US2046979A - Transformer switching arrangement - Google Patents

Description

July 7, 1936. H. R. TURNER TRANSFORMER SWITCHING ARRANGEMENT 3 Sheets-Sheet 1 Filed Oct. 9, 1934 Fi gl.

is Attorney.

July 7, 1936. 1-1. R. TURNER 2,046,979

TRANSFORMER :SWITCHING ARRANGEMENT Filed Oct. 9, 1934 3 Sheet-Sheet 2 Fig. 2.

Inventor Harold R Turner.

is Attorney July 7, 1936. H. R. TURNER TRANSFORMER SWITCHING ARRANGEMENT 3 Sheets-Sheet 5 Filed Oct. 9, 1934 m nun-v11,

lnventov Havold R Turner,

g Attorney.

c m 7/4 iiTill W Patented July 7, 1936 UNITED STATE TRANSFORMER SWITCHING ARRANGE- MENT Harold R. Turner, Pittsfield, Mass, assignor to General Electric Company, a corporation of New York Application October 9, 1934, Serial No. 747,520

18 Claims.

My invention relates to improvements in transformer switching arrangements and more particularly to improvements in arrangements for connecting transformers to feeders, grounding transformers and feeders under predetermined conditions and changing the transformation ratio. An object of my invention is to provide an improved transformer switching arrangement which, with minimum space and insulating fluid requirements, insures maximum safety and accessibility without greatly increased cost.

Transformers used in secondary network systems are usually placed in vaults which are frequently located in buildings. Such transformers have been provided with junction boxes mounted on the outside of the transformer casing and the feeder connections led inthrough the floor of the vault to the junction box. The junction box contained the connections for the feeder, usually a cable, and these connections were accessible only upon removal of the junction box cover and the insulating liquid. The junction box sometimes contained a switch for grounding the transformer under predetermined conditions. In order to prevent operation of the grounding switch while the transformer is energized, an electromagnetically controlled lock was provided, the electromagnet being mounted either in the junction box or in the transformer where it was not only not readily accessible but also was an electrical hazard. The transformers have also been provided with ratio adjusters. In order to prevent operation of the ratio adjusters while the transformer was energized, there has been provided over the ratio 85 adjusting switch handle a cover which could not be removed unless the grounding switch was in the grounding position. This arrangement was not entirely satisfactory because the ratio adjusting switch could be left in an off-tap posi- 40 tion and the grounding switch operated at will. Oil was used as an insulating and cooling fluid and the transformer and junction box required a large volume of oil. Obviously, the fire and explosion hazards placed many structural limita- 45 tions on both the location and construction of the vaults. These limitations-were not conducive toeither simplification of structure or convenience in location of the vaults.

In order to insure greater safety from explosions and fire, there has been'developed a noninfiammablc. and non-explosiveinsulating liquid composed of certain halogenated hydrocarbons.

But the cost of this is so much greater than the cost of oil as to render its use practically pro.- 55 hibitive in the prior transformer switching arrangements because of the great volume of insulating liquid required by the transformer and junction box. In order to take advantage of the safety features of this insulating liquid with the greatest economy and simplification in struc- 5 ture, I provide, in accordance with my invention, an improved transformer switching arrangement in which the feeder connections, grounding switch and ratio adjusting switch are all mounted within the transformer, thereby eliminating the junc- 10 tion box and the space required by it in the vault, as well as the insulating liquid necessary to fill it. Further, by a more compact arrange- I ment of parts, the volume of the transformer itself is reduced. Also in accordance with my 15 invention, I so arrange the feeder connections and the grounding switch as conveniently to arrange for bringing the feeder into the vault 'near the ceiling and as to be accessible for inspection and maintenance of those parts most likely to 20 need attention or renewal. I further provide a positive interlocking arrangement between the grounding switch andthe ratio adjusting switch such that the latter must definitely be in one of its tap operating or switch closing positions 25 before the grounding switch can be operated. Moreover, I provide for the ratio adjusting switch a further improved locking means which is independent of the groundingswitch mechanism. In order to reduce the electrical hazard'ao of the electromagnet for locking the grounding switch against operation while the transformer is energized, I provide an improved grounding switch actuating mechanism which is mounted on the outside of the transformer casing so as to be isolated from the transformer proper and to be more conveniently accessible for inspection and maintenance.

My invention will be better understood from the following description when considered in con- 40 nection with the accompanying three sheets of drawings, and its scope will be pointed out in the appended claims.

