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Патент USA US2129536

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Sept. 6, 1938.
.E, H, RE": ‘
Filed Feb. 12, ‘1958
Eugene H. Reid ,
‘y iileilwh'tor‘ney.
Patented Sept. 6, 1938
Eugene H. Reid, Schenectady, N. Y., assignor to
General Electric Company, a corporation of
New York
ApplicationFebruarylZ, 1938, Serial No.‘190,267
5 Claims. (Cl. 175——363)
My invention relates to ‘electric valve convert
ing systems, and more particularly ‘to such sys
tems providedwith means for suppressing reverse
arcs within the valves of said apparatus.
1" It is commonly known that electric valve con
verting apparatus,.in ‘operation, are subject to
reverse arcs which may be occasioned by any of
a number of disturbing operating conditions. If
such reverse arcs within the valves are permitted
to persist serious damagezmay becaused not‘ only
tothe valves themselves but to thesystem and
other apparatus associated ‘therewith. Heretoe
fore, there havebeen proposedv certain arrange
ments which have had as their objects the elim
ination or suppression-of reverse arcs in electric
are impressed normally either continuous or pe
riodic positive potentials to render the associ
ated anode conductive. A substantially high‘
negative potential is also connected to the shields
or grids through suitable means such as a nor
mally non-conductive electric valve. The control
electrode of this-normally non-conductive elec
tric valve is 50 connected to the system as to be
responsive to transients due to the occurrence
of reverse arcs or abnormal current conditions
in the apparatus.
For example, upon the oc
currence of a reverse arc a conductive member
in contact with the ionizable medium of the elec
tric valve or in the instance of a metal container,
this conductive container when provided with an
insulated cathode changes its potential with re
One of‘ such systems ‘for controlling» reverse I spect to the cathode, so that it becomes negative
arcs or arc backs is ‘disclosed in United States - with respect to the cathode whereas under ordi
Letters Patent No. 2,088,436, granted. July 27,
M1937, upon the application of Eugene..I-I..Reid
for improvements in a Vapor electric rectifying
system. In ,this system the change in potential.
nary normal operating conditions it is positive
with respect to its cathode. This reversal of 20
polarity may be used to control the electrode of
the normally non-conductive auxiliary electric
between the cathodeand a conductive member . valve.
in contact with theionizable vapor or gas .of the
in arelectric valve is used to control a means for ap
plying a negative bias to the grid which surrounds
the anode. In the grid control type of. electric.
valveit is common to include in the grid control
circuit a resistor for limiting the grid circuit cur~
wrent to a safe value. Inboth the uncontrolled
recti?ers and those ‘recti?ers provided with ig
nition electrodes, grids are also provided, and
in each of the circuits for these grids which are
usually maintained at a positive potential with
“respect to the cathodes, there is included .a cur
rent limiting resistor for this same purpose.
Upon the occurrence of an are back and‘ the
application of a negative voltage to the grid it
would be highly desirable if the grid" circuit did
v =‘not contain such current limiting resistors.
It is, therefore, an object of this invention to
provide an improved electric valve converting
system in which a negative potential will be im
pressed‘ upon the anode shields or grids and yet:
have a relatively low resistance value in the‘grid
The normal current limiting resistors of
the circuit for the shields or control grids are
replaced by non-linear voltage-resistance ele
ments which under normal conditions present a
relatively high resistance value to the grid cir
cuit, but which upon application of a high nega
tive potential present to the circuit a relatively
low resistance value.
together with further and other objects thereof,
reference is had to the following description taken
in connection with the accompanying drawing
in which the ?gure illustrates one embodiment of
my invention in which a change in the potential
of the conductive member in contact with the
ionizable vapor of the valve with respect to its
cathode is utilized to suppress the reverse are or
are back in an electric valve.
Referring now to the single ?gure of the draw
ing, I have illustrated an electric valve convert
ing system for transmitting energy from an al
ternating current supply circuit Hi to a direct
current load device illustrated as the motor I I.
