US2683242A - Control device and lighting system - Google Patents

Description

y 1954 R. J. HORSTMANN CONTROL DEVICE AND LIGHTING SYSTEM 5 sheets-sheet 1 r l I l I Filed Feb. 16, 1949 .III II II y 1954 R. J. HORSTMANN CONTROL DEVICE AND LIGHTING SYSTEM 3 Sheets-Sheet 2 Filed Feb. 16, 1949 I I l I I L J July 6, 1954 R. J. HORSTMANN CONTROL DEVICE AND LIGHTING SYSTEM Filed Feb. 16, 1949 5 Sheets-Sheet 3 f [Y El 152 (fen 02".-

Patented July 6, 1954 CONTROL DEVICE AND LIGHTING SYSTEM Roy J. Horstmann, Elmhurst, Ill., assignor to Jefferson Electric Company, Bellwood, 111., a corporation of Illinois Application February 16, 1949, Serial No. 76,738

9 Claims. I

This invention relates to a control device and to a lighting system including the same.

My invention is particularly well adapted for use in a lighting system embodying gaseous conduction tubes. For that reason, the following description has reference to my invention as applied to such a lighting system.

Lighting systems embodying gaseous conduction tubes of the type known as neon tubes and cold cathode tubes include a high reactance transformer for supplying the proper voltage for opera tion of the tube. One characteristic of such systems is that a dangerously high voltage is induced in the secondary circuit. When the secondary circuit is broken, due to tube failure or the like, certain of the parts are still energized, and constitute a source of danger to the electrician who replaces a tube. Control or protective devices have been proposed which automatically open the primary circuit when the secondary circuit is broken, thereby causing the whole system to go dead. Thus, an electrician is protected against shock when replacing a burned out tube, or in otherwise repairing the system.

Such protective devices generally include a cir cult breaker which is controlled by the existence or non-existence of a current flow in the secondary circuit. Such an arrangement has the disadvantage of requiring leads from the secondary circuit to the circuit breaker. The problems in insulating such high voltage leads are such that it has generally been found necessary to locate the circuit breaker immediately adjacent the transformer. Since the transformer is frequently located in an inaccessible position, this disadvantage constitutes a serious obstacle to the use of such control devices in certain types of installations.

It is an object of this invention to provide an improved electric system having a control device in the primary circuit which does not require separate leads from the secondary circuit.

Another object is to provide an improved ligh ing system in which the secondary circuit is protected against short circuit and open circuit conditions.

Still another object is to provide an improved lighting system of the type described which includes a high reactance transformer which is compensated so that the system can be operated at a substantially unity power factor and which also includes circuit breaking means in the primary circuit which is controlled solely by the load as reflected in the primary circuit.

A further object is to provide an improved-con- 2 trol device, the action of which is controlled by a phase shift in the load current.

A still further object is to provide a control device which is responsive to certain unusual changes in the conditions of the load circuit, but which is not sensitive to the transients which occur when the circuit is initially closed.

Other advantages, features and objects will become apparent as the description proceeds.

With reference now to the drawings in which like reference numerals designate like parts:

Fig. 1 is a diagram illustrating a preferred embodiment of my invention;

Figs. 2, 3, and 4 are diagrams illustrating modified forms of my invention;

Fig. 5 is a diagram illustrating a further modification of my invention; and

Figs. 6, '7 and 8 are vector diagrams illustrating certain voltage and current relationships in the foregoing circuits under different conditions.

In Fig. l, the reference numeral ID designates one or more lamps of the neon or cold cathode type. A transformer I I is provided for supplying power to the lamp. Supply leads I2 and I3 supply power to the transformer through the usual double pole switch 50, such as a wall switch. The lamp I0 and transformer II together comprise a load which is indicated generally by the reference numeral I4. A control device I5 is disposed between the load and supply leads I2 and I3.

The transformer I I comprises a primary winding I6 and a condenser winding II connected across the primary winding I6 and inductively coupled thereto. A condenser I8 is connected in series with the condenser winding I I. The trans former also includes a core I9 and a secondary winding 20 which is here shown as being in two sections. There may be a mid-point ground 2| between the two sections so as to provide for balanced operation of the secondary circuit. The transformer I I is a high reactance transformer of a type commonly used in neon or cold cathode systems, and the condenser I8 and condenser winding I I are provided to correct the power factor. Thus, the load I4 as a whole is designed to operate at a power factor of between and The lamp ID is connected to the secondary 20 by means of leads 22.

