US2820180A

US2820180A - Ballast and lighting system for fluorescent lamps

Info

Publication number: US2820180A
Application number: US372310A
Authority: US
Inventors: Albert E Feinberg
Original assignee: Advance Transformer Co
Current assignee: Advance Transformer Co
Priority date: 1953-08-04
Filing date: 1953-08-04
Publication date: 1958-01-14
Anticipated expiration: 1975-01-14

Description

Jan. 14, 1958 A. E. FElNBERG BALLAST AND LIGHTING SYSTEM FOR FLUORESCENT LAMPS Filed Aug. 4, 1955 s Sheets-Sheet 1 &

Jan. 14, 1958 A. E. FEINBERG 2,320,130

BALLAST AND LIGHTING SYSTEM F OR FLUORESCENT LAMPS Filed Aug. 4, 1953 3 Sheets-Sheet 2

445g

55,56, 57 a5 U I 50 Jan. 14, 1958 A. E. FEINBERG 2,820,180

BALLAST AND LIGHTING SYSTEM FOR FLUORESCENT LAMPS Filed Aug. 4, 1953 3 Sheets-Sheet 5 United States Patent BALLAST AND LIGHTING SYSTEM FOR FLUORESCENT LAMPS Albert E. Feinberg, Chicago, Ill., assignor to Advance Transformer (10., Chicago, 111., a corporation of Illinois Application August 4, 1953, Serial No. 372,310

4 Claims. (Cl. 315-257) This invention relates generally to gaseous discharge devices and more particularly is concerned with transformers, or ballasts as they are known, for initiating and subsequently operating lighting systems which include fluorescent lamps.

Of recent years there has been developed a type of lamp which is known as rapid start to designate the same from the lamp heretofore known as the instant start. In the latter, ignition was achieved through the use of high voltages without the necessity of employing preheated filaments to produce clouds of electrons. In the former, filaments are provided but due to their durable construction, it is not necessary to provide starters or switching systems to remove the filaments from the circuit once ignition has been achieved. The filaments of rapid start lamps are connected into the circuits with. which the same are used and carry current at all times. If desired, filament windings may be arranged to have bucking voltages generated therein after ignition to decrease the flow of current through the filaments.

Many problems have arisen in the construction of fixtures and lighting systems in the utilization of these rapid start lamps, among which have been considerations of safety. Consider, for example, a situation where a voltage exists to ground which is of such value as to be v dangerous to one handling the fluorescent lamp. It is possible for one end of the lamp to be touched by one who is himself grounded. If the combined open circuit voltage from ground through the person holding the lamp and through the transformer is greater than ignition voltage or even close to it, the lamp may ignite and current flow. This is dangerous to the person who is holding the lamp, especially if the current through line is overmilliamperes.

This value of 5 milliamperes has therefore been choserr by the Underwriters Laboratories as that current which. is the maximum which may flow to ground through the: circuit.

Through the use of a high resistance inserted between. the primary and the remainder of the transformer, it is. possible to limit the flow of current to ground. This: invention contemplates that type of circuit, i. e. one in which such a high resistance is electrically inserted between the primary winding and the remainder of the transformer.

An important object of the invention is to provide in a circuit of the character which utilizes such an isolating resistance, means so that the voltage which exists from the isolating point to ground may be utilized as an additional starting aid to ignite the lamp or lamps. "m

A further object of the invention is to provide in a. circuit of the character described, means for utilizing a reflector of the lamp fixture as a capacitive coupling toground, so that a flow of current to ground through re' flector may be possible, giving rise to an initial starting; aid voltage for the lamp.

Still a further object of the invention is to provide a;

" point designated A to ground. This, of course, is line" Patented Jan. 14, 1958 'ice 2 novel lighting system utilizing lead-lag circuits for igniting and thereafter providing for the operation of two (2) fluorescent lamps.

Still a further object of the invention is to provide a series-sequence lighting circuit utilizing the principles of the invention.

Other objects will appear as the description of the invention proceeds, especially in view of the detailed exposition of preferred embodiments illustrated in the attached drawings.

In the drawings which include electrical diagrams more or less conventional in nature:

Fig. 1 is an electrical diagram of a lighting system utilizing my invention for operating a single gaseous discharge device in the form of a fluorescent lamp.

