CA1129484A - High efficiency ballast system for gaseous discharge lamps - Google Patents
High efficiency ballast system for gaseous discharge lampsInfo
- Publication number
- CA1129484A CA1129484A CA329,403A CA329403A CA1129484A CA 1129484 A CA1129484 A CA 1129484A CA 329403 A CA329403 A CA 329403A CA 1129484 A CA1129484 A CA 1129484A
- Authority
- CA
- Canada
- Prior art keywords
- lamp
- primary winding
- winding
- starting
- ballast
- 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
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- Circuit Arrangements For Discharge Lamps (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An electrical lamp ballast system of improved efficiency is provided for starting and operating fluorescent lamps. The system includes a high leakage reactance autotransformer having primary and secondary windings, and a ballast capacitor connected in series with the secondary winding and two serially-connected fluorescent lamps of low starting and operating voltage.
The secondary circuit is connected to a tap on the primary winding for reducing the ratio of ballast power input to lamp light output. The system provides reduced lamp current crest factor, thereby improving life and operating characteristics of the lamps.
An electrical lamp ballast system of improved efficiency is provided for starting and operating fluorescent lamps. The system includes a high leakage reactance autotransformer having primary and secondary windings, and a ballast capacitor connected in series with the secondary winding and two serially-connected fluorescent lamps of low starting and operating voltage.
The secondary circuit is connected to a tap on the primary winding for reducing the ratio of ballast power input to lamp light output. The system provides reduced lamp current crest factor, thereby improving life and operating characteristics of the lamps.
Description
llZ9484 The present invention relates to electrical ballast systems for starting and operating gaseous discharge lamps, and more particularly concerns ballast apparatus for operating fluorescent Iamps.
It is a general object of the invention to provide ballast qpparatus of the above type having improved efficiency for operating gaseous discharge lamps, particu-larly fluorescent lamps.
It is another object of the invention to provide a lamp-ballast system of the above type having improved operating characteristics.
A particular object of the invention is to reduce the power applied to ballast systems of the above type without corresponding reduction of the light output of the lamps associated with the ballast system.
Another object of the invention is to provide a ballast system which in combination with low energy lamps produces a lamp current waveform-with reduced crest factor.
Other objects and advantages will become apparent from the following description and the appended claims.
With the above objects in view, the present invention in one of its aspects relates to a ballast apparatus for starting and operating low pressure gaseous discharge lamps comprising, in combination, input terminal means for con-nection to an alternating current supply to provide input power to the ballast apparatus, high leakage reactance autotransformer means having a primary winding and a llZ9484 secondary winding, the primary winding being connected at opposite ends to the input terminal means, secondary circuit means including the secondary winding and means for serially connecting a plurality of low pressure gaseous discharge lamps to the secondary winding and said primary winding, capacitor means serially connected in the secondary circuit means for providing a leading current therein, the secondary circuit means connected to a tap on the primary winding. for supplying from the primary winding a predetermined voltage in the secondary circuit means for reducing the ratio of the power input to the lamp light output.
The invention will be better understood from the following description taken in conjunction with the 15 - accompanying drawings, in which:
FIGURE 1 is a circuit diagram of a lamp ballast system showing an embodiment of the inventioni FIGURE 2 is a circuit diagram showing a modification of the FIGURE 1 ballast system;
FIGURE 3 is a circuit diagram of another embodiment of the lamp-ballast system of the invention;
FIGURE 4 is a diagrammatic sectional view of a fluorescent lamp which may be employed in the lamp-ballast system of the invention;
FIGURE 5 graphically illustrates the lamp current waveform in a typical prior art ballast system using low energy lamps;
It is a general object of the invention to provide ballast qpparatus of the above type having improved efficiency for operating gaseous discharge lamps, particu-larly fluorescent lamps.
It is another object of the invention to provide a lamp-ballast system of the above type having improved operating characteristics.
A particular object of the invention is to reduce the power applied to ballast systems of the above type without corresponding reduction of the light output of the lamps associated with the ballast system.