The control device I5 comprises a resistance 23 connected in series in the primary circuit, a control transformer 24 and a relay 26. The con trol transformer 24 comprises a primary winding 25 and a secondary winding 36, the primary Winding being shunted across the resistance 23.

3 The relay includes a movable contact 2! which is connected by a lead 28 to the resistance 23 and primary 25. The relay also includes two stationary contacts 29 and 39, the former being connected by lead $1 to the primary it of the supply transformer and the latter being connected by a lead 32 to the actuating winding 33 of the relay. The movable contact is normally biased against the stationary contact 29 so as to maintain a circuit through the transformer H. The arrangement is such that when the actuating winding 33 is initially energized so that the movable contact 2? engages the stationary contact at, the line current will hold the relay in operatedposition. If desired, an impedance 35 may be disposed between the actuating winding 33 and the stationary contact 36 so that the current fiowthrough the winding ma be limited. This impedance, when used, is preferabl a resistance, although other types of impedance may be used in certain situations. A lead 3 connects the actuating winding 33 to the supply lead 13.

The secondary 3.6. of the control transformer 2'4 is shunted across the gap between contacts 2'! and 30, and is connected to lead 28 by means of a lead 3?, and is connected to the actuating winding 33 by a lead 38-. The connections are such that the secondary voltage is in bucking relationship to the line voltage. The turn ratio of the control transformer 2 3 is such that the voltage induced in the secondary 36- is equal in magnitude to the line voltage, but opposes the same. Thus, when the load is drawing a current of substantially unity power factor, there wi l be either no current passing through the shunt circuit in cluding the secondary 35. and the actuating winding 33 of the relay or else the current will be sufiiciently small as: to not. cause the relay to operate.

This relationship of the electrical quantities involved i shown in Fig. 6 in which E1 is the voltage acrossv the primary 25, E2 the voltage across leads 3! and i3, E3 the voltage across secondary 38 and E4 the voltage across the relay actuating winding 33. I is the current drawn by the load,

In. is its resistive component and Ix its reactive component.

Fig. 6 represents the circuit at normal operating conditions under a lagging load of about 90% power factor. The voltage E3 of the secondary 3G is of the same magnitude as E2, which is substantially the line voltage. but E3 is 180 out of phase with the load current I, if the reactance of the control transformer 2-! be disregarded. Hence, E is approximately 155 outv of phase with assuming 96%; lagging power factor. Thus E4, which is the vectorsum of E2 and E3, is, of considerably less magnitude than either one.

When the tube circuit, is opened, the electrical quantities will be substantially as shown in Fig. I. Here the current I leads the line voltage E2 by substantially 90 with the result that the voltage across the secondary 3'6 and the actuating winding 33 will be as shown by the vectors E3 and if the reactance oi the transformer 24 is disregarded.

Fig. 8 shows a short circuited condition in the tube circuit. Here the current I is practically Q0" lagging with respect to the line voltage E2, and the vectors it: and E4 represent the voltages of the various parts under the same conditions set forth in connection with Figs. 6 and '7.

It will be observed that the voltage of relay actuating winding 33 is much greater under either short circuit or open circuit conditions than it is during normal operation, with the result that this variation in voltage can be utilized to actuate the relay 2%. The transformer 2% may be designed so that its reactance will cause the voltages E3 and Er to be somewhat different than that shown. in Figs. 6 to 8, but the same, or greater, variation in voltage will be present.

Although m invention is notlimited to specific dimensions, or windings, the following specifications, which are given merely by way of example, may be employed in constructing a system including a sufficient amount of tubing to load a 5000 volt l2-0- M. A. high power factor transformer to 86% of short circuit current. The transformer operates from a 60 cycle volt supply line.

The control transformer 24 comprises a primary winding 25 having 39 turns of No. 18 enamel covered wire. The secondary 36 comprises 2300 turns i No. 35 enamel covered wire. The primary and secondary windings are wound on the center leg of a shell--type core of the type known as three-fourths. inch center leg scrapless lamination core.

The relay may be any suitable type. 60: cycle A- C. relay which will operate. at voltages inexcess of i0 or 56 volts, but which will not oper- I ate at voltages below that point. The resistance 23 may be about half an ohm.

The transformer it is of the type known as a M. A. short circuittransformer which is suitabl compensated for power factor. Preferably the transformer is of the type having a condenser winding although it may be any other type of high power factor transformer.

