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Патент USA US3046446

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July 24, 1962
Filed sept. e, 1960
United States Patent
Charles C. Cavalconte, Mineola, N.Y., assigner to Re
public Aviation Corporation, near Farmingdale, N.Y.,
a corporation of Delaware
Filed Sept. 6, 1960, Ser. No. 54,029
15 Claims. (Cl. 313-146)
This invention relates to electrical switches and, more
particularly, to a high current, high voltage switch, i.e.,
one capable of passing megampere currents at kilovolt
The present invention contemplates an improved switch
design predicated on ‘a novel operating concept whereby
large currents `and voltages are readily passed with an
attendant low erosion and wear to its parts.
Patented July 24, 1962
At the same
electrodes which are adapted to operate in a controlled
atmosphere, the switch being enclosed in a dielectric, gas
ñlled envelope sealed at low pressure.
iIn the preferred form of the invention, a selected,
constant potential is ‘applied to the coaxial conductors,
such potential being less than that required to bridge or
arc lthe gap between the switch electrodes. The gap is
normally maintained at a constant voltage breakdown
value by adjustment of the space between the electrodes
and the ygas or inert iluid pressure therein.
electrical means, including means to control its operation,
is provided to ionize the gas in the gap when desired to
support a current and thereby complete the circuit.
In any case, the coaxial design is employed to produce
when operative substantially coextensive currents of op
posite directions, each with an individual, >associated mag
netic field. The interaction of these magnetic iields in
time, the instant high voltage, high current switch is ca
pable of repeated operation with relatively no time delay
the »area of the gap produces a magnetic pressure on the
between successive switching operations.
current across the gap resulting in a phenomenon known
Moreover, the proposed switch ydesign allows for the 20 as “inverse pinch,” i.e., lateral movement of the currents
handling of a relatively wide range of current «and volt
outwardly from the conductors, ñrst assuming an arc
age values incorporating adjustable and contoured switch
or bow in the current formation lacross the gap which
electrodes whereby the length and path of the arc there
eventually ruptures to break the circuit.
across during operation may be pre-established to the end
'Phe iadjacent surfaces of the switch electrodes are con
.that predictable, conducting characteristics are obtainable. 25 toured in accordance with the particular application to
Such control of the arc finds particular utility in appli
establish »a predetermined current formation across the
cations where pulse-shaping of currents, i.e., accurate
control of the amplitude and phase of current discharges,
gap and movement thereof outwardly rat a prescribed rate
whereby its phase and amplitude are made to correspond
is important.
to Íthe requirements ofthe associated load. Additional
In prior switches capable of passing substantial cur 30 control refinements are accomplished by means of and
rents at high voltages, the Ádesigns have been such that
through adjustment means to locate the electrodes with
reliability of operation is adversely affected with 'the in
reference to each other and thereby determine the length
crease in the value of the currents and voltages handled
of the gap. Thus, by relating the plasma dynamics as
and the attendant heat generated thereby. Thus, several
determined by the particular gas employed tothe resulting
seconds’ elapsed time is required between switching oper 35 magnetic forces established by the electrode shape and
ations in these earlier `designs and they fail to meet the
spacing, ythe conducting characteristics of the high current,
requirements of many present day applications because
high voltage switch can be tailored to a given application'.
of their repetition rate.
For example, switches are cur
‘With the above and other objects in view, as will be
this invention consists in the construction, com
volt-age values approaching those `herein» contemplated, but 40 bination and arrangement of parts -all as hereinafter more
approximately one minute of elapsed time is prescribed
fully described, claimed and illustrated in the raccom
between each switching operation. Such switches are
panying drawings, wherein:
obviously useless in applications, for example in thermo
FIG. l is a transverse section taken through a switch
nuclear and magnetohydrodynamic devices, requiring
constructed in accordance with the teachings of this in
m-any distinct switching operations a second with currents 45 vention to show a preferred embodiment thereof, includ
in the order of, for example, 0.5 megampere and voltages
ing associated electrical control means `for its operation,
of 30 kilovolts.
