US2486198A

US2486198A - Airport lighting system

Info

Publication number: US2486198A
Application number: US624776A
Authority: US
Inventors: Harry N Newstedt
Original assignee: Automatic Electric Laboratories Inc
Current assignee: Automatic Electric Laboratories Inc
Priority date: 1945-10-26
Filing date: 1945-10-26
Publication date: 1949-10-25
Anticipated expiration: 1966-10-25

Description

AIRPORT LIGHTING SYSTEM Filed Oct. 26, 1945 5 Shets-She et 1 FIG. I

TALK DIAL I 5 I06 I07 MISCL. LIGHT" RUNWAY LIGHT L952 INTENSITY LIGHT INDIGATING I IN0IcATIIIs I INDIGATING RELAYS 2?? c5: RELAY-S 5|0 RELAYS HOV.[ T

I INVENTOR. HARRY N. NEWSTEDT ATTORNEY Oct. H. N. NEWSTEDT 9 59 AIRPQRT LIGHTING SYSTEM Filed Oct. 26, 1945 5 Sheets-Shet 2 FIG. 2

BEACON LIGHT BOUNDARY LIGHTS MISCL. LIGHT HOV. AG. 2300 v 40 5 LCLONTROL RELAYSJ AC W IN VEN TOR. HARRY N. NEWSTEDT ATTORN EY 1949 H. N. NEWSTEDT 9 7 9 AIRPORT LIGHTiNG SYSTEM Filed Oct. 26, 1945 5 Shets-Sheet 3 v zzs m FIG. 5 x

HARRY N. NEWSTEDT ATTORNEY 0st. 25, W49.

Filed Oct. 26, 1945 H. N. NEWSTEDT AIRPORT LIGHTING SYSTEM 5 Sheets-Sheet 4 INVENTOR. HARRY N. NEWSTEDT ATTORNEY Get. 25, 1949; H. N. NEWSTEDT 2,486,R

AIRPORT LIGHTING SYSTEM Filed Oct. 26, 1945 5 Sheets-Sheet 5 Tu 1% 54O 550-2 56O ATTORNEY Patented Oct. 25, 1949 UNITED STATES ()FFICE matic Electric Laboratories, Inc., Chicago, Ill a corporation of Delaware Application October 26, 1945, Serial No. 624,776 6 Claims. (01. 177-352) The present invention pertains to airport lighting systems and, more particularly, to improved remote control apparatus therefor.

An airport conventionally comprises a flying field having a plurality of airplane runways thereon, some of the runways being arranged in intersecting relationship with respect to other ones of the runways and in non-intersecting relationship with respect to still other ones of the runways. Illuminating devices of some form are usually provided for the purpose of lighting the runways when the flying field is not otherwise clearly visible; and occasionally traffic signals of some form are provided for the purpose of governing airplane trafiic on the runways.

It has heretofore been proposed to provide switching arrangements, for selectively controlling the illumination of the runways in an airport lighting system of the type noted, which would positively prevent the control of the illuminating means associated with conflicting runways. Such a system has been disclosed .in Ratent 2,296,936, issued to Logan et al. on September 29, 1942.

It is an object of the present invention to provide improved switching arrangements, for selectively controlling the illumination of the runways in an airport lighting system, which will positively prevent the control of the illuminating means associated with conflicting runways, and which is simpler in construction and operation thanpreviously proposed systems.

A further object of the invention is to provide a switching apparatus which is responsive to the successive transmission :of a series of impulses over a control line to alternately energize and ole-energize a corresponding one of the illuminating means associated with the airport.

Still another object of the invention is to provide a switching apparatus which is responsive to a series of impulses transmitted over a control line to energize a corresponding one of the runway illuminating means, and to prevent control of other ones of the illuminating means until said one illuminating means has been de-energized by the subsequent retransmission of the corresponding series of impulses.

A still further object of the invention is to provide a switching apparatus for selectively or simultaneously energizing several different run- 2 way illuminating means which is arranged to prevent selective de-energization of the group of energized runway illuminating means.

A feature of the invention is the provision, in a switching apparatus for selectively energizing different runway illuminating means to a variable degree from a common source, of means responsive to a selection for disabling the source while the selection is completed, whereby smaller and more economical contactors may be employed.

Other objects and features of the invention will appear upon a further perusal of the specification and accompanying drawings, wherein:

Fig. 1 is a schematic diagram of the apparatus which is located in the control tower of the airport;

Fig. 2 is a schematic diagram of the"selecting apparatus, located at a central switching point, together with the beacon light and boundary lights controlled thereby;

Fig. 3 shows the selecting relays which control the intensity of the runway lights which are ener-- gized;

Fig. 4 shows the selecting relays for controlling the illumination of the runways; and

Fig. 5 shows the runway lights and energizing circuits therefor.