In the event that the relay 2-6: is so sensitlwe to transient currents that it will operate when the circuit is initially established, means can be provided to delay the operation of the relay for a few cycles, until after such time as the transients have died down. Various means for achieving this result are shown in Figs. 2, 3 and 4.

In Fi 2, a U-shaped bimetallic element 2!! is connected in series; with the supply circuit and is arranged to close the circuit. between leads Z8 and 3'! after the current in the supplycircuit has heated the bimetallic element. Thus, the shunt circuit which includes secondary circuit 36 and actuating winding 31.3. will not beestablished until after the transient currents have died down.

In Fig. 3, a time delay relay 42 is provided to achieve a similar result. The contacts Q3 of this relay which are biased to open position, are placed in series with the lead 38 and the actuating winding 33, and the actuating winding Moi relay 42 is connected across leads 3| and i3. Thus, the cutting in of the shunt circuit is' delayed until after the transients have died down. The period of time delay aiiorded by the relay #2 may be from a few cycles up to one second.

In i, a half wave copper oxide rectifier 35 is placed in the shunt circuit between the actuating winding 33 and the junction between lea s and 38. This rectifier acts primarily as a resistance load in the shunt circuit and permits the use of a filter condenser 45 around the actuating winding 33 without adding, capacitive react-once into the shunt circuit. Thus, that part of the transient currents which pass beyond the half wave rectifier are caused to by-pass the actuating winding 33 and will not operate the relay. The rectifier 25 may be a full wave rectifier if desired, and need not be of the copper oxide type. The half wave copper oxide rectifier specified herein is preferred fromv a cost viewpoint.

Fig. 4 shows also an alternative arrangement of the resistance 23' and the primary 25. The latter is provided with a plurality of taps 41 to any one of which the supply lead I2 is adapted to be connected. The resistance 23' is connected to the end of primary 25' by means of a lead 48. With this arrangement various values of line current can be accommodated without changing the voltage across the resistance 23' and secondary 36. Thus the control device 15 can be manufactured in a standard type which is adapt ed for use in connection with transformers of various capacities.

Fig. 5 shows an alternative arrangement in which the resistance 23" is located in the shunt circuit, the resistance being connected in parallel circuit with the secondary as of the control transformer. Thus the impedance of the primary 26 is substantially resistive since it reflects the resistive load which is connected to the secondary 36.

While I have shown only certain preferred embodiments of my invention, it will be understood that various modifications and changes may be made in the construction shown without departing from the spirit of my invention as defined in the appended claims.

. I claim:

1. A lighting system comprising a gaseous conduction tube, a high reactance transformer having a primary winding, said tube and said transformer being connected to each other and comprising a load, an A. C. supply circuit connected to said primary winding for supplying current to said load at a substantially constant voltage, a control transformer having a control primary winding and a control secondary winding, said control primary winding being connected in said supply circuit in series with said first-mentioned primary winding, a resistance connected in said supply circuit in series with said first-mentioned primary winding and in shunt relationship to said control primary winding to limit the voltage drop across said control primary winding, a relay having means to break said supply circuit at a point between said control transformer and said load and including an actuating winding, a shunt circuit connected across said supply circuit including said control secondary winding, the latter being arranged so that the voltage induced therein is substantially the same as the voltage across said supply circuit, but in opposition thereto, said shunt circuit including said actuating winding, said actuating winding being nonresponsive to the voltage appli d thereto during normal operation of said tube, but being responsive to the voltage applied thereto when the phase angle of the current drawn by said load is shifted, and condenser means connected to said supply circuit to cause a shift in the phase angle of the current drawn by said load when the tube circuit is opened so that said relay will operate to open said supply circuit thereby deenergizing said tube circuit, said condenser means cooperating with said high reactance transformer during normal operation to provide substantially unity power factor.

