US1612354A - Gap ionizer - Google Patents

Description

Dec. 28 1926. 1,612,354

Q. A. BRACKETT GAP IONIZER Filed Nov. 5, 1919 INVENTOR WITNESSES:

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M f ATTORNEY Patented Dec. 28, 1926. l

UNITED STATES PATENT OFFICE.

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Application filed November 8, 1919. Serial No. 385,820.

My invention relates-to electrolytic lightning arresters and' particularly to arresters in which electrodes made of film-formin material,fsuch as aluminum, are immerse s in a suitable electrolyte, and it has for its object to provide a novel device and system where by the films may be reformed on such electrodes.

My invention is particularly adapted for 10 use in connection with lightning arresters constructed in accordance with the disclosure of Patent No. 1,477,305 on discharge gaps, issued to Chester T. Allcutt and assigned to the Westinghouse Electric & Man- II u acturing Company.

In my copending application on gap ionizers, Serial No. 271,492, patented December 11, 1923, No. 1,477,308, have disclosed a charging device for an electrolytic light- 20 ning arrester comprising a dlscharge gap consisting of two main spaced discharge -members, one of which is connected to ground through an arrester to be charged and the other of which is connected to the 25. line to be protected. An auxiliary electrode is disposed intermediate the two main discharge members and is connected to one of them through an impedance device and a switch connected in series relationship and 80 to the other of the main electrodes through an impedance device of dissimilar character. The impedances are of such value that, when the switch is closed and normal frequency or a flat wave-front impulse is impressed upon '85 the line, the auxiliary electrode is maintained at a potential substantially midway between that of the two main electrodes. Under a high-frequency or steep wave-front impulse the field between the main discharge mem- O hers is distorted and the ga breaks down at relatively low voltages. Vhen 'it is desired to charge the arrester, the switch is opened, raising the potential of the auxiliary electrode to that of the main electrode 5 to which it is still connected, resulting in impressing full potential of the line across substantially one half of the gap, resulting in the desired breakdown of the entire gap.

M present invention is somewhat similar I to that previously described in that the breakdown of the gap results from a change in the electrostatic field adjacent the main electrodes, which may be caused at Wlll. My resent invention difiers however in that one or both of the main discharge members are provided with means which normally prevent distortion of the gap. This permits theuse of a'higher voltage across said gap, and the arrester, which is connected m ser1es with the main ap, is charged by disconnecting said auxi iary electrodes fromthe electrode which it surrounds, thus permitting distortion of the gap such as would occur if the electrostatic-field protective devices were not present. Distortion of the gap immediately results in a breakdown of the gap between the main electrodes, it being a well-known fact that the discharge voltage of the gap is considerably reduced when the field thereof is not maintained uniform. a

The accompanying drawings are views, partially diagrammatic and partially in sec, tion, of various forms of my invention. In' F1g. 1 I show a main discharge gap at 5, bemg formed by main discharge electrodes 6 and 7, preferably of spherical contour and of small diameter and spaced apart more than their diameters. The electrode 6 may be connected to a line wire 8, and the electrode 7 may be connected to ground at 9 through an electrolytic arrester 10, which is to be charged.

A toroidal conducting member 11 is disposed around, and in spaced relation to, the electrode 6 and is connected thereto through a substantially non-capacitative impedance device 12 consisting, preferably, of an inductance device 13 and a resistance device 14.. A switch 15 serves to connect the re sistance device 14 to the discharge member and the line 8. Similarly a toroidal-she, d conducting member 16 surrounds the e ectrode 7 and is connected thereto through an impedance device 17, of a non-capacitative 95 character. A capacitative device 18 may be connected between the members 11 and 16, if desired.

Having thus described the structure of a device embodying my invention, the opera- 1 tion thereof is as follows: Under normal conditions, the adjustment is such that the electrostatic field between the members 6 and 7 would be quite badly distorted in the absence of the members 11 and 16, and the 105 gap would break down under the normal line potential. At normal frequency, assuming the switch 15 to be closed, the device 18 is of extremely high impedance and the devices 12 and 17 serve to maintain the electrodes 11 and 16 respectively, at substantially the potential of the associated discharge members. Under these conditions, the corrective effect of the members 11 and 16 upon the field between the electrodes 6 and 7 is such as to substantially remove the loci of steep potential gradient therefrom. minimizing the liability to break down and largely increasing the ability of the gap to withstand potential.

When it is desired to charge the arrester, the switch 15 is opened, whereupon the member 11 no longer exerts a corre tive influence upon the adjacent electrostatic field, allowing it to become distorted, and the condenser 18 tends to change the potential of the member 11 to that of the electrode 7. thereby further increasing the distortion of the field. Since the gap between the members 6 and 7 is of such length that the field must be maintained uniform in order to prevent breakdown, it will be obvious to those skilled in the art that the opening of the switch 15 will result in a breakdown discharge between the members 6 and 7, through the electrolytic arrester 10, to ground 9. The switch 15 may be operated by hand or by a separate controlling circuit which may extend parallel to the main line 8.

In Fig. 2 I show a structure in which only the electrode 6 is surrounded by a potentialadjusting member 11, which is connected to the electrode 6 and the line 8 through an impedance device 12 and a switch 15, as described in connection with Fig. 1. The member 11 is connected to the electrode 7 through a condenser 19 of relatively low capacity. The operation of this device upon opening the switch 15 is similar to that dcscribed in connection with Fig. 1.

