
commutator A is off phase alternating current
will not only pass through the condenser 44 but
also through the tube 33, causing a momentary
break between the contacts 39 and 40, thereby
breaking the circuit through the motor G and
slowing it down sufficiently to not only maintain
it in phase but also in proper polarity.
The converter shown in Fig. 1 is intended for
a large output of energy and in some instances
an energy of very high voltage. It is for this
reason that the transformer M and the third
commutator are used as a direct current of com~
paratively low voltage; for instance, 1.10 volts are
required for the operation of the control appa
ratus such as the synchronous motor G, the con
trol tube 33, the circuit breaker 46, etc. If the
converter is used for a low voltage output of ?xed 60
value the current for the control apparatus may
be taken directly from the D. C. line or stepped
down through a transformer, and in that case,
the commutator A may be eliminated.
In the use of direct current it is important in 65
many instances that the polarity is in the correct
direction; for instance, in the use of X—ray appa
ratus, electroplating apparatus, high frequency
actuated dust or gas precipitators, in battery
charging, etc. Wherever alternating current is
converted into direct current by synchronous con
version, manual operation to insure the correct
polarity is usually necessary. By using the appa
ratus shown in Fig. 20 correct polarity is auto~
75
2,116,899
matically insured, and while this and other fea
tures of the present invention are more or less
speci?cally described, I wish it understood that
various changes may be resorted to within the
scope of the appended claims. Similarly, that
the materials and ?nish of the several parts em
ployed may be such as the manufacturer may
decide, or varying conditions or uses may demand.
Having thus described my invention, what I
10 claim and desire to secure by Letters Patent is:—
1. In a. converter of the character described, a
main and an auxiliary commutator, and a pair
of collector rings connected therewith, each of
said commutators having a plurality of conductor
15
segments spaced circumferentially with insulat
ing material and the conductor segments on the
auxiliary commutator being aligned with the in
sulating space between the segments on the main
commutator, a pair of brushes for impressing al
ternating current on the segments of the main
commutator, a pair of brushes engaging the seg
ments on the auxiliary commutator, a common
feed wire connecting the ?rst-named and second
named brushes whereby alternating current is
passed through the second-named brushes while
the insulating spaces between the segments on the
main commutator are passing under the ?rst
named brushes, and a ?xed resistance in the con
nection between the ?rst and second-named
30 brushes.
2. In a converter of the character described,
a main and an auxiliary commutator, and a pair
5
5. In a converter of the character described
having a main and an auxiliary commutator and
-a pair of collector rings connected therewith, a
synchronous motor for driving the converter,
and means actuated by the direct current output
of the converter for varying the alternating cur
'rent input to the auxiliary commutator.
6. In a converter of the character described
having‘ a main and an auxiliary commutator and
a pair of collector rings connected therewith, a
synchronous motor for driving the converter, ~10
said motor being supplied with alternating cur
rent from the same source as the A. C. to be con
verted, a third commutator on the converter also
supplied with alternating current from the same
source, means actuated by current output of the 15
third commutator for breaking the A. C‘. sup
plied to the converter if the synchronous, driving
motor gets out of synchronism and other means
for automatically selecting and maintaining the
D. C. output of the converter at a ?xed polarity. 20
7. In a converter of the character described
having a main and an auxiliary commutator and
a pair of collector rings connected therewith, a
synchronous motor for driving the converter,
said motor being supplied with alternating cur
rent from the same source as the A. C. to be
converted, a third commutator on the converter
also supplied with alternating current from the
same source, means actuated by the current out-
0
put of the third commutator for automatically cc
selecting and maintaining the D. C. output of the
converter at a ?xed polarity, and means for
of collector rings connected therewith, each of ‘varying the A. C. input to the converter to vary
said commutators having a. plurality of conduc~ the D. C. output.
tor segments spaced circumferentially with in
8. In a converter of the character described,
sulating material and the conductor segments a main and an auxiliary commutator and a pair
on the auxiliary commutator being aligned with of collector rings connected therewith, each of
the insulating space between the segments on said-cornmutators having a plurality of conduc
the main commutator, a pair of brushes for im
tor segments spaced circumferentially with in
4 0 pressing alternating current on the segments of
sulating material and the conductor segments
the main commutator, a pair of brushes engag~
on the auxiliary commutator being aligned with
ing the segments on the auxiliary commutator, the insulating space between the segments on
a connection between the ?rst-named and sec
the main commutator, brushes for impressing al
ond-named brushes whereby alternating current ternating current on the segments of the main
is passed through the second-named brushes‘ and auxiliary commutators, said brushes being
while the insulating spaces between the segments connected, and a material having a high resist~
on the main commutator are passing under the
a'nce to the ?ow of a current forming the trail
?rst-named brushes, and a ?xed and a variable
ing end of each segment.
resistance in the connection between the ?rst
9. In a converter of the character described, a
and second-named brushes.
