US3538388A - Voltage surge diverter - Google Patents

Voltage surge diverter Download PDF

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Publication number
US3538388A
US3538388A US762265A US3538388DA US3538388A US 3538388 A US3538388 A US 3538388A US 762265 A US762265 A US 762265A US 3538388D A US3538388D A US 3538388DA US 3538388 A US3538388 A US 3538388A
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United States
Prior art keywords
arrester
voltage
current
valve
extra
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Expired - Lifetime
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US762265A
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English (en)
Inventor
Stanley A Miske Jr
James S Kresge
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General Electric Co
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General Electric Co
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Publication date
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Publication of US3538388A publication Critical patent/US3538388A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T1/00—Details of spark gaps
    • H01T1/16—Series resistor structurally associated with spark gap

Definitions

  • This invention relates to voltage surge diverters and more particularly to improvements in valve type lightning arresters with a current limiting main spark gap or gaps.
  • a lightning arrester is a species of voltage surge diverter particularly adapted to divert lightning surges.
  • EHV extra high voltage
  • switching surges impose as severe, if not more severe, protective duty on lightning arresters as do lightning surges. Consequently, the term lightning arrester as used herein is not limited to a device for protecting against lightning surges only, but on the contrary is used practically synonymously with the generic term voltage surge diverter.
  • a valve type lightning arrester comprises essentially at least one valve resistor and at least on spark gap in series.
  • a valve resistor has a negative resistance-current characteristic which gives it a nonlinear volt-ampere characteristic.
  • a current limiting gap is a gap which after sparkover has a rising voltage which, in a time which is long in comparison with the time required for an ordinary impulse surge, such as lightning, to subside to half crest value, but which is short in comparison with the time required for an ordinary switching surge to subside to half crest value, attains a voltage value comparable to its sparkover voltage.
  • valve resistance is desirable to use less valve resistance with a current limiting gap than with a conventional or noncurrent limiting gap in order to limit the arrester voltage ⁇ during discharge, the latter voltage being the sum of the valve and gap voltages.
  • current limiting gap arresters in operation produce what in some applications are undesirably large voltage transients at the instant of sparkover.
  • Simply adding valve resistance is not a satisfactory way to reduce these transients because it produces an objectionable increase in arrester voltage or protective level during the discharge period.
  • time delay or slow shunting means for eXtra valve resistance, such shunting means being specitcally in the form of a special magnetic blow out gap with auxiliary insulated electrodes in the path of the blown out arc.
  • An object of the invention is to provide a new and improved voltage surge diverter.
  • Another object of the invention is to provide a new and improved means for reducing voltage transients produced by lightning arresters with current limiting gaps.
  • FIG. l is a schematic circuit diagram of an application of a presently preferred embodiment of the invenvention
  • y FIG. 2 is a set of arrester voltage versus time and a set of arrester current versus time curves or graphs for explaining the operation of the invention.
  • a high voltage direct current power system comprising a converter 1 which may be either a rectier or an inverter whose A-C side is connected to a conventional commercial frequency power system and whose D-C side is connected to a high voltage D-C transmission line 2.
  • the converter conventionally comprises a plurality of ionic valves and a transformer or transformers'having effective series reactance represented symbolically by the coil 3.
  • the line 2 also has a series smoothing reactor 4 and a socalled shunt damper circuit comprising a resistor 5 and a capacitor 6.
  • a lightning arrester 7 is connected across the D-C side of the converter.
  • the arrester 7 comprises parallel legs A and B and a common leg C.
  • the legs A and B each comprise a current limiting gap unit 8 and a valve resistor 9 in series, while the common leg C comprises a common valve resistor 10, an extra valve resistor 11 and an inductor or inductance coil 12 shunting the extra valve resistance 11.
  • FIGS 2a and 2b are respectively arrester voltage and arrester current curves plotted against the same horizontal time scale.
  • the curve 13 represents a voltage surge and shows a steeply rising arrester voltage with time.
  • the arrester voltage reaches the sparkover voltage of one of the gaps 8.
  • one of the gaps 8 will inherently have a slightly lower sparkover voltage than the other.
  • the gap 8 in leg A has the lower sparkover voltage so that it sparks over and discharge current starts to llow through leg A and common leg C of the arrester, this current being represented by the curve A in FIG. 2b.
  • VAR is the curve of the voltage of the entire arrester shown in FIG. l, i.e., the arrester with the extra valve resistor 11 and shunt inductor 12.
  • the above discussion describes the operation of the arrester in discharging surges originating in either the A-C or D-C systems wherein the surge currents are generally of rather long duration and are limited in magnitude by the impedance of the systems and the inductors 3 and 4.
  • the arrester can also be subjected to other surges such as perhaps a lightning discharge to the converter terminal.
  • the current available from such surges may be for greater than that available from system generated surges and the socalled IR or resistive voltage drop across the extra valve resistor 11 due to these high currents might cause the total arrester voltage to exceed the desired protective level even before the current limiting gaps have had suticient time to build a back voltage.
  • the extra valve resistor is not necessary to limit the transient voltage reduction and in fact it is undesirable because of the increased arrester voltage drop as explained above.
  • the arrester may be subjected to very high currents of short duration, to provide a voltage sensitive shunting gap in parallel with the extra valve resistor 11 and shunting coil 12.
  • the sparkover level of such a gap can be easily set so the extra valve resistor is shunted out during the discharge of fast high current surges but is left active in the circuit during the discharge of slower, limited current surges.
  • leg A or leg B may be omitted so that the arrester is a conventional current limiting arrester.
  • the ilip-tlop principle is an entirely separate invention which per se is disclaimed herein. Its general purpose is to increase the switching surge energy dissipating or absorbing capacity of an arrester by having two or more parallel gaps alternately carrying the discharge current so that they are prevented from overheating by having to carry the heavy discharge current continuously for too long a period of time.
  • the intermittent or ip-op operation permits each set of current limiting gap to cool while the other gaps are carrying the discharge current.
  • a valve type current limiting gap lightning arrester having at least one current limiting sparkgap electrically connected in series with at least one valve resistance, extra series valve resistance electrically connected in series with said at least one valve resistance, and inductive means connected in shunting relationship with said extra valve resistance, whereby said arrester is adapted for protecting serially connected electronic valve converters in high voltage direct current power systems, said extra valve resistance being operable when the arrester is connected to protect such a system to prevent the development of an undesirably high arrester voltage transient while discharging over-voltage surges from the protected system through the arrester, and said inductive means having an ohmic Value, substantially higher than said extra valve resistance at frequencies corresponding to the front of an over-voltage surge and substantially lower than said extra valve resistance at frequencies corresponding to the main portion of an over-voltage surge, thereby to cause the main portion of an over-voltage surge current to be discharged through said inductive means and to force an initial portion of an over-voltage surge current to be discharged primarily through said extra valve
  • a lightning arrester having a current limiting gap electrically connected in series with a Valve resistor to form an over-voltage discharge circuit
  • the improvement comprising means for substantially reducing the voltage level of said arrester below a level that would normally be developed by said lightning arrester when operated without said means during a predetermined interval when an overvoltage surge current is initially discharged through said gap and While the gap voltage is increasing, said means being operatively connected in series with said gap and said series valve resistor.
  • said means comprises an extra valve resistor electrically connected in series with said discharge circuit, and inductive means electrically connected in shunt relation with said extra valve resistor said means being found operable to increase the Voltage level of said arrester above a level that would normally be developed by said arrester during a predetermined portion of the terminating end of an over-voltage surge discharged through the arrester.