All of these figures should be placed side by side in numerical order to form a unified system. Described briefly, the system comprises a selector switch of the Strowger type, located at a central switching point, which is controlled by alternat ing current impulses transmitted over a two wire line from the control tower. This selector switch has access to three groups of selecting relays; one group of which controls miscellaneous lights, such as the beacon and-boundary lights; a second group determines which runway, or group of runways, is to be illuminated; and the third group controls the brightness of the energized runway lights. Each lamp, or group of lamps, is assigned a corresponding two digit number. A further number. is assigned to a combination of the lamps associated with a pair of non-intersecting runways. The miscellaneous and runway light selecting relays are arranged to alternately energize and de-energize the corresponding lamps in response to the successive selection thereof by the selector switch. The runway light selecting relays are further arranged to prevent a new selection from being made while any runway lights are energized. Both the light intensity and the runway light selectin relays are arranged to open a common point in the energizing circuits for the runway lights, during the switching operations resulting from a new selection, whereby the contactors involved. in these switching operations need not make or break energized circuits.

A second selector switch is located in the con- 1 trol tower and is arranged to be operated concurrently with the selector switch at the switching point under the control of an impulse transmitter, or dial, of the type commonly employed in telephone systems. This second selector switch has access to three groups of selecting relays, which are duplicates of those provided at the central switching point, and which control indicating lamps located before the dispatcher to enable him to observe the operation of the system. Sound powered telephone handsets, employing transmitter and receiver units of the type fully described in Patent 2,241,105, issued May 6, 1941, to A. E. Woodruff et al., are provided in the control tower and at the switching point i to permit communication therebetween over the control line.

The switching point is also arranged to permit testing of the switching apparatus thereat, by means of an impulse transmitter, independently of the control tower.

Referring now to Fig. 1, there is shown a sound powered telephone I00, a key IOI, an impulse transmitter I02, a two-digit selector switch I03,

a telephone ringer I04 and associated alternating current relay I00, and three groups of indicating relays I05, I05, and I01 together with the indicating lamps controlled thereby. Conductors I08 and I09 extend between the control tower and the switching point.

In Fig. 2 there is shown a sound powered telephone 200, a key 20 I, an impulse transmitter 202, a two-digit selector 203, a telephone ringer 204 and associated relay 2 20, an alarm relay 2 35 and associated alarm lamp 249, miscellaneous

light control relays

250, 255, 200 and 265, and contactors H and 215 which control the circuits to the beacon light 2'82 and the boundary lights 211, respectively, the latter being energized through a constant current transformer 278. The miscellaneous light control relays are connected to the bank contacts of selector switch 203 over cable 205. The light intensity control relays (Fig. 3) and runway light control relays (Fig. 4) are similarly connected to the bank contacts of selector switch 203 over

cables

305 and 405, respectively. The last two groups of relays control contactors 510 to 530 and 540 to 560, respectively. Contactors 5I0 to 530 control the primary to secondary turns ratio of current transformer 510 and thus control the brilliance of runway lamps RI to R3 which are not short-circuited by contactors 540 to 550. Transformer 510 is energized by the constant current transformer 580 from a source of high voltage alternating current through contacts of contactor 500.

It will be noted that when the miscellaneous light control relays are restored the contactors 210 and 215 are operated to energize the beacon light 2l2 and the boundar lights H1. The corresponding indicating lamps N2 and 21?, respectively, shown in Fig. 1 will also be energized. In order to extinguish the beacon light the dispatcher operates key IOI to the right and then dials the two digit number assigned to the beacon 4 light. When key MI is operated to the right it completes a circuit to relay I in series with the impulse transmitter I02. Relay I20 operates, closes a circuit to relay I at contacts I22, and completes a circuit to relay 220 at contacts I2I. The latter circuit may be traced from one side of the 110 v. A. C. supply through cont-acts IZI, contacts of key IOI, contacts I4I, over conductor I09, through contacts of key 20I, full wave rectifier 209 and relay 220, contacts 246, contacts of key 20I, over conductor I08, and through contacts of key I0| to the other side of the 110 v. A. C. supply. Relay 220 operates and closes a circuit to relay 225 at contacts 22I. Relays I25 and 225 operate.

The dispatcher now dials the number assigned to the beacon light, which number will be assumed to be 41. When the impulse transmitter I02 is operated to transmit the first digit, the circuit to relay I20 is momentaril interrupted four times in succession. Each time that relay I20 restores it opens the circuit to relay 220 at contacts I2I and closes a circuit to the vertical magnet I05 of the selector switch in series with relay I30. The latter circuit is completed from ground through contacts I22, I26, and normally closed contacts of the vertical ofi-normal springs I06, initially, and through make contacts of the vertical off-normal springs I05 and contacts I3I after relay I has operated and the vertical off-normal springs have been operated in response to the operation of the switch shaft to the first level by the vertical magnet I05. Relay 220' is momentarily restored four times in succession concurrently with relay I20 causing the vertical magnet 205 to step the switch shaft of selector switch 203 to the fourth level. The circuits of the selector switch 203 need not be traced since they are identical to those traced for selector switch I03. Relays I25, I30, 225 and 230 are rendered slow to release by copper sleeves placed over their cores so that they remain operated during impulsing. Shortly after the series of impulses have been transmitted by the impulse transmitter I02, relays I30 and 230 restore to transfer the impulsing circuits of the selector switches from the vertical magnets I05 and 205 to the rotary magnets H0 and 2 I0, respectively.

