US3462645A - Electrical transformer suitable for pole or vault mounting - Google Patents

Description

Aug. 19, 1969 M. G. LEONARD ELECTRICAL TRANSFORMER SUITABLE FOR POLE OR VAULT MOUNTING 2 Sheets-Sheet 1 Filed June 9, 1967 Aug. 19, 1969 M. G. LE-ONARD ELECTRICAL TRANSFORMER SUITABLE FOR POLE OR VAULT-MOUNTING Filed June 9 1967 2 Sheets-Sheet 2 QB IA Av.

lot-O FIG. 2

United States Patent 3,462,645 ELECTRICAL TRANSFORMER SUITABLE FOR POLE 0R VAULT MOUNTING Merrill G. Leonard, Fowler, Ohio, assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., :1 corporation of Pennsylvania Filed June 9, 1967, Ser. No. 644,948 Int. Cl. H02h 7/14 U.S. Cl. 317-l5 6 Claims ABSTRACT OF THE DISCLOSURE An electrical distribution transformer which facilitates either pole or vault mounting. The high voltage terminals are recessed, and allow either pole type or vault type bushings to be used therewith. A channel type hanger lug for pole mounting also provides the functions of concealing and protecting the interconnections between the low voltage leads of the transformer and the secondary circuit, and conceals and protects a rod which is connected to the actuator of the transformer protective circuit breaker.

Background of the invention Field of the invention.The invention relates in general to electrical distribution type transformers, and more specifically to distribution type transformers which are suitable for either pole or vault mounting.

Description of the prior art.-In the prior art, distribution transformers for underground or vault use are quite different in their finish and hardware, from distribution transformers for pole mounting. This distinction in the transformers for the different environments, not only adds to the complexity of manufacturing distribution type transformers, but creates stocking problems for both the manufacturer and user. Further, it requires that transformers now in service on poles, be replaced when the service is changed to the underground type. It would, therefore, be desirable to provide a new and improved electrical distribution type transformer which is suitable for pole mounting, or for vault mounting, and should be easily convertible in the field from one type mounting to another. However, this object should not be accomplished at the expense of making the versatile unit non-competitive price-wise with prior art single purpose type apparatus.

Summary of the invention The invention is a new and improved distribution type transformer which may be pole or vault mounted, and once pole or vault mounted, may be easily converted by field personnel from one type mounting to the other. The transformer includes a substantially U-shaped channel type hanger or mounting lug for pole mounting, which also functions to conceal the connections between the transformers secondary leads and the overhead line drop, when pole mounted, and which also allows the secondary leads to be lifted therefrom when the transformer is vault mounted. The low voltage bushing is disposed on the cover of the transformer, directly above the hanger lug, and contains a plurality of secondary leads which are long enough to extend into the hanger lug. Also, disposed through the low voltage bushing is the actuating mechanism for operating the transformers protective circuit breaker. This actuating mechanism includes a rod member which is disposed vertically downward through the hanger lug, and is accessible from below by hookstick, if pole mounted. The actuating mechanism also contains a portion which may be operated by hook-stick from above, in the event the transformer is vault mounted.

The high voltage bushing, or bushings, consist of two 3,462,645 Patented Aug. 19, 1969 separable parts. The first part comprises a hollow tapered sleeve, which is sealed in the cover of the transformer, and extends inwardly into the transformer casing, and a second part which is removably insertable into the first part, with electrical contact being made between the first and second parts within the hollow body portion of the first part. If the transformer is to be pole mounted, the second part is a bushing assembly containing the necessary hardware for connection to an open line. If the transformer is to be vault mounted, the second part is a bushing assembly adapted for connection to shielded cable.

The transformer also includes a stainless steel mounting base, which enables it to withstand rough handling without scraping and scuffing its protective finish, which would cause corrosion problems, especially if the transformer is vault mounted.