The system illustrated shows a transformer i2,
It is another- object of this invention to pro
an' electric valve l3, and a high speed direct curvide an improved electric valve converting sys
rentcircuit breaker M, which may be of any of
tem in which the grid circuitunder normal oper-‘ the several types well known in the art. The
‘ation will have a relatively high resistance value , electric valve apparatus I 3, which may be any
and under abnormal circuit conditions a rela-. of the types Well known in the art, is shown as
tively low resistance value.
being a metal tank or other conductive container
In accordance with my invention, an electric
l5, an insulated mercury pool cathode It, a pair
valve converting apparatus is provided with con
of anodes I1 ‘and a pair of conducting shields or
rductive anode shieldsor control grids upon which
30 ~
For a better understanding of my invention,
grids l8 surrounding the anodes H and insulated
While the arrangement illustrated
shows a system for transferring energy from al
ternating current circuits to direct current cir
cuits, it will be apparent that the invention is
also applicable to inverting circuits and further
more that any number of anodes may be utilized
in the valve I3. It will also be apparent that a
plurality of single anode valves may be utilized
which may be provided with igniter electrodes
and protective shields about the anodes. Simi
larly, the envelope may comprise a glass con
tainer and an auxiliary conductive member may
be enclosed within the envelope so as to be in
contact with the ionizable vapor within the valve.
15 If the valve I3 is of the uncontrolled type, it is
common to impress a positive potential upon the
grid I8 in order to maintain, under normal con
ditions, the valve I3 in a conductive condition.
One of the grid members I8 is shown as being
20 connected through a circuit including a non
linear voltage-resistance element I9, a positive
potential source 20 and a resistor H to the con
tainer walls I5 or to a conductive member in
contact with the ionizable vapor of the valve I3.
The non-linear voltage-resistance element I9 may
be of the type disclosed in United States Let
ters Patent No. 1,822,742, granted September 8,
1931 on the application of Karl B. McEachron.
Such material has the characteristic of present
30 ing under normal conditions a relatively high re
sistance value to the grid circuits and under ab
normal conditions a relatively low value of re
sistance. A similar non-linear voltage-resistance
element is connected in the circuit of the other
grid member I8 and by way of illustration this
is being shown as comprising a resistor 22 con
nected in parallel to a series circuit comprising
a resistor 23 and a contact recti?er 24, which
recti?er may be of the copper oxide type dis
closed in United States Letters Patent No. 1,640,
conditions will cause the circuit breaker I4 to
open and thus interrupt the flow of reverse power
but when the are back is occurring between the
two anodes, the short circuit will not be removed
from the transformer I2. Under abnormal con
ditions, however, the potential of the tank I5 re
verses in polarity with respect to the cathode I6
substantially instantaneously so that the tank I5
or conductive member in contact with the ioniz
able vapor of the valve I3 is negative with re 10
spect to the cathode I6. If the cathode is not
taken as a reference point on the apparatus but
some other point such as ground or some conduc
tor of which the absolute potential remains sub
stantially constant under all conditions utilized, 15
the change in potential between the tank or con
ductive member in contact with the vapor there
in is utilized to actuate the grid of the valve 26.
The necessary changes in the circuit of the con
trol electrode or grid connections will be obvious 20
to those skilled in the art. With the connections
as described above, this results in placing a posi
tive potential upon the control electrode of the
valve 26 to render it conductive, thus connecting
the grid I6 to the conductive member or tank 25
I5 through the non-linear voltage-resistance ele
ment, the negative bias battery 25 and the elec
tric valve 26. Upon the application of the high
negative bias from the source 25 to the grid cir
cuit the non-linear voltage-resistance element 30
such as the element l9 and the combined ele
ments 22, 23 and 24 now present to the grid cir
cuits relatively low resistance values. Under this
condition the are back will persist only for the
remainder of the particular half cycle and there 35
after the negative potential on the grids I8 pre
vents the discharge from continuing. If it is de
sired to prevent operation of the valve 26 upon
occurrence of extremely short transients, a con
denser may be connected between the grid and
cathode of the valve 26 to absorb these short
of Lars O. Grondahl. Upon occurrence of abnor
transients. In such cases it is preferable to pro
mal current conditions the grids I8 are arranged vide the condenser with a grid leak in order to
to be connected through a suitable source of neg
allow the charge to leak off the condenser.