Referring to the form of my invention shown in Fig. 3, the electrode 6 is disposed opposite the electrode 7 in such manner as to normally tend to produce a badly distorted field. The electrode 7 is connected to ground through an electrolytic lightning arrester 10, as described in connection with Fig. 1. The guard ring 11 surrounds the electrode 6 and is connected thereto through an impedance device 12 and a switch 15. as previously described. The guard ring 11 is mounted upon an insulator 20 having a grounded metallic pin 21 which combination serves as a condenser of very low capacity tending to reduce the potential of the electrode 11 to that of ground. As described in connection with Fig. 1, the ring 11 will be normally maintained at the potential of the electrode 6, but, upon opening the switch 15, the insulator 2O performs the function of a condenser and will change the rin 11 to substantially ground potential, thereby permitting distortion of the electrostatic field between the electrodes 6 and 7 In the apparatus shown in Fig. 4, the

toroidal electrode 11 is mounted upon an insulator 20, as described in connection with Fig. 3, and is connected to the line 8 and the electrode by means of a choke coil 13 and a resistance 14 connected in series with a switch 15, as shown in Fig. 1. The electrode 7 and the ring 11 are provided with horns 22 and 23, respectively. Disturbances of normal frequency but of high voltage take place between the guard ring 11 and the electrode 7 and are extinguished by the joint action of the arrester l0 and the horn gap 2223, as is customary in such structures.

From the foregoing description it will be obvious to those skilled in the art that the structure described in connection with the accompanying drawings functions as a lightning arrester, as long as the switch 15 is closed, but that, as soon as the switch 15 is opened, the device becomes the equivalent of an ordinary spark gap which has a higher potential impressed across it than it can bear without breaking down so that the discharge of the gap, resulting in charging the arrester is the inevitable result of breaking the connection between the guard ring and the associated electrode by opening the switch 15.

While I have shown my invention in a plurality of forms, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various minor changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed there upon as are imposed by the prior art or are 11 specifically set forth in the appended claims.

I claim as my invention:

1. In a protective apparatus, the combination with a discharge-gap device comprising two spaced gap electrodes proportioned to break down at a predetermined voltage, of auxiliary frequency-responsive means controlling the electric field conditions between said electrodes to increase the breakdown voltage of said gap device under normal voltage conditions and to give a reduced breakdown voltage under steep wave-front impulses, and means for controlling the action of said auxiliary means.

2. The combination with an electric line and a valve-type lightning-arrester connected parallel to said line, said arrester requiring periodical charging, of a gap device connected in series with said arrester, said gap device being so proportioned as to break down under normal line-voltage conditions, means controlling the electric field conditions between said electrodes to increase the breakdown voltage of said gap device under normal Voltage conditions and to give a reduced breakdown voltage under steep wave-front impulses, and means for controlling the action of said means.

3. The combination with an electric line to be protected and an excess-voltage protil) tective device connected in parallel thereto, said protective device bein of a type requiring periodical charging, o a gap device connected in series with said rotective device and comprising two space electrodes normally having a distorted electrostatic field therebetween and set to break down under normal line-voltage conditions, conducting means dis osed around the electrode connected to the ine in spaced relation to said electrode and out of the gap discharge path biatween said electrodes, a circuit for chargin said conducting means from the line, said conducting means operating, when charged,

- to largely eradicate the field distortion and to cause the gap between said electrodes to break down only at voltages higher than normal line voltage, and means for rendering said charging circuit inoperative.

4. The method of maintaining an electrolytic lightning arrester connected to a line through a series ga device, which consists in setting said gap evice to break down un der normal line-voltage conditions, causing the electrostatic-field conditions surrounding said gap1 device to be so changed as to increase t e breakdown'voltage of said gap device to a value higher than said normal line voltage, whereby said electrolytic lightning arrested is normally disconnected from said line, and causing said electrostatic-field conditions to be restored to cause said ap device to break down and charge said e ec-v trolytic lightning arrester at normal line voltage. I

5. The combination with a discharge gap comprising two spaced main electrodes, of an auxiliary electrode so mounted as to surround one of said main electrodes in spaced relation and connected thereto through an 1 impedance and a switch connected in series relationship.

6. The combination with a dischar e gap comprising two spaced main electro es, of an auxiliary electrode of toroidal shape mounted to surround one of said discharge members in spaced relation, of a connection betwepnjsaid auxiliary electrode and the main electrode which it surrounds comprising a non-capacitative impedance and a switch.

7 The combination with a dischar e gap comprising two spaced main electro es, of an auxiliary electrode of toroidal shape mounted to surround one of said discharge members in spaced relation, of a connection between said auxiliary electrode and the main electrode which it surrounds comprising an inductive impedance, a charging resistance, and a switc D (it) 8. In electrical discharge gap apparatus,

two spaced main discharge members, of an auxiliary electrole mounted adjacent each of said main discharge members and connected thereto and to each other by means of connections having impedances of dissimilar character, and means for breakin the connection between one of said auxi 'ary electrodes and the main electrode which it surrounds.

9. In electrical discharge gap apparatus,

two spaced main discharge members, of anauxiliary electrode mounted adjacent each of said main discharge members and connected thereto by means of non-capacitative impedance members and to each other by a connection embod ing capacitance, and means for breaking t 1e connection through one of said non-capacitative members.

10. The combination with an electrolytic lightning arrester connected to ground, a dis- I charge gap comprising two spaced main elec- QUINCY A, BRACKETT.

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