CA1046165A - Multiple output level power supply apparatus for thermionic device - Google Patents
Multiple output level power supply apparatus for thermionic deviceInfo
- Publication number
- CA1046165A CA1046165A CA230,961A CA230961A CA1046165A CA 1046165 A CA1046165 A CA 1046165A CA 230961 A CA230961 A CA 230961A CA 1046165 A CA1046165 A CA 1046165A
- Authority
- CA
- Canada
- Prior art keywords
- capacitors
- coupled
- thermionic device
- series
- capacitor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 58
- 238000004804 winding Methods 0.000 claims description 39
- 230000001419 dependent effect Effects 0.000 claims description 3
- 230000001939 inductive effect Effects 0.000 claims description 3
- 239000004020 conductor Substances 0.000 description 16
- 238000009730 filament winding Methods 0.000 description 5
- 238000005286 illumination Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/36—Controlling
- H05B41/38—Controlling the intensity of light
- H05B41/40—Controlling the intensity of light discontinuously
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S315/00—Electric lamp and discharge devices: systems
- Y10S315/04—Dimming circuit for fluorescent lamps
Landscapes
- Circuit Arrangements For Discharge Lamps (AREA)
Abstract
ABSTRACT
Apparatus for supplying power to start and operate a thermionic device such as a fflourescent lamp includes a multiposition switch coupled to the running capacitor means in the power circuit. The switch can be selectively operated to a number of positions for varying the value of capacitance in circuit with the transformer and the thermionic device. A variation in the capacitor reactance varies the impendance of the series circuit thus varying the current in the device thus causing a change in the output level produced by the thermionic device. In respect of the fluorescent lamps, the change is manifested in change in light level produced by the lamps.
Apparatus for supplying power to start and operate a thermionic device such as a fflourescent lamp includes a multiposition switch coupled to the running capacitor means in the power circuit. The switch can be selectively operated to a number of positions for varying the value of capacitance in circuit with the transformer and the thermionic device. A variation in the capacitor reactance varies the impendance of the series circuit thus varying the current in the device thus causing a change in the output level produced by the thermionic device. In respect of the fluorescent lamps, the change is manifested in change in light level produced by the lamps.
Description
104~6S
This invention relates generally to apparatus for supplying power to start and operate at least one thermionic device whose output is dependent upon the total reactance in the power circuit serving said device and is concerned particularly with such apparatus intended for use in providing multiple output levels.
A thermionic device is one which operates on the basis of the liberation of eiectrons emitted from a solid or a liquid as a result of its thermal energy. One type of thermionic device is the fluorescent lamp used to provide industrial, residential and commercial lighting.
In the past, in order to reduce the light level and still provide uniform fluorescent type illumination, switching was provided for turning on or off alternate groups or banks of lamps. This is expensive and potentially wasteful because it results in non-uniform lighting with dark areas or multiple ballast usage to provide uniform lighting.
We have found that a number of different output levels of a thermionic device such as a fluorescent lamp can be achieved by providing a multiposition switch coupled to the running capacitor means in the power circuit, and selectively operating said switch to a number of positions varying the value of capacitance in circuit with the transformer and the thermionic device. We have found that a variation in the capacitor reactance varies the impedance of the series circuit thus varying the current in the device thus causing a change in the output level produced by the thermionic ~ - 2 -1~4~i165 device. The switch has one more position than the number of capacitors in the circuit.
More particularly, there is provided apparatus for supplying power to start and operate at least one thermionic device whose output is dependent upon the total reactance in the power circuit serving the said thermionic device which comprises: high leakage reactance transformer having a primary winding and a secondary winding; a plurality of capacitors in series with one another and with said secondary winding the capactitive reactance of said 2a -1~146165 ~
plurality relative to the inductive reactance of the ;~
secondary winding being such as to cause a leading current f-o flow in said capacitors and secondary winding, means inclu~ing electrical leads for extending connections from the said secondary winding and capac.itors to the thermionic device to form a series circuit therewith when connected thereto; and switching means coupled to said plurality of capacitors and having a plurality of selectable switch :
positions, the latter plurality being greater than the plurality of capacitors by one, the output of said thermionic device being selectively variable to any one of a certain number of output levels when connected as aforesaid which is greater than the plurality of capacitors by one~ one practical example of which is embodied in a ballast for starting and operating at least one fluorescent .:
lamp, the change in output level being manifested in a -~
: change in light level produced by such lamp.
