Document 6604971

Jan. 15, 1963
A RODEWALD
3,073,973
CIRCUIT ARRANGEMENTS FOR THE DAMPING OF EXCESS
VOLTAGES IN SHOCK POTENTIAL GENERATORS
Filed July 5, 1960
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ARNOLD RODEVALD
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United grates Fatent Q17 c.Md
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3,073,973
CIRCUHT ARRANGEMENTFJ FQR THE DAMkiNG
(EF EXCESS VULTAGE§ EN SHG'CK PCTENTEAL
GENERATCRS
3,573,973
Patented Jan. 15, 1953
2
The assumed concentration of the stray capacity at K
between the points 2. and 3 is arbitrary; it could for ex
ample be assumed as on the ground side of the condensers
C, between the points 5 and 4.
If now the potential across the switch spark gap F col
Arnold Rodewald, Basel, dwitzerland, assignor to
FiledEmil
July Haeieiy
S, 196%, &Ser.
CieNo. 49,354
Claims priority, application Switzerland Mar. 4, H60
7 Claims. (Cl. 3tl7—-l.l.ti)
lapses during the striking operation of the generator, the
stray capacity K is charged up to the voltage U, through
and then suddenly connected in series through spark gaps.
essary for the production of a standard wave form,
The sum of the component voltages then produces the
actual impulse potential. As the voltage in relation to
an oscillatory charging of the stray capacity K takes
place. The maximum value of the oscillation ampli
the internal series resistance R1, because the impulse con~
densers C possess a very much greater capacitance than
10 the stray capacity K. The internal series resistance R;,
Shock or impulse electrical generators for high voltages
the impulse condensers C and also the current loop each
are mostly constructed nowadays according to the voltage
contain inductance, which can be assumed to be combined
multiplier circuit arrangement proposed by Marx. The
in the inductance L. On account of the presence of this
characteristic feature of this circuit arrangement is that a
inductance, the small magnitude of the stray capacitance
plurality of condensers are charged up to a speci?c voltage 15 and the relatively small internal series resistance nec
ground increases along the series-connected condensers,
tude amounts to nearly 2U (see curve a in FIG. 2).
it is an obvious measure in the constructional design of 20 The insulation distance between two generator stages is
the circuit arrangement to arrange the individual capaci
tors vertically one above the other circuit elemets for the
thus subjected not only to the voltage U, but to the much
higher voltage 111. Similar conditions occur in the strik
production of the wave form.
ing of the other switch spark gaps between the other stages
For various reasons it is advantageous to keep this con
of the generator. The possibility of damping this oscilla
struction as compact as possible, especially in installations 25 tion by increasing the internal series resistance is not re
for the production of high voltages of great power.
sorted to because, as already indicated above, it is not
Primarily the height of the impulse generator has been
feasible to produce a standard voltage wave with the gen
dependent upon the height of the high tension test cham
erator.
ber. Therefore, for constructional reasons, great impor
in accordance with the present invention, the excess
tance is attached to a shock installation which is as 30 oscillation is reduced by connecting additional condensers
low as possible. Furthermore certain considerations exist
K1 in parallel with the stray capacity K, for with pre
regarding the form of the voltage wave emitted by the
determined ?xed inductance and ?xed resistance it is pos
impulse generator, according to which considerations the
sible to make the periodic transient phenomenon in a
high frequency oscillations, which may be superimposed
series oscillation circuit aperiodic by increasing the capaci
upon the voltage wave should not exceed certain limits. 35 tance. Curve b in FIG. 2 shows the voltage characteristic
This means that the total inductance of the discharge
between the generator stages, as damped by the condensers
circuit must be kept as low as possible, which is equivalent
K1, the insulation being therefore only subjected to volt
to the requirement for a small spatial extent of the high
age U.
tension installation.
it is usual in the operation of an impulse generator to
In the operation of an impulse generator excess voltages
use a so-called basic loading in the form of a separate
of considerable magnitude occur between the individual
external capacitance. Thus it is possible to produce a
stages. On account of these excess voltages, the insula
standard Wave form even when the generator is idle or
tion distances must be made greater than would be neces
when testing objects with a very small capacitance. As
sary for the production of the actual shock voltage wave.