Another object of the invention is to provide a ballast system which in combination with low energy lamps produces a lamp current waveform-with reduced crest factor.
Other objects and advantages will become apparent from the following description and the appended claims.
With the above objects in view, the present invention in one of its aspects relates to a ballast apparatus for starting and operating low pressure gaseous discharge lamps comprising, in combination, input terminal means for con-nection to an alternating current supply to provide input power to the ballast apparatus, high leakage reactance autotransformer means having a primary winding and a llZ9484 secondary winding, the primary winding being connected at opposite ends to the input terminal means, secondary circuit means including the secondary winding and means for serially connecting a plurality of low pressure gaseous discharge lamps to the secondary winding and said primary winding, capacitor means serially connected in the secondary circuit means for providing a leading current therein, the secondary circuit means connected to a tap on the primary winding. for supplying from the primary winding a predetermined voltage in the secondary circuit means for reducing the ratio of the power input to the lamp light output.
The invention will be better understood from the following description taken in conjunction with the 15 - accompanying drawings, in which:
FIGURE 1 is a circuit diagram of a lamp ballast system showing an embodiment of the inventioni FIGURE 2 is a circuit diagram showing a modification of the FIGURE 1 ballast system;
FIGURE 3 is a circuit diagram of another embodiment of the lamp-ballast system of the invention;
FIGURE 4 is a diagrammatic sectional view of a fluorescent lamp which may be employed in the lamp-ballast system of the invention;
FIGURE 5 graphically illustrates the lamp current waveform in a typical prior art ballast system using low energy lamps;
-2-1~29484 FIGURE 6 graphically illustrates the lamp current waveform obtained with the ballast system of the invention;
and FIGURE 7 graphically illustrates the reduction in secondary output voltage required to start the lamps by the ballast ~stem of the invention.
Referring now to the drawings, and particularly to FIGURE 1, there is shown a lamp ballast circuit l embodying the invention for starting and operating a pair of serially connected fluorescent lamps 2 and 3.
Such lamps may be of the known low energy type shown in FlGURE 4, which in the illustrated form comprises a glass envelope 21 having electrodes 30, 34 at its opposite ends, a thin, transparent coating of activated tin oxide 22 serving as an internal starting aid, and a fluorescent phosphor coating 23. Contained within envelope 21 is a filling gas comprising mercury and a mixture of:krypton and neon in a ~olume ratio of about 80~ to 20% at a pressure of about 1.5 torr. Qther inert gases such as argon may replace the neon gas. By "low energy lamp type" is meant lamps which operate at lower wattage than those.of equivalent size without proportional loss of lamp efficiency.
Ballast apparatus lO as illustrated in FIGURE 1 is shown enclosed in a dashed rectangle 11 which schematically represents a ballast case. Ballast apparatus 10 includesa high ~akage reactance autotransformer 12 having a magnetic core 13, magnetic shunts 14, a primary winding P and a secondary winding S inductively coupled therewith. A
plurality of cathode heating windings 15, 16, and 25, are inductively coupled with primary winding P to supply heating current to the lamp filaments 17, 18 and 19, 20 of lam~s 2 and 3 respectively. A pair of input terminals 21, 22 are provided for connection to a suitable alter-nating current supply (not shown) such as a 60 cycle, 120 volt AC supply.
In the illustrated embodiment, a flux leakage path is provided between primary winding P and secondary winding S by virtue of shunts 14 arranged between the windings.
Series capacitor 7 connected at onè side to secondary winding S and at the other side to lamp 3 provides leading current in the secondary ~lamp) circuit, and in combination with autotra~ormer 12 provides a current limiting ballast function for the lamp load, as well understood in the art.
Secondary winding S is connected with one terminal of lamp 3 by circuit means which include capacitor 7 and conductor lead 24, while the other end of serially connected lamp 2 is connected by conductor lead 29 to the end of primary winding P which is connected to input terminal 22.
A starting capacitor 6 is connected across lamp 3 so that open circuit starting voltage is initially applied across lamp 2. Resistors 33 and 35 which respectively ~129484 shunt series capacitor 7 and starting capacitor 6 are bleeder resistors for removing the charge on the capacitors when the circuit is de-energized.
