US1366078A - Method of locating faulty suspension-insulators on live-wire transmission-lines - Google Patents

Description

T. F. JOHNSON, In. METHOD 0.? LO CATING FAULTY SUSPENSION INSULATORS 0N LIVE WIRE TRANSMISSION LINES. APPLICATION FILED MAR. I6. 1918.

1,366,078. Patented Jan. 18, 1921.

WITNESSES UNITED sTArEs PA' lENT omen.

TOMLINSON FORT JOHNSON, JR., OF ATLANTA, GEORGIA.

Application filed March 16, 1918.

To all whom it may concern:

Be it known that I, TOMLINSON F. JOHN- SON, Jr., a citizen of the United States,-residin at Atlanta, in the county of Fulton and tate of Georgia, have invented a new and useful Method of Locating Faulty Suspension-Insulators on Live-Wire Transmission-Lines, of which the following is a specification.

This invention has reference to the method of locating faulty suspension insulators on live wire transmission lines, and its object is to locate faults in the line-wire insulators without the necessity of cutting off the current.

The invention is designed to be used on transmission lines carrying high voltage currents, ranging up to one hundred thousand volts or more and may be used where the insulators are arranged in strings of two or more units.

In accordance with the invention it is first necessary to feel out the string lnsulators by an instrument which, because of the noise produced in feeling out, is termed a buzzer, the feeling out proceeding from the line-wire toward the end of the string of insulators remote from the line-wire, this procedure avoiding danger of burning out the string of insulators should it transpire that the string is badly at fault. Having thus ascertained whether the faults be great or small, the insulator units of the string are then tested one at a timeiby short circuiting them in receding order from the line wire. In this manner the defective or faulty insulators are readily picked out and markedfor future replacing, the whole procedure being performed while the transmission line is alive and in fact depending upon such condition of the transmission line for the carrying outof the method.

The invention will be best understood from a consideration of the following. de tailed description taken in connection with the accompanying drawing forming part of this specification, with the understanding, however, that the invention is not confined to any strict conformity with the showing of the drawing but maybe changed and modified so long as such changes and Specification of Letters Patent.

Patented Jan. 18, 1921.

Serial No. 222,947.

modifications mar-k no material departure from the salient features of the invention as expressed in the appended claims.

In the drawings Flgure 1 is an elevation of a string of insulators showing the line-wire in cross section and a portion of a supporting cross arm and also showing a testing oifr't tool in full and dotted lines in different operative relations to the string of insulators.

Fig. 2 is a view similar to Fig. l but omitting the cross arm and showin the testing out tool in short circuiting re ation to the insulators of the string.

Referring to the drawing, there is shown a cross arm 1 in Fig. 1, which cross arm may be taken as indicative of any suitable support such as a transmission line tower or as a cross arm on a transmission line pole. Fast to the cross arm 1 is a clip 2 from which is hung a string of insulators 3 of the suspension type customarily employed in high tension transmission lines, but the specific construction of these insulators is not necessary to an understanding of the invention further than to state that each insulator is provided with a metallic cap 4 and an insu-,

lating skirt 5, the several insulators being hung one from the other and the bottom insulator carrying a hanger 6 which suspends a line wire 7.

Considering the string of insulators, which may range from two insulators in relatively low tension circuits up to seven or more insulators for high tension circuits, each insulator is in the nature of a condenser with a difference of potential between the hanger below the skirt 5 and the cap 4 above the skirt 5. This condition is utilized in testing out the insulators of a string and in ascertaining the particular insulator units which are defective.

For the testing purposes there is employed an instrument which, because of the peculiar sound produced in the use of the instrument has received the name of buzz-rod.

The instrument comprises an elongated stick mates in an angle point 10 and the finger 9 has a straight terminal point 10. The fingers are pivoted to the handle or pole 8 so that they may be approached or moved apart at their pointed ends for a purpose which will hereinafter appear. It is not obligatory that the fingers or horns 9 and 9 should be pivoted or jointed to the stick or pole but the arrangement shown is advantageous in making the device somewhat more flexible in its adaptation than otherwise.

