US2792556A - Ballast - Google Patents

Description

May 14, 1957 w. OGLESBEE BALLAST 2 Sheets-Sheet 1 Filed Aug. 20, 1955 11/ III INVENTOR Wendell Oglesbee.

BY (him 7% ATTORNEY WITNESSES: 9% Z May 14, 1957 w. OGLESBEE BALLAST 2 Sheets-Sheet 2 Filed Aug. 20, 1953 a e Rb 05 m 0 V mo 8 d. n m

WITNESSES:

BY WZM ATTORNEY BALLAST Wendell Oglesbee, Lakewood, house Electric Corporation, poration of Pennsylvania Ohio, assignor to Westing- East Pittsburgh, Pa., a cor- My invention relates generally to apparatus for starting and operating gaseous discharge devices, such as fluorescent lamps, and more specifically to transformer and ballast provisions for one of such discharge devices.

When electric gaseous discharge devices, of which the fluorescent lamp is an example, are operated, it has been the general practice to energize them from the standard commercially available low voltage sources. Since such discharge devices require a higher voltage than those generally available, a transformer, such as an auto-tran-sformer, is often used, having a discharge device connected across its secondary to obtain the necessary higher starting voltage for the discharge devices. Also, as such devices have a negative resistance, it has been customary to connect the transformer secondary in series with a reactor in order to stabilize the operation of such a device. It is also customary to connect a condenser between the reactor and the discharge device in order to obtain a leading power factor and to obtain lamp stability with reference to variations in line voltage.

Such prior practice has required several transformer and ballast coils which, though satisfactory from an operational standpoint, have required relatively large amounts of copper and iron. Such large metal components are unsatisfactory both in relation to initial cost and fabrication, and in relation to size and weight.

Accordingly, it is an object of my invention to provide a novel unitary combined transformer and ballast assembly for the control of gaseous discharge devices which is substantially less in size and weight than those previously used.

The transformer and ballast assemblies, incorporating the circuit previously discussed, having a lagging power factor, are undesirable from an efficiency standpoint. Accordingly, another object of my invention is to provide a novel unitary combined transformer and ballast'assembly for the control of gaseous discharge devices having a higher efiiciency than devices previously used.

Another object of my invention is to provide a novel unitary combined transformer and ballast assembly for the control of gaseous discharge devices which utilizes a common coil for such transformer and ballast.

Another object of my invention is to provide a novel unitary combined transformer and ballast assembly for the control of gaseous discharge devices wherein such transformer and ballast coils are, in part, combined.

Another object of my invention is to provide a novel unitary combined transformer and ballast assembly for the control of gaseous discharge devices wherein such transformer and ballast cores are closely positioned so that the transformer and ballast coils are combined in part.

Still another object of my invention is to provide a novel unitary combined transformer and ballast assembly for the control of gaseous discharge devices wherein such transformer and ballast cores may be identicalin construction and configuration.

" l hese and other objects of this invention will become States Patent-O Patented May 14, 1957 'ice more apparent upon consideration of the following detailed description of preferred embodiments thereof, when taken in connection with the attached drawings, in which:

Figure l is an elevational view of a transformer and ballast assembly for the control of gaseous discharge devices constructed in accordance with the principles of my invention;

Fig. 2 is a schematic diagram showing the electrical connections for the assembly shown illustrated in Fig. 1 together with the circuits for connecting the assembly to a discharge device;

Fig. 3 is an elevational view of another transformer and ballast assembly different from that shown in Fig. l, but also constructed in accordance with the principles of my invention;

Fig. 4 is a schematic diagram showing the electrical connections for the assembly shown illustrated in Fig. 3 together with the circuit for connecting the assembly to a discharge device;

Fig. 5 is an elevational view of still another transformer and ballast assembly different from those shown in Figs. 1 and 3, but constructed in accordance with the principles of my invention; and

Fig. 6 is a schematic diagram showing the electrical connections for the assembly shown illustrated in Fig. 5, together with the circuit for connecting the assembly to a discharge device.

In accordance with this invention, a portion of the transformer and the ballast for controlling the operation of a gaseous discharge device, such as a fluorescent lamp, are assembled with a common coil. As this detailed description proceeds, the benefits obtained from such a design with respect to reduction in size, weight and efiiciency will become apparent. While this invention is hereinafter specifically described in connection with the operation of a single lamp, it is not limited to a single lamp, but may be embodied in the control for operation of a greater number of lamps.

