US 3702421 A
An electric choke is embedded in a sealing compound filling part of a metal housing acting as a heat sink. The core of the choke has a support member fixed therein, which extends beyond the sealing compound and supports ancillary equipment.
Description (OCR text may contain errors)
United States Patent Grul 1 Nov. 7, 1972  I CHOKE UNIT  References Cited Irv/em" gaggzag UNITED STATES PATENTS 3,160,836 12/1964 Jones ..336/67 x  Ass1gnee: Ferguson Transformers Pty.
, Chatswood, Australia I Henderson X 1 3,646,401 2/1972 Freegard ..3l7/100 1 Flled= 1971 3,516,040 6/1970 Ripley ..336/96  Appl. No.: 186,286
Primary Examiner-Darrell L. Clay Assistant Examiner-Gerald P. Tolin  Forelgn Applicatpn Pnomy Dam Attorney-Emory L. Groff et al.
Oct. 6, 1970 Australia ..2764/70 57 ABSTRACT  U.S.Cl. ..317/99,317/100,336/67, 1
336/96 An electric choke is embedded in a sealing compound  Int. Cl .1102!) 1/18, HOlf 15/02 filling part of a metal housing acting as a heat sink.  Field of Search 317/99, 100; 336/67, 96 The core-of the choke has a support member fixed' therein, which extends beyond the sealing compound and supports ancillary equipment.
- 9 Claims, 8 Drawing Figures CHOKE'UNIT choke itself was enclosed in theusual manner in a. cover or shield and impregnated with a suitable sealing compound. g
The casing was, then either suspended on the lamp pole or secured withina cavity'or recess of such a pole.
This known arrangement is not only rather heavy and costly in manufacture but has the additional disadvantage that owing to the low thermalconductivity of the air within the casing and surrounding the choke dissipation of the heat developed in the choke is rather poor and may necessitate a larger choke as otherwise called for. I j
. These disadvantages are overcome according to the invention by an electric choke unit comprising ahousing, an electric choke embedded in a sealing compound filling a portion of said housing a support member fixed in the core of. said choke and extending beyond said sealing compound, and ancillary equipment mounted on said support member, said housing forming aheat sink for said choke. 1,
The invention will be described hereinafter in more detail in connection with the drawings showing one embodiment of the invention and some modifications thereof.
I In'the drawings; FIGS. 1 to 3 show three different views of an electric choke unit according to embodiment of the invention. r
, FIG. 4 is the circuit diagram of the unit shown in' 2 used as a cover or shield for the choke 4-itself and a top part 3 forming a cover for the ancillary components. The housing l-may be spun fromaluminum to keep its weight as low as possible and the top part 3 has a rim 5 of slightly greater diameter than the bottom part 2 to fit over the bottom part 2, being secured thereto by wing nuts 6 or other suitable fixing means which permit easy removal of the top part 3. A sealing ring 7 inserted between the top part 3 and bottom part 2 makes the joint watertight.
The choke 4 is secured in the bottom part 2 of the housing by brackets 8 fixed to the core 9 of the choke 4 and heldagainst the housing wall by means of screws l0 passing through the housing wall and an external bracket 11 designed to mount the choke unit ona pole or the like.
The bottom part 2 of the housing 1 is filled with a suitable compound 12, for example in epoxy resin, which completely encloses the choke 4 with its core 9 to exclude any air. Conduit inlets 13 are provided on opposite sides of the housing bottom part 2 just above the level of the epoxy resin 12 to pass the connections from the power supply and the lamp into the housing 1.
If the-lead-in wires areto be brought into the unit from the bottom thereof suitable apertures 14 (FIG. 8) are provided in the bottom 2 of the housing and conduits are inserted through the'apertures passing along the choke and throughthe sealing compound. and being held in position'thereby.
The ancillary equipment is mounted on a metal support 15 consisting of a metal plate which is inserted with one end between the laminations of the core 9 of the choke 4and secured therein by screws (not shown) passing through the laminations. The'support 15 extends upwardly into the top part 3 of the housing 1 so that on removal of the top part 3 all components mounted on the support 15 are easily accessible.
The metal plate of the support l5 can have an overlay .of insulating material 16 on the side on which the additional equipment is mounted.
In a simple case of a low power choke'unit the support 15 carries only a fuse-holder 17 with fuse, a terminal block .18 for connection with 'tappings on the choke, a terminal block 19 mounted on an angle bracket 20 for connection to the lamp and power supply respectively and an earth terminal 21. As the earth terminal 21 is metallically connected to the support plate which inturn is in metallic contact with the choke core, and as this core is connected by metal brackets .to the housing and the external mounting bracket, connection of the terminal with earth will at the same time connect earth to all metal parts of the choke unit. The leads from the choke itself, passing through the epoxy resin, are connected in normal manner with the terminal block and fuse holder respectively.
In the case of a high power choke unit in which a capacitor 22is included to correct the power factor this latter capacitor-22 can be mounted on the rear of the support plate 15 within the top part 3 of the housing.
The electrical connections of the various parts of the unit are shown in FIG. 4.
The choke 4 is provided with tappings whichare connected with the terminal block 18 to "make the unit adaptableto different supply voltages. The power leads A and N are connected to the terminalblock 19 which is also designed to accept the connections from a lamp 23. The fuse 17 is connectable to any of the tappings on terminal block 18, and the capacitor 22 is connected between the fuse l7 and the power supply if a correction of the power factor is required.
The modification shown in FIG. 5 is designed for cases where the housing 1 is to be supported by a bracket 24. In this case the socket for lamp 23 (FIG. 4) can be mounted directly on the bottom of housing 1.
FIG. 7 shows an arrangement in which the housing 1 has no outside mounting bracket but has a recess25 at part and being releasably secured thereto, and a sealing ring interposed between said parts.
' 3. An electric choke unit according to claim 1 wherein the ancillary equipment comprises terminal blocks, a fuse holder incorporating a fuse, and an earth terminal.
4. An electric choke .unit according to claim 3 wherein a condenser for power factor correction is mounted on the back of the support member, the front of said member carrying the remainder of the ancillary equipment.
5. An electric choke unit according to claim 1 wherein the choke has choke brackets secured to its core, said brackets contacting the inner surface of said housing, a choke unit mounting bracket being provided at the outer surface of said housing, said mounting bracket being fixed to said choke brackets through apertures in said housing.
. 4 r 6. An electric choke unit according to claim 1 wherein the housing is provided with cable inlet openings on opposite sides thereof and above said sealing compound.
7. An. electric'choke unit according to claim 1 wherein cable inlet channels are provided adjacent the a choke and passing through the sealing compound and the corresponding end of the housing.
. 8. An electric choke unit according to claim -1 wherein one end of the housing has a recess adapted to fit on a lamp post.
t 9. An electric choke unit comprising a housing having two cylindrical parts spun from aluminum, one part over-lapping the other part and being releasably secured thereto, an electric choke embedded in a sealing compound filling a portion of said housing, a support member fixed in the core of said choke and extending beyond said sealing compound, choke brackets secured to said core, said brackets contacting the inner surface of said housing, a choke unit mounting bracket at the outer surface of said housing and being fixed to said choke brackets through apertures in said housing,
cable inlet openings in said housing and ancillary equipment mounted on said support member, said ancillary equipment comprising terminal blocks, a condenser, a fuse holder and an earth terminal.