In the accompanying sheets of drawings, Fig. 1 represents in perspective, with part of the casing broken away. a transformer embodying my invention; Fig. 2 is a part perspective and a part diagrammatic illustration-of a transformer switching arrangement embodying my invention as illustrated in Fig. 1; Fig. 3 is an elevation illustrating how certain contacts of my switching arrangement may be removed for inspection and renewal; Fig. 4 is a perspective view partly in section illustrating the isolated phase contact mounting for the terminal and grounding contacts of my switching arrangement; Fig. 5 is a v perspective view with parts broken away illustrating my improved grounding switch actuat= ing mechanism; and Fig. 6 is a plan view illustrating my improved arrangement for locking the ratio adjusting switch handle independently of the grounding switch mechanism.

Referring now particularly to Figs. ii and 2, a liquid-immersed, self-cooled transformer is shown as having low-voltage windings iii, tapped high-voltage windings M, a ratio adjusting switch i2, and also within the transformer casing E3, in accordance with my invention, a grounding switch it, contact means H5 for line terminals I6 connected to the terminals of the high-voltage windings and engageable by the grounding switch it, actuating means it for the grounding switch and interlocked therewith actuating means it for the ratioadjusting switch, and eleetromagnetically controlled means it for preventing the closing of the grounding switch !4 while the transformer is energized. Further in accordance with my invention, for compactness, simplicity and accessibility, the contact means i5, the grounding switch it and the ratio adjusting switch it together with the actuating means for these switches are mounted on a suitable support such as the frame 9 within the easing l3, as more clearly shown in Figs. 1 and 3.

As shown, the contact means it comprises a pair of interconnected contacts for each phase of the circuit. Also as illustrated, the contacts it are of the segmental garter-springsockettype,the

corresponding segments of each pair being interconnected by flexible leads 2b in such a way that the forces produced by the circuit currents tend to increase the contact pressure. In Fig. 2, for simplicity, only one lead Zil is shown for each phase, but it is to be assumed that there is an interconnecting lead for the corresponding segments of each pair, as shown more clearly in Fig. 4. For cooperating with each upper socket contact l5, the line terminals iii are provided with plug contacts 2| which are suitably secured to the line feeder conductors 22, usually cables, and the insulation tapered to form a bushing, as shown in Fig. 3, in order to grade the voltage stresses.

In order that the contact means l5 of eachphase may be suitably isolated and at the same time readily removable through the openings 23 in the top of the transformer for inspection and maintenance, they may be mounted in an insulating cylinder 21 which is removably secured to a supporting cylinder 28. This may be of insulating material suitably fastenedto the frame 9, as shown more clearly in Fig. 4. In order that the contacts l5 may be readily removable the cylinder 21 may be provided with an inset metallic portion such as the threaded collar 29 which screws into a terminal ring 30 secured to the cylinder 28. The collar 29 is so secured to the collar 21, by lugs and pins as shown for example, as 'to prevent relative movement. Similarly, the terminal ring 30 is so secured to the cyl- The line terminals 96 withthe contacts 2| are insertable in the upper contacts I5- inder 2b as to prevent relative movement, for example by lugs and pins as shown, engaging a sleeve 30 whichis rigidly secured to the cylinder 28. Each terminal ring 38 may be provided with a suitable stud connector 32 to which the high voltage windings M are connected. The seg-' ments of the contacts 55 are maintained in proper alignment and the contacts suitably spaced by sleeves 33, 34 and 35, which may be of insulation. The inner connectors 20 extend to the collar 29. The upper sleeve 35 may be secured to the cylinder 2i by pins as shown and may be tapered to fit the line terminal bushing. In order to remove the whole assembly within and including the cylinder 21, this cylinder may be provided with a metal collar 36 which is suitably secured to the cylinder 21 and provided with suitable means, such as notches 31', which are engageable by projections on a T-wrench 38 insertable through the openings 23 as shown in Fig. 3. observable that the whole contact assembly is readily removable for inspection and repairs and that a whole new unit may be quickly substituted for one which has outlived its usefulness. In order that the grounding switch contacts 26 may likewise be readily removable, the supporting movable member M for these contacts may be made of metal and tapped to receive the lower threaded ends of the contacts 26. These contacts are provided with a suitable enlarged portion which is engageable by the head of a T- wrench 39 insertable through the openings 23. Thus any one of the contacts 26 can be readily removed and replaced without any necessity for taking the transformer apart.