2. A lighting system comprising a gaseous conduction tube, a high reactance transformer having primary and secondary windings, an A. C. supply circuit connected to said primary winding for supplying current thereto at a substantially constant voltage, said gaseous conduction tube being connected in series to said secondary win"- ing, a control transformer having a control primary and a control secondary winding, said control primary winding being connected in said supply circuit in series with said first-mentioned primary winding, a resistance connected in said supply circuit in series with said first-mentioned primary winding and in shunt relationship to said control primary winding to limit the voltage drop across said control primary winding, a relay having means to break said supply circuit at a point between said control transformer and said firstmentioned transformer and including an actuating winding, a shunt circuit connected across said supply circuit at a point between said control transformer and said circuit breaking means and including said control secondary winding, the latter being arranged so that the voltage induced therein is substantially the same as the voltage across said supply circuit, but in opposition thereto, said shunt circuit including said actuating winding, said actuating winding being non-responsive to the voltage applied thereto during normal operation of said tube, but being responsive to the voltage applied thereto when the phase angle of the current drawn by said tube and supply transformer is shifted, condenser means connected to said supply circuit to cause a shift in the phase angle of the current drawn by said load when the tube circuit is opened so that said relay will operate to open said supply circuit thereby de-energizing said tube circuit, said condenser means cooperating with said high reactance transformer during normal operation to provide substantially unity power factor, and means to maintain said relay in operated position.

3. A lighting system as claimed in claim 2 in which said means to maintain said relay in operated position includes means for establishing a by-pass shunt circuit which by-passes said control secondary winding and which includes said actuating winding.

4. A lighting system as claimed in claim 2 which includes means for preventing operation of said relay by the transient currents occasioned by the initial energization of said supply circuit.

5. A control device adapted for connection in the primary circuit of a high power factor lighting system, to which primary circuit, a voltage is to be applied from an A. C. source, which includes a gaseous conduction tube, a high reactance supply transformer, and power factor correcting means, comprising a control transformer having a primary winding and a secondary winding, said primary winding being connected in series in said primary circuit, a resistance connected in said primary circuit in shunt relationship to said primary winding, the impedance of said resistance being substantially less than the impedance of said primary winding, a relay hav ing movable contact means disposed between said control transformer and said supply transformer for breaking the primary circuit to said supply transformer and for establishing a shunt circuit around said supply transformer, said relay also including an actuating winding in said shunt circuit, means connecting the secondary winding of said control transformer in shunt relationship across said movable contact means and in series with said actuating winding, the turn ratio of said primary and secondary windings being such that the voltage induced in said secondary winding is substantially equal in magnitude to the voltage across said primary circuit, but in opposed phase relationship thereto whereby said relay Will remain in unoperated position during normal operation of said lighting system, hut operate to cut out saidsupply transformer when. the phase angle of the. cur-rentv drawn by said supply transformer is shifted.

6. A. control device as claimed in claim 5 including means for delaying the energizing of said actuating means when said tube is. initially enersi ed.

7. ,A control device as claimed in claim 5. having. a bimetallic elementw connected in series in said primary circuit and contact means cooperating with said bimetallic element to establish the circuit through said secondary winding after said primary circuit has been initially energized, said contact,- means being normally in open circuit position when said primary circuit is not. energized.

8. A control device as, claimed in claim 5. having a. circuit closing means: in series circuit. connection withsaid: secondary winding and cooperating therewith to establish a shunt circuit around said movable contact means. of said relay, and a second actuating winding connected in said primary circuit in shunt relationship with said supply transformer for operating said circnit closing means when said primary circuit is initially energized, said second actuating winding and said circuit closing means constituting a time delay relay.

9 A control device as claimed in, claim 5 having a rectifier disposed in said shunt. circuit. at a point between said actuating winding and. the point where said secondary winding is. commented to said shunt circuit, and lay-passv filter means shunted across said actuatingv winding to. filter out the transient. currents occasioned by the initial energization of said primary circuit- References Cited. in the file of' this patent UNITED STATES PATENTS Number Name Date- 769,973 Wilson Sept. 13, 1904 863,163 Eveleth Aug. 13, 1907 1,491,402 Holbrook Apr. 22-, 1924 1,611,377 Riggs Dec. 21, 1926 1,774,944 Petch Sept. 2 1930 1,787,277 Kennedy Dec. 36, 1930 1,976,645 Westenclorp Oct. 9, 1934 2,170,457 Lord Aug; 22, 1939 2,213,877 Beeman Sept. 3, 1940 2,246,324 Schroder June 17', 19.41 2,284,407 Edwards May 2.6, 1942 2,290,101 Guttmann July 14, 1942 2,303,581 Rudd Dec. 1, 1942 2,305,096 McDermott: Dec, 15, 1942 2,422,288 Boynton June 17, 1947 2,425,759 Sonnemann Aug, 19, 1947 2,461,265 Gates Feb. 8,. 1949

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