connected in an illustrative high voltage, high current
The present invention is, among other things, directed
carrying circuit;
toward a switch that will meet the requirements set forth
FIG. 2 is a schematic exploded view of the inner and
above and to this end proposes a switch design predicated 50
outer conductors of the coaxial design illustrating the
on a novel concept by which a greater repetition rate is
current path of each and for purposes of analysis the
obtained at high current and voltage. Moreover, this
magnetic fields established thereby; and
proposed design lends itself to pulse-shaping of currents
FIG. 3 is a ldiagram symbolizing the individual current
and `a long life expectancy of its components.
rently available which adequately handle current and
The switch lherein proposed is founded on a triggered 55 direction of each conductor Iand Ithe summation forces
gap principle depending for its operation on the ionization
of the resulting magnetic iield directions illustrated in
of a gas in the gap and the creation of magnetic fields
which interact to control the current path through the
FIG. 2.
With particular reference to the drawings, 10 desig
switch. More specifically, the instant switch comprises
nates the present switch 'assembly ‘adapted to be con
coaxial conductors insulated lineally and interconnected 60 nected to, and control the current passing through, a cir
adjacent corresponding ends. One of these conductors is
cuit 11 connecting a power supply 12 to a loadY 13 re
interrupted in its length rto establish »a space or gap pre
quiring a large current »at high voltage. A battery of
venting a completed circuit. The terminals of the in
capacitors 14 is operatively connected to the power supply
terrupted conductor ydefini-ng this gap constitute the switch
12, being charged vthereby «and upon operation off the
switch 10 to effect large current discharges satisfying the
requirements of the load 13.
The switch assembly 10 comprises a pair of coaxial
conductors 15 and 16, the inner conductor 15 constituting
a rod the outer end of which is adapted to form one ter
minal by which the switch 10 is connected to the power
side of the circuit 11. The corresponding end of the
outer conductor 16 is adapted to form the other terminal
for connection of the switch y10 to the load side of the
circuit 11. Medially of its length the outer conductor 16
is interrupted, creating a gap 19 with the adjacent ends
of the conductor that define this gap constituting a pair
of coacting electrodes 17 and 18.
The inner conductor 15 is electrically connected to the
electrode 17, for example, being press fitted in a recess
provided in the center thereof and electrically insulated
from the electrode 18 by a wrapper 20 of dielectric ma
terial preferably one having good heat resistance proper
ties which overlies and encloses that portion of the inner
nected by a conductor 31 to the opposite ends of the high
voltage side of a step-up transformer 32. The low volt
age side of the transformer 32 is connected at its opposed
ends in a circuit 33 comprising a power source such as,
for example, battery 34 and a push button on-off switch
The operation of the assembly as above described is as
Constant power is available from the supply 12 and the
capacitors 14 to the inner conductor 15 and electrode 17
of the outer conductor 16. However, the rod 15 is ad»
justed lineally and secured in the adjusted position by
lock-nut 22 to establish the dimensions of gap 19 whereby
the circuit 11 through the outer conductor 16 to the load
`13 is interrupted. When it is desired to complete this
circuit, switch 35 is closed momentarily whereby a -rela
tively small current from battery 34 passes through the
circuit 33 including the primary of the transformer 32.
When the primary is thus energized, a sufficient voltage
conductor 15 adjacent the electrode 18 and across the L is induced in the secondary of transformer 32 to produce
gap 19.
The electrodes 17 and »18 are provided with coacting
adjacent surfaces 17a and 18a, respectively, that are gen
erally convex to locate the minimal distance point adja
cent the axial center of the gap 19. Adjacent its center,
surface 17a is additionally formed with a recess 17b
adapted to surround and thereby separate the rod 15 and
insulating wrapper 20 from the minimal distant point be
a current arc across the probes 28. The gases in the gap
19 are thereby ionized, causing a breakdown of this gap
whereby the voltage applied on electrode 17 of the outer
conductor 16 results in a current across the gap, complet
r ing the circuit to the load 13.