Brief description of the drawings Further advantages of the invention will become more apparent when considered in view of the following detailed description and drawings, in which:

FIGURE 1 is a front elevational view of a transformer constructed according to the teachings of the invention;

FIG. 2 is a plan view of the transformer shown in FIG. 1;

FIG. 3 is a fragmentary, side elevational view of the transformer shown in FIG. 1; and

FIG. 4 is a cross-sectional view of a high voltage bushing assembly which may be used by the transformer shown in FIG. 1.

Description of the preferred embodiments Referring now to the drawings, and FIGS. 1, 2 and 3 in particular, there is shown front, plan and side views, respectively, of an electrical distribution type transformer 10 constructed according to the teachings of the invention. In general, transformer 10 includes a tank or casing 12 which includes side wall portion 14 joined and sealed by bottom portion 16, and a top portion or cover 18. A high voltage bushing assembly 20 is mounted in sealed engagement with the cover 18, through a suitable opening therein. High voltage bushing assembly 20, as will hereinafter be described in greater detail, includes first and second parts or portions 22 and 24. The first portion 22 is sealingly mounted through the cover 18, and the second portion 24 is removably inserted into portion 22, making electrical contact with each other within the body of portion 22. Also shown in FIGS. 1 and 2 is the first portion 26 of another high voltage bushing assembly, without the second portion being shown.

A single, molded type low voltage bushing 30 is dis posed in sealed engagement through an opening in cover 18. Low voltage bushing asembly 30 includes secondary leads 32 and 34, which are molded or cast into bushing 30, and which extend outwardly from a first portion of the low voltage bushing. The secondary leads 32 and 34 are electrically connected, within the body portion of the bushing 30, to mounting studs or terminals 36, shown in phantom in FIG. 3, which extend from a second portion of the bushing 30, into casing 12. As shown most clearly in FIG. 3, the direction in which the secondary leads 32 and 34 extend from low voltage bushing 30, is substantially perpendicular to the direction in which the terminals 36 extend from the bushing.

Low voltage bushing 30 also contains an actuating mechanism 38, which extends through the molded or cast low voltage bushing 30 to operate the transformer protective circuit breaker 51, shown in FIG. 2, if a circuit breaker is used. The actuating mechanism 38 may be made rotatably actuable while retaining a seal through the bushing 30, by using the teachings disclosed in co-pending application Ser. No. 595,698, filed Nov. 21, 1966, by A. Keto,

which application is assigned to the same assignee as the present application. The low voltage bushing 30 is disposed adjacent one edge of the cover 18, on a portion of the cover which makes an angle of substantially 30 with a line perpendicular to a vertical axis through the transformer 10. This allows the actuating mechanism 38 to be disposed through bushing assembly 30 in a direction perpendicular to the vertical axis of the transformer 10, it allows the terminals 36 to be easily accessible within the transformer casing 12 for connection to the winding assembly, and by bringing out the secondary leads 32 and 34 in a direction which is substantially 90 to the direction of bringing out the terminals 36, the secondary leads may be directed along the side wall portion 14 of the casing 12, for purposes which will be hereinafter explained.

Transformer also includes a new and improved substantially U-shaped channel hanger lug member 40, with the leg portions of the hanger lug being fixed to the side wall portion 14, directly below the low voltage bushing assembly 30. The hanger lug 40, in addition to being used for mounting the transformer 10 on a utility pole, has many other functions which will be hereinafter explained.

Transformer 10 also has a stainless steel bottom support structure 42, which protects the bottom portion 16 of the transformer 10 from scrapes and abrasions due to handling of the transformer. It is important that the protective finish on the transformer casing be protected, as any scrapes or abrasions may start corrosion, especially if the transformer is mounted underground. The stainless steel support will take the handling abuse, without damage to the protective coating on the side wall portion 14 and bottom portion 16, of the transformer 10.

