US1512817A - Overload-indicating apparatus for transformers - Google Patents

Description

Oct. 21,1924. I 1,512,817

D. BOYDEN OVERLOAD INDICATING APPARATUS FOR TRANSFORMERS Filed June 16. 1921 Patented Get. 21, 192.4.

' unrraa sra'res DAVIS S. BOYDEN, OF ALLSTON, MASSACHUSETTS.

OVERLOAD-INDICATING APPARATUS F'Olit TRANSFORMERS.

Application filed June 16, 1921. Serial No. 473,205.

fl '0 all whom it may concern Be it known that I. DAVIS citizen of the United States, residing at .Allston, in the county of Suffolk and State of Massachusetts, have invented certain new and useful Improvements in Overload-Indicating Apparatus for Transformers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to an improvement in overload indicating apparatus for transformers. 7 3

The present invention constitutes an improvement upon the construction illustrated and described in the application executed by me of even date herewith for an improvement in transformers.

The object of the invention is to produce an overload indicating apparatus having provision for indicating the attainment of different degrees of overload, and to this end the invention consists in the apparatus hereinafter described and particularly defined in the claims.

In the accompanying drawings illustrating the preferred form of the invention, Fig. 1. is an elevation of a transformer showing the overload indicating apparatus in posi= tion; Fig. 2 is a rear elevation of the apparatus with the box removed; Fig. 3 is a vertical section taken on the line 3-3, Fig. 2, showing the box; Fig. {1 is a horizontal section taken on the line 1- 1, Fig. 3; and Fig. 5 is' an enlarged detail hereinafter referred to. V

The overload indicating apparatus illus trated inthe drawings is described as followsz This apparatus cons1sts of a heat sensitiveeleme'nt 10 supported on the lower end of a tube 11 from the base 12, adapted to be inserted through the cover of the transformer 20, into the oil 21, and in close proximity to the coil 22. The instrument is secured in 'place in the cover by means of a nipple 13 which is inserted in the hole in the cover of the transformer and secured in place by a' nut mounted aplate 15 which carries standards 16 supporting two horizontalplates 17, 18. These standards and plates constitute the frame work of the indicating portion of the apparatus. The heat sensitive elementcom sists of a coil or spiral 30 of any usual or the trip 7 lower end lof the spring detent 52, engages 14. Upon the base 12 is preferred construction, to which is attached S. BoYonN, a

the vertical rod 31 adapted to be turned by the heat sensitive coil 30 with variations in temperature of the oil in the transformer. The upper end of the rod 31 passes through a hole in the plate 17, which supports and ,steadies the rod in position. Near the upper end ofthe rod 31 is secured a collar 32. Loosely mounted on theupper end of the rod and resting on the collar 32 is the trip disk 33, which is held from endwise movement of the red by a collar 34. secured by a screw 35 to the rod 31. The trip disk 33 is provided with aipin 36, and the collar 3.4 is provided with a pin 37. A hair spring 38 is bent upon itself and embraces the pin 36 at one end, and is secured to the pin 37 at the other end by means of a screw 39. The

disk33 is also provided with a second pin 10 against which thepin 37 is held by the tendency ofthehair spring 38 to straighten out. This arrangement is such that the trip disk 33 is normally held in position with its pin 10 against the collar pin 37, so that as the temperature rises, therod 31 turns counterclockwise, as viewed in Fig. 5,. and turns thetrip disk by means of the engagement of the collar pin 37 with the disk pin 40, The semaphoreoO is mounted to slide vertically on the rods 51, which are sup'-. ported at the bottom in the plate 15 and at the top in 'the -plate 18. To the semaphore is attached a spring detent 52, the lower end of which normally. rests upon the upper surface of the trip disk 33, as shown in Figs. 2,3 and 4 When the rod 31 is turned by a rise in thetemperature, the trip disk moves counter-clockwise bringing the notch in the disk'under the lower end of the spring ,detent; 52 ,cthereby permitting the semaphore 50 to fall. This spring detent, however, is provided'with'a shoulder 53,-which, when diskypasses out from under the the, trip disk inlthe descent of the, some phore. This arrests the descent of the semaphore before it has completed its fall. and holds the semaphore in what may be called its middle or tolerableoverload position.

until the f attainment of a second critical temperature, "when the trip disk moves out fr-omunder the shoulder 53, thus permitting the semaphoreto' complete its descent' Thusitwill belseen that in this apparatus, upon the attainment of the firstcrit-ical temperature, thesemaphore drops to middle or tolerable overload position, and indicates the attainment of the first critical temperature. If the temperature now turning of the rod 31 isnot prevented because the hair spring 38 permits the rod to turn, resisted only by the slight resistance oflfered by the hair spring to such return turning movement. If observed at this time, the observer will understand that the temperature of the transformer rose to the first critical point, andgvhile it may have risen above that point, it did not attain the second critical point. He may then reset thesemaphoreby means of the resetting device, consisting of the lever 60, carrying the pin 61, which is adapted to engage the under side of the semaphore 50, to lift it up when the push pin 62 is'pressed upward to actuate the resetting lever 60, the latter being pivoted at 63 one. bracket in the upper end of a stud 6 4, within whichthe push pin 62 is mounted. If the temperature of the transformer now rises to the firstcritical point, the semacured to the phore will again drop to its middle position and rema n 111 that position unt l reset, or

until the second critical temperature is reached, when the semaphore will be per? mitted to dro 3 to the limit of its descent.

