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Патент USA US3093782

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June 11, 1963
Filed May 2, 1958
|_ ~_
United States Patent 0
Fatented June 11, 1963
Alan David Miller, Wigan, England, assignor to Asso
ciated Electrical Industries (Manchester) Limited, a
British company
The invention will be better understood from the ac
companying drawing, in which:
FIG. 1 shows by way of example a preferred embodi
ment of a surge diverter according to the invention; and
FIG. 2 shows graphs explaining its operation.
Referring to FIG. 1 the circuit to be protected, such as
a high voltage transmission line 1, is connected to earth
through a spark gap arrangement 2 and a non-linear
resistance, conventionally formed by a stack of series
This invention relates to surge diverter devices and 10 connected discs of non-linear resistance material the
aims at providing an improved arrangement suitable to
ohmic value of which decreases as the current flowing
overcome di?iculties which have been experienced up to
through it increases as known in the art. In the present
now with conventional protecting devices where electric
case this resistance is shown as comprising two sections
apparatus and machinery, particularly of the A.C. kind,
3, 4. According to the invention a vacuum circuit
have to be safeguarded against the destructive effect of
breaker 5 of known construction is connected in series
Filed May 2, 1958, Ser. No. 732,529
Claims priority, application Great Britain May 9, 1957
2 Claims. (til. 317-75)
voltage and current surges. The new device ensures
circuit relationship, preferably between the two resist
rapid current interruption at commercial frequency which
ance sections, 3, 4 and its energising coil 6 is connected
safely prevents “follow” ‘current, ‘and permits to derive
in parallel to the resistance section 4.
the full advantage of a close tolerance setting of the spark
In FIG. 2 the A.C. voltage wave on the transmission
gaps. Thus greater safety and reliability of operation at 20 line is denoted a, and the current wave ?owing through
a predetermined voltage can be ensured, which in turn
makes it possible to achieve savings in space, material
and costs, as the dielectric strength of the insulation used
in the circuit to be protected, such as machinery, appa
the surge diverter is denoted b. When surge occurs the
value of this current rises to a peak 0. After the surge
the shape of the current Wave b becomes similar to that
of a as shown by the graph. Now the follow current is
ratus distribution lines and so on can be more closely 25
de?nitely and safely interrupted by the breaker 5 at the
This is achieved by a vacuum switch arranged in series
?rst or second zero point e, or f of the wave b.
it will be understood that details of the arrangement
shown can be varied without departing from this inven
linear resistance, the switch opening means including a
tion as de?ned by the appended claims. For instance
coil which is connected in parallel to a portion at least 30 the non-linear resistance need not be sub-divided, and
of said resistance. As the ohmic effect of the resistance
if it is subdivided the ener-gising coil of the vacuum cir
decreases with current increase, the operating coil is safe
cuit breaker could be connected across the section 3 in
circuit relationship with at least one spark gap, and a non
guarded against damage by surges, and this enhances the
reliability of operation.
More especially the invention provides a means for 35
safe and reliable interruption of the “follow current” by
using in conjunction with a spark gap means a circuit
stead of across section 4 shown in FIG. 1.
What I claim is:
1. A surge diverter comprising for connection between
an A.C. circuit and earth, a series arrangement of at least
two switch contacts, at least one spark gap, and a non
breaker of the rapid action vacuum type and has its op
erating coil energised with a voltage which cannot rise
linear resistance whose ohmic value decreases as the cur
rent traversing it increases, means providing a vacuum
to a value dangerous to the coil insulation even if the 40 space in which said contacts are mounted, and means
current ?owing through the spark gap rises to an exces
for effecting switch opening comprising an operating coil,
sive value. Thus the operation of the surge diverter is
said coil being connected parallel to a portion at least
made more effective and more reliable than could be
of said resistance.
achieved with constructions known and used up ‘to now,
2. A device as claimed in claim 1, wherein the con
while the new device is also economical and space saving. 45 tacts of the vacuum switch are connected between two
Accordingly, the present invention resides in the pro
vision of a surge diverter comprising in series circuit rela
tionship at least one sparking gap, a resistance, and con
tacts of a circuit breaker wherein the circuit breaker is of
the vacuum type and wherein the energizing coil of the 50
circuit breaker is connected in parallel to a resistance
which has a non-linear, decreasing ohmic value with cur
rent increase so as to limit the voltage applied to the
operating coil of the circuit breaker.
In a preferred embodiment the energising coil of the 55
circuit breaker is connected in parallel to a portion only
of the non-linear resistance.
portions of the non-linear resistance.
References Cited in the ?le of this patent
Jones _______________ __ Jan. 30,
Vatter ______________ .._ June 30,
‘Greenwood __________ __. June 30,
Jennings _____________ .. Jan. 5,
Switzerland __________ __ July 17, 1933
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