The preferred em~odiments of this invention will now be described, by way of example, with reference to the drawings accompanying this specification in which: -;
Figure 1 is a schematic diagram of the ballast apparatus -of this invention in circuit with a pair of series-connected rapid-start fluorescent lamps; and Figure 2 is a schematic diagram of the prior art apparatus.
..
: ~ . . . ., ; ... ~
1~)4~165 A practical example of the invention shall be described in respect of a series-seauence-start-circuit for a thermionic device such as a rapid start fluorescent lamp.
A prior art circuit is illustrated in Figure 2 for reference purposes.
Referring to Figure l, the series-seauence-start ballast 10 includes a high leakage reactance transformer 12 h~ving a magnetic core 14, a primary winding P, a secondary winding S, and magnetic shunts 16. Three filament windings Fl, F2, and F3 are closely coupled with the primary winding P on magnetic core 14. Primary winding P and secondary winding S are series-conducted forming an autotransformer con~iguration. Input leads 18 and 20 couple primary winding P across a source of A.C. voltage Ss.
A pair of rapid-start fluorescent lamps designated Ll and L2 respectively is series-connected and the lamps are designated with a numeric subscript in the order of ignition. Primary winding P and secondary winding S are connected in series additive voltage arrangement across lamps Ll and L2.
A grounded conductive plate 21, which in most applica-tions is the fixture in which the lamps and ballasts are mounted, is positioned in close proximity to lamps Ll and L2 so as to be capacitively coupled therewith. Conductive plate 21 is normally necessary for proper starting of the lamps.
1q;~46~65 Lamp Ll has two filaments 22 and 24. One side of filament 22 is connected via conductor 26 to the junction of primary winding P and filament winding Fl. The other ~ide of filament 22 is coupled via conductor 28 to the second side of filament ~inding Fl. As illustrated in Figure
This invention relates generally to apparatus for supplying power to start and operate at least one thermionic device whose output is dependent upon the total reactance in the power circuit serving said device and is concerned particularly with such apparatus intended for use in providing multiple output levels.
A thermionic device is one which operates on the basis of the liberation of eiectrons emitted from a solid or a liquid as a result of its thermal energy. One type of thermionic device is the fluorescent lamp used to provide industrial, residential and commercial lighting.
In the past, in order to reduce the light level and still provide uniform fluorescent type illumination, switching was provided for turning on or off alternate groups or banks of lamps. This is expensive and potentially wasteful because it results in non-uniform lighting with dark areas or multiple ballast usage to provide uniform lighting.
We have found that a number of different output levels of a thermionic device such as a fluorescent lamp can be achieved by providing a multiposition switch coupled to the running capacitor means in the power circuit, and selectively operating said switch to a number of positions varying the value of capacitance in circuit with the transformer and the thermionic device. We have found that a variation in the capacitor reactance varies the impedance of the series circuit thus varying the current in the device thus causing a change in the output level produced by the thermionic ~ - 2 -1~4~i165 device. The switch has one more position than the number of capacitors in the circuit.
More particularly, there is provided apparatus for supplying power to start and operate at least one thermionic device whose output is dependent upon the total reactance in the power circuit serving the said thermionic device which comprises: high leakage reactance transformer having a primary winding and a secondary winding; a plurality of capacitors in series with one another and with said secondary winding the capactitive reactance of said 2a -1~146165 ~
plurality relative to the inductive reactance of the ;~
secondary winding being such as to cause a leading current f-o flow in said capacitors and secondary winding, means inclu~ing electrical leads for extending connections from the said secondary winding and capac.itors to the thermionic device to form a series circuit therewith when connected thereto; and switching means coupled to said plurality of capacitors and having a plurality of selectable switch :
positions, the latter plurality being greater than the plurality of capacitors by one, the output of said thermionic device being selectively variable to any one of a certain number of output levels when connected as aforesaid which is greater than the plurality of capacitors by one~ one practical example of which is embodied in a ballast for starting and operating at least one fluorescent .:
lamp, the change in output level being manifested in a -~
: change in light level produced by such lamp.