Transformer 10 includes a magnetic core-winding assembly 41, comprising a winding assembly 44, which includes both the high and low voltage coils, disposed in inductive relation with magnetic core assembly 46, with the assembly being shown in phantom in FIG. 1. The magnetic core-winding assembly 41 is disposed within casing or tank 14, and the tank 14 may contain a suitable insulating and cooling fluid, such as oil, for cooling and insulating the magnetic core-winding assembly 41. The winding assembly 44 includes a plurality of high and low voltage leads or conductors (not shown), which are connected to the high and low voltage coils of the winding assembly, and to the internal mounting terminals of the high and low voltage bushing assemblies. The number of high voltage bushings and low voltage secondary leads shown in the figures is for purposes of example only. It will be understood that the invention applies to any number of high voltage bushing assemblies, and low voltage secondary leads. Casing 12 also includes lifting lugs 48 and 50, attached to the cover 18 by any suitable means, such as by welding. The lifting lugs extend outwardly from cover 18, with their projecting portions cooperating with a sling for either lifting the transformer 10 to a pole position, or lowering the transformer into a vault. The lifting lugs 48 and 50 have channel shaped upper portions 52 and 54, respectively, shown most clearly in FIG. 2, with the channels of the two lifting lugs being aligned with one another. Thus, the lifting lugs 48 and 50 provide fixed channel shaped guides for receiving a banding strap, when the transformer is fixed to a shipping pallet. The projecting portions of the lifting lugs 48 and 50 may also include suitable openings 99 and 101, respectively, which may cooperate with a bolt to secure a grounding lead. If it is not desirable to continue the banding strap across the top of the transformer, the projecting portions of the lifting lubs 48 and 50 may also contain suitable slots through which banding straps from the shipping pallet may be looped.

As best shown in FIG. 2, a suitable fitting 89 may be secured to the cover 18 for attaching a valve or expulsion type lightning arrester (not shown).

The high voltage bushings of transformer 10, such as high voltage bushing assembly 20, must be able to receive either a conductor from an open wire circuit, when pole mounted, or a shielded cable when vault mounted. This is accomplished by constructing the high voltage bushing assembly of first and second portions 22 and 24, respectively. The first portion 22 of bushing assembly 20 is standard for either pole or vault mounting, and, as shown in cross-section in FIG. 4, includes a hollow cylindrical body portion 56, formed of an electrical insulating material, such as an epoxy resin system. Body portion 56 has first and second ends, with the first end defining an opening in the body portion, and which also includes an outwardly extending flange portion 58. The second end of body portion 56 is closed, and contains terminal means 60 which extends coaxially through the closed or blind end. Terminal means 60 includes a terminal 62 disposed within body portion 56, of a type which will receive the conductor from the second portion of the bushing. Terminal 62 may have a plurality of projecting finger like mem bars 66 which flexibly engage the conductor of the second portion, when the conductor of the second portion is axially advanced, or rotated into position. Inwardly extending projections on the finger like members 66 may provide a slight interference fit with the conductor of the second portion, and may cooperate with a groove in the mating conductor to lock into the desired position. The inner surface of the body portion 56 may be threaded, such as thread 74, for removably securing the second or insert portion of the high voltage bushing assembly 20. The external surface of the body portion 56 may also be threaded, having threads such as thread 75, for cooperating with a locking nut 76, 'which will secure body portion 56 to the cover 18. A gasket member 78 may be disposed between flange portion 58 and the cover 18 to provide a seal between the body portion 56 and cover 18.

As shown in FIGS. 1, 2 and 3, the second portion 24 of high voltage bushing assembly 20 may be of the type which contains hardware 68 for receiving an open line 70, when transformer 10 is mounted on a utility pole, or, as shown in FIG. 4, the second portion may be an insert 72 adapted for receiving a plug-in shielded cable connector (not shown). If the second or insertable portion of the high voltage bushing assembly 20 is of the type for receiving an open overhead line, insert 24 may have the appearance of a conventional outdoor bushing, having a cylindrical body portion 80 formed of an electrical insulating material, such as an epoxy system, and having a plurality of weather sheds 82 on the weather end of the insert. The end of the insert 24 which extends into the opening in the first portion 22 contains threads 84 on its external surface which cooperates with the threads 74 on the inner surface of the first portion 22. A gasket member 81 may be used to seal the first and second portions of the high voltage bushing assembly 20, when the second portion is threadably engaged with the first portion. In the event the creepage path from terminal means 62 to the grounded casing is not long enough to prevent flashover through the air film between the two portions of the bushing, silicone grease may be used to drive out the air between, the two portions as the insertable portion is placed into position; or, a resilient sleeve may be disposed between the two portions of the bushing assembly, with a bayonet type construction being used to secure the two portions in assembled relation, instead of a plurality of threads.

