US2479468A - Overload indicator - Google Patents

Description

1949- E. s. BUNDY 2,479,468

OVERLOAD INDICATOR Filed Jan. 17, 1947 f I m INVENTOR. EDWlN Smeon BUNDY ATTORNEY Patented Aug. 16, 1949 UNITED STATES PATENT OFFICE OVERLOAD INDICATOR Edwin Simeon Bundy, Hamburg. N. Y., assignor to Line Material Company, Milwaukee, Wis., a

corporation of Delaware Application January 17, 1947 Serial No. 722,516

transformers are mounted on poles and these visual means are not readily noticeable to persons on the ground unless they are specifically looking for the indication.

This invention has for its primary object the" provision of an audible overload indicator for distribution transformers which will give a clearly audible signal designed to attract the attention not only of a lineman who may or may not be looking for the indication, but also will attract the attention of any person in the vicinity and of the customers who will hear the audible indications in their homes as the device is so arranged and associated with the transformer and its casin that a part of the casing, such as the cover, acts as a sounding board. It is expected that the customers or other persons in the vicinity, in turn, will'call up the power company and notify it.

Further objects are to provide a very simple and easily produced device which may be installed in the casing of a transformer with the utmost ease and without requiring any changes in the transformer. The device is held in place by the cover of the transformer, and will coact with the casing of the transformer to give a clearly audible sound when the transformer is overloaded.

Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a fragmentary view partly in section showing the device installed within the casing of a distribution transformer.

-Figure 2 is a fragmentary diagrammatic view of the electrical circuits employed.

Figure 3 is a viewof a modified form of a thermally responsive device.

Figure 4 is a view of a further form of a thermally responsive device.

Referring to the drawings, it will be seen that a distribution transformer has been indicated by the reference character I. This transformer is housed within a casing whose body portion is indicated by the reference character 2 and whose cover is indicated by the reference character 3. The cover is provided with a gasket 4 and is clamped down on to the body portion 2 in any well known manner, not shown. The casing'2 is partially filled with oil, for instance to the level indicated by the dotted line 5. The overload indicating device comprises a hanger 6 which is of bell crank shape and has one arm '1 projecting downwardly and bearing against the inner side of 3 Claims. (Cl. 177-311) the body portion 2 of the casing. The other portion of the hanger carries the audible indicating device indicated generally by the reference character 8. This device may comprise an electromagnet whose energizing winding is indicated by the reference character 9. This energizing windin is wound around a bolt III which forms the core of the electromagnet and terminates in a downwardly projecting head II. A yoke l2 of magnetic material is also held in place by means of the bolt Ill. The bolt I passes through the hanger 6 and thus secures the electromagnet firmly to the hanger. A vibrating armature is indicated by the reference character l3 and is formed of resilient magnetic material. One end is securely fastened to the hanger 6 and the other end is in spaced relation to the head ll of the core or bolt Ill and the yoke l2, the yoke I2 it being noted having its lower end spaced from the head ll of the core.

It is clear that when the electromagnet is energized with alternating current that the armature l3 willvibrate rapidly and will strike a multitude of blows on the head I l of the core or bolt Ill. The resiliency, length and weight of the armature l3 are so chosen that the armature is resonant to the alternating current frequency of the supply circuit.

The hanger B is somewhat resilient and is arranged to force the bolt or core in into firm engagement with the cover 3 so that the impact of the blows is transmitted to the cover 3 and the cover, therefore, acts as a sounding board. A convenient way of securing the hanger in place is to provide it with a hook-like portion l 4 which is hooked over the bead l5 of the body portion 2 of the casing of the transformer and is clamped in place between the cover 3 and the body portion 2 thus securely positioning the hanger and the lectromagnet. The electromagnet has one lead l6 which extends to one side of a thermally responsive device indicated generally by the reference character IT. The other side of the thermally responsive device is connected by means of a lead l8 with one side of a clip type or cartridge type fuse Ill. The other side of the fuse i9 is connected to a bracket secured to the line terminal 2| of the secondary of the transformer. The other lead 22 from the electromagnet is secured to the neutral terminal 23 of the secondary. The leads l6 and I8 and 22 are bound together by suitable clips 24. They are relatively stiff and serve to hold the thermally responsive member in any adjusted position below the level 5 of the oil within the body portion 2 of the casing of the transformer.

The thermally responsive member ll may comprise a U-shaped Bakelite member 25 which has one arm of a U-shaped member 26 formed of conducting material secured to one of the arms of the member 25. The upper ends of the arm of the member 25 overlap and are soldered together aslindicate'd 'at 2l'zby a'lowamelting point solder such as rosemetal 75 C. solder. The member 25 is made of spring metal and the arms of the member 25 tend to spring apart and when the temperature of the oil arrives at a predetermined point, it will melt the solder 21 and allow the free arm of the membersZEztoispr'ingroutwardly to the dotted line position'shown in Figure 1 and engage the terminal 28 to which the lead I8 is attached, and thus closeithe circuitcof'the electromagnet. This causes alternating current to be supplied from the winding of the tranS- former to the electromagnet and causes the armature. l-Moproduceamultitude of. :blows against the'rhead ll *of the 'core ID, the impact fleeing transmitted-to the-cover '3"WhiCh'aCtS. as a sounding rboard :and gives .-adistinctly audible indication of theoverload condition. :.Not-.on1y-wi1la lineman who may or maynot'be looking for this indication be apprised of .the-overloadicondition of thetransformencbut it-has been found that customers or other ,persons :in the vicinity -.will also be .apprised of this condition. :The customers =r persons in the vicinity will, in -turn, notify the power company and suitable steps will be taken to. remedy the overload acondition without delay *thus avoiding a long interruption to service.

