US1531971A - Protective device - Google Patents

Description

L F. w. PEEK .5R v

PROTECTIVE DEVICE mmh 31. 1925.'

Filed Mai' 20 191,8

Figa.

`rasata Masai, 1925.

.UNITED STATES' RMENTA OFFICE.

ELECTRIC COMPANY, CORIOATION OF NEW YORK.

. PROTECTIVE 'nnvrcla applicati@ med nay 2o, 191s; serial no. 235,451."

i Tand other over-vo tage phenomena.

The object of my invention is to provide a device which v1s operative to relieve a conductor from excessive voltage conditions caused'. by transients, surges and' vsimilar phenomena land more specifically to provide a'spark gap device for use iii outdoor service the discharge of which can'be controlled by its dry arc-over voltage setting, which has substantially no time delay between the' application of ard-over voltage and the discharge` across the device andwhich is, in general, an improvement on similar devices heretofore knownv in the art.

It is well known, as described in nited.

States LettersPatent 1,232,467, granted to me that a spark gap devicej comprising two cooperating electrodes' having their weather by a protectinghood or.umbrella. 55

memberV and controlling ythe discharge -o the, device, and the other unprotected gaps. In order. to eliminate any time delay between the discharge of the series gaps, I

provide means whereby both said gapsarc- G0 over practically simultaneously. I also have embod1ed`1n my device means for, simultaneously-extinguishing the arcs formed across the gapsbefore the dynamic current can followv the discharge an\d \have, rovided f improvements-in other details 4t at will,

be hereinafter set forth. Thenovel features which 'I believe to be characteristic of'vmy invention will be definitely indicated in4 the v'claims appended' 7a hereto, `while the features of construction and method of operation will be understood' by reference to theaccompanying drawings in w uch:

v Fig. 1 is' a diagrammatic view of a ro- 75 tective device embodying the features o my invention; Figs. 2, 3, 4:, 5 and Bare diagrammatic views showing modied forms of my invention.

In Fig. "1, is shown a protective device 9 9 comprising a discharge path having, for

purposes of illustration, .two spark gaps, 1j

and 2 arranged in'series. Asshown in this figure, gap 1 consists of two cooperating roximal surfaces .spherical and separated 'electrodes' 3 and 4 having their proximal 85 y a certain distance relative to theradius of the spheres, forms a device in which there fsurfaces spherical and gap 2r consists of two similar electrodes 5 and 6, butt is underis no appreciable time delay between the stood that the two pairs of cooperating\ a plication of arc-over voltage and the c lis-vv electrodes .maybe any surface of revolution. "f c arge across the gap, and 11n :which the im- One ot the series gaps, for instance, gap 1, 9o

jelectrodes acts to lower the' arc-over voltage u ccording to my invention, I provide a spark gap device of `the generic type described, which isladapted for outdoor service and which comprises a discharge path having a plurality of spark gaps in series, atleast one gapbeing protected from the is shieldedjrom the weather by a protecting hood or umbrella member?, preferably of conducting material, which surrounds or,

partiallyv incloses the-electrodes 3 and 4.-

.The umbrella member .7 is adapted to be 95 connected to the conductor to be protected and is also inconductive relation with one of the electrodes of gap 1, electrode 3 for instance. ,'Gap 2, 'which is in .series with gap 1, is unprotected from the weather, 100

electrode 5 of gap 2 being in conductive relation with electrode 4 of gap 1. As

shown in Fig. 1 the unprotected gap 2 is l mounted adjacent the lower end or edge of the umbrella 7 for the purpose to be speci- 1W" fied.v By providing a discharge path having two spark gaps in series, I am able to pro-` tect one `gap from the .weather and utilize than the protected gap. ln practice the unprotected gap may, for instance, he set at- 20% of the protected gap. Then if the total dry spark-over is 10() plus 20, or 100 kv.

on vthel protected gap.y and 2O kv. on the unprotected gap, a reduction in spark-over on the unprotected gap of 25% or 5 kv., due to rain, ete. reduces the total spark-over to 115 kv., or only about 4%. Iffthe total gap had heen exposed the total reduction would have been about 25%, making it necessary to set the total gap at a much higher value of dry spark-over voltage.

