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‘Aug. 19, 1947.
Filed Feb. 27, 1945
' (>4
I h’erberz‘?l Pose.
Patented Aug. 19, 1947
Herbert A. Rose, Pittsburgh 21, Pa., assignor to
Westinghouse Electric Corporation, East Pitts
‘ burgh, Pa., a corporation of Pennsylvania
Application February 27, 1943, Serial No. 477,386
4 Claims. (01. 175-363)
My invention relates to a vapor electric device
and particularly to a control system for insuring
initiation of a power are in the various valves
of a make-alive type converter.
In the operation of vapor electric converters,
particularly of the make-alive type, it has here
tofore been customary to provide periodic con
trol impulses for initiating the cathode spot in
the individual valves at the beginning of each
conducting portion of a cycle therein. With cer
tain transformer connections and with certain
operating conditions the main power are in a
valve or group of valves may fail to pick up dur
to a direct current circuit I I by means of a recti
?er transformer I2 which is connected to. the
alternating current circuit by a suitable breaker
52 and to the direct current circuit by a circuit
breaker 12.
The recti?er transformer I2 has a
plurality of phase terminals herein designated
I to 6, these phase terminals being connected
to the anodes I3 of vapor electric valves herein
designated as Ia to 611.
Each of the vapor electric valves Ia to Sc com
prises, in addition to the main anode I3, a co
operating vaporizablereconstructing cathode I4
' of suitable material such asv mercury and a make
ing the necessarily short interval in which the
alive electrode I5 of high resistant material in
make-alive impulse is operative. In installa
withthe cathode I4. The make-alive
tions fed by transformers which operate in mul
electrode I5 is preferably provided either with a
tiple groups such as double three phase, double
portion of substantially lower resistant material
bi-phase or other multiple grouping utilizing in
or with a metallic connection which may operate
terphase windings the mis?re in a single valve
as an exciting electrode after the cathode spot
may nullify the‘ excitation of the interphase
has been initiated“ The cathode spots are ini
windings and result in a lack‘ of commutating po 20 tiated by supplying a control impulse of rela
tential at the normal commutating instant. One '
tively steep wave front and of relatively short
or more of the valve groups may then “back out”
duration with respect to the Wave length of the
and will only resume current conduction after
alternating current supply from circuit I0.
the entire converter has been shut down and re 25
While any suitable impulsing system may be
started. This results in some of the valves or
I prefer to utilize an impulsing system
valve groups becoming completely inoperative, - of the so-Called
wave distorter or reactor ?ring
with consequent loss in capacity and other ill
type in which any suitable source of alternating
which may conveniently be a transformer
According to my invention this di?iculty is 30 current,
I6 fed from the alternating current circuit III by
avoided by providing an auxiliary source of exci
an insulating transformer I‘! and controlled by
tation potential which will maintain the cathode
circuit breaker 3|, supplies energy through a wave
spot for a predetermined interval after the con
system comprising a storage device
trol impulse has operated. I accomplish this by
providing an auxiliary source of alternating cur 35 preferably in the form of a capacitor 20 and hav
ing the current thereto controlled by means of an
rent potential connected to the individual make
impedance such as a linear reactor 2|. The
alive electrodes of the separate valves. This alter
current ?ow'to the make-alive electrodes I5 is
nating source of potential has a peak value which
then determined by means of a non-linear im~
is insu?icient of itself to initiate a cathode spot
pedance, preferably in the form of a saturable
but, which, after the cathode spot has been ini 40 reactor 22.
tiated, is sufficient to maintain the spot for the
of the wave distorter type
critical interval of time.
produces a symmetrical Wave and the application
It ‘is, accordingly, an object of my invention to
to one or the other of a pair of electrodes I5 is
provide a control system in which a cathode spot
determined by a polarity sensitive network in
is maintained for a predetermined interval after
cluding a unidirectional conductor 23 (usually of
it has been initiated.
so called dry type) in series with each make
It is a further object of my invention to provide
a more reliable control system for a vapor elec
tric valve.
It is a further object of my invention to provide
a control system having a mainand auxiliary
alive electrode and a further unidirectional con
ductor 24 in shunt around the make-alive elec
trode I5 and its series recti?er 23. The use of the.
polarity responsive network is desirable to pre
vent reverse current through the make-alive
excitation source.
I5 and also to reduce the energy losses
Other objects and advantages of my invention
system, however the losses are
will be apparent from the following detailed de
scription taken in conjunction with the accom 55 of such small amount that the polarity responsive
means would probably be'dispensed with when
panying drawing in which the ?gure is a sche
make-alive electrodes I5 which were submatic illustration of a ‘vapor electric converter
embodying my invention.
I In the illustrative embodiment of my inven
'stantially undamaged by reverse current ?ow
therein. ,
In operation this impulsing system periodically '
tion an alternating current circuit I0 is connected 60
supplies make-alive impulses of su?icient ampli
may not reliably initiate a discharge between
the main anode l3 and cathode l4. For this
reason I have provided an auxiliary source of ex
sufficient to normally initiate a cathode spot in
said valve and means including a unidirectional
conductor for impressing half waves of the po~
tential of said source on said make-alive elec
tilde to create a cathode spot but of relatively
short duration. The time at which the cathode
spot is initiated may be determined by any suit
able phase shifting device such as the induction
phase shifter 25.