ative bias potential 25 and a normally non-con
It therefore will be apparent to those skilled
ductive electric valve 26 to the conductive por
the art that the present invention may be ap
tions I5 of the electric valve I3. The normally
plied to single and multi-anode tank recti?ers
non-conductive valve 26 is provided with an an
ode, a cathode and a control grid or electrode which may be either uncontrolled, grid controlled
and may be any of the several types well known or controlled by starting or ignitor electrodes. In
50 in the art, such as the grid glow or Thyraton each instance it is desirable that under normal op
erating conditions the shields or grids should be
type. The grid of the electric valve 26 is con
nected through a grid circuit resistor 2's’ to the connected in a circuit having a relatively high
resistance value under normal operating condi
cathode I6 of the electric valve I3.
The general principles of operation of the rec~ tions and a relatively low resistance value under
tifying system. comprising the transformer I2, the abnormal current conditions.
While I have described what I at present con
electric valve I3 and the direct current load de
vice II will be well understood by those skilled sider preferred embodiments of my invention, it
in the art, so that a detailed explanation is not will be obvious to those skilled in the art that
various changes. and modi?cations may be made
60 deemed necessary. Under normal operating con
ditions, the grids I8 will be maintained at a posi-v in the circuit and instrumentalities without de
parting from my invention, and I therefore aim
tive potential with respect to the tank or conduc
tive member I5 by means of the voltage supplied in the appended claims to cover all such changes
by the battery 26; and the tank member I5 is and modi?cations as fall within the true spirit
normally slightly positive with respect to the and scope of my invention.
What I claim as new and desire to secure by
cathode I6. Under such conditions the appara
tus I3 is completely conductive and the grids Letters Patent of the United States, is,—
1. In combination with an electric valve com
I8 permit the rectifying system to operate as an
uncontrolled rectifying apparatus. It will be as— prising an envelope containing an ionizable me
dium, an anode, a cathode, a grid and a conduc
70 sumed that the circuit breaker I4 is closed and tive member in contact with said ionizable me
that energy is being supplied to the direct cur
335, granted August 23, 1927 on the application
rent motor l I. Upon the occurrence of a reverse
are or are back, a short circuit may appear across
the transformer I2 or the current may rise to ab
75 normally high values.
Such abnormal current
dium, a circuit for said grid including a non
linear voltage-resistance element having normal
ly a high resistance value, and means cooperat
ing with said conductive member upon abnormal 75
conditions to apply through said non-linear ele
ment a negative bias potential to said grid.
2. In combination with an electric valve appa
ratus comprising an anode, a cathode, a grid and
a conductive member in contact with the ioniz
able vapor of said apparatus, a circuit for said
for said grid including a non-linear voltage-re
sistance element normally presenting a high re
sistance value to said circuit, means responsive
to a reversal of the potential between said cath
ode and said conductive member upon abnormal
conditions for impressing a negative bias poten
grid including a non-linear voltage-resistance
tial upon said grid circuit whereby said non
linear voltage-resistance element presents a rel
potential between said conductive member and ’ atively low resistance value to said circuit.
10 said cathode for applying to said grid through
5. In combination with an electric converter
said non-linear element a negative bias poten
comprising a conductive container, an insulated
cathode, a plurality of anodes and associated
3. In combination with an electric-valve ap
grids, a circuit for each of said grids including
paratus comprising a conductive container, an a non-linear voltage-resistance element normal
insulated cathode, a grid for said anode, a cir
ly presenting a high resistance value to said cir
cuit for said grid including a non-linear voltage
cuit, means for suppressing an are between said
resistance element, and means responsive to a anodes comprising means responsive to a re
change in potential between said cathode and versal of the potential between said cathode and
said container for impressing upon said grid 21. said container for impressing a bias potential
20 negative bias potential.
upon each of said grid circuits whereby said non
4. In combination with an electric valve com
linear elements of said circuits present low re
prising a cathode, an anode, a grid for said sistance value to said circuits.
anode and a conductive member in contact with
the ionizable vapor of said apparatus, a circuit
element, and means responsive to a change of
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