In order to extinguish the arcs 'formed across gaps 1 and 2 when a dischargeloccurs,

I provide a means cooperating lwith the unwith great rapidity.

protected gap 2 for taking the arc occurring across the unprotected gap in such a manner as vto short circuit both the series gaps 1 and 2 and then extinguish the are so taken For this purpose, l provide a discharge path in shunt to the pathineluding the series gaps 1 and 2 and in which is included a horn gap 8 which is `so related to the unprotected gap 2 that 35. any are occurring across the electrodes 5 and 6 of gap 2 is taken or transferred to the horn gap rising on the horns untilv it is extinguished by attenuation. In order to maintain the horn gap action, I may utilize, as shown in Fig. 1, the contour of the umbrella member 7 to forni one `electrode of the horn gap 8 and cooperating with the umbrella is an arcing horn member 9. The electrodes 5 and 6, of the unprotected gap,

are located in close proximity to the unibrella 7 and horn member 9 respective-ly so that any are occurring across the elec trodes is transferred to the horn gap.

The horn member 9 and electrode G of gap 2 are connected to ground through a device which serves to extinguish the are .which follows the discharge across the horn gap 8, such a device being shown, by way of illustration, as an velectrolytic cell 10. As the umbrella electrode 7 is connected to the conductorto be protected and the horn member 9 is connected to ground, the ypath to ground through horn gap-8 comprises a discharge path which is in shunt 'to the discharge path ineludin the gaps 1 and 2, in series. Due to tlie construction of ,the gaps 1 and 2,:.lsuch ga shave no appreciable time lagvwhile tlie horn gap 8 has an appreciable time delay so that excessive potentials will'pass-to ground over the path including the series gaps 1 and 2 in preference lo the path including the horn gap tv', the discharge being lin'ally trans- Vferr-ed to the horn gap where 1t is extinguished. As soonv as the discharge across the unprotected gap 2 is transferred to the horn gap tl, the path including gaps 1 and 2 is short circuited and the arcs across such `gaps 'are quickly extinguished. The shunt path is then subsequently interrupted by the extinguishment of the arc due to the horn gap 8.

lVith a discharge path including two gaps in series, one protected and the other unprotected, the complete discharge of the gaps is controlled by the dry arc-over setting oi the protected gap but in a discharge path including at least two gaps in series whether either or said gaps are protected or unprotected from the weather, unless some provision is made to cause a practically simultaneous arc-over of both series gaps or a complete discharge over the ath, a time delay will occur between the recharge of one gap and the discharge or the other gap which is detrimental' to the ecient operation of the device. -If gap 1, for instance, breaks down first then the discharge path includes gap '2 in series with the resistance of thebroken down gap 1 which introduces a time delay before lga 2' arcs over. In order to overcome this disadvantage provide a means for causing two or more gaps, such as gaps l and 2, to arc-over practically simultaneously. A

I have found that a plurality of gaps 'in series will break down simultaneously when a voltage is applied across them, if the capacities of thev gaps are adjusted so that the division in voltage is in .proportion to the break-down voltages of the various gaps. For two gaps 'n series this result is obtained by shunting yne of the gaps by a condenser of such a capacitance or a devicel having a condenser action such that the ratio of the capacitance of the combination of that gap in parallel with the condenser, to the capacitance ot' the other gap, is equal. to the inverse ratio of the im ulse of (30 cycle voltages required to spart over the two gaps taken singly. For example. as shown in Fig. 5, a discharge path includes two sphere gaps, A. and B, in series, set to arc-over at 10 kv. and 20 kv. respectively, if taken singly. If the capacitance C, of gap A and C, of gap B are equal, any applied voltage will divide equally between the gaps and cause gap B to breakdown first, or as soon as its voltage becomes 20 hv., when the .voltage across gap A will also be 2O kv. In order to provide a means whereby applied voltages will divide in the proportion of 10() and 20, I place in shunt to gap B a condenser D having a ca aeitance C3. As the voltage across the .con ensers in series divides inversely in,

nin

y proportion to their'capacitance in thev eX- incitar l ample given: l

include. v

fromwhich weandihacztefcz.