The preferred em~odiments of this invention will now be described, by way of example, with reference to the drawings accompanying this specification in which: -;
Figure 1 is a schematic diagram of the ballast apparatus -of this invention in circuit with a pair of series-connected rapid-start fluorescent lamps; and Figure 2 is a schematic diagram of the prior art apparatus.
..
: ~ . . . ., ; ... ~
1~)4~165 A practical example of the invention shall be described in respect of a series-seauence-start-circuit for a thermionic device such as a rapid start fluorescent lamp.
A prior art circuit is illustrated in Figure 2 for reference purposes.
Referring to Figure l, the series-seauence-start ballast 10 includes a high leakage reactance transformer 12 h~ving a magnetic core 14, a primary winding P, a secondary winding S, and magnetic shunts 16. Three filament windings Fl, F2, and F3 are closely coupled with the primary winding P on magnetic core 14. Primary winding P and secondary winding S are series-conducted forming an autotransformer con~iguration. Input leads 18 and 20 couple primary winding P across a source of A.C. voltage Ss.
A pair of rapid-start fluorescent lamps designated Ll and L2 respectively is series-connected and the lamps are designated with a numeric subscript in the order of ignition. Primary winding P and secondary winding S are connected in series additive voltage arrangement across lamps Ll and L2.
A grounded conductive plate 21, which in most applica-tions is the fixture in which the lamps and ballasts are mounted, is positioned in close proximity to lamps Ll and L2 so as to be capacitively coupled therewith. Conductive plate 21 is normally necessary for proper starting of the lamps.
1q;~46~65 Lamp Ll has two filaments 22 and 24. One side of filament 22 is connected via conductor 26 to the junction of primary winding P and filament winding Fl. The other ~ide of filament 22 is coupled via conductor 28 to the second side of filament ~inding Fl. As illustrated in Figure
2 filament winding Flis a part of the primary winding P
so that the junction is a tap.
Rapid-start fluorescent lamp L2 includes a filament 30 and filament 32. The ends of filament 30 are respectively connected to the ends of filament 27 of lamp Ll via conductors 33 and 34. A conductor 36 connects conductor 33 to one end of filament winding F2 and a conductor 38 connects conductor 34 to the other end of filament windiny F2.
Filament 32 is connected across filament winding F3 via conductors 40 and 42.
A capacitor Cl has one terminal connected to conductor 38 and the other terminal connected to conductor 42 so that capacitor Cl is in parallel with lamp L2. Capacitor Cl is commonly known in the art as the starting condenser.
Capacitors C2 and C2b are series-connected from one end of secondary winding S to conductor 42 so that capacitors C2a annd C2b, primary winding P, secondary winding S and lamp Ll and L2 are all in series-circuit relationship.
Capacitors C2a and C2b may be considered together as the series condenser to provide a leading current during operation of the lamps.
'' . . - ~ . .
, 104f~;~65 A switch swl is provided having outer contacts 46 and 48, a center contact 50 and a movable center arm 52 which can be selectively connected to any one of contacts 46, ~ or 50. Movable center arm 52 is connected via a conductor 54 to the junction of capacitors C2 and C2b.
Outer contact 46 is connected to the second terminal of capacitor C , which is connected to one end of secondary winding winding S and contact 50 is connected to the second terminal of capacitor C2b which is connected to conductor 42. With contact arm 52 connected to contact 46, capacitor C2 is short-circuited and the total series capacitanae is provided by capacitor C2b. With movable arm 52 in contact with contact 48, both capacitors C2a and C2b, in series, are in serie~-circuit relationship with the transformer and fluorescent lamps and the total capacitance is the reciprocal of the sum of the reciprocals of the two capacitors.
With contact arm 52 ln contact with terminal 50, capacitor C2b is shorted and capacitor C2a only is in series-circuit relationship with the transformer and fluorescent lamps.
Although switch SWl can be mounted on a wall, it is most conveniently mounted directly on the fixture containing the lamps and ballast with the conductors brought out of the ballast to switch SWl. The mounting of switch SWl to fixture 21 is shown schematically in Figure 1 via the dotted line connection between switch SWl and fixture 21.