In accordance with the invention, one end of ~5 secondary winding S is connected to a tap 19 on primary winding P so as to reduce the voltage in the lamp circuit.
It has been found that this arrangement results in a number of advantages in the ballast system as, for example, improving the operating efficiency of the ballast circuit, lowering the series capacitor voltage, and reducing the crest factor of the lamp current waveform, !' i.e., the ratio of the peak lamp current to the RMS
value of lamp current.
0~
Typically, the number of turns tapped of primary winding P by the end of secondary winding S in the embodiment illustrated in FIGURE 1, i.e., the turns between tap 19 and the upper end of the primary winding, is such as to reduce the voltage contributed by the primary winding to the secondary circuit about 40 volts, 2Q i.e., a reduction of about 10% - 15% from the secondary circuit voltage which would otherwise result in an arrangement without a tapped primary winding.
In a ballast system of the rapid start type such as shown in FIGURE 1 and which has produced satisfactory results in accordance with the invention, the components had the following values:
Primary winding P -853 turns Secondary winding S -1,422 turns Turns tapped off primary -204 turns Transformer core -Shell type Ce-ter leg, cross section -.57 in2.
Cathode heating winding 25 - 28 turns Cathode heating winding 15 - 33 turns Cathode heating winding 16 - 31 turns Series capacitor 7 -4.5 mfd Starting capacitor 6 -.1 mfd Bleeder resistor 35 -100 K ohms Lamps, two -48 in.,35 watt, Rapid Start Tests made on a lamp-ballast system of the above ~ specified construction showed that the total lamp lumens was about 5980 lumens with a power input of ~9 watts.
FIGURE 2 shows a portion of the FIGURE 1 rapid start ballast system depicting an alternative means for reducing the primary voltage in the lamp circuit. As shown, removal of a portion of the primary voltage from the lamp circuit in accordance with the invention is achieved by re-locating the cathode heating winding 25 so as to tap off the desired number of primary winding turns, instead of tapping the primary winding P with the end of secondary winding S as in the FIGURE 1 embodiment.
FIGURE 3 shows a different embodiment of the invention comprising an instant start ballast system having an 1~29484 . LD7706 autotransformer 40 comprising a primary winding formed of portions Pl and P2 connecte,d at adjacent ends at a connection constituting a tap on the primary winding, and wherein the remote end of portion P2 is connected directly to AC supply terminal 41 and the remote end of portion Pl is connected to the other AC supply terminal 42 via a connection 43 in a disconnect lampholder for fluorescent lamp 44, while the remaining ends of portions Pl and P2 are connected to,a similar connection 45 in fluorescent lamp 46. Secondary winding S2 is in autotransformer relationship with primary winding portion Pl serially connected through series capacitor 47 and lamps 44 and 46. Portion P2, and its corresponding voltage, thus is effectively removed from the secondary (lamp) circuit.
Secondary winding Sl connected at one end to primary portion Pl and at the other end in series with series capacitor 47 and lamp 44 serves to provide a starting voltage for lamp 44. After lamp starting, secondary winding Sl, due to its relatively high impedance, supplies minimal current to the lamp circuit during operation of the lamp.
FIGUR~S 5 and 6 graphically show the improvement in operating lamp current characteristics obtained in connection with the present invention. FIGURE 5 shows the lamp current waveform resulting from the use of a ballast circuit similar to that shown in FIGURE 1 except that the secondary winding was connected to the end of the primary winding ratherlto a tap on the latter.
The lamps used in this test were low energy fluorescent lamps of the construction shown in FIGURE 4. As will be seen, the peak lamp current is relatively high with respect to the RMS lamp current, the lamp current crest factor being at a level typical of prior ballast systems of this type. FIGURE 6 is a graph on the same scale as the FIGURE 5 graph depicting the lamp current waveform obtained with the- FIGURE 1 ballast circuit including the tapped primary arrangement and the FIGURE 4 lamp.