V gaps will occur.

With more than two gaps`inseries,l vfor instance three gaps,cA, BI and C',- as shown inFig. 6, the simultaneous discharge of these gaps may be obtained bythe use of one or indre condnsers, for instance, condensers D and E in shunt to gaps B and C respectively, proportioned in the manner described.

I obtainthe simultaneous discharge of .gaps 1 and 2, according to above description, by providingapondenser 11 in'shunt to gap 2 which is so" roportioned relative to the capacities' of tie gaps as to obtain the requisite voltage distribution. With,

two gaps in series, one' of which is protected, I preferably provide tlieunprotected gap with the condenser shunt.'l v

Instead of acondenser in shunt, I may obtain a simultaneous discharge of the gaps 1 land 2 by the uscoi aresistance element 12 in shunt to gap 2 as shown in Fig. 2. The resistance is of a value such that the divisin in voltage across the aps is in proportion to the breakdown vo tage of the gaps.

Asshown in Fig. 3, I inay use the coinbination of thevcondenser 11 and resistance 12 in shunt to the gap 2 to vary the capacity of the gap' and maintain the proper voltage distribution. I

In Fig. 4 I haveshown a modified torni oi' my invention in which the umbrella mein-l ber 7 cooperates with the electrode 4 and serves as'one electrode ofthe protected gap .1. In this modieation, coo erating with the horn member 9 to forint ie horn gap 8 adjacent the unprotected gap 2, is a similar horn; member 13 which is'in conductive relationv with ,the umbrella member 7. In

' shunt-to gap 2, I provide a condenser 11 for the purpose described but it is understood that I may use instead of a condenser,

. a resistance element or aA combination of a condenser and a resistance, as previously described.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to haveitunderstood that the apparatus shown is only-illustrative and- 'other means. l

When a rising impulse voltage.

that' theinventioncan be carried out by What I claim as new and desire to secure 1. In a protective device, the combination with a discharge path including a plurality of gaps of dilterent breakdown voltages in series, oi means for causing transient voltages across said gaps. to divide across the individual .gaps in proportion to their transient break-down voltages.

2. In a protectiveadevice, the .combination with a dischar o path including a plurality of gaps of di erent breakdown voltages in series, of means foi-"adjusting the relative 4by Letters Patent oit' the United States, is:

capacities across said gaps so that transient sp`ai=k-over will occur practicallysimultane- 1 Ously across all said ga s.

3. In a protective device, the combination with a discharge path including a plurality ofgaps of different breakdown voltages in Series, of devices having a condenser action so related to said gaps that spark overwill occur practically simultaneously across said gaps. I

At. In a protective device, the combination with a dischar e path including a plurality of gaps of .di erent breakdown` voltages in series, of condepsers for kadjusting the capacities across said gaps so that the division in voltage is in proportion to the break down voltages of said gaps.

5. n a protective device, the combination with a discharge path of gaps of diiierent breakdown voltages in series, of means ttor preventing any of said gaps from discharging before the others.

6. The combination with a plurality of y gaps in series, or' shunt aths to' )part of said including a plurality gap protected from weather conditions andjlo a secondv unprotected gap in series therewith.

8. A protective device comprising a spark gap protected from weather conditions, a second unprotected spark gap in Series therewith, and a horn gap for extinguishing the arc formed as said series gaps break down.

.9. In a protective device, the combination with a ldischarge path including a spark gap protected from the weather, a second unprotected gap in series therewith," means for causing a spark over of said gapssimultaneously, :and means for interrupting said discharge path after said gaps .break down.

10. In a protective device, the combination' with a discharge path including two spark gaps in series, dt means for protecting one of said gaps from weather conditions, and I means for causing both said practically simultaneously. il. In a protective device, thel combina gaps to arc-over tion with a. discharge path including two spark gaps in series, of shielding means ior one ol said gaps, a second discharge path in shunt to said gaps, and means iii said i shunt path for taking the discharge over said gaps and sul'isi'rquently interrupting it.