Fig. 2 is a schematic plan view, with portions shown in section, of a transformer embodying the invention.

Fig. 3 is an electrical diagram of a fluorescent lighting system embodying the invention, in which two (2) fluorescent lamps are connected in circuit in lead-lag arrangement.

Figs. 4 and 5 are views similar to that of Fig. 2, but showing a transformer intended for use with the circuit shown in Fig. 3.

Fig. 6 is a modified form of the circuit shown in Fig. 3.

Fig. 7 is a circuit diagram of a fluorescent lighting system embodying the invention, utilizing two (2) fluorescent lamps and operating on the series sequence principle.

Fig. 8 is a simplified perspective view of the type for fixture which may be used in practising the invention.

As explained previously, the Underwriters Laboratories have established requirements for fluorescent ballasts utilizing rapid start lamps such that the flow of current to ground is limited to 5 milliamperes. This is achieved by isolating the primary from the remainder of the transformer and, hence, it has been necessary to increase the number of turns in the windings which provide the starting voltages in the lamps. The voltage generated across the primary has not been available as an aid n starting.

In my invention I utilize a coupling of capacitive nature between the fluorescent lamp or lamps and a metal reflector which is formed as a part of the fixture within which lamps are installed. This provides a path to ground through the lamp and thereby gives the added voltage of the line in addition to that of the secondary windings as an aid in starting the lamp.

In its simplest form, the invention is shown in Fig. 1. Reference character 10 is used to designate generally the circuit and it will be seen that the usual lines conventionally designating iron cores have been excluded to render more lucid the explanation. There is a primary winding 11 and a secondary winding 12 separated by a high resistance 13. The winding 11 is connected across the

terminals

14 and 15, the remote terminal 14 being grounded as shown at 16.

As a matter of convention, the electrical lead 17 will be white and the lead 18 black, contrary to common usage. A fluorescent lamp 19 is connected across the secondary winding 12 by means of the

leads

20 and 21. It is required that the voltage appearing across the secondary winding 12 be sufficient in and of itself to ignite the lamp 19, unless some additional aid is provided. Without this aid it would be necessary, in the case of a 40 \watt rapid start lamp, that the winding 12 generate well over 300 volts. In accordance with my invention, 1 provide a capacitive coupling which extends from the reflecrtor 22 to the lamp 19 and providing a path through the electrical conductor 23 to ground 16. This adds to the voltage which has been developed across the secondary winding 12, at least that voltage which appears from the '5 said reflector 127 being connected to ground through the lead 128.

The transformer construction which is used in connection with the circuit of Fig. 6 is shown in Fig. 4 and differs only in the respect that there is no secondary winding equivalent to the secondary 52 and there is an additional filament winding. It is also obvious that the lead and

lag secondaries

108 and 109 will have to have more turns in order to provide sufiicient igniting voltage for the respective lamps.

In Fig. 7 I have illustrated still another embodiment of the invention which utilizes a series sequence starting arrangement. In this case substantially all of the igniting voltage for the lamps is provided by a single secondary winding, augmented by the voltage developed between ground and the reflector of the fixture with which the lamps are associated. Also in this case, the lamps are ignited one at a time so that all the voltage which need be developed in the secondary winding is the igniting voltage of one lamp.

Referring now to the details, there is illustrated a primary 150 which is connected to

line terminals

151 and 152 by

leads

153 and 154. The terminal 151 is grounded as shown at 155 and a high ohmage resistor 156 is connected between the right-hand terminal of the primary winding 150 and the remainder of the transformer. Tracing the principal circuit, the right-hand terminal of the resistor 156, which is designated A, connects by way of the lead 158 to the left-hand terminal of the lamp 159, thence by the lead 160 to the left-hand terminal of the secondary winding 161, thence by way of the lead 162 and the series condenser 163 to the right-hand terminal of the lamp 164 and back to the terminal A. Across the lamp 164 there is provided a condenser 165 to aid in series igniting the lamps. Obviously, first the lamp 159 will ignite after which the lamp 164 will ignite. After the lamps have ignited, the condenser 165 serves as a high reactance and the circuit is a series circuit through both lamps.