The transformer and ballast assembly shown in Figs. 1 and 2 comprises an autotransformer 2 having a primary coil portion 4, connected between supply lines 23-39. Primary coil portion 4 is also connected by a conductor 6 to a secondary coil portion 8 of transformer 2, the other side of which is connected in series by a conductor 10 with a condenser 12, and a fluorescent lamp 14-, to the other supply line 28 and the primary coil portion 4. In order to accomplish the purpose of my invention, transformer 2 is provided with two C-shaped cores 16, each having inwardly extending and facing arms 18, whereby an air gap 29 is formed at each side of trans former 2. As has been indicated, gaseous discharge de vices such as fluorescent lamp 114 have a negative resistance and in order to stabilize the operation of such a lamp, some ballasting means must be provided. Accordingly two C-shaped cores 22 having inwardly extending and facing arms 24 are located in juxtaposition with cores 16 so that an air gap 26 is formed at each side of the cores 22- between the opposed arms 24. As shown one pair of opposed arms 24 between cores 22 are approximately parallel with and closely adjacent to one pair of opposed arms 18 of transformer 2 so that the secondary coil portion 8 of transformer 2 may be wound around the adjacent pair of opposed arms 13 and 24 of the cores 15 and 22, respectively. As also shown, one air gap 26 of cores 22 is adjacent air gap 20 of transformer 2 a such an arrangement has been found advantageous from a fabricating standpoint in that an overall symmetry of the transformer and ballast assembly is obtained. Such ar rangement is not however essential from the operational standpoint of my invention. Each of the cores 16 and 22 may be built up from a plurality of laminations of any suitable magnetizable material, such as silicon steel,

3 with the laminations secured together in any desired manner, as by welding.

In the operation of a transformer and ballast assembly constructed in accordance with the principles of my in yention, an alternating current source of power is connected to the supply lines 283tl across theprimary coil portion 4 of transformer 2. Due to relationship of the secondary coil portion 8 with the primary coil portion 4, a higher voltage than the source, which is the sum of the voltage across the primary coil portion 4 and that induced in the secondary coil portion 8, is impressed across the lamp 114. As lamp 14 is a the transformer 2 and no appreciable current will flow through lamp 14- until the open-circuit voltage of trans former 2 is sufiicient to ionize the lamp 1 3, whereupon a. discharge across lamp 14 will occur. The open circuit voltages necessary to start such a discharge are well known, and transformer 2 has been so designed to produce such a discharge across lamp 14 in view of the various commercially available voltages to which supply lines 2830 may be connected.

ages, the primary coil portion 4 in order of transformer 2.

In the event line 30 is connected to tap 33, the primary coil portion of transformer 2 is only that part of the prior primary coil portion 4 between the supply lines 2830. The remaining portion 19 of the primary coil portion 4 then becomes a part of the secondary coil portion of transformer 2, and functions in the well-known manner of autotransformers to increase the voltage output of transformer 2.

Once an initial discharge has occurred across lamp 14, the voltage required to maintain such a discharge is substarting voltage and a resultant current then flows through the circuit. in view of the flow of current demanded by the lamp 14, corresponding currents flow through the coils of transformer 2. As

current to lamp 14.

As has been indicated, cores 16 are assembled with air gaps 2t at each side. For a particular air gap 2t! existing between cores 16, the cores 16 have a fixed reluctance and require a magnetizing current dependent upon such reluctance. The magnitude of the magnetizing current can, however, be varied by changing the air gaps 26, i. e., the reluctance of the cores 16. In constructing the transformer and ballast assembly in accordance with my invention, it is one of my purposes to construct cores 16 so that in view of the other circuit components the magnetizing current of cores 16 is of such a magnitude that the resultant line current is in phase with the voltage. Under such circumstances, a unity power factor is obtained which provides an efiicient assembly.

Another transformer and ballast assembly incorporating the principles of my invention is shown illustrated in Figs. 3 and 4. It will be noted that certain elements identical with those previously described have been utilized and, accordingly, such like parts have been given the same reference numerals as before. As in the manner previously discussed, the transformer and ballast assembly shown in Figs. 3 and 4 comprises an autotransformer 2' haying a pair of opposed C-shaped cores 16 in juxtaposition with an identical pair of opposed C-shaped cores 16'. As can readily be appreciated, by utilizing such identical cores areduction in producing costsmay be obtained as all the cores may be fabricated and assembled by the same It will be noted howall) tools and methods. The embodiment of my invention in Figs. 3 and 4 is further illustrative of a relocation of the primary coil portion 4' in order that a concentric coil construction may be obtained. It will be noted that primary coil portion 4' is Wound around the adjacent legs of cores 16 and 16' and around the other leg of core 16' so that it does not affect the core 16'. By such a con struction primary coil portion 4 functions in the identical manner as heretofore described and is electrically connected to the secondary coil portion 8 which is disposed and functions in the identical manner as heretofore discussed, by a conductor 6.

