CA1079338A - Reversible terminal block for immersion heater - Google Patents

Abstract

REVERSIBLE TERMINAL BLOCK
FOR
IMMERSION HEATER

ABSTRACT OF THE DISCLOSURE

A reversible terminal block for an immersion heater which facilitates wiring in the field by providing a disc-like body with parallel axial bores, arranged in spaced, circular configuration, for receiving six leads from three looped elec-trical heating elements and the ends of a pair of associated thermowells, the one face of the block being substantially flat and adapted for single phase wire-up, and the opposite face having a recess for accommodating a connecting strap extending between two of the bores so as to position the strap in the recess at a different level from two associated straps for connecting adjoining pairs of heating element leads thereby permitting wire-up for a three phase load connection without the need for separating insulation, by merely reversing the block and positioning it to receive the leads in the proper bores.

Description

~ 7933~

l BA~D C~IE INVE'NTION

¦ This invention relates -to elec-trical equipment for use ¦ in wiring an immersion heater and is more particularly concerned ¦ with improvements in a terminal block for supporting the connect-¦ ing end portions of the electric heating elements and enabling wire-up for single or three phase load.
Terminal blocks for supporting immersion type electrical heaters have been developed heretofore for use in the field where it may be desirable to connect the heating elements in parallel, with straps or jumpers forming connections between ¦ heating element leads, for a single phase load, or it may be ¦ desirable to connect the heating elements in delta, with a ¦ different arrangement of lead connec-ting straps, for a three I phase load. In previous arrangements for this type wiring, ¦ with the supporting blocks currently available,it has been ¦ necessary to provide for proper electrical c].earances or spacing .
¦ between lead connecting straps or jumpers by employing insulating ¦ washersand. fish paper, in three phase wiring, resulting in the use of additional material and a loss of time in mounting .
the heaters. . ~

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SUMMARY_OF THE INVENTION
I . , It is, thereforel a general object of -the present ¦ invention to provide an improved terminal block structure which is more convenient or use, in connection with the supporting and wiring:of immersion heaters, than the terminal blocks hereto.fore employed for this purpose. .
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¦ A more specific object of the invention is to provicle ¦ improvements in terminal block structures of the -type which are . ¦ especially adapted for use in supporting and wiring immersion : ~ I type electric heaters, so as to enable wiring in either single phase or in three phase load arrangement, without the use o e ¦ the supplemen-tal insula-ting materials heretofore employed, in order to provide for proper electrical clearances in a three ¦ phase load arrangement.
Another object of the invention is to provide an ,~ I improved reversible terminal block structure for use in wiring ,. . ¦ electrical immersion heaters in either single phase or three ¦ phase load arrangements wherein proper electrical clearances ~ ¦ between lead connecting strap or jumper elements are built into ~ hl~ ¦ the block and the use of separating washers or other insulating . ¦ material is not required for either single phase or three phase .
¦ load arrangementO ~
A further object of the invention is to provide improve-. ` ¦ ments in terminal block structures, for the purpose described, which will enable easier installation, which are more dependable -; ¦ in operation than the terminal block structures heretofore available, and which may be produced in an economical manner .
from readily available material having the required insulating characteristics. ~
. To this end the invention as claimed herein is embodied .
¦ in a terminal block structure which comprises a body member in ¦ the form of a disc having substantial axial dimension and a plurality of parallel axial bores which are arranged in spaced ¦ relation ln a circle and open on oppositely disposed faces of ¦ the body member wh1ch bores are of a size and spaced so as to ,",~ I
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¦ receive there:in leads extending from the terminal ends of the ¦ electrical elements in an immersion heater when the heater is . ¦ mounted on either of said faces, one of said faces being sub-stantially flat and adapted fo:r wire-up of said elemen-ts for ¦ single phase load with proper electrical clearances between lead connecting strap members and the opposite one of said I faces having means in the form of a diametrical recess for : ¦ seating therein a lead connect:ing strap member at a level - ¦ which is a substantial distance.inward, in the direction of the heater, from the level of the remainder of -the face on which ~: ¦ associated strap memhers are adapted to be positioned, therehy ~ ¦ providing for wire-uo for three phase load wi-th proper electrical : I clearances between lead connecting strap members and without :
. I additional insulating materials.
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DESCRIPTION OF THE DRAWLNGS ..

~: ¦ The invention will be best understood with reference to the accompanying description of the terminal bloc]c structure . .
¦ which is illustrated in the drawings and wherein like parts in ~ the several views are identified by the same numerals.
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FIG. 1 is a plan view of an end face of a termlnal block whi:ch.is adapted for use in single phase or in~three phase wiring of an immersion type heater assembly, the end face shown being adapted for positioning against the mounting end of an immersion heater assembly, . :with an opposite end face outermos-t so as to receive thereon connecting straps for a three phase: wire up; : .