In operation, when leads 18 and 20 are connected to the source of A.C. voltage Ss, a high voltage is induced in 16~46165 secondary winding S. The combined voltages across primary winding P and secondary winding S appear across only lamp L , i e., from conductor 26 to conductor 42 since capacitor Cl and capacitors C2a and c2b have practically no e~fect on the circuit when power is initially applied and no current flows in the secondary circuit. Consequently, the relatively large voltage appearing across the lamp Ll causes it to ignite. As soon as current begins to flow through lamp Ll, current flows through capacitor Cl which now develops a voltage thereacross. The voltage across capacitor Cl will increase to a point where it is sufficient to ignite lamp L2.
Current flowing in lamp L2 now by-passes condenser C
because of its lower impedance. Thereafter, both lamp~
are supplied with current in series through capacitors C2 and C2b, primary winding P and secondary winding 5.
Capacitors C2a and C2b, as noted above, act to provide the necessary lead current in the secondary circuit and to some extent affect the power factor of the circut.
It should be noted that in ballast circuits for fluorescent lamps, a perfect power factor would exist when the primary reactive current neutralizes the leading secondary current provided by capacitor C2 and C2b. For this reason in modern ballast circuits of this type a leadlng secondary current is preferred. This leading secondary current occurs when the net reactance provided in the series circuit is capacitive. It is the capacitive reactance in the 1~46165 serjes circuit which is varied in the instant invention so that irrespective of which condensers are switched into the circuit the net reactance will still be capacitive.
rrhis particular circuit feature and operation are emplo~ed via selective operation of switch SWl.
Switch SWl is operative to vary the value of capacitance in series-circuit relation with transformer 12 and lamps Ll and L2. The variation in value of capacitive reactance causes a variation in the circuit impedance which causes a variation in the light level produced by lamps Ll and L2.
In a practical example, capacitor C is 8.95 microfarads and capacitor C2b is 1.9 microfarads. In po~ition 1 with center arm 52 in contact with terminal 46, maximum illumination is provided by lamps Ll and L2 because the capacitive reactance furnished by the capacltance C2 (3 95 mfd.) is minimum and current flow is maximum. In position 2 with movable arm 52 in contact with terminal 50, -~ ' only the smaller capacitor C2 is in series-circuit relationship and the illumination provided-by lamps Ll and L2 is at the level intermediate that of positions l and 3 which in the preferred embodiment is 50 percent of maximum.
At this condition the level of capacitive reactance is intermediate. In position 3 with movable arm 52 in contact with terminal 48, the total series capacitance is minimized, capacitive reactance is greatest and therefore the least current flows. This results in the lowest light level .: - . .
1~46165 output which in this embodiment is 25 percent of maximum.
It must be appreciated that the total capacitive reactance x of the secondary circuit must always be yreater than the total inductive reactance XL of the circuit for the current to be leading. Thus, when condenser C is in the circuit and maximum current ~lows an 2b increase in capacitive reactance (decrease in capacitance) ~;
must result in a decrease in current. The circuit is therefore always leading.
The switch SWl is shown as a three-position toggle type switch with position 3 open permitting an expected sequence from high to medium to low illumination. Switch SWl can also be a three-position toggle type in which there is only one contact to the movable arm and two~s~ationary contacts. If this type switch is employed the center position, which would be for the lowest light level, would be detented for properly locating the toggle. The two stationary outer contacts would be connected so as to -provide the high and low light levels.
While the present invention has been described by reference to a specific example, it is to be understood that modifications may be made by those skilled in the art without actually departing from the invention. For example, this invention can be employed with e~ual advantage in a single lamp rapid start circuit, in a rapid start circuit employing more than two lamps, in other fluorescent lamp ~allast circuits or in the supply of power to other type _ g _ 1~46i165 thermionic devices. A high leakage reactance isolated primary and secondary transformer also can be provided in place of autotransformer 12 in certain practical examples.
It is, therefore, intended that the appended claims cover 5 all variations that fall within the scope and spirit of the invention.
so that the junction is a tap.
Rapid-start fluorescent lamp L2 includes a filament 30 and filament 32. The ends of filament 30 are respectively connected to the ends of filament 27 of lamp Ll via conductors 33 and 34. A conductor 36 connects conductor 33 to one end of filament winding F2 and a conductor 38 connects conductor 34 to the other end of filament windiny F2.