When it is desired to test out a string of insulators one horn, say the horn 9, of the buzz-rod, is touched to the line wire and then moved away therefrom to draw an arc. The character of sound produced by such are is noted. Then the same procedure is brought about with relation to the cap at of the insulator next to the line-Wire. If this insulator is in perfect condition the are will be less pronounced and the sound less intense than in the case of the line-wire itself, but the sound will be a snappy sharp sound. When the same procedure is followed with respect to the second insulator from the line Wire the sound and the are will be noticeably less intense than with the first insulator, and so on to the next to the last insulator in order from the line-wire where the are and sound will be very weak, the are being very short. Considering the string "of insulators as all sound or perfect the sound and length of the arc diminishes progressively as the insulators recede from the line wire until the are is drawn from the cap of the insulator next to the cross arm 1 representing the tower. Although the cap of this insulator is dead grounded it gives more sound and a longer spark than the second one from the tower. Othe1 ise, however, the diminution in sound and spark is practically progressive as the testing recedes from the line-wire.

If, however, any one of the string of insulators is defective the spark will have the same intensity, or nearly so, on either the cap or the hook of the same insulator, since the insulator body offers no insulating characteristic as between the cap and the hook or suspension means carrying the next insulator below it.

The procedure just described is what is called the feeling out the string of insula tors and is needful to prevent burning out the string should it transpire that, say, only one of the string of insulators is a perfect one and the others are all defective or most of them are defective. Such burning out would occur in the next step of the precedure in which the testing is to ascertain the particular insulators in a string that are defective, especially when such defects ocour in the major portion of the number of insulators in the string.

Having ascertained that the string as a whole is not perfect throughout and that only the minority of the insulators are defective, say one or two of them, then the buzz stick is adjusted with respect to its fingers or horns 9 and 9 so as to bridge around the insulating skirt 5, thus short circuiting the hanger of an insulator onto the cap thereof. For instance, the finger 9 is made to contact with the hanger of the lowermost insulator and the finger 9 is made to touch the cap of the same insulator and an arc is drawn from the cap and its character noted. The same procedure then follows with respect to the second insulator above the line-wire and the character of the arc is noted. If the lowermost insulator is in perfect condition there will be a corresponding diminution in the sound and the length of the are. If the lowermost insulator be imperfect such diminution will not occur and the insulator may be marked by a dab of paint from a brush on the end of a stick long enough to protect the operator from liability of shock. In this way each insulator is tested in turn by short circuiting the neighboring insulators, the defective insulator acting the same as though it were not present. The invention permits the delinite and accurate location of all bad or partially bad or defective insulators of the suspension type on power transmission lilies while the latter are in use and fully alive. In fact, the invention utilizes the electrical energy of the line directly for locating the defective insulators. Because the invention permits the location of the defective insulators without 'killing or putting the line out of service, it contributes greatly to continuous and a more satisfactory service than heretofore. Moreover, the invention is more accurate and rapid than other methods for the purpose which have been proposed. The invention cuts the cost of the insulator testing fully ninety per cent. and consequently is correspondingly cheaper than other methods in use. The invention has the further advantage of giving equally good results in damp weather as are obtained in dry weather. The invention may also be used to determine the proper number of insulator units to be used to insulate a line of any voltage and Will determine the distribution of stresses over a string of insul atois. It may further be used in fautly pillar type of insulators, faulty bushings and other faults.

The preliminary procedure or feeling out process is needful to prevent a. flash-over and a knock-out which would result if there should be but one good insulator in a string and this insulator was short circuited in the. final test locating the particular faulty in sulators. Such danger is removed by the feeling out process which does not go to the extent of short circuiting any insulator and it gives a rather clear indication as to whether there are enough good insulators in the string to stand the short circuiting process.

The procedure is the same for all voltages and all strings of insulators down to two in a string. Obviously it cannot be worked on a line where there is only one suspension insulator per support.