ain and an auxiliary commutator and a pair
3. In a converter of the character described
collector rings connected therewith, each of
having a main and an auxiliary commutator and 5 id commutators having a plurality of conductor
a pair of collector rings connected therewith, a segments spaced circumferentially with insulat
synchronous motor for driving the converter, ing material and the conductor segments on the
55 said motor being supplied with alternating cur
auxiliary commutator being aligned with the in
rent from the same source as the A. C. to be con
sulating space between the segments on the main
verted, a third commutator on the converter also
>
50
55
commutator, brushes for impressing alternating
supplied with alternating current from the same
current on the segments of the main and auxil
source, and means actuated by the current out
iary commutators, said brushes being connected, 60
a material having a high resistance to the ?ow
60 put of the third commutator for breaking the
A. C. supplied to the converter if the synchro
nous driving motor gets out of synchronism.
4. In a converter of the character described
having a main and an auxiliary commutator and
65 a pair of collector rings connected therewith, a
synchronous motor for driving the converter,
said motor being supplied with alternating cur
rent from the same source as the A. C. to be con
verted, a third commutator on the converter also
supplied with alternating current from the same
source, and means actuated by direct current out
75
40
put of the third commutator for automatically
selecting and maintaining the direct current out
put of the converter at a ?xed polarity.
of a current forming the trailing end of each
segment, and a ?xed and a variable resistance
in the connection between the brushes.
10. In a converter of the character described
having a main and an auxiliary commutator and 65
a pair of collector rings connected therewith, a
synchronous motor for driving the converter,
said motor being supplied with alternating cur
rent from the same source as the alternating
70
current to be converted, a third commutator on
the converter also supplied with alternating cur
rent from the same source, means actuated by
the current output of the third commutator for
breaking the alternating current supplied to the 75
6
2,116,899
converter if the synchronous driving motor gets
out of synchronism, and means for varying the
direct current output of the converter by vary
ingjthe alternating current input.
11. In a converter of the character described
halving a main and an auxiliary commutator and
a pair of collector rings connected therewith, a
synchronous motor for driving the converter, said
motor being supplied with alternating current
10 from the same source as the alternating current
to be converted, a third commutator on the con
verter also supplied with alternating current from
the same source, means actuated by the current
15
output of the third commutator for automatical
ly selecting and maintaining the direct current
output of the converter at a ?xed polarity, and
means for varying the direct current output of
the converter by varying the alternating current
input.
20
.
12. In a converter of the character described
a main and an auxiliary commutator and a pair
of collector rings connected therewith, each of
said commutators having a plurality of conductor
segments spaced circumferentially with insulat:
7 ing material and the conductor segments on the
auxiliary commutator being aligned with the in;
sulating spaces between the segments on the
main commutator, brushes for impressing alter
nating current on the segments of the main and
auxiliary commutators, said brushes being con
nected, a material haying a high resistance to the
flow of a current forming the trailing end of each
segment, and a ?xed resistance in the connection
between the brushes.
"
~
13. In a converter of the character described
a main and an auxiliary commutator and a. pair
of collector rings connected therewith, each of
said commutators having a plurality of conduc
tor segments spaced circumferentially with in
40 sulating material and the ".conductor segments
on the auxiliary commutator being aligned with
connected, a material having a high resistance to
the flow of a current forming the trailing end
of each segment, and a variable resistance in the
connection between the brushes.
14. In a rotary converter for converting alter
nating current to direct current, a synchronous
motor for driving the converter in synchronism
with the alternating current to be converted,
means for automatically breaking the current to
the alternating converter if the converter gets
out of synchronism, said means including a
switch in the alternating current supply circuit
of the converter, a commutator driven by the
motor and supplying alternating current to the
control circuit to open the switch when the con
verter is out of synchronism, said commutator
supplying direct current when the converter is
in synchronism, and a condenser interposed be
tween the commutator and the control circuit to
render the control circuit inoperative when direct
current is supplied thereto.
15. In a rotary converter for converting alter
nating current into direct current, a synchro~
nous motor for driving the converter in synchro
nism with the alternating current, means for
automatically selecting the polarity of the con
vcrter’s curr'nt output and for automatically
maintaining the cirect current output at the po
larity selected, said means comprising a commutator driven by the synchronous motor, said commutator supplying current to a control cir
cuit, a switch adapted to be opened or closed by
. the control circuit, said switch controlling the
alternating current supply to the synchronous
motor, and a photoelectric relay in the control
circuit, said relay preventing current of a selected
polarity from passing through the control cir
cuit but passing current of an opposite polarity,
said current of opposite polarity actuating the
the main commutator, brushes for impressing al
control circuit to open the switch to momentarily 40
break the alternating current circuit through the
synchronous motor and thereby change the polar
ity of the output of the converter to the selected
ternating current on the segments of the main
polarity.
the insulating spaces between the segments on
and auxiliary commutators, said brushes being
'
JOHN KALSEY.
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