Referring momentarily to FIG. 2, it is seen that a cur
rent passing through the inner conductor 15 takes a path
in a direction I and establishes an associated magnetic
field B. On the other hand, a current passing between
tween the surfaces 17a and 18a. Thus, when a discharge
of current is effected, by means to be described, across 30 the electrodes 17 and 18 has a direction I' and an asso
the electrodes 17 and 18, this current and accompanying
heat is directed away from the wrapper 20 to prevent
the deterioration thereof.
The end of the electrode 18 remote from the gap 19
terminates in a threaded concentric projection 21 adapted
to receive a coacting nut 22, The nut 22 is pierced cen
trally by a hole through which the rod 15 passes and to
which it is secured against lineal movement by suitable
means such as a lock-ring and seal 23 of flexible material
ciated magnetic field B’. Since the current density ap~
` pearing on the inner conductor 15 is greater than that of
the outer conductor 16, the magnetic field B' is of less
magnitude than the field B. Moreover, these fields B and
f B’ due to the current direction in the conductors 15 and
16 are of opposite direction (FIG. 3). The natural inter
action of these opposed fields results in a radially out
ward magnetic pressure that forces the current in the gap
19 from an initial position substantially parallel to the
adapted to -be compressed against the end surface of the 40 axis of the conductors 15 and 16 to an arcuate or bowed
projection 21 and the surface of the wrapper 20 upon
Thus, the current l' passing between the surfaces 17a
tightening of the nut 22. Thus, the position of the -rod 15
may be adjusted in the electrode 18 and maintained in the
adjusted position, establishing the relative positions of the
electrode surfaces 17a and 18a and the length of the gap
19 accordingly.
and 17b 0f the electrodes 17 and 18 of the outer con
ductor 16 is not concentrated in any loaclized area but
distributed rapidly over the entire area of the electrode
surfaces by successive lines of current moving from a
point or points adjacent the axial center of the gap 19
Adjacent the projection 21 the electrode 18 is provided
outwardly. Normal electrode erosion is thereby held to
with a lateral flange 24, the peripheral surface of which
a minimum during operation of the gap switch.
engages and is suitably secured, as by press fit, to the
In addition, the frequency and amplitude of the current
inner marginal surface of an envelope or casing 2S which 50
discharge across gap 19 and to the load 13 as determined
encloses and houses the coaxial conductors 15 and 16.
by the current formation and bowing as described may
A removable and replaceable cover plate 25a closes this
be controlled by preselecting the areas and contours of
end of the envelope 25. The length of the ñange 24 is
the electrode surfaces which define the gap 19. Addi
such that the interior walls of the casing 25 are disposed in
tional control is obtained by precise adjustment of the
spaced relation to the conductors 15 and 16 and thereby
length of the gap 19, i.e., the spacing between the surfaces
Acreate a chamber 26 in which the conductors are concen
17a and 18a, by locating the position of the electrode 17
trically mounted. The envelope 25 including cover 25a
relative to electrode 18 through means 22. The size of
is fabricated of dielectric material and is provided with a
the envelope 25 is such that the width of the chamber
port adapted to receive and connect an inlet duct and
check valve 27 by `means of which an inert fluid such as 60 26 permits total bowing of the current across gap 19 and
ultimate rupture of the current lines prior to contact with
nitrogen, argon, etc., is admitted into and fills the cham
ber 26 where it is maintained at a selected low pressure.
the walls of the envelope 25. It may, therefore, be said
A pair of opposed conducting probes 28 are mounted
that the current discharge across the electrodes is uncon~
within the envelope 25 and terminate inwardly thereof
fined and controlled solely by the magnetic pressure or
in ends disposed within the gap 19 in spaced relation. 65 blow out effect produced by interaction of the current
The outer end of each probe 28 is secured in a recessed
fields as described.
bearing 30 of dielectric material, preferably one having
From repeated operations of switches constructed as
good heat resistance properties, forming a localized area
hereinabove described, it has been learned that current
of the wall of the envelope 25. The bearings 30 also
discharges across the electrodes 17 and 18 have had sub
serve as seals to prevent ñuid leakage from the chamber 70
stantially no deleterious effect upon the probes 28. Pre
26. O-rings 29 may be employed if desired for the same
purpose adjacent each opening in the envelope 25 through
which the duct 27 and conductors 15 and 16 are adapted
to pass.