As shown, the actuating means for the grounding switch comprises an operating member such as the crank 40 which is secured to the shaft l1, cranks 42 secured to the shaft 4!, and links 43 interconnecting the cranks 42 with the movable contact supporting member M of the grounding switch. The member I4 is provided with guides 44 which slide in suitable guideways 45 in the frame 9.

In order to prevent operation of the grounding switch when open while the transformer is energized, I provide electromagnetically controlled means for preventing movement on the grounding switch actuating mechanism if the transformer is energized. As shown, this means comprises an It will thus be ing member is arranged to engage a recessed portion associated with the operating shaft l'l. long as the magnet winding 46 is energized to hold the locking member 41 in the locking position and the grounding switch is open, the crank 40 can not be turned in the direction of the arrow 48 to close the grounding switch. Upon 4168111 ergization of the magnet winding 46, the counter-' weighted armature I 9 raises thelocking member 41 to release the shaft I'I so that it can be rotated in the direction to close the grounding switch. U

While the locking mechanism. above described is generally satisfactory, it has the disadvantage of being completely within the transformer casing. It is therefore not conveniently accessible and the magnetwinding introduces an electrical hazard which is not desirable. Accordingly, I prefer, in accordance with my invention, to use the operating handle mechanism shown in Fla-75 till purposes of illustration.

amaova 5 because this mechanism is entirely self-contained and mounted exteriorly of the transformer. In this mechanism the crank or handie lever is secured to a stub shaft it which is bifurcated at the inner end to engage a suitably flattened portion, not shown, on the shaft IT. The stub shaft of each is provided with a projecting portion which may be in the form of a cam so shaped as to be engaged by a locking member 5| mounted in the path of movement of the cam to the end connected to be actuated in response to the movement of the armature 52 of the electromagnet 53. In Fig. 5, the locking member 5i is shown in the releasing position, for clearness of illustration. This locking member is rotatively mounted in the frame 5 3 of the operating mechanism and for simplicity may be mounted to rock on its circular end portion in a correspondingly shaped socket in the frame. The construction and arrangement of the parts is such that the locking member at is subjected only to compression when an attempt is made to turn the shaft in the direction of the arrow 55 while the magnet id maintains the locking member raised into the locking position. The mechanism frame 5d is secured to the transformer casing ill by suitable means, such as bolts tit, only one of which is indicated in Fig. 5. In order mechanicaly to lock the operating mechanism in either one of itstwo positions, there may be provided a sliding bar loci: bl which is carried by the operating lever it and is arranged to engage holes oil in the frame 56. Cooperating with the sliding bar lock Ell is an eye member 59 carried by the operating lever it, and a padlock inserted through the eye in this member and the eye in the member Ell serves to secure the switch in either of its two positions so that the switch cannot be operated while padlocked. The connecting lead tt from the low voltage winding extends through suitable insulation in the wall of the transformer casing 113 and thence through the frame to the electromagnet it will accord ingly be clear that with the mechanism so ar= ranged any faults in the winding of the electro= magnet do not spread to the transformer and the whole mechanism is conveniently accessible without disturbing anything within the transformer.

The actuating mechanism tor the ratio adjusting switch i2 comprises a cranlr. such as a handle lever 6i secured to the shaft ill, a shaft 62 suitably geared to the shaft it and gears [63 and Lid for rotating the movable contacts d5 of the ratio adjusting switch into any one of the various on-tap positions, three being shown'tor The contacts E55 may be mounted within insulating cylinders designat ed by the number i2 in Fig. l. The handle lever 6i may, in accordance with my invention, include an extension 636 which is retractable in the part 63 and, as shown in Fig. 6, a cover provided with pockets or recesses for so receiving one end or the handle that the ratio adjusting switch must be in a definite on-tap position before the cover bl] can be bolted in place against the side of the transformer casing it, the bolt holes for the cover being so spaced as to permit mounting the cover in only one way.

In order to prevent operation of the ratio adlusting switch l2 while the grounding switch is open, I provide a positive interlock between the actuating means of these switches, such that, even when the grounding switch actuating mechill in the cam it only when the grounding switch is in the grounding position.