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~ ~ 33~3 ¦ FIG. 2 is a plan view of the opposite end ¦ face of the terminal block of FIG. 1 showing ¦ the face configuration whichis outermost and which is adapted to accommodate the wiring ¦ connections for three phase load;

¦ FIG. 3 is a diametrical cross sec-tional I view -taken on the line 3-3 of Fig. 1 with ¦ mounting end portions of heater elements shown in position and lead connecting elements disposed in three phase load arrangement;
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; ¦ FIG. 4 is a diametrical cross sectional view taken on the line 4-4 of Fig. 1, with ¦ heater lead connecting elements shown in ¦ three phase load arrangement; -I .
I ¦ FIG. 5 is a diametrical cross sectional ¦ view taken on the line 5-5 of Fig. 1, with heater lead connecting elements shown in three phase load arrangement;

¦ FIG. 6 is a diametrical cross sectional view taken on the line 6 6 of Fig. 1, with block and heater elements shown in posi-tion ¦ for three phase load connection; and I
¦ FIG. 7 is a schematic perspective view with portlons broken away or omitted, showing r.
the arrangement of the electric heater elements and associated thermowells of an immersion type heater with which the terminal block is adapted to be used.
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10~933~1 DESCRIPTION OE A PREFERRED_EMBODIMEMrr Referring first to FIG. 7 of -the drawings there is illustrated, particularly, the mounting end portions of -the heater and -thermowell elements which make up the operative elements of an immersion type electric heater assembly HA. The illustrated hea-ter assembly HA includes three electric heater elements Hl, M2 and H3 each of which is in a looped arrangement and positioned within a housing (not shown) or o-ther supporting structure so that, the terminal ends thereof are in a spaced circular configuration. Leads for connecting the heater elements Hl, H2 and H3 into proper electric circuitry for supplying . ~ ~operating current to the heaters are shown projecting frorn the terminal ends thereof as indicated at 11, 12 for heater element Hl, at 13, 14 for heater element H2, at 15, 16 for heater element H3. The assembly HA also includes two thermowells Tl and T2, the one being provided for temperature control and the other being provided for high temperature limit control. The thermo-wells Tl and T2 extend parallel with the legs of the looped heaters and have their mounting ends terminating in a substan-tially common transverse plane with the terminal ends of the heaters. The terminal ends of the thermowells are arxanged in spaced, circular alignment between the ends of heaters Hl and H3, with the end portions of capilliary tubes 17 and 18 disposed between the heater leads 11, 12 of Hl and 15, 16 of H3, and aligned diametrlcally in the circle arrangement.
The terminal block 20, as it is illustrated in FIGS. 1 to~6, is in the form of a cylindrical section of non-conducting ..
material with a main body portion 22 of suitable thickness, and having end faces 23 (FIG. 1) and 24 (FIG.2), which are defined 1 ` . ., ;~ ~ l ~ :
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` ~ ~'79338 laterally by annular flanges 25 and 26 formed integral with the main body portion 22, which flanges 25 and 26 have outside wall surfaces extending in a common axial ~lane with -the outside wall surfaces of the body portion 22. A series of axially extending, parallel bores 31, 32, 33, 34, 35, 36, and 37 are disposed in a circle configuration, and in spaced relation, with opposite ends opening in the outermost rnargins of the block, end eaces 23 and 24. The bores extend through the main body portion 22 so that they may be entered Erom either the end face 23 or the end face 24. The bores 31, 32, 33, 34, 35, 36, 37, and 38, are of a size and positioned so as to accommoda-te the six heating element leads 11, 12, 13, 14, 15, 16 and the two lead elements 17, 18 of the thermowells Tl and T2, in the -two posi-tions of orientation of the block 20 relative to the heater assembly HA, which are employed in using the block for either single phase or three phase load connections. The block 20 is reversed and oriented for mounting on the base or lead bearing end of the heater assembly HA when changing from one of the phase load arrangements to the other. The bores are of a size to accommodate the heater elements in either of the two positions.
In the form shown the bores 31 (FIG. 3), 32 (FIG. 5), 35 (FIG. 3), and 36 (FrG~ 5) are made substantially the same cross sectional diameter. The bores;33 (FIG. 4) and 38 (FIG. 6) are made of like cross sectional diameters, somewhat larger than the bores 31, 32, 35, and 36, while the bores 34 and 37 are made of li]ce cross~sectional diameter which is somewhat larger than that of the bores 33 e~nd 38. The bores are spaced in the circle in .
the following clockwise order as viewed in FIG. 1: 31, 34, 36, 38, 35, 33, 32 and 37, so as to enable the block 20 to be : ~ :