Filament windings are provided as shown at 166, 167 and 168 and these are connected to the various filaments of the lamps as shown. It will be seen that in the ignition of each lamp in turn there will be added a voltage caused by capacitive coupling between the reflector 170 and the

lamps

159 and 164. This provides a path through the conductor 171 to ground and adds to the voltage induced in the secondary winding 161, that voltage appearing from the point A to ground. In addition, as in the case of all other circuits herein described, the resistor 156 effectively isolates the primary winding and limits the flow of current to that required by the Underwriters Laboratones.

The transformer core with which the

ballast comprising windings

150, 161, 166, 167 and 168 are associated, does not differ greatly from that illustrated in Fig. 1.

In Fig. 8 I have shown a rather simplified form of fixture with which the invention is intended to be used. The fixture is designated generally 200 and only the lefthand end is shown. There is a base or standard which may be either a flat plate or an enclosed housing. As shown it is in the form of a rectangular housing for holding the ballast. The housing includes a bottom plate 201 and

side reflector wings

203 and 204 which surround the

lamps

205 and 206. These lamps are held in the

usual holders

207 and 208 provided at the ends of the fixture. In accordance with the invention the spacing between the

lamps

205 and 206 and the reflector formation comprising the plate 201 and the

wings

203 and 204 is such as to provide a capacitive connection. When the reflector formation is grounded as explained hereinbefore, there will be a voltage existing across the capacitive connection suitable for use as a starting aid.

It is believed that one skilled in the art could readily construct and use the ballast and systems as set forth hereinabove. Depending upon the types of lamps used and the line voltage, one may readily determinethe number of turns for the respective windings and the value of resistance of the isolating resistor. For example, in the case of the circuit of Fig. 1 and the transformer of Fig. 2, the resistor 13 was approximately 1.5 megohms for the case of a 40 watt fluorescent lamp. Line voltage was 118 volts. The primary was 670 turns of number 23 gauge wire and the secondary was approximately 1350 turns of number 28 wire. The Width of the winding leg 31 was .8 inch and the total width of the shell core was 2.25 inches. A 1 inch stack of laminations was used and the length was adjusted to provide a sufiicient shunt 34 and suflicient bridging ends to accommodate the number of turns. The voltage developed across the secondary winding from the point A to the lead 21 was approximately 205 volts. During starting there was available to parts of the lamp 205 plus 118 or 323 volts which gave quite an assist in igniting the rapid start lamp 19.

The specific dimensions and physical specifications of the other circuits and transformers illustrated may be worked out on the basis of the technique set forth above.

It is believed that the invention has been fully set forth as required by the patent laws, and it is also desired to point out that considerable variation is possible without in any way departing from the spirit or scope of the invention as defined in the appended claims.

What it is desired to claim by Letters Patent of the United States is:

1. A system for igniting and operating at least one gaseous discharge lamp from a source of A. C. voltage substantially less than the igniting voltage of the said lamp which comprises, an iron core transformer having a primary winding and at least one secondary winding inductively coupled thereto to have a voltage induced in the secondary winding, an elongate gaseous discharge lamp in circuit with the secondary winding, a fixture supporting said lamp and having an elongate, grounded metal part thereof extending along the length of said lamp contiguous and capacitively coupled therewith, a high ohmage resistor connected between one terminal of the primary winding and one terminal of said lamp and providing a connection with said circuit electrically separating the primary and said circuit, the second terminal of the primary winding being grounded, the primary winding being connected across said source, the secondary winding being connected to the lamp to provide igniting and operating voltage therefor, the instantaneous open circuit voltage sense of said primary winding relative said lamp I and secondary winding being such as to provide an augmenting additive starting voltage for said lamp, said resistor having a value such as to provide a substantial electrical connection between the primary winding and the circuit, including the secondary winding while limiting current flow through the system to a relatively safe value.