Referring now to Fig. 2 for the operation of my invention, it will first be assumed that the transformer is energized and that the parts are positioned as shown. If now for any reason it becomes desirable to work on the transformer either for inspection, renewal of parts or changing the tap setting, it will first be necessary to deenergize the transformer in order to release the lock F on the actuating mechanism of the grounding switch. The transformer is deenergized by opening the circuit breaker in the feeder 22 at the supply station and opening the network cir= cult breaker on the low voltage side of the transformer. The network circuit breaker and its associated relay mechanism may be mounted in a casing l5 secured to the transformer, as shown in Fig. 1. As soon as the transformer is deenergized, the electromagnet so no longer retains its armature i9 and the adjustably mounted coun terweight 'lti thereon raises the locking member ll from its recess on the shaft ill. The operating crank to may then be turned in the direction of the arrow 68 to close the grounding switch. When the grounding switch is closed, the notch it on the shaft li is in the plane of the cam it and the shaft it? so that the actuating mechanism of the ratio adjusting switch can be operated upon removal of the cover til. Accordingly, the tap position may be varied, but in any case some one of the notches 72 must be definitely positioned in the plane of the earn it; otherwise, it will not be possible to open the grounding switch.

' If it is desired to examine the contacts it or the contacts 2i; oi the grounding switch, these may be removed in the manner heretofore described and repairedii found necessary, or new ones substituted. It is to be noted that all this can be done without material disturbance to the transformer, since it is merely necessary to remove the end bells and the plate in order to gain access to the contacts i5 and 26.

While "i have shown and described my invention in considerable detail, i do not desire to be limited to the exact arrangements shown, but seal: to cover in the appended claims all those modifications that iali within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

l. in combination with a transformer and a casing therefor, a switch within said casing operative in one position to ground the high voltage windingoi the transformer and means for actuating said switch mounted on the outside of said casing and including an operating shaft extending through said casing and means for preventing movement of said'shaft in a dimotion. to move the switch to the grounding position while the transformer is energized including an electromagnet connected to be energized from the transformer, a projection on said shaft, a locking member mounted for of said casing and including electromagneticallycontrolled means energized from the transformer for preventing actuation of the switching means to the grounding position while the transformer is energized.

3. In combination with a transformer and a casing therefor, a switch within said casing operative in one position to ground the high voltage winding of the transformer and means for actuating said switch mounted on the outside of said casing and including an operating member and means for preventing movement of said member in a direction to move the switch to the grounding position when the transformer is energized,'including an electromagnet connected to be energized from a low-voltage winding of the transformer.

i. In combination with a transformer and a casing therefor, a grounding switch within said casing, an operating mechanism for said ground ing switch mounted exteriorly of said casing and comprising a shaft, and means for preventing rotation of said shaft under a predetermined condition of the transformer including a projection on said shaft, a member movable in the plane of rotation of said projection and engageable thereby only under compression when the shaft is turned in one direction and the member is in a predetermined position and electromagnetically controlled means for moving said member into said position connected to be energized from the transformer.

5. In combination with a polyphase transformer and a casing therefor, a frame mounted within said casing and switching means mounted on said frame and comprising an isolated pair of interconnected contacts for each phase,'each pair being respectively connected to a phase winding of the transformer, phase conductor terminal contacts respectively engageable with one of the contacts of each of said pairs, a grounding switch comprising a movable bridging member of conducting material connected to ground, a contact for each phase mounted on said member and means for actuating said member to move the contacts mounted thereon into engagement with the other contact of said pairs whereby to ground the transformer windings connected thereto and said conductor terminals.

6. In combination with a polyphase transformer and a casing therefor, a frame mounted within said casing and switching means mounted on said-frame and comprising an isolated pair of interconnected contacts for each phase, each pair being respectively connected to a phase winding of the transformer, phase conductor terminal contacts respectively engageable with one of the contacts of each of said pairs, a grounding switch comprising a movable member, a contact for each phase mounted on said member and grounded and means for actuating said member to move the contacts mounted thereon into engagement with the other contacts of said pairs whereby to ground the transformer windings connected thereto and said conductor terminals.

aocacrc 7. In combination with a polyphase transformer and a casing therefor, a frame mounted within said casing and switching means mounted on said frame and comprising an isolated pair of interconnected contacts for each phase, each pair being respectively connected to a phase winding of the transformer, phase conductor terminal contacts respectively engageable with one of the contacts of each of said pairs, at groundting switch comprising a movable bridging member of conducting material connected to ground, a contact for each phase mounted on said member, means for actuating said member to move the contacts mounted thereon into engagement with the other contact of said pairs whereby to ground the transformer windings connected thereto and said conductor terminals, means for preventing movement of said member while the transformer is energized, a ratio adjusting switch connected to the transformer windings which are connected to the pairs of contacts, means for actuating said ratio adjusting switch and means interlocking the actuating means for said member and the actuating means for said ratio adjusting switch for permitting actuation of the .ratio adjusting switch only when the grounding lllll) switch is in the grounding position. 1'