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  • Emergency Protection Circuit Devices (AREA)
  • Thermistors And Varistors (AREA)
US762265A 1968-09-16 1968-09-16 Voltage surge diverter Expired - Lifetime US3538388A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US76226568A 1968-09-16 1968-09-16

Publications (1)

Publication Number Publication Date
US3538388A true US3538388A (en) 1970-11-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
US762265A Expired - Lifetime US3538388A (en) 1968-09-16 1968-09-16 Voltage surge diverter

Country Status (6)

Country Link
US (1) US3538388A (fr)
JP (1) JPS5440734B1 (fr)
CH (1) CH505488A (fr)
DE (1) DE1944817B2 (fr)
GB (1) GB1274888A (fr)
SE (1) SE369991B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070223171A1 (en) * 2003-12-30 2007-09-27 Lafon Guy Protector Device with Improved Capacity to Break Follow Current

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3019367A (en) * 1957-01-04 1962-01-30 Ohio Brass Co Lighting arrester and gap unit therefor
US3320482A (en) * 1964-06-02 1967-05-16 Gen Electric Lightning arrester for high energy switching surges
US3348100A (en) * 1965-03-22 1967-10-17 Gen Electric Sparkover control circuit for lightning arrester shunt gap unit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3019367A (en) * 1957-01-04 1962-01-30 Ohio Brass Co Lighting arrester and gap unit therefor
US3320482A (en) * 1964-06-02 1967-05-16 Gen Electric Lightning arrester for high energy switching surges
US3348100A (en) * 1965-03-22 1967-10-17 Gen Electric Sparkover control circuit for lightning arrester shunt gap unit

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070223171A1 (en) * 2003-12-30 2007-09-27 Lafon Guy Protector Device with Improved Capacity to Break Follow Current

Also Published As

Publication number Publication date
DE1944817C3 (fr) 1975-04-10
CH505488A (de) 1971-03-31
DE1944817B2 (de) 1972-12-14
DE1944817A1 (de) 1970-03-26
JPS5440734B1 (fr) 1979-12-05
SE369991B (fr) 1974-09-23
GB1274888A (en) 1972-05-17

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