US1754158A - Lightning arrester - Google Patents

Description

April 8, 1930.

v. E. GOODWIN 1,754,158

y .LIGHTNING ARRESTER Filed April 13. 1922 Inventor: Victor* E. Goodwin, by

Patented pr. 8, 1930 UNITED: STATES PATENT' oFFlcE VICTOR E. GOODWIN, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW lYORK LIGHTNING ARRESTER This invention relates generally to lightning arresters andmore particularly to arresters of the multi-gap type. 4

Heretofore it has been common to provide multi-gap arresters with a resistance arranged to bridge certain of the gaps. It has also been suggested to provide such arresters with a grounded conductor arranged to lie in proximity to certain of the gaps, whereby the capacity between the electrodes of the gaps and ground' is increased and as a result the break-down voltage of the gaps is lowered. I have discovered that by a novel combination of a shunting resistance and a capacity, I am enabled to secure an arrester which has marked advantages over arresters of the type heretofore employed.

Further details of my invention, as well as numerous objects and advantages thereof, will appear from the following description taken in connection with the accompanying drawing, wherein'F ig. 1 represents in longitudinal section, partly broken away and partly in elevation, a lightning arrester embodying my invention, and Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1.

As shown in the drawing, the arrester comprises a porcelain tube 10 which is adapted to be secured to a suitable support by means of a strap 11. The tube 10 is provided with a member 12 which partially closes its lower end and with a member or cap 13 which 1s cemented to its Aupper end. Interposed between the member 12 and cap 13 are a series of gaps 14 to 27. These gaps arey divlded into three groups, two of the groups, namely, gaps 14 to 16 and 25 to 27, are being located adjacent the cap 13 and the member 12 respectively. The gaps o f these two groups are formed of a plurality ofdished brass or other non-arcing metal disc electrodes 30 having central serrated, studded or otherwise roughened discharge surfaces 31, the two opposing electrodes of each gap being separated by a ring 32 of porcelain on other insulating material. Interposed between these two groups of gapsis a resistance rod 33 of carbon or other suitable material and upon this rod is supported the third group of gaps 17 to 24. These are formed Application led v.April 13,

of electrodes 34 having flat central portions and offset or conical outer discharge portions. The electrodes of each pair forming a gap are spaced apart by porcelain rings 35 which fit snugly around the rod 33. It will be noticed that the outer faces of the electrodes may bel said to lie substantially along a cylindrical surface. The electrodes forming the gaps 17 to 24 in the form of my invention illustrated in the drawing do not eX- tend inwardly into contact with the rod'33 but are held away from the rod by engagement of the rings 35 with the conical portions of the electrodes. To the ends of the rod 33 are secured caps`36 which serve to form electrical connections between the ends of the rod and the adjacent electrodes 34 of the third group of gaps and also to form contacts with plates 39 which rest against and form lelectrical connections with the adjacent electrodes of the first and second groups. The lower disc 30 of the arrester is connected to a conducting member 40 hereafter more fully to be described and this member in turn is connected by means of a plate 41 to a terminal conductor 42 which passes through a central opening formed in the member 12.

The upper disc 30 of the arrester is in contact with the lower of a series of metal spacing plates 4l which are inserted to take care of slight variations which are apt to oc-v cur in the' lengths of the outer tubes. Pressing upon the upper plate 41 and serving to maintain the discs 30 and spacing rings 32 in close contact and to hold the rod 33' firmly between the upper and lower groups of gaps is a spring 45 which bears at its upper end against the conducting cap 46. This cap encloses the upper end of the tube l() and is surrounded by a metallic strap 47 which is connected to the line terminal 48. The cap 46, strap 47 and connected end of the line terminal are embedded in cement which serves to secure the cap 13 to the tube 10.

Interposed between the series of gaps and the tube 10 is an insulating'lining 49, preferably of mica, and surrounding said lining is the conducting member 40 which as shown is in the form of a cylinder and which in the present instance extends upwardly within the tube as far as the top of the middle group of gaps. As shown in Fig. l the cylinder 40 is connected at its lower end with the terminal conductor -l-Q. y

In operation, low power discharges pass over the unshunted gaps and through the resistance 33 but do not pass over the shunted gaps. The dynamic voltages being insufhcient to maintain the arcs across the unshunted gaps which are in series with the .resistance 33, no appreciable dynamic current follows the discharge, the arcs are extinguished and the circuit through the arrester broken. High power discharges will pass over both shunted and unshunted gaps but because of the resistance 38 and capacity due to the presence of the conductor 40 the dynamic current which follows is quickly shifted from the shunted gaps to the resistance 33 and is then quickly interrupted at the unshunted gaps. I have found that due to the presence of the conductor 40 there is an increased tendency of the dynamic current to be shifted to the resistance rather than to pass over the shunted gaps. In other words, the arrester may be safely employed at a higher line potential.

I also lind that the presence of the conductor has'the effect of lowering the length of equivalent sphere gap of the entire arrester. This is particularly true when the equivalent Y sphere gap of unshunted gaps taken as a single groupeis less than the equivalent sphere gap of the shunted gaps. The conductor 40 may be said to constitute a plate of a condenser and as such is adapted to cooperate with the adjacent portions ofthe spark gap electrodes.

What I claiin'vas new and desire to secure by Letters Patent of the United States, is

l. A lightning arrester comprising a resistance rod', a series of spark gapssurrounding said rod `and formed of electrodes having extended surfaces arranged substantially along a cylindrical surface, and a cylindrical conductor concentric with said surface and arranged to form a condenser with said surfaces, said conductor being in electrical connection with one terminal of the arrester.

2. In a lightning arrester, three groupsof gaps in series, annular electrodes located between the gaps of one of said series, a resistance rod, the terminals of the annular electrode series being connected to the resistance rod, andV a metallic cylinder electrically connected to one terminal of the arrester and enclosing two of said groups of gaps, one of the y connected in series in said tube and connected between the two said terminals, and a resistance rod within said tube, said electrodes each surrounding said rod, the latter being y connected with the terminal electrodes of the

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