US1634440A - Transformer - Google Patents

Description

July 5, 1927. 1,634,440

T. D. ADAlR, JR

TRANSFORMER Filed April 8. 1921 l iiy.l

Inventor \zflmymfr fmwl Patented July 5, 1927.

UNITED STATES PATENT OFFICE.

THOMAS DONALD ADAIR, JR, OF DQRCHESTER, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, '10 LEONARD L.

ELDEN', 0F BBOOKLINE, MASSACHUSETTS, AND

DAVIS S. BOYDEN, 0F BOSTON, MASSACHUSETTS.

TRAN SFORMEB.

Application filed April 8,

This invention relates to transformers.

It is generally recognized that the line transformers used in electrical transmission work are frequently subject to overload resulting in the generation of an amount of heat oftentimes sufiicient to burn out the insulation of the transformer coils. These overload conditions are brought about by the application of excessive load usually through simultaneous use of power by a large number of consumers. The transformers themselves are designed for average capacity and even to take care of some overload, but repeated occurrence of overload conditions operates in practice to burn out a number of transformers each year. At the present time no practical method exists for determining rapidly and regularly the extent to which line transformers on a central station system are subjected to over loads or overheating in daily service.

The object of the present invention is to provide a novel and improved construction of transformer having provision for visibly indicating that an overload has existed thus facilitating the inspection of the transformer for overload conditions.

To this end the improved transformer is provided with a semaphore and with means for displaying the same in a visible position when the transformer coils are subjected to an overload. The semaphore is preferably arranged to continue in an indicating position thus showing that an overload has existed, so that an inspector may determine the fact as he passes along the highway below the transmission lines. Pro vision is made for resetting the semaphore so that an inspector may determine the recurrence of overload for any particular transformer. p

In the drawing illustrating the preferred form of the invention Fig. 1 is an elcvation of the transformer with a portion of the casing broken away; Fig. 2 is a side elevation of the heat-responsively operated semaphore; Fig. 3 is a vertical section on the line 33 of Fig. 2; and Fig. 4 is a crosssection on the line 1- 1 of Fig. 3.

The transformer illustrated in the drawings comprises a casing 10 Within which the usual transformer coils 11 are received. The latter are immersed in a body of oil or other cooling medium for assisting in the dissipa- 1921. Serial NO. 459,574.

tion of the heat generated by the transformer coils during normal use. The transformer casing 10 is provided with a removable cover 18 and the parts thus far described are wellknown and of the construction usually employed at the present time.

In order to indicate existence of overload conditions upon the transformer coils, the transformer is provided with a semaphore 19 arranged to be displayed in a visible position when the coils are subjected to overload. The semaphore is operated by mechanism responsive to the overload conditions of the coils comprising preferably a heatresponsive coil or spiral 21 of well-known construction enclosed within a tubular casing 20 immersed in the bath of oil surrounding the transformer coils. The upper end of the heatsresponsive coil is secured to a rotatable spindle 25 journaled in a cross-bar 27 within a semaphore box 28 secured upon the upper end of the tubular casing. The semaphore box 28 is provided with a depending boss 29 having a threaded portion 30 adapted to be extended through a hole in the cover 18 and upon which a nut 31 is thereafter screwed to clamp the annular shoulder 33 to the cover. Variations in temperature of the oil bath therefore operate through the expansion or contraction of the heat-responsive coil or spiral to cause rotation of the rotatable spindle 25.

I The semaphore box 28 is provided with a window 30 in the lower portion of the front side thereof with which a semaphore 19 is arranged to register to indicate the existence of overload conditions on the transformer coils. The sema hore 19 comprises a white enameled plate s idably mounted upon vertical standards 32, normally held in raised position and permitted to fall when the temperature of the oil bath reaches a point corresponding to an overload condition upon justably secured to the lower segmental disk 36 through a set screw 39 extended through a slot 41 in the upper segmental disk and screwed into the lower segi'i'iental disk. An adjusting screw 43 is provided for the purpose of moving the upper segmental disk with relation to the lower segniental disln Both disks and 36 are provided with notches 38, 89 through which the supporting spring is pern'iitted to pass when the cam members are rotated under the influence of the heat of the oil bath tl'ireugh the heat responsive coil and spindle as above described. The position of the radial trip edge 45 of the notch 38 in the upper segmental disk 35 with relation to the leaf spring 33 determines the temperature at which the plate 19 will fall into a displaying position. The position of this edge -5 may be conveniently adjusted by the adjustiiw' screw 43. In the preferred embodiment of the invention in which the transformer coils 11 are immersed in a bath of oil, thc position of the edge 45 of the trip member preferably such that the semaphore plate is not displayed until the temperature of the oil bath becomes sufiiciently high to subject the coils to the liability of being burnt out. In this manner the transformer may be sub jected to small overloads or overloads of short duration without causing a display of the semaphore plate, in neither case sui'licient heat being generated to endanger the coils.