A cylindrical rod-like conductor 86 extends coaxially through the insert 24, which is connected to hardware means 68 at the weather end of the insert 24, and extends outwardly from the opposite end of the insert 24, with the outwardly extending end being adapted for making an electrical connection with terminal means 62.

If the insertable portion of the high voltage bushing assembly 20 is of the type for receiving a shielded cable, it may be formed similar to the insert 72 shown in FIG. 4. Insert 72 includes a cylindrical body portion 88 formed of an electrical insulating material, such as an epoxy system, and has a conductor portion 90 which extends coaxially therethrough. Conductor portion 90 terminates at the first end of the body portion, which end may be a cylindrical projection for cooperating with a shielded cable connector, and is hollow for receiving a projecting conductor portion of the shielded cable connector. Conductor portion 90 extends outwardly from the opposite end of insert 72, and is adapted for making an electrical connection with terminal 62. Insert 72, like insert 24 shown in FIG. 1, may have threads 92 on its external surface for threadably engaging the internal threads of the first or fixed portion 22 of the bushing assembly 20.

Removable insert 72, instead of being of the type for receiving a shielded cable connector, may also be the end of the shielded cable itself, which contains means for adapting the cable end to fit the fixed or first portion of the bushing assembly. For example, means may be slipped over a prepared cable end which terminates the cable shield in a stress cone, and which also contains means for securing itself within a first portion 22, and for firmly anchoring the shielded cable therein.

Low voltage bushing assembly 30 has a molded body portion formed of a cast resinous insulating material, such as an epoxy resin system, and includes a plurality of low voltage secondary leads, such as leads 32 and 34, which extend outwardly from one side of the bushing, and a plurality of terminals, such as terminal 36, which extends from one end of the bushing assembly 30 into the casing 12. The connection between the low voltage secondary leads and the low voltage terminals is shown in phantom in FIG. 3. As shown in FIG. 1, the length of the secondary leads 32 and 34 should be sufficient to extend well into the hanger lug 40. Bringing the secondary leads 32 and 34 from a side wall portion of low voltage bushing assembly 30, instead of from the end opposite terminals 36, allows the low voltage bushing 30 to be disposed on a sloping portion of the cover 18, and the bringing of the low voltage secondary leads into the hanger lug 40, with only a slight bend.

Low voltage bushing assembly 30, between the secondary leads 32 and 34, or otherwise disposed on the same side of the bushing assembly as the low voltage leads 32 and 34, contains a projecting portion 107, having an outer surface which is substantially parallel with the side wall portion 14 of the tank 12, when the low voltage bushing assembly 30 is in its mounted position. Actuating means 38 is disposed completely through low voltage bushing assembly 30, starting at this projecting portion 107, and extending through the body portion of the bushing assembly 30 into the inner portion of casing 12. The actuating mechanism 38 engages an operating linkage within the transformer casing for operating the circuit breaker 51. The external portion of the operating mechanism 38 includes a first portion 93 in which an operating rod 94 is inserted, which extends downwardly through the hanger lug 40, and ends in a curved portion 96, shown in FIG. 1, which may be reached by operating personnel from below with a hook-stick when the transformer is pole mounted. Curved portion 96 may extend through a slot in the hanger lug 40, with the upper end of the slot being labeled on, and the lower end of the slot being labeled off, so that the operating personnel can tell at a glance the position of the internal protective circuit breaker. The actuating mechanism 38 also includes a portion 98, which forms an opening which may be operated by a hook-stick from above the transformer, when the transformer is vault mounted.