8. In combination with a polyphase transformer and a casing therefor, a frame mounted within said casing and switching means mounted on said frame and comprising an isolated pair of interconnected contacts for each phase, each pair being respectively connected to a phase winding of the transformer, phase conductor terminal contacts respectively engageable with one of the contacts of each of said pairs, a grounding switch comprising a grounded movable contact for each phase, means for actuating said movable contacts into engagement with the other contact of said pairs whereby to ground the transformer windings connected thereto and said conductor terminals, means for preventing movement of said grounding switch contacts while the transformer is energized, a ratio adjusting switch connected to the transformer windings which are connected to the pairs of contacts, means for actuating said ratio adjusting switch and means interlocking the actuating means for said grounding switch contacts and the actuating means for said ratio adjusting switch for permitting actuation of the ratio adjusting switch only when the grounding switch contacts are in the grounding position.

9. In combination with a transformer and a casing therefor, switching means mounted within said casing and comprising a pair of interconnected contacts connected to a winding of the transformer, a conductor terminal contact insertable through said casing and engageable with one contact of said pair, a switch comprising a movable contact connected to ground and means for actuating said movable contact into engagement with the other contact of said pair whereby to ground the transformer winding connected thereto and said conductor terminal, means for preventing movement of said movable contact while the transformer is energized, a ratio adjusting switch comprising actuating means therefor and means interlocking the actuating means for said movable contact and the actuating means for said ratio adjusting switch for permitting actuation of the ratio adjusting switch only when the movable contact is in engagement with the other contact of said pair.

10. In combination with a transformer and a casing therefor, switching means mounted within aosaovo said casing and comprising a pair of interconnected contacts connected to a winding of the transformer, a conductor terminal contact insertable through said casing and engageable'with one contact of said pair, a switch comprising a movable contact connected to ground and means for actuating saicl movable contact into engagement with the other contact of said pair whereby to ground the transformer winding connected thereto and said conductor terminal contact.

11. In combination with a transformer and a casing therefor, switching means mounted within said casing and comprising contact means connected to a winding of the transformer, a terminal contact insertable through said casing and engageable with said contact means, a switch comprising a movable contact connected to ground and means for actuating said movable contact into engagement with said contact means whereby to ground the transformer winding connected thereto and said terminal contact.

12. In combination with a transformer and a casing therefor, a readily removable housing supported within said casing and withdrawable through an opening therein, contact means carried by said housing, a terminal contact insertable through said casing opening to engage said contact means, a readily removable contact movably supported within said casing and engageable upon a predetermined movement in one direction with said contact means and means for removing said movable contact through said casing openmg.

13. In combination with a transformer and a casing therefor, a readily removable insulating housing supported within said casing and withdrawable through an opening therein, two inter-' connected socket contacts carried by said housing, a plug contact insertable through said casing opening to engage one of said socket contacts, .a readily removable plug contact movably supported within said casing and engageable upon a predetermined movement in one direction with the other of said socket contacts and means for removing said movable plug contact through said casing opening subsequently to the removal of said housing.

14. In combination with a transformer and' a casing therefor, readily removable contact means supported within said casing and withdrawable through an opening therein, a terminal contact insertable through said opening to engage said contact means, a readily removable contact movably supported within said casing and engageable with said contact means on a predetermined movement in one direction and means for removing said movable contact through said casing opening subsequently to the removal of said contact means.

15. In combination with a transformer and a casing therefor, a readily removable socket con tact means supported within said casing and withdrawable through an opening therein and a cooperating plug contact insertable through said casing opening to engage said socket contact means.

16. In combination with a transformer and a casing therefor, a readily removable socket contact means supported within said casing and withdrawable through an opening therein, a. cooperating plug contact insertable through said casing opening to engage said socket contact means, and a readily removable plug contact means removably supported within said casing substantially in alignment with said cooperating socket and plug contact means and engageable with the socket contact means upon a predetermined movement in one direction.

17. In combination with a. transformer and a. casing therefor having a cover provided with an opening, a readily removable socket contact means insertable through said cover opening and.

supported within said casing, and a cooperating plug contact insertable through said cover opening to engage said socket contact means.

18. In combination with a transformer and a casing therefor, readily removable contact means supported within said casing and withdrawable through an opening therein, a contact readily removable through said opening movably sup ported within said casing and engageable with said contact means on a predetermined movement in one direction, and means for effecting the movement of said movable contact.

HAROLD R. TURNER.

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