Filament 32 is connected across filament winding F3 via conductors 40 and 42.
A capacitor Cl has one terminal connected to conductor 38 and the other terminal connected to conductor 42 so that capacitor Cl is in parallel with lamp L2. Capacitor Cl is commonly known in the art as the starting condenser.
Capacitors C2 and C2b are series-connected from one end of secondary winding S to conductor 42 so that capacitors C2a annd C2b, primary winding P, secondary winding S and lamp Ll and L2 are all in series-circuit relationship.
Capacitors C2a and C2b may be considered together as the series condenser to provide a leading current during operation of the lamps.
'' . . - ~ . .
, 104f~;~65 A switch swl is provided having outer contacts 46 and 48, a center contact 50 and a movable center arm 52 which can be selectively connected to any one of contacts 46, ~ or 50. Movable center arm 52 is connected via a conductor 54 to the junction of capacitors C2 and C2b.
Outer contact 46 is connected to the second terminal of capacitor C , which is connected to one end of secondary winding winding S and contact 50 is connected to the second terminal of capacitor C2b which is connected to conductor 42. With contact arm 52 connected to contact 46, capacitor C2 is short-circuited and the total series capacitanae is provided by capacitor C2b. With movable arm 52 in contact with contact 48, both capacitors C2a and C2b, in series, are in serie~-circuit relationship with the transformer and fluorescent lamps and the total capacitance is the reciprocal of the sum of the reciprocals of the two capacitors.
With contact arm 52 ln contact with terminal 50, capacitor C2b is shorted and capacitor C2a only is in series-circuit relationship with the transformer and fluorescent lamps.
Although switch SWl can be mounted on a wall, it is most conveniently mounted directly on the fixture containing the lamps and ballast with the conductors brought out of the ballast to switch SWl. The mounting of switch SWl to fixture 21 is shown schematically in Figure 1 via the dotted line connection between switch SWl and fixture 21.
In operation, when leads 18 and 20 are connected to the source of A.C. voltage Ss, a high voltage is induced in 16~46165 secondary winding S. The combined voltages across primary winding P and secondary winding S appear across only lamp L , i e., from conductor 26 to conductor 42 since capacitor Cl and capacitors C2a and c2b have practically no e~fect on the circuit when power is initially applied and no current flows in the secondary circuit. Consequently, the relatively large voltage appearing across the lamp Ll causes it to ignite. As soon as current begins to flow through lamp Ll, current flows through capacitor Cl which now develops a voltage thereacross. The voltage across capacitor Cl will increase to a point where it is sufficient to ignite lamp L2.
Current flowing in lamp L2 now by-passes condenser C
because of its lower impedance. Thereafter, both lamp~
are supplied with current in series through capacitors C2 and C2b, primary winding P and secondary winding 5.
Capacitors C2a and C2b, as noted above, act to provide the necessary lead current in the secondary circuit and to some extent affect the power factor of the circut.
It should be noted that in ballast circuits for fluorescent lamps, a perfect power factor would exist when the primary reactive current neutralizes the leading secondary current provided by capacitor C2 and C2b. For this reason in modern ballast circuits of this type a leadlng secondary current is preferred. This leading secondary current occurs when the net reactance provided in the series circuit is capacitive. It is the capacitive reactance in the 1~46165 serjes circuit which is varied in the instant invention so that irrespective of which condensers are switched into the circuit the net reactance will still be capacitive.
rrhis particular circuit feature and operation are emplo~ed via selective operation of switch SWl.
Switch SWl is operative to vary the value of capacitance in series-circuit relation with transformer 12 and lamps Ll and L2. The variation in value of capacitive reactance causes a variation in the circuit impedance which causes a variation in the light level produced by lamps Ll and L2.
In a practical example, capacitor C is 8.95 microfarads and capacitor C2b is 1.9 microfarads. In po~ition 1 with center arm 52 in contact with terminal 46, maximum illumination is provided by lamps Ll and L2 because the capacitive reactance furnished by the capacltance C2 (3 95 mfd.) is minimum and current flow is maximum. In position 2 with movable arm 52 in contact with terminal 50, -~ ' only the smaller capacitor C2 is in series-circuit relationship and the illumination provided-by lamps Ll and L2 is at the level intermediate that of positions l and 3 which in the preferred embodiment is 50 percent of maximum.