In the foregoing description the procedure of feeling out and short-circuiting is a preferable one, but the invention is not confined to such particular procedure. Either or both the feeling out and short-circuiting may begin at the tower end of the string of insulators and continue to the line end thereof, the i only difference being that the intensity of the spark will then increase instead of diminishing. It is also possible to start either or both the feeling out or short-circuiting at an intermediate point of the string of insulators and work both ways, although this last procedure requires a greater degree of expertness than when the procedure begins at one end or the other of the string of insulators.

\Vhat is claimed is f 1. The method of locating faulty suspension insulators arranged in strings on live transmission lines, which consists in first determining by a controlled local action of the current flowing through the line the extent of the fault in a string of insulators, and then definitely locating, also by a controlled action of the current flowing through the line, the particular insulator or insulators at. fault.

2. The method of locating faulty suspension insulators arranged in strings on live transmission lines, which consists in drawing arcs in chosen order from isolated points along the string for comparison of the intensity of the arcs, and then short-circuiting the insulators one at a time to definitely locate the faulty ones.

3. The method of locating faulty suspension insulators arranged in strings on live transmission lines, which consists in first feeling out a string by drawing an are from the line and from the insulators in receding order from the line, and then short-circuiting the insulators, one at a time, to definitely locate the faulty or defective ones.

4,. The method of locating faulty or defective insulators in strings thereof on live transmission lines, which consists in first determining by the character of the local action of the current on the line that a string contains one or more defective insulators and is safe for the next step, and'then shortcircuiting each insulator and drawing an are from a metallic part thereof to ascertain by the character of the are the degree of the defect.

5. The method of ascertaining the efficiency of insulation of high tension transmission lines where a plurality of insulating units in series is employed, which consists in drawing arcs from the metallic parts of the insulating units to determine by the character of the arcs whether the insulation is sufficient or deficient and then definitely locating the defects in the insulation by short-circuiting the units and drawing arcs thereat, and noting by the character of the arcs the particular units showing deficiency of insulating qualities.

6. A method of testing out strings of suspension insulators on live transmission lines, which consists in applying a testing device to the separate insulatin units in chosen order so as to cause sensible indications of the current on the line at the insulators and thereby ascertain by the character of the indications whether or not any of the 8-5 insulator units is defective.

7. The method of locating faulty or defective suspension insulators arranged in strings on live transmission lines, which consists in first testing each insulator, one at a time, by drawing an arc therefrom, to ascertain whether there is sufiicient good insulation in the string to permit further testing, and then testing each insulator by first short-circuiting it and then drawing an arc therefrom.

8. The method of testing out strings of suspension insulators on live transmission lines, which consists in drawing arcs from metallic parts of the insulators in chosen 100 order to ascertain by the character of the I are whether or not any of the insulators is defective.

9. The method of testing out strings of suspension insulators on live transmission lines, which consists in drawing arcs from metallic parts of successive insulators of a string beginning with the line wire end of the string, to ascertain by the effect produced whether or not any of the insulators is defective.

10. The method of definitely selecting faulty or defective insulators in a string thereof on live transmission lines, which consists in short-circuiting each insulator of a string separately and then drawing an are from a metallic part thereof, and comparing the effect produced by the arc with the effect produced in similarly testing neighboring insulators. 120

11. The method of ascertainin the efiiciency of insulation of high tenslon transmission lines where a plurality of insulating units in series is employed, which consists in drawing arcs successively from the metallic parts of the insulating units in receding order with respect to the live transmission line to determine by the character of the arcs whether the insulation is sufficient or deficient.

12. The method of locating faulty suspension insulators arranged in strings on live transmission lines. which consists in first feeling out a string by drawing an are from an isolated point of each insulator and comparing the effects produced to ascertain to what extent the string as a whole is lacking in insulating qualities, and then shortcireuiting each insulator and drawing an arc r'or selecting the detective iusnlatois by comparison of the arcs produced with those of the efficient insulators.

In testimony that I claim the foregoing as my own, I have hereto aflixed my signature in the presence of two Witnesses. I

E. H. W'ILDBERGER, D. W. GREENE.

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