US1591449A - Electrical transformer - Google Patents

Description

' Acz. M. WELCHY July 6, 1926.

ELECTRICAL TRANSFORMER Filed Oct. 24, 1921 I I l INVENTOR R7' Sm Patented July 6, 1926.

UNITED STATES CHARLES M. WELCH, OF OGDENfARKANSAS.

ELECTRICAL TRANSFORMER.

Application filed October 24, 1921. Serial No. 510,170.

My invention `pertains to improvements in electrical transformers, in which the active elements consisting of induction coils with suitable insulating material and magnetic cores, are operated in a body of insulating fluid within a containing case having supporting means and with outlets to the supply and service connections.

rlhe object of my improvement is:

(l) To provide a light weight, safe, durable and efficient construction, plain, `sensible and rugged, and easy to build at a reasonable cost.

(2) To render the terminals more convenient and secure in making service connections to meet developments in the art of electric wiring.

(3) 'Io secure a simple positive support for the core and coils for making the various parts safe in handling in transportation, removing any possibility of mechanical strainV on the insulation, and rendering the parts accessible in manufacture and repair.

(4) To provide a transformer which can be shipped with the case filled with insulating fiuid. This is intended to protect the coils against absorbing moisture from the atmosphere as often occurs when transformers are shipped dry in an ordinary case.

(5) To secure the abolishment of cast iron in the construction. Cast iron is a poor conductor of heat and breaks easy in handling.

(6) To do away with all tap connections with no looseparts inside the case.

(7) To standardize a line of distributing transformers to maintain a uniform voltage.

(S) To secure a combination structure that will permit design and successful manufacture of small high tension units.

I attain the object by the arrangement illustrated in the accompanying drawings, in which:

Fig. 1, is a vertical section of the entire transformer. Fig. 2, is a top View. Fig. 3, shows a back view, -Fig. l, is ahorizontal cross sectional elevation taken at approximately thc center of the .arrangement shown in Fig. l, and shows the arrangement of the coils around the core.

Similar letters refer to similar throughout the several views.

These drawings illustrate a transformer of simple cylindrical like pattern, in which parts irregular form has been avoided. The con-- taining case is made up of two parts, a formed sheet steel body A., and a boiler plate top` cover piece B. A gasket C, rest-s" be- -ween the top flange of the steel vbody and the top cover piece. The gasket, is clamped by the holding bolts D, which prevents breathing action from drawing moisture in the case. The low tension leads E, pass vthrough a pipe F, fitted in the top cover piece. To the pipe F, is fitted a U shaped hollow metal piece Gr, having a porcelain terminal entrance under a protecting iron hood forming an outlet to the service connection. The space around the leads in the pipe F, is filled with an oil and moisture proof solid compound thus sealing the outlet excepting by the electrical connection. The high tension leads I, issue from the case through a similar arrangementr with the pipe F, for the more moderate high potential systems. This construction of the formed outlets assumes the supply and. service lines are carried in the open, but, the. convenience and safety in joining conduit pipe directly to the pipe F, is obvious to any one skilled in the art of electrical wiring. In practice where a transformer is placed between the various wiring systems in use there arises the necessity of employing various adapting devices'which `greatly increases the expense of the work and complicates the system. My transformer in the arrangement of the terminals is novel anduseful in eliminating` these difliculites.

For the higher potential systems I employ a high tension insulator construction vJ, similar to pot head or cable terminal work. The lower part of the insulator vcarrying the high tension lead from the transformer coil is hermctically sealed and fastened in the top cover piece B, through the pipe K, with the inner end of theinsulator projecting under the insulating yfluid and the outer end extended and spaced for the required test voltage. A porcelain rain cap is provided which isshipped separate from the transformer preventing possible damage in transit.V The rain cap has large fluted surface which effectively sheds all water.` A vportion of the high tension cable is hermet- Vically sealed in` theL cap for connection to the line. Connectors are provided in the cap and in the stem 1n the top cover piece B, forming a means for readily disconnect- Cit Cill

ing the circuit When necessary. T he cap should be handled with tongs on live circuits.

A lifting ring L, is attached in the center of the top cover piece which beingthe approximate center pointof gravity, holds the transformer in line when being raised to the cross arms.

The top cover piece B, provides a support to which the core M, and the coils N, are suspended and held by means of core clam-ps O, having one of their sides fastened directly to the cover.

Lugs P, are fastened to the top and bottom of the containing casete which lugs pole hangers Q, are secured for attaching the transformer to cross arms.

The case has at the bottom a valve R, for draining ivatery fluid from the isolating chamber S. The isolating chamber is formed by 'placing an inclined shelf T, with an aperture U, in the loiver part of the case. y Any water in the fluid ivill settle by gravity to the shelf T and drip through the small aperture U into t-he isolating chamber S Where it is prevented from circulating into the main body of insulating fluid, as is more fully described and claimed in my application #495,522 lilcd august 25, 1921, covering improvement in transformers.

insulating fluid may be placed in the case by means of removing a pipe plug V. in the top cover piece B. A pct cock lV, indi- Cates by overflow when a sutlicient amount ofrlui'd is in the case. A relief pressure valve X, is fastened in the top and is set for a dangerous pressure inside but it is not intended for the valve to act as a breather since the construction tlnoughout is dcsigned to prevent drawing moisture into the case by breathing; action. A suitable name plate Y, of stamped material is secured to the case.