Under certain operating characteristics of the
device the mere initiation of the cathode spot
2. An excitation system for a vapor electric
device having alternate conducting and non
conducting intervals comprising an exciting elec
trode in contact with a main current carrying
10 electrode of said device, a source of exciting cur
rent impulsing means energized from said source
citation potential which is preferably in the form
of a transformer 30 energized from any suitable
source having a frequency similar to the fre
quency of the main alternating current circuit In
and may very conveniently be the alternating 15
current circuit 10.
The phase terminals of the auxiliary source 30
are connected to the make~alive electrodes l5
preferably between the series unidirectional con—
ductor 23 and the connection to' the make-alive
for producing impulses of steep wavefront and
short duration with respect to the conducting
interval of said device, circuit means including
a unidirectional conductor for impressing said
impulses on said exciting electrode, an auxiliary
source of alternating exciting potential, a second
circuit means independent of said ?rst mentioned
circuit means for periodically impressing the
20 potential of said auxiliary source on said exciting
electrode, said second circuit means including a
electrode [5. In order to prevent reverse cur
unidirectional conductor.
rent flow through the make-alive electrode I5, I
3; An electric current conversion system for
prefer to insert a unidirectional conductor 32
transferring electric energy between dissimilar
between the phase terminals of the auxiliary
source and each of the make-alive electrodes 15. 25 electric circuits at least one of which is an alter
nating current circuit there being at least a pair
After the impulsing system has operated to
of alternating conducting vapor electric valves
initiate the cathode spot, the auxiliary source 30
connected to control current flow between said
will maintain an excitation arc during the period
circuits, each of said valves including a main
through which the connected auxiliary terminal
is positive. In order to prevent undesirable op 30 anode and cathode and an exciting electrode in
contact with the cathode, an exciting system for
eration, I prefer to maintain the maximum po
said valves comprising a source of alternating
tential of the auxiliary source 30 sufficiently low
control potential, circuit means connected be
that it will not, of itself, initiate the cathode
tween said source and said exciting electrodes for
spot but of sufficient potential to maintain an
periodically applying current impulses from said
are after the cathode spot has been initiated
source to said exciting electrode, an auxiliary
so that any delay in the establishment of the
source of exciting current, and circuit means in
main arc will not cause a mis?re in the valve
dependent of said ?rst mentioned circuit means
undergoing excitation.
for periodically applying the potential of said
Where voltage control is desired it is prefer
able to utilize some form of phase shift in con 40 auxiliary source to said exciting electrodes, and
circuit means in shunt with said exciting elec
nection with the impulsing devices and I have
trode for relieving the flow of reverse current
herein shown the ‘well known inductive type of
phase shifter 25 but obviously any other type of
4. An excitation system for a converter hav
phase shifting means may be utilized. Usually
it is more desirable to have the auxiliary excita 45 ing at least a pair of alternating conducting
vapor electric valves of the make-alive type com
tion substantially in phase with the main anode
prising a make-alive electrode for each of said
potential so that there is no danger of the exci
tation persisting into the normally nonconduct
ing period. I have therefore shown the auxil
valves. 9. source of exciting potential, a wave dis
the phase shifting means 25. The entire excita
tion system may be supported from any suitable
source of alternating current of the desired fre
front and short duration, polarity selective means
including a unidirectional conductor in series
with each of said make-alive electrodes for alter
torting network connected between said source
iary source 30 connected to an excitation source 50 and said make-alive electrodes for applying to
said make-alive electrodes impulses of steep wave
such as an insulating transformer l1 ahead of
quency herein shown as an insulating trans
‘ former i1 energized from the line 10 through a
switching device 3|.
nately applying said impulses to the respective
make-alive electrodes, an auxiliary source of pe
riodic exciting potential and connecting means
including a unidirectional conductor for simul
While for purposes of illustration I have shown
taneously impressing the potentials of said auxil
and described speci?c embodiments of my in
vention, it will be apparent that changes and 60 iar‘y source and said wave distorting network on
one of said make-alive electrodes.
modifications may be made therein without de
parting from the true spirit of my invention or
the scope of the appended claims.
Iv claim as my invention:
1. In an electric conversion system having a 65
The following references are of record in the
plurality of make-alive type valves an excitation
file of this patent:
system comprising a make-alive electrode for
each of said valves, an impulsing system includ
ing a uniconductor device for applying periodic
impulses of short duration to said make-alive
Slepian ___________ __ Nov. 12, 1940
electrodes, said impulses being of su?icient po
Klemperer ________ __ Nov. 26, 1940
tential to reliably initiate a cathode spot in said
Cox et a1 __________ __ July 28, 1942
valve, a source of auxiliary alternating exciting
potential, the potential of said source being in
Lord ______________ .. Feb. 2, 1943
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