The fuse. l9. not onlyacts as a protectingmeans to -protect the1transformer:inthe-event of: failure of the-electromagnetbutalso may be used as -a disconnectingymeans if=so desired.

In the form of the invention showniin Figure 1, after overloadhas occurred,.,theoverload audible indication -.is continuously given until -suitable steps have-been taken to correctuthe condition. However, it may be desired to 'useaother-means whichwill give an audibleindication only :during the overload condition. -Any-.suitable'-means may be employed forthis purpose. For instanca-a thermostatically responsive bellows F29, sec :Figures3, imayebe used. This ibellows -may=be made of -metal =.-and may carrythemovable contacted designed =to engage the stationary :contact -3I when an'overload occurs, the bellows and the contact 5! being suitabl-y supported .on a .U- shaped insulating member :32. If desired abimetal thermostatic member, indicated: by the reference character 33- in'FigureA may: be employed and may..-carry:the movable: contact 34 adapted to engagethe stationary contact :35 upon overload conditions.

Referringto:Figure.-2,-itiwillzbe seen that the transformer 'has "been indicated-generallyby the reference character 4 and is provided Witha .primary 35 and a'secondary 31. :I'hethermallyresponsivamember is indicated; in Figure :2 generally-by'the reference character '11, the fuse at |.9,- and ethe electromagnet generally at '8.

It will be seen thata' novel formof overload indicating means, :particularly suitable 'for distribution transformers, has been provided by this invention which will give 5a distinct audibleindication of the overload condition and .which not only will apprise a lineman :when: in *the vicinity of the transformerwhether heris lookingxfor the indication 'or not, but Will also apprise the customers or-ianyiperson in the vicinityiof the overload condition whogit 'is-expected, will-in turn notify the power "company.

.It'will be "seen that zthe device "can be very cheaply made primarily from standardstock material sand :also :can "be rmosteasily installed in tion of a transformer provided ivitii g easing containing oil, and an overload indicator arrangedito produce an audible sound and com, ising an electromagnet having an armature-arranged to strike blows when the electromagnet is energized 1 by aiternating current andzinolndingi means'for transmitting the: impact ofesaidblows to the casingof the transformer, a portion at least-of said casingibeing.arrangedtto act-as asounding board, andthermally. responsive means-'immersedin-said oil and arranged'toelectrically connect saidaelectromagnetto'the .tr.ansformer when the oil rreaches a-prcdetermined temperature.

'2. The-combination of a transformerprovided with-a scasingncontaim'ng ,oil I and having a body portion and a cover, and an overload indicator arranged toproduce Ql'lr'dlldlblBSOllIldzfiHd comprising an electromagnet and an:armature,'said electromagnet comprising a imainyportion and arr armature: arranged .tostrike-said main; portion a multitude ofblows when; said electromagnetis energized with alternating-:current, a hanger having aportion clampedbetween the" cover and body portion of :said casing andarranged to hold-the main portion .of theeelectromagnet against said cover,-andthermallyresponsive means immersed in the oil 'and :arranged to electrically" connect said electromagnet with the transformer when theoil reachesa predetermined temperature.

- 3. An audible indicator for an encased transformer tcomprising-a hanger arranged to besecured tozthe casingofsa-id transformer; arr-electromagnet carried -.by.-said hanger and having a body portion arranged to be held by. said hanger in 1 contact =With the a casing of said transformer and having an armature:arrangedtmstrike-the body portion .of said electromagnet a-.mu1titude of blows whensaid electromagnet.is energized with alternating current to thereby' cause a portion at=-leastof said casingitoa-ctas asounding board, said armature being resiliently supported and being arranged toresonate with. the alternating current, and means including thermallyi'responsive means arranged :to electrically connect said electromagnet to the. transformer when said thermally responsive means is heatedto a predetermined degree.

EDWIN SIMEO'N BUNDY.

"REFERENCES CITED .The'following"references'areof record in the file .of this patent:

" UNITED STATES PATENTS Number Name Date 1,443,786 aDolph Jan. 30, 1923 1,635;348 i-Samper July12, 192'7 =,1,'71'7 ;216 Isaac June 11, 1929 1,718,216 .Burnham .June 25, 1929 975,459 Holslag Oct. 2, 1934 2,298,126 Hodnette Oct," 6, 1942 2,3195% Treanor May 18, 1943 223251470 .Bonanno July 2'7, 1943 2,327,684 Warrick Aug. 24,1943

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