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Publication numberUS3733520 A
Publication typeGrant
Publication dateMay 15, 1973
Filing dateApr 28, 1972
Priority dateMay 3, 1971
Also published asCA986574A, CA986574A1, DE2218962A1
Publication numberUS 3733520 A, US 3733520A, US-A-3733520, US3733520 A, US3733520A
InventorsA Schei
Original AssigneeAsea Ab
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Means for limiting the residual level during superimposed over-voltage conditions in a surge diverter
US 3733520 A
Abstract
In a surge diverter, in order to limit the residual level during superimposed over-voltage conditions, a plurality of spark gap stacks with associated non-linear resistors are provided with a shunt spark gap shunting at least one spark gap stack with the associated non-linear resistor. A shunt impedance is provided shunting at least one spark gap stack which is shunted by the shunt spark gap. The surge diverter includes a sufficient number of shunt gaps to prevent the total voltage over the diverter upon super-imposed over-voltage conditions from exceeding the protection level of the diverter.
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ilnited States Patent 1191 Schei 1 May 15, 1973 [54] MEANS FOR LIMITING THE [56] References Cited RESIDUAL LEVEL DURING UNITED STATES PATENTS SUPERIMPOSED OVER-VOLTAGE 3,489,949 1/1970 Carpenter ..3I7/69 X CONDITIONS IN A SURGE DIVERTER 3,673,459 6/1972 Carpenter ..3l5/36 3,348,100 10/1967 Kres e l ..3l7/70 [75] Invent Asle sch", Ludvlka, Sweden 3,414,759 12/1968 Conn ell et a1. ....317 70 x Assignee: Aumanna Svenska Elektriska 3,413,524 11/1968 Tram ..3]7/69 tlebolaget Vasteras Sweden Primary ExaminerC. L. Albritton [22] Filed: Apr. 28, 1972 Attorney-Jennings Bailey, Jr. [21] App]. No.: 248,601 ABSTRACT In a surge diverter, in order to limit the residual level [30] Foreign Application Priority Data during superimposed over-voltage conditions, a plurality of spark gap stacks with associated non-linear May 3, 1971 Sweden ..5673/71 resistors are provided with a Shunt spark p shunting at least one spark gap stack with the associated non- CL 317/70, linear resistor. A shunt impedance is provided shunt- 338/2] ing at least one spark gap stack which is shunted by [51] Int. Cl. ..H02h l/00 the shunt spark gap. The surge diverter includes a suf- [58] Field of Search ..338/2l, 13, 20; ficient number of shunt gaps to prevent the total voltage over the diverter upon super-imposed over-voltage conditions from exceeding the protection level of the diverter.

4 Claims, 7 Drawing Figures I MEANS FOR LIMITING THE RESIDUAL LEVEL DURING SUPERIMPOSED OVER-VOLTAGE CONDITIONS IN A SURGE DIVERTER BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a means for limiting the residual level during super-imposed over-voltage conditions in a surge diverter.

2. The Prior Art A surge diverter in an electric power line may under certain conditions during the extinguishing interval of the diverter be subjected to superimposed overvoltages or over-voltages superimposed on the operating voltage. Such conditions are most likely to appear in equipment for high voltage direct current and may occur when different diverters in the equipment ignite at different moments. An example of this is when a diverter for a converter-rectifier sparks-over while a phase-earth diverter discharges a connection overvoltage from the AC side. The phase-earth diverter is then connected to the DC line over the diverter of the converter-rectifier, thus causing a current increase in the phase-earth diverter. At the moment when the diverter over the converter-rectifier is ignited, the phaseearth diverter may very well operate with arcs extended by a magnetic field and under such conditions normal diverters do not give sufficient protection.

SUMMARY OF THE INVENTION The present invention relates to a means for surge diverters, preferably in equipment for high voltage direct current, to limit the residual level during superimposed over-voltage conditions.

According to the invention, in a surge diverter, in order to limit the residual level during super-imposed over-voltage conditions, a plurality of spark gap stacks with associated non-linear resistors are provided with a shunt spark gap shunting at least one spark gap stack with the associated nonlinear resistor. A shunt impedance is provided shunting at least one spark gap stack which is shunted by the shunt spark gap. The surge diverter includes a sufficient number of shunt gaps to prevent the total voltage over the diverter upon superimposed over-voltage conditions from exceeding the protection level of the diverter.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings FIGS. 1, 2 and 3 show three different embodiments of the invention and FIG. 4 shows the total discharge current through the surge diverter as a function of the time;

FIGS. 5 and 6 show the voltage over the non-linear valve-resistors and the voltage over the spark gap in a phase-earth diverter, for example;

FIG. 7 shows the total voltage over the diverter as a function of the time. The four latter figures show the conditions during super-imposed over-voltage conditrons.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A surge diverter according to FIGS. 1, 2, and 3 comprises a number of spark gap stacks 1 alternating with non-linear valve-resistors 2. Parallel therewith is a control chain with control impedances 3. The figures only show part of a diverter.