At this condition the level of capacitive reactance is intermediate. In position 3 with movable arm 52 in contact with terminal 48, the total series capacitance is minimized, capacitive reactance is greatest and therefore the least current flows. This results in the lowest light level .: - . .
1~46165 output which in this embodiment is 25 percent of maximum.
It must be appreciated that the total capacitive reactance x of the secondary circuit must always be yreater than the total inductive reactance XL of the circuit for the current to be leading. Thus, when condenser C is in the circuit and maximum current ~lows an 2b increase in capacitive reactance (decrease in capacitance) ~;
must result in a decrease in current. The circuit is therefore always leading.
The switch SWl is shown as a three-position toggle type switch with position 3 open permitting an expected sequence from high to medium to low illumination. Switch SWl can also be a three-position toggle type in which there is only one contact to the movable arm and two~s~ationary contacts. If this type switch is employed the center position, which would be for the lowest light level, would be detented for properly locating the toggle. The two stationary outer contacts would be connected so as to -provide the high and low light levels.
While the present invention has been described by reference to a specific example, it is to be understood that modifications may be made by those skilled in the art without actually departing from the invention. For example, this invention can be employed with e~ual advantage in a single lamp rapid start circuit, in a rapid start circuit employing more than two lamps, in other fluorescent lamp ~allast circuits or in the supply of power to other type _ g _ 1~46i165 thermionic devices. A high leakage reactance isolated primary and secondary transformer also can be provided in place of autotransformer 12 in certain practical examples.
It is, therefore, intended that the appended claims cover 5 all variations that fall within the scope and spirit of the invention.
Claims (13)
1. Apparatus for supplying power to start and operate at least one thermionic device whose output is dependent upon the total reactance in the power circuit serving the said thermionic device, which comprises:
a high leakage reactance transformer having a primary winding and a secondary winding;
a plurality of capacitors in series with one another and with said secondary winding, the capacitive reactance of said plurality relative to the inductive reactance of the secondary winding being such as to cause a leading current to flow in said capacitors and secondary winding;
means including electrical leads for extending connections from the said secondary winding and capacitors to the thermionic device to form a series circuit therewith when connected thereto; and switching means coupled to said plurality of capacitors and having a plurality of selectable switch positions, the latter plurality being greater than the plurality of capacitors by one, the output of said thermionic device being selectively variable to any one of a certain number of -output levels when connected as aforesaid which is greater than the plurality of capacitors by one.
a high leakage reactance transformer having a primary winding and a secondary winding;
a plurality of capacitors in series with one another and with said secondary winding, the capacitive reactance of said plurality relative to the inductive reactance of the secondary winding being such as to cause a leading current to flow in said capacitors and secondary winding;
means including electrical leads for extending connections from the said secondary winding and capacitors to the thermionic device to form a series circuit therewith when connected thereto; and switching means coupled to said plurality of capacitors and having a plurality of selectable switch positions, the latter plurality being greater than the plurality of capacitors by one, the output of said thermionic device being selectively variable to any one of a certain number of -output levels when connected as aforesaid which is greater than the plurality of capacitors by one.
2. The apparatus as defined in claim 1 wherein the thermionic device comprises at least one fluorescent lamp.
3. The apparatus as defined in claim 1 wherein the thermionic device comprises at least a pair of fluorescent lamps arranged electrically coupled in a series-circuit relation.
4. The apparatus as defined in any one of claims 1, 2 or 3 in which the primary winding and secondary winding are connected in an autotransformer relation.
5. The apparatus as defined in and one of claims 1, 2 or 3 in which the primary winding and secondary winding are connected in an auto-transformer relation and the capacitors and the thermionic device are all connected in series across both windings.
6. The apparatus as defined in any one of claims 1, 2 or 3 wherein there are two capacitors and said switching means are operative selectively to couple one or the other or both of said capacitors in series-circuit relation with said transformer.
7. The apparatus as defined in any one of claims 1, 2 or 3 wherein there are two capacitors and said switch means comprise a three-position switch.