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positioned on the end of the heater HA and properly orientedin relation to -the heater elemen-t leads fer wire-up in the two different phase load arrangemen-ts.
The end face 23 (FIG. 1) of the block 20, which is adapted to be outermost and to accommodate the lead connections when the block is properly positioned on the heater end for single phase wire-up, is in a sinyle or common plane except for the shallow recesses 40 and 42 which are each oE a depth to accommodate a lead connec-ting strap utilized in wire-up for single phase load. The recess 40 encompasses the ends of the bores 31 ancl 37 and is of a size to seat thereln a lead connecting strap 40'. The recess 42 encompasses the ends of the bores 35 and 38 and is of a depth to seat therein a strap 42', also utilized in the wire-up for single phase operation.
The face 23, in the form shown, is provided with a pair of spaced lead gripping blocks 43 and 44 which are aligned between bores 33 and 34, and~ which have outwardly opening grooves 43' and 44' for seating therein the leads 17 and 18 from .
the thermowells Tl and T2 in the single phase wire-up arrangement.
The end face 24 (FIG. 2) of the block 20, which is adapted to be outermost and to accommodate lead connecting .
straps when the block is properly positioned for three phase wire-up, has a relatively deep strap receiving recess 45 which extends diametr1cally and encompassès the ends of the bores 31 ;and 3~5. The recess 45 is o~ a width sufficient to accommodate a narrow lead connecting strap 46 which permits connection of .
the heater~element leads 11 and 15 of heater members Hl and ~3 ~at a~substantially lower level than the level of the major sur ace of tl~ block~acc 24. The recess 45 is enlarged or ~ ~
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increased in width at its ends so as to permit the application of strap anchoring nu-ts 47, 47'. A power line -terminal 48, shown in FIG. 3, may be connec-ted at one encl o~ the s-trap 46 by the strap anchoring nut 47. Recesses 50 and 52, of shallow depth, relative to the depth of the recess 45, extend on opposite sides of the recess 45. The recess 50 encompasses the terminal ends of the bores 34 and 36, and the recess 52 encompasses the ends of the bores 32 and 33. The recesses 50 and 52 have outwardly directed flange formations 53 and 54 of relatively small cross section which define the edge of the recess. Short lead connecting straps 55 and 56 are adapted to be sea-ted in the recesses 50 and 52 and to be clamped therein by pairs of clamping nuts 57, 57' and 58, 58' which may also serve to clamp the power supply leads (not shown) so as to provide a three phase load arrangement. In the three phase arrangement the strap 46 connects the lead 11 of heater Hl and the lead 15 of heater H3. The strap 55 connects the lead 14 of heater H2 and the lead 16 of heater H3. The strap 56 connects the lead 12 of heater Hl and ~he lead 13 of heater H2.
Slotted lead holders or grippers 60, 62 are provided on the face 24 for holding the leads 17 and 18 from Tl and T2.
The blocks 20 may be readily fabricated of suitable molded plastic material such as bakelite or similar resin.
The manner in which it may be applied to the base of an immersion heater assembly for either single phase load wire-ups will be understood from the foregoing description.
While the invention has been described with reerence to : . .
a preferred embodiment, lt will be understood by those skilled in the art that various changes may be made and equivalents may ~ ' ~ .
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107933t3 ¦ be substituted for elements -thereof without departiny from the ¦ scope of the invention. In addition, many modifications may be . I made to adap-t a particular situation or material to -the teachings . ¦ of the invention without departing from the essential scope . ¦ thereof. There:Eore, it is intended that the inven-tion not be . ¦ limited to the particular embodiment disclosed as. the best mode ¦ contemplated for carrying out t.his invention, but that the .~ ¦ invention will include all embodiments falling within the scope ~.~ ~ of the appe ded claims.
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Claims (5)

WHAT IS CLAIMED IS:

1. A reversible terminal block for use with either single phase or three phase wire-up of an electrical immersion heater assembly comprising an electrical insulator body having the form of a disc of substantial axial dimension with one face contoured for single phase wiring and an opposite face contoured for three phase wiring, a series of bores extending through said body with their axes generally parallel, said bores being spaced in a circular arrangement and opening on said opposite contoured faces, said face which is contoured for three phase wiring having strap receiving areas in a common plane for seating in spaced, generally parallel relation, a pair of lead connecting straps, and a recess intermediate said strap receiving areas for seating therein a lead connecting strap, said recess having a depth sufficient to space a strap seated therein from said pair of lead connecting straps to provide electrical clearance between the straps.

2. A reversible terminal block as set forth in Claim 1 wherein said intermediate recess is on a diametrical line and encompasses end openings of diametrically opposite bores in said block body.

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3. A reversible terminal block as set forth in Claim 1 wherein said block body is cylindrical and opposite faces of said block are defined by peripheral flange members with said bores opening adjacent the inner faces of said flange members.

4. A reversible terminal block as set forth in Claim 3 wherein said bores are arranged in a circle and spaced approxi-mately equal distances from the axis of said block body with the bores arranged in pairs of the same cross sectional diameter and the bores of each pair thereof being aligned and positioned on opposite sides of said intermediate recess.

5. A reversible terminal block as set forth in Claim 1 wherein said surface areas for seating a pair of lead connecting straps is defined by relatively narrow outwardly projecting flange formations.

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