In this circuit, 250 turns were tapped off the primary winding. As is evident,the peak lamp cu~rent is markedly lower than that obtained with the prior art ballast arrangement represented by FIGURE 5, resulting in a correspondingly reduced lamp current crest factor. The life and operating characteristics of the lamps are thereby substantially improved.
In accordance with another feature of the invention, starting capacitor 6 in the FIGURE 1 circuit is preferably of higher value than previously used with low energy lamps of the type depicted in FIGURE 4 to facilitate starting of the lamps. In a circuit of the described type, it has been found that use of a starting type capacitor having a value in the range of about .08 - .16 mfd produced unexpectedly large improvement in the starting of lamps of the described type. FIGURE 7 graphically shows the effects on lamp starting with the ~lZ94~4 use of starting capacitors of various values and two lamps of different types. In-the graph, in which secondary circuit starting voltage is plotted against cathode ~eating-voltage, Curves A, B and C depict the starting effects of different capacitor values on a conventional 40 watt ~luorescent lamp, whereas Curves D, E, and F
depict the starting effects of different capacitor values on a low energy fluorescent lamp of the type shown in FIGURE 4, Associated with each of the curves is the value of the starting capacitor employed in the circuit. As will be evident from the graph, the reduction in starting voltage required to start lamps of the described low energy type using higher capacitor values in accordance with the invention is unexpectedly lS greater than that obtained by similar means with respect to the conventional lamp. The graph also shows an unexpected reduction in required starting voltage for a given increase in cathode heating voltage.
While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually depàrting from the scope of the invention. Therefore, the appended claims are intended to cover all such equivalent variations as come within the true spirit and scope of the invention.
and FIGURE 7 graphically illustrates the reduction in secondary output voltage required to start the lamps by the ballast ~stem of the invention.
Referring now to the drawings, and particularly to FIGURE 1, there is shown a lamp ballast circuit l embodying the invention for starting and operating a pair of serially connected fluorescent lamps 2 and 3.
Such lamps may be of the known low energy type shown in FlGURE 4, which in the illustrated form comprises a glass envelope 21 having electrodes 30, 34 at its opposite ends, a thin, transparent coating of activated tin oxide 22 serving as an internal starting aid, and a fluorescent phosphor coating 23. Contained within envelope 21 is a filling gas comprising mercury and a mixture of:krypton and neon in a ~olume ratio of about 80~ to 20% at a pressure of about 1.5 torr. Qther inert gases such as argon may replace the neon gas. By "low energy lamp type" is meant lamps which operate at lower wattage than those.of equivalent size without proportional loss of lamp efficiency.
Ballast apparatus lO as illustrated in FIGURE 1 is shown enclosed in a dashed rectangle 11 which schematically represents a ballast case. Ballast apparatus 10 includesa high ~akage reactance autotransformer 12 having a magnetic core 13, magnetic shunts 14, a primary winding P and a secondary winding S inductively coupled therewith. A
plurality of cathode heating windings 15, 16, and 25, are inductively coupled with primary winding P to supply heating current to the lamp filaments 17, 18 and 19, 20 of lam~s 2 and 3 respectively. A pair of input terminals 21, 22 are provided for connection to a suitable alter-nating current supply (not shown) such as a 60 cycle, 120 volt AC supply.
In the illustrated embodiment, a flux leakage path is provided between primary winding P and secondary winding S by virtue of shunts 14 arranged between the windings.
Series capacitor 7 connected at onè side to secondary winding S and at the other side to lamp 3 provides leading current in the secondary ~lamp) circuit, and in combination with autotra~ormer 12 provides a current limiting ballast function for the lamp load, as well understood in the art.
Secondary winding S is connected with one terminal of lamp 3 by circuit means which include capacitor 7 and conductor lead 24, while the other end of serially connected lamp 2 is connected by conductor lead 29 to the end of primary winding P which is connected to input terminal 22.
A starting capacitor 6 is connected across lamp 3 so that open circuit starting voltage is initially applied across lamp 2. Resistors 33 and 35 which respectively ~129484 shunt series capacitor 7 and starting capacitor 6 are bleeder resistors for removing the charge on the capacitors when the circuit is de-energized.