The outer end of each probe 28 is appropriately con
sumably, this is explained by the fact that such discharges
are of short duration, i.e., less than 100 microseconds.
Moreover, no backup effect has been experienced in the
75 circuits 31 and 33 as a result of the current discharges
across the electrodes 17 and 18, since the circuit 3‘1 has a
high impedance relative to the circuit 11.
What is claimed is:
l. An electrical switch comprising coaxial conductors
insulated lineally from each other and electrically con
nected adjacent one of their ends and electrically uncon
nected adjacent their other ends, each being individually
connected at said other ends to opposite sides of a circuit,
a gap in the length of one of the conductors interrupting
electrodes, a power supply and a load, respectively, con
nected to the other ends of said conductors, and means
operative to discharge said power supply producing a dis
charge current across said electrodes completing la circuit
to said load whereby magnetic fields are created in said
gap to force the current therein in a radial `direction and
eventually breaking said circuit.
10. An electrical switch comprising a gas-filled enve
lope having individual, insulated terminals, a pair of in
current continuity, and control means operative to bridge 10 sulated coaxial conductors within said envelope connected
said gap whereby current continuity is established through
at one of their ends tto said terminals, respectively, means
the conductors.
2. A switch as recited in claim 1 including means to ad
just said gap.
3. An electrical switch comprising a pair of coaxial
conductors insulated lineally one from the other and elec
trically connected one to the other adjacent correspond
ing ends, individual -terminals adjacent the other corre
sponding ends of said conductors, a lead connecting each
of said terminals to a power supply and load, respectively,
a gap in the length of one of the conductors interrupting
current continuity, and means operative to bridge said
gap whereby said power supply is electrically connected
to said load.
4. An electrical switch comprising a pair of coaxial,
substantially coextensive conductors insulated one from the
establishing opposite current directions through the con;
ductors, means establishing a gap in one of said current
directions, a source of applied voltage constantly con
nected to one of said terminals and normaly inoperative
to pass a current across said gap, electrical means opera
tive in the gap to ionize gas therein and support a current,
and a control to render said electrical means 'operative
whereby current passes bet-Ween said terminals.
11. An electrical switch comprising `a duid-tight enve
lope, a pair of coaxial conductrs interconnected at corre
sponding ends and disposed within said envelope, a gap in
the length of `one of -said ‘conductors norm-aly operative to
interrupt current continuity therethrough, means con
nected to and forming a part of the envelope for iilling
and maintaining it including said gap with gas at a selected
other and electrically connected adjacent corresponding
pressure, and control means mounted in and opera-ble ex
ends, a gap in the length of One of the conductors inter
ter-nally of the envelope to ionize gas thereiniwhereby
rupting current continuity, means maintaining inert fluid
current Icontinuity is established 'across said gap and
in said gap at low pressure, and means operative on said 30 through the conductors.
ñuid to ionize it whereby current continuity is established
12. An electrical switch comp-rising a pair of coaxial
through said conductors.
conductors electrically interconnected adjacent one of
5. A switch comprising a pair of coaxial conductors
their ends and insulated lineally one Ifrom the other, a gap
electrically connected adjacent one of their ends and insu
i-n the length of the outer of said conductors deñned by ad
lated lineally, terminals at the other ends of said conduc
jacent, generally convex surfaces, means constantly con
tors, one said terminal ybeing connected to a power supply
necting a source of electric power -to the free end of the
and the other said terminal being connected to a load,
inner conductor, means connecting a load to the free end
a gap in the length of one of the conductors interrupting
of the outer conductor, the dimensions of the ygap being
current continuity, current discharging means operative in
such as to normally interrupt current continuity --front the
said gap to ionize iiuid therein, and control means for the 40 source to the load and establish a voltage diiferential
operation of said current discharging means whereby cur
across the gap, means to maintain a gas in the gap, and
rent continuity is established through the conductors from
electrical means operative to ionize -said gas thereby
the power supply to the load.
establishing current continuity yacross the gap.