12. In a protective device, the combination with a protected spark gap, of an iiiiprotected spark gap in series therewith, and means responsive to a discharge over said series gaps for short circuit-ing said gaps and subsequently.interrupting said short circuit.

13. In a protective device, the combination with a protected spark gap, of an iinprotected spark gap in series therewith, means for causing said gaps to arc-over practically simultaneously, and means responsive to a discharge over said gaps for completing a path in shunt thereto .and subsequently opening said shunt circuit.

,14. In a protective device, the combination with a spark'gap, an umbrella member enclosing said gap, and means for estinguishing the arc across said gap comprising 'a second gap in series with said first inentioned gap, ashunt circuit to` both said gaps'to which the discharge across said second gap is transferred, and means for interrupting said shunt circuit.

15. yIn' a4 protective device, the combination with a discharge path including two gapsin series, of shielding means toi.- one of said gaps, a horn gap adjacent the other 'of said gaps in a discharge path in shunt to said path including said series gaps, and means for causing said series gaps to arcover practically simultaneously.

16. In combination, a plurality of gaps in series forming a discharge path, means for distributing the' voltage across said gaps to cause said gaps to break down practically simultaneously, and means including a portion only of said 'gaps for controlling the discharge of" said gaps independent of weather conditions.

1T. A protective doevice comprisingY a spark gap protected from the weather, a second gap in series therewith, and means cooperating with said second gap to enable an applied voltage to so divide across both said gaps that both gaps discharge practically simultaneously, -and means lor short ciijcuitjng said gaps in response to their discharge and subsequently opening said short circuit. I

18. A 'protective device comprising a discharge path including 'two spark gaps in series, an umbrella member protecting one of said gaps, a horn meinher in shunt to said gaps cooperating with said umbrella and spaced apart therefrom to provide a horn gap, said horn gap being so related to the other of said gaps to take the are formed as said gap discharges.

rasiert A ,protective device comprising a spark gap, an umbrella member protecting said gap from the weather, a second 1111-' protected gap in series therewith, a member in shunt to said gaps cooperating with said umbrella member to foi-mn horn gap, said horn gap having such a relation to said unprotected gap that` discharges across said p iin protected gap ai'iejtransierred to said horn gap and extinguished'.

20. An outdoor arrester for protecting electrical systems against abnormal volte age comprising a spark gap provided with cooperating electrodes having their proximal surfaces substantially spherical and spaced apart to provide a uniform dielectric Held in which corona does not precede spark-over and spaced to permit sparkover if wet at a voltage lower than the predetermined voltage at which spark-over is cle-- sired but, when dry, to permit spark-over at such predetermined voltage and to resist spark-over at lower voltages, and a shield tor protecting said gap from the weather whereby the gap will discharge at its dry are-over voltage setting independently ot to divide, across the individual in proportion to their breakdown voltages.

22. in a protective device, the combination withy a discharge path including two or more spark gaps in series, one of said f gaps being protected from the Weather, and

means whereby said gaps are short circiiited in response to an arc discharge across' said gaps and the discharge interrupted in a circuit in shunt to said gaps.

23. ln al protective device, the comhination with two cooperating electrodes spaced apart to forni a spark gap, of an ui'nhrella member in conductive relation with one of said electrodes aiid enclosing said gap to protectpthe gap li'oin the weather. i A

24C. In a protective devicefthe combination with two coojieratii'ig electrodes spaced apart to form a spark gap, of means in conductive relation ir ith one ot said electrodes and capable oi -ausiiig said gap to discharge at the same breakdown rvoltage independent oi" the weather.

25. .ln a protective device, the eoiiihination with cooperating' electrodes spaced apart to form a spark gap, of a protective member cooperating with said gap `for causing the gap to always discharge at its dry arc-over setting, and means for short cir` cuitlng said gap including said protective member.

In witness whereof, l have hereunto set iny hand this 14th day ot May, 1918.

. FRANK il". TREK, dii.

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