Hanger lug 40 is fixed to the side wall portion 14 of the casing 12, directly below the low voltage bushing assembly 30, and it provides the functions of mounting the transformer on a utility pole, when pole mounted, and also for protecting the connections between the secondary leads 32 and 34 and the line drop conductors, when pole mounted. It also houses the rod 94 for operating the actuating mechanism 38 for the protective circuit breaker,

and serves as a guide and indication for the operating rod to indicate the position of the circuit breaker.

Hanger lug 40 is substantially channel shaped, as shown most clearly in FIG. 2, having first and second leg members and 102 which are fixed to the side wall portion 14 of transformer 10, and with the sides of the leg members opposite to the side wall portion 14 being joined by back portions 104 and 106. Back portions 104 and 106 have slotted portions 108 and 110, respectively, for receiving mounting bolts, shown in phantom at 112 and 114, when the transformer is pole mounted. The back portions 104 and 106 are vertically spaced apart, in order to allow secondary leads 32 and 34 to be brought out from the hanger lug, when the transformer is vault mounted, for connection to the underground secondary circuit, and also to allow room for connections to be made to the secondary leads by the line drop when pole mounted. When pole mounted, the interconnections between the secondary leads 32 and 34 and the line drop are placed within the protective confines of the hanger lug 40. long enough to extend to the secondary distribution line. If desired, the secondary leads 32 and 34 may be made in which case the hanger lug 40 serves to conceal the secondary leads.

Thus, during manufacturing and assembly of transformer 10, the basic transformer may be assembled without the insertable portion of the high voltage bushing assembly 20, and therefore without regard to whether the transformer is to be pole or vault mounted. The user may also order and stock the basic portion of the transformer without regard to its intended environment. Then, when the transformer is placed in service, it is only necessary to select the type of insert for the high voltage bushing assembly demanded by the particular application. Once installed in a particular application, the transformer 10 may be easily converted to another environment, by merely replacing the high voltage bushing insert with the type demanded by the new environment.

In summary, there has been disclosed a new and improved electrical transformer of the distribution type, which may be either pole or vault mounted, and once installed, may be easily converted from pole to vault mounting, or from vault to pole mounting, by field personnel. By combining many functions into certain components, the transformer is able to provide excellent service, as well as operating convenience, while either pole or vault mounted, without deleteriously affecting the cost of the versatile unit, as compared with a single purpose unit. For example, the hanger lug not only provides pole mounting means which is pleasing to the eye, but it protects and encloses the interconnections between the secondary leads and the line drop, it allows the removal of the ends of the secondary leads from the protective enclosure when the transformer is to be vault mounted, and it protects and serves as a guide for the operating rod for the circuit breaker actuating mechanism, which operating rod is accessible from below.

The high voltage bushing assembly includes a fixed universal portion mounted in the transformer, which allows quick assembly with an insertable portion containing the necessary hardware for receiving the type of incoming line the transformer is to be connected to.

The low voltage bushing assembly is a one-piece molded assembly which includes secondary leads, terminals for connection to the internal secondary circuit of the trans former, and an actuating mechanism for the protective circuit breaker which may be operated from above or below the transformer.

The transformer tank 12 includes a stainless steel bottom portion which prevents the protected portion of the casing from being damaged during handling, and thus enables the corrosion resistant finish on the transformer casing to perform its function without danger of its being impaired due to the handling of the transformer. When 7 vault mounted, the stainless steel mounting support provides an excellent mounting ring for supporting the transformer within the vault.

Finally, the lifting lugs on the transformer facilitate handling for either pole or vault mounting, and additionally allow the transformer to be banded to a shipping pallet without danger of damaging the finish of the easing 12. The lifting lugs may also provide a convenient grounding point for grounding the transformer casing.