In accordance with the invention, one end of ~5 secondary winding S is connected to a tap 19 on primary winding P so as to reduce the voltage in the lamp circuit.
It has been found that this arrangement results in a number of advantages in the ballast system as, for example, improving the operating efficiency of the ballast circuit, lowering the series capacitor voltage, and reducing the crest factor of the lamp current waveform, !' i.e., the ratio of the peak lamp current to the RMS
value of lamp current.
0~
Typically, the number of turns tapped of primary winding P by the end of secondary winding S in the embodiment illustrated in FIGURE 1, i.e., the turns between tap 19 and the upper end of the primary winding, is such as to reduce the voltage contributed by the primary winding to the secondary circuit about 40 volts, 2Q i.e., a reduction of about 10% - 15% from the secondary circuit voltage which would otherwise result in an arrangement without a tapped primary winding.
In a ballast system of the rapid start type such as shown in FIGURE 1 and which has produced satisfactory results in accordance with the invention, the components had the following values:
Primary winding P -853 turns Secondary winding S -1,422 turns Turns tapped off primary -204 turns Transformer core -Shell type Ce-ter leg, cross section -.57 in2.
Cathode heating winding 25 - 28 turns Cathode heating winding 15 - 33 turns Cathode heating winding 16 - 31 turns Series capacitor 7 -4.5 mfd Starting capacitor 6 -.1 mfd Bleeder resistor 35 -100 K ohms Lamps, two -48 in.,35 watt, Rapid Start Tests made on a lamp-ballast system of the above ~ specified construction showed that the total lamp lumens was about 5980 lumens with a power input of ~9 watts.
FIGURE 2 shows a portion of the FIGURE 1 rapid start ballast system depicting an alternative means for reducing the primary voltage in the lamp circuit. As shown, removal of a portion of the primary voltage from the lamp circuit in accordance with the invention is achieved by re-locating the cathode heating winding 25 so as to tap off the desired number of primary winding turns, instead of tapping the primary winding P with the end of secondary winding S as in the FIGURE 1 embodiment.
FIGURE 3 shows a different embodiment of the invention comprising an instant start ballast system having an 1~29484 . LD7706 autotransformer 40 comprising a primary winding formed of portions Pl and P2 connecte,d at adjacent ends at a connection constituting a tap on the primary winding, and wherein the remote end of portion P2 is connected directly to AC supply terminal 41 and the remote end of portion Pl is connected to the other AC supply terminal 42 via a connection 43 in a disconnect lampholder for fluorescent lamp 44, while the remaining ends of portions Pl and P2 are connected to,a similar connection 45 in fluorescent lamp 46. Secondary winding S2 is in autotransformer relationship with primary winding portion Pl serially connected through series capacitor 47 and lamps 44 and 46. Portion P2, and its corresponding voltage, thus is effectively removed from the secondary (lamp) circuit.
Secondary winding Sl connected at one end to primary portion Pl and at the other end in series with series capacitor 47 and lamp 44 serves to provide a starting voltage for lamp 44. After lamp starting, secondary winding Sl, due to its relatively high impedance, supplies minimal current to the lamp circuit during operation of the lamp.
FIGUR~S 5 and 6 graphically show the improvement in operating lamp current characteristics obtained in connection with the present invention. FIGURE 5 shows the lamp current waveform resulting from the use of a ballast circuit similar to that shown in FIGURE 1 except that the secondary winding was connected to the end of the primary winding ratherlto a tap on the latter.
The lamps used in this test were low energy fluorescent lamps of the construction shown in FIGURE 4. As will be seen, the peak lamp current is relatively high with respect to the RMS lamp current, the lamp current crest factor being at a level typical of prior ballast systems of this type. FIGURE 6 is a graph on the same scale as the FIGURE 5 graph depicting the lamp current waveform obtained with the- FIGURE 1 ballast circuit including the tapped primary arrangement and the FIGURE 4 lamp.