' This semaphoreand the devices above'described are enclosed within a box 70, provided with a window 71, which box is seplate 15 by screws entering through the screw-holes 72, and in the bottom of the plate 1 5. hen the first critical temperature is reached, the semaphore is half exposed through the window 71. When the second critical temperatureis reached,

the semaphore is wholly exposed through the window 71. I

This overload indicating apparatus in use on transformers will,"therefo re, indicate by the position of the semaphore whether or not the transformer has been subjected to an overload, and whether or not such overload was the moderate overload corresponding to the middle position of the semaphore, or the greater overload corresponding to theqbottom position :of the semaphore. Thus the character of theoverload to which theindieating apparatus is subjected, is indicated. Thefmd'dle position of the semaphore may con vei ently betaltenas nidicating a to ler,-

able overload, the bottom position of i V to indicate an intolerable overload, so, that when a transformer is subjected to tolerable 0verlo-ad,its identity may be noted and it may .be made the subject of a regular and frequent inspection, because it is a transformer which, while liable to intolerable overload, does not require immediate replacement, whereas when a transformer shows intolerable overload, it should be replaced at once.

- he em era e ts ir n hich any given transformer is located will determine falls, the

This fact renders any even when the transformer coils are hotter, with the result that with the same overload indicating apparatus set for thesame critical temperatures, the liability of burning out willbe greater in winter than in summer,

as stated. The present overload indicating apparatus, since it has two indications of overload, or two indications of arrival at higher temperatures, affords provision for indicating dangerous temperature both insummer and in winter. In sunnner upon the indication oftolerable overload, or the attainment of av firstrcritical temperature, the observer will reset or note the condition, and put the transformer under observation. Then when in summer intolerable overload, or the second critical temperature point, is reached, the observer will 'know and understand that the transformer must be replaced by another of larger. capacity. In winter time, however, this semaphore, on the arrival of what in summer would be a condition of tolerable overload, maybe taken to indicate a condition of intolerable overload, and replacement of the transformer should be made at once. So thea'pparatushas a double temperature indication in' summer,

anda single useful temperature or overload indicating provision in winter.

Having thus described the invention, what is claimed is 5- 1. Overload indicating apparatus for transformers having, in combination, a heat sensitive element, asem'aphore,a rod adapted to be rotated by the heat sensitive element provided with a trip disk connected tothe rod to yield in one direction, and to be positively moved thereby in the other direction, said semaphore being provided with a part to engage the trip disk.

2. Overload ind-i'cati g apparatus for transformers havingg in combination, a heatsensitiveelement, a semaphore, a trip member connected with the heat sensitive element, ,a detent connected'with thesema phore, the trip member and detent having provision, for pe mitting movement of the semaphore from non-indicating position, first to tolerable overload indicating position, and second to intolerable overload" indicating position;

transformers having, in combination, a heat a semaphore,- a rotary trip sensitive element,

disk connected with and actuated by the heat sensitive element, a detent connected with the semaphore having two portions adapted to engage the trip disk at positions of the semaphore indicating normal load and tolerable overload.

4. Overload indicating apparatus for transformers having, in combination, a heat sensitive element, an indicator, and connections between the heat sensitive element and the indicator to normally retain the indicator in inoperative position constructed and arranged to permit theindicator to move into position for indicating tolerable overload at a certain predetermined temperature and to a second position for indicating a greater overload at a higher predetermined temperature and for preventing the indicator from moving to inoperative position.

5. Overload indicating apparatus for transformers having, in combination, a heat sensitive element, a semaphore, means for normally retaining the semaphore in nonindicating position, and connections between the heat sensitive element and the retaining means for allowing the semaphore to first move into and to be retained in tolerable overload indicating position at a predetermined temperature and to thereafter move into and be retained in intolerable overload position at a higher predetermined temperature.

6. Overload indicating apparatus for transformers having, in combination, a heat sensitive element, a semaphore, and connections between the heat sensitive element and the semaphore to normally hold the semaphore in non-indicating position con structed and arranged to permit the semaphore to move by a step-bystep movement for indicating a plurality of different overload conditions to which the transformer may be subjected havingvprovision for retaining it in such position.

7. Overload indicating apparatus transformers having, in combination, a heat sensitive element, an indicator normally retained in a first fixed non-indicating position, and connections between the heat sensitive element and the indicator constructed and arranged to permit the indicator to first move to a second fixed position for indicating tolerable overload, and then upon further increase in temperature to a third fixed position to indicate intole "able overload.

8. Overload indicating apparatus for transformers having, in combination, a casing, a heat-responsive element, a trip mechanism connected with the heat-responsive element, a gravity actuated semaphore, and means cooperating with the trip mechanism for holding the semaphore in non-warning position at normal temperature, means be ing provided whereby a predetermined increase in temperature will permit the semaphore to drop and stop at a predetermined point, indicating tolerable overload, and to thereafter, upon increase in temperature, permit'the semaphore to drop another step to thereby indicate intolerable overload.

DAVIS S. BOYDEN.

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