6. A switch comprising a pair of coaxial conductors
13. An electrical switch comprising la lfluid-tight enve
electrically interconnected adjacent corresponding ends 45 lope, a pair of coaxial conductors mounted within said
and insulated one from the other substantially throughout
envelope, the inner of said conductors including a central
their length, a source of applied voltage connected to the
conductive rod disposed within and projecting externally
free end of one of said conductors, a load connected to
from the envelope and connected to a source «of electrical
the free end of the other of said conductors, a gap in
power, the end of said rod with-in the envelope being
the length of one of the conductors interrupting current 50 electrically connected to the corresponding end of the
continuity therethrough, means maintaining inert fluid
in said gap at pressure below that required to support a
current across the gap, and means operative on said iiuid
outer conductor, a pair of spaced coacting electrode ele
ments in the length of the outer conductor overlying and
surrounding the rod and creating a gap, electrical connec
tion means between the outer conductor and a load, and
to ionize it whereby said applied voltage results in a cur
rent discharge across said gap to said lo-ad.
55 means operable externally of the envelope to ionize fluid
7. An electrical switch comprising a pair of electrodes,
in the gap aforesaid whereby current continuity is estab
a gap between adjacent ends of said electrodes, means pro
lished across the gap between the electrode elements afore
ducing a discharge current between said electrode ends
and across said gap outwardly of the axial centerline
14. An electrical switch comprising a ñuid-tight enve
thereof, and a current of opposite direction to said dis 60 lope, a pair of insulated, coaxial conductors mounted
charge current adjacent said centerline, said current es
within said envelope, the inner of said conductors corn
tablishing a magnetic ñeld at right angles to said discharge
current forcing it radially outward of the gap.
8. An electrical switch comprising a pair of axially
prising a lineally adjustable, conductive rod disposed with
in and projecting externally from the envelope to connect
a source of electrical power, the end of said rod within the
aligned electrodes, a gap 'between said electrodes, lmeans 65 envelope being electrically connected to the outer con
producing a discharge current and an associated magnetic
ductor, the outer of said conductors including a pair of
ñeld across said electrodes outwardly of their centerline,
spaced, axially aligned, concentric electrode elements es
and a current of opposite direction to said discharge cur
tablishing a variable gap therebetween as determined by
rent adjacent said centerline establishing a magnetic iield
the adjusted position of the rod, an insulator between the
in opposition to the iirst magnetic ñeld whereby said cur
rod and said gap, an electrical connection between said
rent discharge is forced radially outward orf the ‘gap and
outer conductor and a load, an inert gas in the gap, and
eventually interrupted.
means to ionize said gas whereby current from the source
9. An electrical switch comprising coaxial conductors
is discharged across said gap and applied to the load.
interconnected at one of their ends, «a pair of electrodes in
15. An electrical switch comprising a fluid-tight enve
the length of one of said conductors, a gap between said 75 lope, a pair of insulated coaxial conductors mounted
within said envelope, the inner of said conductors com
prising a central conductive rod disposed within and pro
jecting externally from the envelope to connect a source
of electrical power, the end of said rod within the envelope
being electrically connected to the outer conductor, a pair
nally of -the envelope to ionize ñuid in the gap aforesaid
whereby current continuity is established across the gap
between the electrode elements whereby electrical power
from the source is applied to the load.
of coacting electrode elements in the length of said outer
References Cited in the fiile of this patent
conductor one connected to the rod and the other to the
envelope in spaced relation to the ñrst to create a gap, ad
justment means to regulate the length of the rod disposed
within the envelope whereby the length of said gap is 10
`established and current continuity through the conductors
is interrupted, electrical-connecting means between said
electrode element and a load, and means operable exter
Randall ______________ __ Sept. 9, 1924
Broluska _____________ _„ Dec. 9,
Lindenblad __________ __ Mar. 28,
Barnett _______________ __ Feb. 2,
Soulary ______________ __ June 2,
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