In this circuit, 250 turns were tapped off the primary winding. As is evident,the peak lamp cu~rent is markedly lower than that obtained with the prior art ballast arrangement represented by FIGURE 5, resulting in a correspondingly reduced lamp current crest factor. The life and operating characteristics of the lamps are thereby substantially improved.
In accordance with another feature of the invention, starting capacitor 6 in the FIGURE 1 circuit is preferably of higher value than previously used with low energy lamps of the type depicted in FIGURE 4 to facilitate starting of the lamps. In a circuit of the described type, it has been found that use of a starting type capacitor having a value in the range of about .08 - .16 mfd produced unexpectedly large improvement in the starting of lamps of the described type. FIGURE 7 graphically shows the effects on lamp starting with the ~lZ94~4 use of starting capacitors of various values and two lamps of different types. In-the graph, in which secondary circuit starting voltage is plotted against cathode ~eating-voltage, Curves A, B and C depict the starting effects of different capacitor values on a conventional 40 watt ~luorescent lamp, whereas Curves D, E, and F
depict the starting effects of different capacitor values on a low energy fluorescent lamp of the type shown in FIGURE 4, Associated with each of the curves is the value of the starting capacitor employed in the circuit. As will be evident from the graph, the reduction in starting voltage required to start lamps of the described low energy type using higher capacitor values in accordance with the invention is unexpectedly lS greater than that obtained by similar means with respect to the conventional lamp. The graph also shows an unexpected reduction in required starting voltage for a given increase in cathode heating voltage.
While the present invention has been described with reference to particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without actually depàrting from the scope of the invention. Therefore, the appended claims are intended to cover all such equivalent variations as come within the true spirit and scope of the invention.
Claims (5)
1. Ballast apparatus for starting and operating low pressure gaseous discharge lamps comprising, in combination, input terminal means for connection to an alternating current supply to provide input power to the ballast apparatus, high leakage reactance autotransformer means having primary winding means and secondary winding means, said primary winding means comprising first and second winding portions having adjacent ends connected at a tap, operating secondary circuit means including at least a portion of said secondary winding means and means for serially connecting low pressure gaseous discharge lamp means to at least said portion of said secondary winding means and to said tap on said primary winding means, capacitor means serially connected in said operating secondary circuit means for providing a leading current therein, said operating secondary circuit means connected to said tap on said primary winding means for supplying from said primary winding means a predetermined voltage in said secondary circuit means for reducing the ratio of said power input to the lamp light output, the portions of said primary winding means on opposite sides of said tap having the same polarity and the remote end of said first primary winding portion being connected to said input terminal means by said lamp connecting means and the remote end of said second primary winding portion being connected to said input terminal means, said secondary winding means having a single polarity.
2. Ballast apparatus as defined in claim 1, said secondary winding means having first and second winding portions, said first winding portion thereof being connected to said tap and in series with said capacitor and said lamp connecting means for starting said lamp means, said second winding portion thereof being connected serially with said capacitor and said first primary winding portion by said lamp connecting means for providing operating voltage for the lamp means.
3. Ballast apparatus as defined in claim 2, including lamp cathode heating windings inductively coupled to said primary winding means.
4. Ballast apparatus as defined in claim 3, including a lamp starting capacitor connected to said lamp connected to said lamp connecting means.
5. Ballast apparatus as defined in claim 4, said starting capacitor having a value of about 0.08 to 0.16 microfarads.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA329,403A CA1129484A (en) | 1979-06-08 | 1979-06-08 | High efficiency ballast system for gaseous discharge lamps |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA329,403A CA1129484A (en) | 1979-06-08 | 1979-06-08 | High efficiency ballast system for gaseous discharge lamps |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1129484A true CA1129484A (en) | 1982-08-10 |
Family
ID=4114395
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA329,403A Expired CA1129484A (en) | 1979-06-08 | 1979-06-08 | High efficiency ballast system for gaseous discharge lamps |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1129484A (en) |
-
1979
- 1979-06-08 CA CA329,403A patent/CA1129484A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |