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Патент USA US2126291

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Aug. 9, 1938.
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7
J, SLEPIAN
2,126,291
VAPOR ELECTRIC CONVERTER
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Filed March 24, 1937
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Patented Aug. 9, 1938
2,125,291‘
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2,126,291
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VAPOR ELECTRIC CONVERTER
Joseph Slepian, Pittsburgh, Pa, assignor to West
inghouse Electric & Manufacturing Company,
East Pittsburgh, Pa, a corporation of Penn
‘ sylvania
.
Application March 24, 1937, Serial No. 132,830
8 Claims.
(Cl. 1'75—363)
My invention relates to a vapor electric‘ con
verter and particularly to an ignition system for
such a converter.
Since this block of
cathode material, the heater circuit is never
In the operation of vapor electric converters
having a make-alive type of excitation, it has
been found that there is considerable delay inthe
formation of the rectifying arc to the anode. This
delay has been particularly noted in regard to
the high resistance low current type of igniter,
10 sometimes being of the order of several thousand
micro-seconds. By observation of the operation
of these devices, I believe that this effect results
because the startingcurrent arc does not produce
su?icient vapor for the quick transfer of the arc
15 to the main electrodes.
the material of the cathode.
metal remains permanently in contact with the
broken.
Another method of preventing the heating cir
‘cuit from being interrupted by motion of the
cathode material, .is to provide two terminals to
the make-alive electrode for the flow of heating
current, which are independent of‘ the cathode
material. This may be done by making the make
alive electrode of hair-lpin form.
Other objects and advantages of my invention
will be apparent. from the following detailed de
scription taken in conjunction with the accom
panying drawing, in which:
'
Another trouble met with in converters of this
type is that liquid mercury may condense or be
thrown upon the igniter electrode and stick there.
This condensed mercury causes a large increase
20 in the current required by the igniter for starting
the arc.
According to my invention, this delay in start~
ing may be eliminated and the sticking of mer
cury to the igniter prevented by‘applying heat to
the vicinity of the auxiliary or make-alive elec
trode. This heat may be applied directly to the
make-alive electrode‘ by passing a suitable heat-‘
> Fig- 1 is a schematic illustration of a converter
embodying my invention;
Fig. 2 is a similar view of a converter embocly—
ing an independent heater;
7
Fig. 3 is a modi?cation similar to Fig. 1, but 20
having an independent sourceof excitation;
Fig. 4 is a further modi?cation showing the use
of an independent heater element; and
Fig. 5 is a modi?cation showing a hairpin type
of make-alive electrode.
.
25
The construction according to my invention is
a simple arc chamber I having a single anode 2
ing current therethrough, or may be applied in
and a cathode 3 with a make-alive electrode 4
directly by an independent heating element adja
supplied from the anode circuit 5 by a suitable
uni-directional conductor, such as a glow tube 6. 30
In normal operation of my device, the glowtube
cent to the electrode.
In either event sufficient
heat should be generated to keep the auxiliary
electrode free of condensed mercury and to main
tain a slight vapor pressure in the vicinity thereof.
When the heating current is passed through‘
' the auxiliary electrode, it has been noted that a
current much smaller than the current which will
regularly produce a cathode spot will occasionally
cause a random occurrence of a cathode spot.
I
believe‘ that this random occurrence is caused by
40 the heating current producing sufficient vapor
pressure to push the ‘cathode material away from
contact with the auxiliary electrode and thus
5 will,’ break downupon the application of posi
tive potential'to the anode 2 and passes starting
current‘ to the make-alive electrode li, which initi
ates a cathode spot, which in turn strikes the 35
main arc and short circuits the glow tube 6 re
moving current from the make-alive electrode.
To this simple converter I add a heating circuit
by placing in shunt with the glow tube a resistance
it which allows a continuous heating current to 40
?ow through‘ the make—alive electrode. This re
sistance iii should‘ be of such a value that the
heating current is‘ well below the value of‘ cur
create a spark which initiates the cathode spot.
I have found that this random occurrence can be
rent‘ necessary‘ to initiate a cathode spot.
prevented by, suitably cooling the end of the
make-‘alive electrode in contact with the cathode
In order to prevent unnecessary heating of that
portion‘ of the electrode 4 in contact with the.
material or by having the end of the make-alive
electrode in permanent electrical contact with a
highly conducting element which is in permanent
50 electrical contact with the‘ cathode material.
While this cooling may be done by immersing the
cathode, I prefer to provide a cooling element by
cathode material ' 3“, _I provide“ the make-alive
electrode with a suitable cooling element in the
form of a metallic block i l attached to the elec
trode and immersed in the cathode material 3.
In the modi?cation according to Fig. 2, the
heating of the auxiliary electrode i is accom
plished by means of a heating coil l5 supplied
attaching a block of metal, such as iron, to the
tip of the electrode and immersing the same into
transformer l6.
45
‘ make-alive electrode a suitable depth into the
55
,
from a suitable source of current, such as a
55
2
2,126,291
In the modi?cation according to Fig. 3, the ex
citation or ignition current for the converter is
applied to the make-alive electrode 4 from a
suitable source, such as a transformer 20, through
a grid-controlled discharge device 2|, the grid of
which is controlled bythe potential applied to the
anode 2 of the converter. The auxiliary dis
charge tube is by-passed by a suitable resistance
IE! for providing heating current to the make
alive electrode 4.
In the modi?cation according to Fig. 4 the
make-alive current is controlled by a commutat
ing device 25 driven by a suitable motor 26 pref
erably a synchronous motor. In order to prevent
sparking at the commutator I provide a suitable
capacitor 21 bridging the contacts. A resistor
28 of proper capacity may be placed in parallel
with the capacitor 2'! to pass heating current
through the electrode 4. By properly propor
tioning resistors l0 and 28 the heating effect may
be divided between the heater coil l5 and the
heating. current passing through the electrode 4.
While the return connection from the coil l5 to
25
the current source 29 may be made in any pre
ferred way I prefer to connect the coil 15 directly
to the cathode 3 and protect it from the arc by
a suitable insulating sleeve 30 in order to reduce
the number of vacuum seals required.
In the modi?cation according to Fig. 5 a hair
30
pin type of make-alive electrode is utilized com
prizing two make-alive elements connected to
gether by means of the cooling block II’. A
suitable heating current is circulated through the
and means for cooling the portion of the make
alive electrode immersed in the vaporizable
cathode.
2. A vapor-electric converter comprising an
arc chamber, a plurality of main electrodes in
said chamber, one of said main electrodes being
of vaporizable material, a make-alive electrode
in contact with said vaporizable electrode, means
for periodically passing make-alive current
through said make-alive electrode, and means
for continuously passing a lesser current through
said make-alive electrode.
3. A vapor-electric converter comprising an
arc chamber, a plurality of main electrodes in
said chamber, one of said main electrodes being
of vaporizable material, a make-alive electrode
in contact with said vaporizable electrode, means
for ‘periodically
passing
make-alive
current
through said make-alive electrode, means for
continuously passing a lesser current through
said make-alive electrode, and means for pre
venting said lesser current from accidentally
creating a cathode spot on said vaporizable
electrode.
4.. An ignition system for a vapor-electric de 9.5
vice comprising an ignition electrode in contact
with the cathode of the device, a source of poten
tial for said electrode, a uni-directional conductor
for passing igniting current to said electrode, and
means for heating the ignition electrode.
3 (l
5. An ignition system for a vapor-electric de
vice comprising an ignition electrode in contact
with the cathode of the device, a source of poten
tial for said electrode, a unidirectional conductor
make~alive electrodes from any suitable source
such as a heating transformer 35. The make
for passing igniting current to said electrode,
alive current from anode connection 5 is supplied
by discharge device 6 preferably to a mid tap on
the secondary winding of transformer 35.
In the operation of these devices whether the
current is supplied directly to the auxiliary elec
trode or to an independent heating element l5
associated therewith, the heating current pro
the vicinity of the ignition electrode.
6. A make-alive system for a vapor-electric
converter comprising a make-alive electrode in
duces a continual evaporation of the material
ously supplying a heating current to said make
alive.
7. An ignition system for a vapor-electric con
verter having an arc-chamber and a plurality
of main electrodes therein, comprising an auxil
iary electrode having a portion thereof immersed
in one of said main electrodes, a source of poten
tial for said auxiliary electrode, means for inter
adjacent to the auxiliary electrode, and conse
quently maintains a vapor pressure in the vicinity
of the auxiliary electrode 4. Also by maintaining
the auxiliary electrode at a relatively high tem
perature, it prevents condensation of the cathode
material on the surface of the auxiliary electrode.
While I have shown and described speci?c
embodiments of my invention, it will be apparent
to those skilled in the art that many modi?ca
tions can be made therein without departing from
the true spirit of my invention by the scope of the
appended claims.
I claim as my invention:
1. A vapor~electric converter comprising an
arc-chamber, a pair of main electrodes therein,
60 at least one of said electrodes being of vaporizable
material, a make-alive electrode having a portion
thereof immersed in said vaporizable electrode,
means responsive to the polarity of the potential
impressed on the main electrodes for impressing
make-alive current on said make-alive electrode,
a resistance in shunt with said means for impress
ing a lesser current on said make-alive electrode
and means for maintaining a vapor pressure in
contact with the cathode material of said con 40
verter, a source of potential for supplying cur
rent to said make-alive, means for interrupting
the make-alive current and means for continu
mittently applying said potential to said auxiliary
electrode and means for heating said auxiliary
electrode.
8. An ignition system for a vapor-electric con
verter having an arc-chamber and a plurality of
main electrodes therein, comprising an auxiliary
electrode having a portion thereof in contact with
one of the main electrodes, a connection with the
main electrode supply circuit for supplying cur
rent to said auxiliary electrode, means in said
circuit for interrupting the current to said auxil
iary electrode and means for by-passing current
around said interrupting means for heating the
auxiliary electrode.
JOSEPH SLEPIAN.
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