In order for the diverter to be able to protect even under the conditions mentioned during super-imposed over-voltages, it is now proposed that a number of gapplus-block units are shunted with an extra spark gap, shunt gap,4. FIG. 1 shows two gap stacks and a resistor being shunted, whereas FIG. 2 shows the case in which the shunt gap bridges a gap stack and a resistor. In FIG. 3 the valve-resistor 2 is a part of the control chain. Other combinations are of course also possible. In view of the ability of the diverter to limit the ensuing current it is advisable to use gaps with magnetic blowing for the shunt gaps as well. In the examples shown in FIGS. 1 and 3 it is preferable to shunt one of the spark gap stacks l shunted by the spark gap 4, with a shunt impedanceS. The spark-over voltage of the shunt gap 4 is chosen so high that it does not fire during normal over-voltages but only when such superimposed overvoltages occur as might jeopardize the protective capacity of the diverter. The number of shunts necessary for a certain diverter may vary from time to time and can be determined so that the diverter can ensure the necessary protection level.

FIG. 4 shows the current as a function of the time in a phase-earth diverter,for example. At the time t 0 the phase-earth diverter sparks-over and the current increases to its maximum value, after which it decreases in the normal manner. At the time 2,, however, a converter-rectifier diverter sparks-over so that the DC line is connected to earth over the two diverters in series, the current increasing almost instantaneously to a high value and then decreasing.

FIG. 5 shows the corresponding sequence for the voltage U,, over the resistance block in the first sparked-over phase-earth diverter. At the time t, a voltage peak appears. In the same way, FIG. 6 shows the voltage over the gap stacks. From a low value immediately after the gaps have sparked-over the gap voltage increases as the arcs are extended because of the magnetic blowing. However, here also a strong voltage peak occurs at the time t when the second diverter sparks-over.

FIG. 7 shows the voltage U,, over the phase-earth diverter, this voltage being U,, U

In the last three figures the protection level U of the diverter is indicated by a broken line and from FIG. 7 it is clear that the total voltage over the diverter exceeds its protection level, so that the diverter is not capable of protecting the equipment.

If according to the invention some of the spark gaps and valve-resistor blocks are shunted with extra gaps, this means that part of the voltage peak occuring at the time t in FIGS. 5 and 6 can be removed. The number of shunt gaps is chosen so that the voltage peak at t shown in FIG. 7 is kept under the line U,,.

I claim:

1. In a surge diverter, means to limit the residual level during superimposed over-voltage conditions, said means comprising a plurality of spark gap stacks (1) with associated serially connected non-linear resistors, and a shunt spark gap shunting at least one spark gap stack (1) with the associated non-linear resistor (2).

2. In a device according to claim 1, said shunt spark gap shunting two spark gap stacks (1) having a nonlinear resistor (2) connected therebetween.

3,733,520 3 4 3. In a device according to claim 1, having a shunt vent total voltage (U over the diverter upon superimpedance (5) shunting at least one Spark gap Smck imposed over-voltage conditions from exceeding the (1) which is shunted by the shunt spark gap.

4. In a device according to claim 1, the surge diverter includes a sufficient number of shunt gaps (4) to pre- 5 protection level (U,,) of the diverter.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3348100 *Mar 22, 1965Oct 17, 1967Gen ElectricSparkover control circuit for lightning arrester shunt gap unit
US3413524 *Jul 13, 1965Nov 26, 1968English Electric Co LtdApparatus for providing a protective spark gap for a d.c. powerline
US3414759 *Dec 1, 1966Dec 3, 1968Ohio Brass CoSpark gap unit for lightning arresters
US3489949 *Nov 13, 1967Jan 13, 1970Gen ElectricLightning arrester with main and preionizing gaps
US3673459 *Nov 18, 1970Jun 27, 1972Gen ElectricTwo-wire preionizer for surge voltage arresters
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4029997 *Dec 9, 1974Jun 14, 1977Siemens AktiengesellschaftSurge voltage arrester arrangement
US4174530 *Jan 20, 1978Nov 13, 1979General Electric CompanyVoltage surge arrester device
US4472754 *Jul 16, 1982Sep 18, 1984Hitachi, Ltd.Surge arrester with a bypass gap
US7697252Aug 15, 2007Apr 13, 2010Leviton Manufacturing Company, Inc.Overvoltage device with enhanced surge suppression
US7907371Jan 14, 2008Mar 15, 2011Leviton Manufacturing Company, Inc.Circuit interrupting device with reset lockout and reverse wiring protection and method of manufacture
US8054595Nov 10, 2009Nov 8, 2011Leviton Manufacturing Co., Inc.Circuit interrupting device with reset lockout
US8130480Jul 28, 2011Mar 6, 2012Leviton Manufactuing Co., Inc.Circuit interrupting device with reset lockout
US8599522Jul 29, 2011Dec 3, 2013Leviton Manufacturing Co., Inc.Circuit interrupter with improved surge suppression
US20090046406 *Aug 15, 2007Feb 19, 2009Leviton Manufacturing Company Inc.Overvoltage device with enhanced surge suppression
Classifications
U.S. Classification361/130, 338/21, 315/36
International ClassificationH02H9/06, H02H3/22, H01T4/16
Cooperative ClassificationH02H3/22, H01T4/16, H02H9/06
European ClassificationH01T4/16, H02H9/06, H02H3/22