Provision is made for resetting the semaphore plate and for this'purp se a lever 40 provided with a pin 42 is adapted to engage the under surface of the plate and is pivoted upon a bracket 44: upstanding from the bottom of the semaphore box. The bracket is provided with a forked member 48 between the arms of which the lever moves, and a slidable plunger 50 is extended downwardly through the bottom wall Lof the semaphore box and projects a sufficient distance from the bottom of the box to enable an operator or inspector to push up the plunger to cause the lever to swing about its pivot through a sutficient arc to raise the plate. As the plate is raised the spring 33 resumes its position on the upper surface of the cam 35 substantially as shown in Fig. 3,

From the description thus far it will be apparent that the present construction of transformer permits determination of the fact that the transformer coils have been subjected to overload. resetting the semaphore the character of the overload may be determined, that is, repeated indications of an overload condition would indicate that the transformer did not pos sufiicient capacity for the load upon the particular line. On the other hand if the semaphore is not again displayed after having been reset, then it may be assumed that the overload was due to a particular excessive consumption of power and that the transformer is not normally subjected to overload.

The employment of transformers embodying the present invention will successfully eliminate the burn-outs experienced at the 'esent time by practically all of-the electrictransmission companies, so that the cost of replacing the damaged transformer is eliminated as well as the loss of revenue incident to the interruption of the electric service. l u'tliermore, transformers embodying the sent invention of approximately 25' per cent less capacity than those at present employed, may be used for the reason that more accurate control and inspection may be had of the transformers when in use. This resultsnot only in the saving of the initial expense of installation but is also accompanied by a direct saving in the operating expense of the transformer because of the decreased no load loss.

It will be observed that a feature of importance lies in the fact that the rockable trip-member 35 is free atall times to be moved to abnormal position and back to normal position without regard to the position of the semaphore, so that the trip-plate may return to normal position while the (:IGl'l'lftPllOIG is in its Warning position, whereby the said trip-plate will be in proper position to lock the semaphore up when it is raised to non-warning position by the inspector. It will be observed further that the detent 83 is made yieldable at its lower free end in order that it will be cammed outwardly as it passes by the tripanember in raising the semaphore and will snap over upon the top side of the trip-member when the semaphore reaches its non-warning position. I

An additional advantage of transformers embodying the present invention resides in the fact that an economical system of in spection is afforded for the reason that an inspector riding along the highway along which the transmission lines are installed, may determine the condition of the transformers without alighting from an automobile. It is estimated that an inspector could conveniently inspect a large number of transformers per day.

Having thus described the invention what is claimed is l. ()verload indicating apparatus for transformers having, in combination, a semaphore, detent on the semaphore, heat re,- sponsive means, a device connected with and actuated by the heat responsive means upon change of temperature for engaging the detent on the semaphore and holding the semaphore from movement within certain lower ranges of temperature.

2. @verload indicating apparatus for transformers having, in combination, a semaphore, heat responsive means, a rod c 0 n nected With the heat responsive means adapted to be actuated thereby upon changes of temperature, said rod being provided With two disks, one rigidly secured to the rod and the other adjustably secured to the first disk, said latter disk having a notch to permit a projection on the semaphore to pass therethrough upon the attainment of a predetermined temperature.

3. Overload indicating for apparatus transformers having, in combination, a semaphore, a spring tongue attached to the semaphore, heat responsive means, a rotary element connected With and actuated thereby, providing a surface adapted to be en gaged by the spring tongue on the semaphore to hold the latter from movement until the attainment of a predetermined temperature.

T. DONALD ADAIR, JR.

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