2. A system for igniting and operating a pair of gaseous discharge devices in lead-lag arrangement, which comprises, an iron core transformer having a primary winding and a secondary winding inductively coupled therewith to have a voltage induced therein and loosely coupled relative to the primary to provide high leakage reactance, a lead circuit connected across the secondary winding and comprising first inductive means. a first elongate gaseous discharge device and a capacitor all in series, a lag circuit also connected across the secondary winding and comprising second inductive means and a second elongate gaseous discharge device both in series, a high impedance element connected between one terminal of said primary winding and a terminal of each of said gaseous discharge devices and being also electrically interposed between said one primary terminal and the circuit including said secondary winding, the second terminal of said primary winding being grounded, elongate grounded metallic means extending adjacent and capactively coupled with said discharge devices, the open circuit instantaneous voltage senseaofeaid primary winding being additive -relative to thatot:said:secondary windi-ngwhereby to provide an additional \starting voltage for said devicesg the high impedanceelement-being of a value to limit current in said system to a safe valuewhile providing-asubstantial electrical connection to sai'd p'rimary winding.

3. JA-system-"for ignitingand operating two gaseous discharge-devices comprising, .a source of A. C; vo1tage,an iron core; transformer having a primary winding-connected across 'the source with one-terminal grounded, a high ohm-age resistor having one side connected to 'the'other terminal ofthe primary winding, two loops -;connecte"d to' the-second side of the resistor and "electrically isolated from said primary --winding' thereby whereby any current flowing from -sa-id loops i to said primary must traverse said resistor and be limited'-thereby,-one loop comprising afirst -gaseous discharge device, -a condenser and ,afirst secondary winding all connected in series, "with :Ihe secondary --winding inductively -related to 'said primary winding andoneterminal of saidgaseous dischar gejdevice connected to said-second-side-of-said resistor, said, second loop comprisinga secondgaseous discharge device and a secondsecon'dar-y winding inseries with the secondary winding inductively relatedto said primary winding and said--second gaseous discharge 'devicehaving one terminal connected to said'secon'dsideofsaid,resistor, metallic electrode means eapactively coupled to both devices and connected to ground, the instantaneous open circuit voltagesense ofsaid-secondary'winiiings bothbe'ing additive relative to-t-he primarywinding whereby on open circuit the=voltageof saidprimary-will aid said secondatiesin igniting -said discharge devices through said electrode means.

4. A-eireuit including two gaseous ,discharge devices,

a aouree of *A. "Cavoltage, -an I iren -cora transformer, -a' primary winding mounted on the transformer andconneeted across said --source to -be energized thereby "With one terminal grounded, a high ohma'ge --resistor--having one side-connected to the second terminal of theprimary winding, a loop comprising a secondary winding in'ductively-related to theprimary winding,- saidtwo gaseous-diseharge devices, and *a capacitor all connected in --series' with-asecond eapacitor shunting -one device; 't-he:second side of saidresistor being connected to said-loop electrically Fisolating said loop from the 1 primary, the connection -of*said'second"side of "said -re'sistor'-being-at a terminal of at least the'second gaseous discharge device, there being a "grounded metallic -mernber capactively copple'd'afleaSt -tosaid-second'gaseons discharge device, the relative open circuit instantaneous voltage sense of the primaryyand secondarywindings being additive such thatsaid primaryiwinding aids in the starting. of at least sai'd*seConddischarge device, the-value of sai'dresistor being such as to limit the flowrof current betweenloop and primaryto--a relativelyrsafe valuewhile providing a substantial :iect'rical connection 'therebetween.

RefereneeS CiteEin-the fileof this-patent .UNI'IIEDJSTATES PATENTS $961,516 ;Mitscherling :lan.;112,'i19 .37 :2,2S2-, 5 3.0 Sweenyaet;al....... Aug. 12, 1941 253545626 Mett-ler Aug. 1, 1944 $462,336 Rufi Feb. :22, 1949 294 5119 i'Komm "1vI-ar.;22,1949 2513x394 .-Arvidsson Jan. '5, 1954 21668359 fStutsman :Feb. 12, 1954 2,683,2541 'Eassmore July*6, 179-54 Disclaimer 2,820,1'80.A Zbert E. Fez'nberg, Chicago, Ill. BALLAST AND LIGHTING SYSTEM FOR FLUORESCENT LAMPS. Patent dated J an. 14, 1958. Disclaimer filed July 30, 1964, by the inventor, the assignee, Advance Transfomwr 00., assenting.

Hereby enters this disclaimer to claim 1 of said patent.

[Ofiez'al Gazette September 1, 1.964.]