Since numerous changes may be made in the above described apparatus and dilferent embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings, shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. An electrical transformer suitable for either pole or vault mounting, comprising:

a casing having side wall, bottom, and cover portions,

magnetic core means, 7 a winding assembly disposed in inductive relation with i said magnetic core means, said magnetic core means and winding assembly being disposed within said casing,

a low voltage bushing assembly including a body portion having a plurality of electrical leads extending outwardly from a first portion thereof, and a plurality of electrical terminals extending outwardly from a second portion thereof, said low voltage bushing assembly being fixed to the cover portion of said casing, with its electrical leads depending therefrom, its second portion extending into said casing and its electrical terminals being connected to said winding assembly,

at least one high voltage bushing assembly having first and second separable portions, said first portion being fixed to said cover portion and extending through an opening therein, said first portion having terminal means connected to said winding assembly, said second portion including a conductor, one end of which has terminal means removably engaged with the terminal means of said first portion, and the other end of which is adapted for connection to an external conductor,

and a substantially U-shaped channel hanger lug having first and second spaced leg members joined by a back portion having first and second spaced slotted portions which are adapted to receive means for mounting the transformer on a utility pole, the first and second spaced leg members being fixed to the side wall portion of said casing and circumferentially oriented to receive and provide a partial enclosure for the depending leads from said low voltage bushing assembly, the depending leads from said low voltage bushing assembly entering said hanger lug, with the opening between the spaced slotted portions allowing the leads to be lifted therefrom when the transformer is to be vault mounted.

2. The electrical transformer of claim l'wherein the second portion of said at least one high voltage bushing includes terminal means suitable for connection to an open line conductor.

3. The electrical transformer of claim 1 wherein the second portion of said at least one high voltage bushing includes a cylindrical projection surrounding a conductor portion suitable for co-operating with a plug-in type shielded cable connector.

4. An electrical transformer suitable for either pole or vault mounting, comprising:

a casing having side wall, bottom, and cover portions,

magnetic core means,

a winding assembly disposed in inductive relation with said magnetic core means, said magnetic core means and winding assembly being disposed within said casing,

a low voltage bushing assembly including a body portion having a plurality of electrical leads extending outwardly from a first portion thereof, and a plurality of electrical terminals extending outwardly from a second portion thereof, said plurality of electrical leads being connected to certain of the plurality of electrical terminals within said body portion, said low voltage bushing assembly being fixed to the cover portion of said casing, with its second portion extending into said casing and with its electrical terminals being connected to said winding assembly,

at least one high voltage bushing assembly having first and second separable portions, said first portion being fixed to said cover portion and extending through an opening therein, said first portion having terminal means connected to said winding assembly, said second portion including a conductor, one end of which has terminal means removably engaged with the terminal means of said first portion, and the other end of which is adapted for connection to an external conductor,

' a substantially U-shaped channel hanger lug having first and second spaced leg members joined by a slotted back portion adapted to receive means for mounting the transformer on a utility pole, the first and second spaced leg members being fixed to the side wall portion of said casing, forming a partial enclosure for the secondary leads from said low voltage bushing assembly,

a circuit breaker disposed within said casing,

and an actuating mechanism for operating said circuit breaker, said actuating mechanism extending in sealed operable relation through said low voltage bushing into said casing, the end of said actuating mechanism within the casing being connected to operate said circuit breaker, and its external end being operable from above and below the transformer.

5. The electrical transformer of claim 4 wherein said low voltage bushing is disposed adajacent the side of said cover means directly over said U-shaped channel hanger lug, said secondary leads extending into said U-shaped channel hanger lug, and rod means having a first end connected to a first portion of said actuating mechanism, said rod means extending into said U-shaped channel hanger lug, and having a second end which is adapted to be engaged and vertically operated from below the transformer, said actuating mechanism having a second portion operable from above the transformer.

6. The transformer of claim 1 including first and second lifting lugs disposed on opposite edges of said cover portion, said first and second lifting lugs having upwardly extending portions which define channels in said lifting lugs which are aligned with one another, the channels in said first and second lifting lugs being adapted to receive a" banding strap when said transformer is strapped to a shipping pallet.

' References Cited UNITED STATES PATENTS LEWIS H. MYERS, Primary Examiner T. J. KOZMA, Assistant Examiner US. Cl. X.R.

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