A third transformer and ballast assembly incorporating the principles of my invention is shown illustrated in Figs. 5 and 6 and has certain identical components as those previously discussed with the embodiment of my invention shown illustrated in Figs. 1 and 2. Accordingly, identical reference numerals have been used to identify identical parts. This assembly differs from that shown in Figs. 1 and 2 in that a substantially larger magnetically continuous core 16" is utilized in transformer 2" in order that cores 22 may be positioned within core 16'. By such an arrangement, a concentric core construction is obtained. Also, a continuous core 16 has a lower reluctance than a similar core having an air gap therein, whereby the phase relationship between the sup ply voltage and the supply current is different so that the powerfactor of the supply line is also different and approaches a unity power factor. I

Thus, it will be noted that I have provided a transformer and ballast assembly which substantially reduces the amount of copper required over those previously utilized as only one coil is used which functions both as a portion of the secondary of an autotransformer and as a reactor coil by virtue of a novel core arrangement. In

View of this double functioning of the single coil, the copper heretofore required for tures have been obtained without sacrificing any of the V atransformer and ballast assembly and in fact have resulted in a superior assembly. the adjustments required to are all factory made and are not dependent upon any field adjustments or alterations.

Having described preferred embodiments of my invention in accordance with the patent statutes, it is desired that the invention be not limited to those specific constructions inasmuch as it is apparent that many additional modifications may be made without departing from the broad spirit and scope of my invention. Thus, for ex ample, if desired, the air gaps of the cores may be located at positions other than the particular ones illustrated, or

' other relative positions, withpossible and that it be limited only as required by the prior art.

I claim as my invention:

1. A transformer and ballast assembly for controlling the operation of a gaseous discharge device comprising, a first magnetic core which is continuous except for at least one air gap therein, said first magnetic core having at least a portion located adjacent at least a portion of a separate magnetic reactor core, said reactor core being continuous except for at least one air gap therein of a size to substantially increase the reluctance of the reactor core, a transformer winding including primary and secondary winding portions, said primary winding portion being mounted solely on said first magnetic core, said secondary winding portion encircling said adjacent portions of said first core and said reactor core, and each of said cores having a cross section which is non-saturating at normal load current through said windings.

2. A transformer and ballast assembly for controlling the operation of a gaseous discharge device comprising a continuous first magnetic core having at least a portion located adjacent at least a portion of a separate magnetic reactor core, said reactor core being continuous except for at least one air gap therein of a size to substantially increase the reluctance of the reactor core, a transformer winding including primary and secondary winding portions, said primary winding portion being mounted solely on said first magnetic core, said secondary winding portion encircling said adjacent portions of said first core and said reactor core, and each of said cores having a cross section which is non-saturating at normal load current through said windings.

3. A transformer and ballast assembly for controlling the operation of a gaseous discharge device comprising, a first magnetic core having at least a portion located adjacent at least a portion of a second magnetic core, each of said magnetic cores comprising two oppositely facing generally C-shaped elements which are spaced form each other to form air gaps between the arms thereof, a transformer winding including primary and secondary winding portions, said primary winding portion being mounted solely on said first magnetic core, and said secondary winding portion encircling said adjacent portions of said first and second magnetic cores.

4. A transformer and ballast assembly for controlling the operation of a gaseous discharge device comprising, a first magnetic core providing a continuous path of magnetic material a portion of which is located adjacent at least a portion of a second magnetic core, said second magnetic core comprising two oppositely facing generally C-shaped elements which are spaced from each other to form air gaps between the arms thereof, a transformer winding including primary and secondary winding portions, said primary winding porton being mounted solely on said first magnetic core, and said secondary winding portion encircling said adjacent portions of said first and second magnetic cores.

5. A transformer and ballast assembly for controlling the operation of a gaseous discharge device comprising, a first magnetic core providing a continuous path of magnetic material a portion of which is located adjacent at least a portion of a second magnetic core, said second magnetic core comprising two oppositely facing generally C-shaped elements which are spaced from each other to form air gaps between the arms thereof, a transformer winding including primary and secondary winding portions, said primary winding portion being mounted solely on said first magnetic core, said secondary winding portion encircling said adjacent portons of said first and second magnetic cores, and said first magnetic core encircling said second magnetic core.

6. A transformer and ballast assembly for controlling the operation of a gaseous discharge device comprising, a first magnetic core having at least a portion located adjacent at least a portion of a second magnetic core, each of said magnetic cores comprising two oppositely facing generally C-shaped elements which are spaced from each other to form air gaps between the arms thereof, a transformer winding including primary and secondary winding portions, said secondary winding portion encircling said adjacent portions of said first and second magnetic cores, and said primary winding portion being wound to encircle said secondary winding portion, all of said arms of said second magnetic core and at least a portion of said first magnetic core.

References Cited in the file of this patent UNITED STATES PATENTS

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