a result of the additional condensers distributed in ac
In accordance with the invention these excess voltages
cordance with the invention along the entire impulse gen
can be reduced by the provision of additional condensers
erator for the reduction of the excess voltages, this ex
in parallel with the stray capacities between the generator
ternal basic loading now becomes entirely or partially
stages necessitated by the construction.
super?ous, since these condensers similarly present a load
An example of embodiment of the invention is herein
for the generator.
after described with reference to the accompanying draw 50
Whatl claim is:
ing, in which:
_
1. An impulse generator comprising a plurality of
FIG. 1 is a diagram of a three-stage impulse generator,
vertically superimposed stages connected in cascade, each
and
stage comprising in combination, a damping resistor, an
‘FIG. 2 is a voltage diagram.
impulse capacitor and a spark gap in series connection
Each stage of the impulse generator according to FIG.
and having inherent inductance, an additional resistor
1 comprises an impulse condenser C, a spark gap F, a
bridging said spark gap and said damping resistor, an elec
damping resistance R1, a parallel resistance RD and ?nally
trical conductor connected intermediate said capacitor and
a certain inductance L.
Charging resistance RL are
said spark gap and leading to a terminal for connection
provided between the individual stages for charging the
to one pole of a direct current voltage source, directly
generator. K represents stray capacity between the gen 60 in the case of the ?rst stage and via a charging resistor
erator stages. The external shock circuit is formed by the
in the case of subsequent stages, an electrical conductor
damping resistance Rd and a loading capacitance CB.
leading from the damping resistor of the ?rst stage to the
A voltage divider RM is connected in parallel with this
other pole of said direct current voltage source, said im
loading capacitance. K1 are additional condensers pro
pulse generator having stray capacitance between stages
vided for damping the excess voltages.
forming with said inherent inductance a series oscillation
After the charging of the impulse condensers C with
circuit capable of building up excess transient voltages of
the direct current voltage U, the points 2 and 3 in FIG. 1,
considerable magnitude between said superimposed stages,
which are situated in spaced relation one above the other
and additional capacitance provided in parallel with said
respectively in the ?rst and second generator stages,
stray capacitance to reduce said excess voltages.
possess the same potential. The voltage U can be meas
2. An impulse generator according to claim 1, wherein
ured from both points to ground. The stray capacity K 70
said additional capacitance is connected between two con
between the two generator stages is thus free from charge.
3,073,973
3
secutive stages intermediate the spark gaps and the impulse
condensers.
3. An impulse generator according to claim 1, wherein
said additional capacitance is connected between two con
secutive stages intermediate the damping resistance and
the impulse condensers.
‘it. A multi-stage impulse generator, each stage com
additional capacitances server as part of the basic loading
for said generator.
6. An impulse generator comprising a plurality of
stages connected in cascade, each stage comprising, in
combination, a damping resistor, an impulse capacitor
and a spark gap in series connection and having inherent
inductance, means for applying a DC. potential to said
stages in parallel with each other to charge the capacitors
prising a damping resistance, an impulse condenser and
thereof, said impulse generator having stray capacitance
a spark gap in series connection and having inherent in
ductance, an electrical conductor connected intermediate 10 between stages and forming, with said inherent inductance,
a series oscillation circuit capable of building up, between
said condenser and said spark gap and leading to a ter~
stages, transient voltages of a value substantially in excess
minal for connection to one pole of a direct current volt
of said potentional, said transient voltages having a peri
age source, an electrical conductor leading from said
odic characteristic, and additional capacitance provided
damping resistance to the other pole of said direct current
voltage source, said impulse generator having stray capaci 15 between the stages in parallel with said stray capacitance
tance between stages of markedly lower magnitude than
that of said impulse condensers and forming with said
to render said transient characteristic aperiodic.
7. A multi-stage impulse generator as claimed in claim
inhertent inductance a series oscillation circuit having a
6, in which said additional capacitance provides the basic
loading for the impulse generator.
periodic transient characteristic, and additional capaci
tance provided between each stage to damp out the oscila
latory charging of said stray capacitance.
References (Cited in the ?le of this patent
5. An impulse generator according to claim 1, wherein
the output of the generator is connected via a damping
UNITED STATES PATENTS
resistance to a loading capacitor and a voltage divider
1,997,064
Lusignan ____________ __ Apr. 9, 1935
connected in parallel with one another, and wherein said 25
2,064,630
Rorden ______________ __ Dec. 15, 1936,