8. The apparatus as defined in any one of claims 1, 2 or 3 wherein said switch means comprise a multi-position toggle switch, connected in parallel with the series coupled capacitors.
9. The apparatus as defined in any one of claims 1, 2 or 3 wherein there are two capacitors, each having first and second ends and said switch means include a three-position switch having a center arm movable to a first and second position to contact first and second contacts respectively and a third position, said center arm being coupled to the junction of the two capacitors, said first contact being coupled to a second end of one capacitor and said second contact being coupled to a second end of the other capacitor.
10. The apparatus as defined in any one of claims 1, 2 or 3 wherein there are two capacitors, each having first and second ends and said switch means include a three-position to contact first and second contacts respectively, and a third position without electrical connection to either capacitor, said center arm being coupled to the junction of the two capacitors, said first contact being coupled to a second end of one capacitor and said second contact being coupled to a second end of the other capacitor whereby one or the other of said two capacitors is short-circuited by said switch means in one of said first and second positions.
11. The apparatus as defined in any one of claims 1, 2 or 3 wherein there is at least one starting capacitor capable of being coupled in parallel with said thermionic device.
12. The apparatus as defined in any one of claims 1, 2 or 3 wherein said primary and secondary windings are coupled in series with one another and said plurality of capacitors and said primary winding is connected to a source of alternating current.
13. The apparatus as defined in claim 2 or claim 3 and a fixture having said thermionic device mounted thereto, said switching means being mounted on said fixture.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US494413A US3911320A (en) | 1974-08-05 | 1974-08-05 | Multiple lighting level ballast for fluorescent lamps |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1046165A true CA1046165A (en) | 1979-01-09 |
Family
ID=23964372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA230,961A Expired CA1046165A (en) | 1974-08-05 | 1975-07-07 | Multiple output level power supply apparatus for thermionic device |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US3911320A (en) |
| CA (1) | CA1046165A (en) |
| ZA (1) | ZA754375B (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3996495A (en) * | 1975-07-25 | 1976-12-07 | North American Philips Corporation | High efficiency ballast system for electric discharge lamps |
| US4097783A (en) * | 1976-09-13 | 1978-06-27 | Ppg Industries, Inc. | Ultraviolet light processor |
| US4256993A (en) * | 1979-06-04 | 1981-03-17 | Westinghouse Electric Corp. | Energy saving device for rapid-start fluorescent lamp system |
| US4417181A (en) * | 1979-07-06 | 1983-11-22 | Sonelt Corporation | Electronic ballast |
| US4388564A (en) * | 1981-03-09 | 1983-06-14 | General Electric Company | Energy saving fluorescent lamp circuit |
| US4517498A (en) * | 1982-02-22 | 1985-05-14 | Advance Transformer Co. | Sequence start lamp ballast with current spike suppression means |
| US4559479A (en) * | 1983-06-20 | 1985-12-17 | Emerson Electric Co. | Starting and dimming circuit for fluorescent lamps |
| JPS6116900U (en) * | 1984-07-04 | 1986-01-31 | 能幸 眞田 | fluorescent lamp device |
| JPS6116899U (en) * | 1984-07-04 | 1986-01-31 | 能幸 眞田 | fluorescent lamp device |
| US4686427A (en) * | 1985-08-13 | 1987-08-11 | Magnetek, Inc. | Fluorescent lamp dimming switch |
| US4994718A (en) * | 1989-02-07 | 1991-02-19 | Musco Corporation | Method and means for dimming ballasted lamps |
| US5184113A (en) * | 1990-10-01 | 1993-02-02 | Greg Baron | Electrical field display/signal device |
| US5204587A (en) * | 1991-02-19 | 1993-04-20 | Magnetek, Inc. | Fluorescent lamp power control |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3323013A (en) * | 1964-11-30 | 1967-05-30 | Gen Electric | Systems and ballast apparatus for operating fluorescent lamps at preselected levels of illumination |
-
1974
- 1974-08-05 US US494413A patent/US3911320A/en not_active Expired - Lifetime
-
1975
- 1975-07-07 CA CA230,961A patent/CA1046165A/en not_active Expired
- 1975-07-08 ZA ZA00754375A patent/ZA754375B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| ZA754375B (en) | 1976-08-25 |
| US3911320A (en) | 1975-10-07 |
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