The coils N, are cylindrical like in shape and are Wound on a round Winding form. A round cylindrical. coil secures in Winding 'an equal tension oi' the ivire at all points ivith an absence of corners which break the insulation. The uniform tension throughout the coils renders also a uniform eXpansion of parts under heat` and saves the insulation from injury. The windings are divided into thin coil sections which are secured by placing treated spacers with suitable insulation betiveen the concentric coils and between the concentric coils and the core, the procedure being to Wind the Wire tightlyover these spacers and treating the finished sections by the vacuum drying and insulating process which renders the insulation more impervious to moisture. I use commercial materials for insulating but I limit the use of fibre insulations as they are non-conductors of heat. I secure a better self cooling effect by providing an open structure with ample fluid ducts. in these particulars the form of the coils and core employed in my transformer are of pa'amount consideration in securing the objects set fort-h.

rThe core of the magnetic circuit is con structed of laminated material assembled with the laminatioiis on a plane with a right angle to the axis of the coils and closed through a common single yoke. By this arrangement the assembled laminations are clamped securely on parallel sides and fastened directly by theclamping means to the top cover piece ivhich therebyv suspends the coils in the fluid in such Yfashion as to sccure a it'ree circulation of the fluid to all the active parts.

Transformers of the soscalled tiro limb core type' are commonly employed in the smaller sizes and higher voltages. and it has heretofore been considered impractical to build a closer approach to the shell type for such work. in my transformer the core section is increased over the tivo limb type ier a given rating and by so doing` l dccre so the convolutions of nire resulting in sonic increase in the core uf'eight ivith a reduced copper Weight also. By placing lan'iinations of different Widths in the core l am able to utilize a very large part of the av;..ible core area in active core material which i. can operate at a moderately high magnetic density by reason of the convenience pri-Psented of incri-asinp` the area in the yoke. This enables me to give ample room for my coil spacing ivith no impairment oi regulation or efhciency. Instead of joining up the core with the yolie by interleaved end members of a common length, l use a uniform length interleaving on the yolre side and vary the length. of the end men'ibers'interleaving on the core side, which produces a shape in the yoke that is convenient to assemble and iusulate around the coil and vfhich prese! i chamfered section that secures the mmamum distribution of the nnrgnetic linx through the yoke with an absence ot" dead corners.

On account of limited space in small high voltage transformers, the use ot terminal blocks with tap connections thereon are rcsponsible for many potential flash-overs and break downs. hiloreover, poor line i:oiif;,ti'u tion causing unreasonable voltage drop, involving the use oil' distribution transformers having poor inherent reeul'ation (a natural result ivith the tivo limb core tyiie) with the use of tap connections to boost the voltage is a reprehensible method of distribution. The usual thing with such systems is an abnormally high voltage on light load With the voltage aboutnormal on moderate load but falling too loiv on heavy load. Moreover, the paralleling, interconnecting, and joining transformers in multiples on polyphase lines introduces dangerous hazards if the distribution transformer ratios are even slightly varied by using tap connections. In order to provide a method of maintaining a more uniform and constant voltage on the distribution system using my transformers, I have fixed a ratio between the primary and secondary windings to secure the following results.

(a) Systems maintaining a high primary voltage, can secure approximately 120 volts secondary or multiples thereof.

(b) Systems maintaining a moderate primary voltage can secure approximately 115 volts secondary or multiples thereof.

(c) Systems maintaining a moderately low primary voltage can secure approximately 110 volts secondary or multiples thereof.

These transformer ratios I have proportioned for the various commercial primary systems as follows:

volts-transformer volts-transformer volts-transformer volts-transformer volts-transformer volts-transformer ratio, Y volts-transformer ratio, volts-transformer ratio, 280:

This standardization of ratios ratio, ratio, ratio, ratio, ratio, Y

and and and and and a nd and Handen-WAHM is vital to show how I am able to do away with all non-capillary in extending them through the cover above the fluid level.

What I claim is:

l. The combination with a fluid insulated self cooled transformer, a hanger support on the back thereof, a transformer cover supported by a forward projecting means from the said back hanger support, core clamps engaging the cover, a transformer comprising a core secured by compression means clamping the core between the said core clamps, with a conduit pipe in the cover, and a plurality of leads connected to the terminal conductors leading upwardr through the conduit pipe in the cover.

2. The combination with a fluid insulated self cooled transformer, a hanger support on the back thereof, a transformer cover supported by a forward proj ecting.l means from the said back hanger support, core clamps engaging the cover, a transformer comprising a core secured by compression means clamping the core between the said core clamps, with a core medium of the single magnetic circuit type in which a complete set of coils are wound on a common core leg having only one enclosing yoke, and round cylindrical shaped coils placed on the said core leg, substantially as described for the purpose of securing a simple construction.

8. The combination with a fluid insulated self cooled transformer, a hanger support on the back thereof, a transformer cover supported'by a forward projecting means from the said back hanger support, core clamps engaging the cover, a transformer comprising a core secured by compression means clamping the core between the said core clamps, terminal outlets through the cover, a casing holding all the necessary fluid around the transformer, and a detachable means adjacent the upper end of the casing attaching the casing to the said back hanger supported cover, for providing a means of securing the transformer in a suspended manner from the back hanger supported cover whereby the casing may be detached and removed from around the transformer pro-per in manufacture and in case of inspection and repair on the line. c

a. The combination with a fluid insulated self cooled transformer having a cover supported by a back hanger, a transformer comprising core and coils and terminals, means engaging portions of the transformer casing rendering the casing fluid tight, means engaging the terminals and the casing effectively sealing the terminals in the casing excepting the electrical connection whereby all of the necessary fluid may be shipped in the casing with the transformer, and a means providing switch insulators comprising an insulator portion adapted to be hcrmetically secured in the cover of the casing with a detachable rain cap which may be shipped separate from the 'transformer' for providing a means to disconnect the transformer from circuit and reduce theVL liability of damage to porcelain parts in shipment.

In testimony I afliX my signature.

CHARLES M. WELCH.

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