When impulse transmitter I02 is again operated to transmit the second digit relays I 20 and 220' will each be momentarily released once. When relay I20 restores it 'completes a circuit from ground through contacts I22, I26, make contacts of the vertical off-normal springs I06, contacts I3I, and through relay I and rotary magnets IIO to battery. Relay 220 completes a similar circuit to rotary magnets 2 I0 in series with relay 235. Relays I35 and 235 operate and open points in the circuits to wipers I31 and 231, respectively. Rotary magnets I I0 and 2 I0 operate to rotate the wipers I3! and 231, respectively, to the first bank contacts of the fourth level. Relays I35 and 235 restore shortly after relays I20 and 220 have reoperated. When relay 235 restores it completes a circuit from ground through contacts 22I and 230 to wiper 231, thence to the first contact on the fourth level and over conductor GM to cable 205 to the lower winding of relay 255. Rela 255 operates, opens the circuit to contactor 210 at contacts 255, and closes a holding circuit to its lower winding in series with the lower winding of relay 250 at contacts 258. Contactor 210 restores and disconnects the 2300 v. A. C. supply from beacon light 272 at contacts 2'. In a similar manner, ground is extended through wiper I31 and the first bank contact on the fourth level of selector switch I03 and over conductor GM to operate a relay correspondingto relay 255 and thereby extinguish the indicatin lamp 212'.

Key IGI is now restored causing relays E and 220 to restore and remove grounds from wiper I31 and relay I at contacts I22 and from wiper 231 and relay 225 at contacts 224. When ground is removed from conductor C4I a short-circuit is removed from the lower winding of relay 250 causing it to be energized in series with the lower winding of relay 255. Relay 250 operates and transfers conductor C ll to the upper windings of

relays

250 and 255 in multiple at contacts 25I. A similar operation takes place in the miscellaneous light indicating relay group I05. When relays I 20 and 220 restored they also reclosed the circuits to rotary magnets H0 and 2l0 causing wipers I37 and 231 to rotate to the next contact but without efiect. Relays E25 and 225 subsequently restore and complete obvious circuits to the selector switch release magnets H8 and 238 at contacts I20 and 233, respectively. The circuits to the rotary magnets are also opened at the latter contacts. The release magnets operate to permit the selector switch shafts to restore to normal when the vertical ofi-normal springs restore to open the release magnet circuits.

The boundary lights may be extinguished in the same manner by dialing the number 31 assigned thereto. In this case wipers I31 and 233 will be stepped to the first contact in the third level to ground conductors C3I and C34 Relay 285 will then be operated to release contactor 275. and a corresponding relay in the miscellaneous light indicating relay group E05 will be operated to extinguish indicating lamp 271.

The beacon lights may be re-energized by again dialing 41. When conductor CM is grounded the second time a circuit is completed from ground over conductor C4I through contacts 25! directly to the upper winding of relay 250, and through contacts 25'! to the upper Winding of relay 255. The latter relay is diiferentially wound and therefore restores when both of its windings are energized, closes the circuit to contactor 210 at contacts 255, opens the circuit to its upper winding at contacts 251, and opens the circuit to its lower winding in series with the lower winding of relay 255 at contacts 253. C'ontactor 275 reoperates to close the circuit to beacon light 272 at contacts 2. Relay 250 is held by its upper winding until ground is removed from conductor C4! by the restoration of relay 220. The second grounding of conductor C4! causes corresponding operations to take place in the miscellaneous light indicating relay group I05 to reenergize lamp 212'. I

For the sake of simplicity only three groups of runway lights have been shown. The system is arranged to permit selective energization of any one of these three groups, or simultaneous energization of groups two and three. All three groups of lamps are connected in series and each group is normally short-circuited by contacts of a corresponding one of the contactors 540 to 550. Any one of these contactors may be operated by the dispatcher by dialing the corresponding numbers 21 to 23, or contactors 550 and 500 may be operated simultaneously by dialing 20, in a manner to be described presently. Operation of these contactors will have no effect until the light intensity control relays are operated by dialing 51, 52 or 53, unless these relays have previously been operated.

If it is desired to cause the first group of runway lights RI to be energized at a low value of current, either the corresponding runway light number 21 or the corresponding intensity number 51 may be dialed first. It will be assumed that 21 is dialed first and that no previous selection has been made. The dispatcher first operates key IM to the right and then proceeds to dial 21 by means of the impulse transmitter I02 to step the selector switches I03 and 203 to the first contact of the second level in the same manner as previously described. Selector 203 then extends ground over conductor CZI of cable 405, through contacts 4I4, M0 and 472 to relay 490. Relay 490 operates; closes a circuit from one side of the v. A. C. supply over conductor 510, through contacts 49d, over conductor 542, and through contactor 540 to the other side of the 110 v. A. C. supply; and closes a holding circuit to itself through the upper winding of relay 410 and contacts 432 at contacts 432. When ground is removed from conductor C2I in response to the restoration of key IN a short circuit is removed from the upper winding of relay 410, thus causing it to be energized in series with relay 490. Relay 410 operates and closes a circuit to relay 4| 0 at contacts 474. Relay 4I0 operates, closes a circuit to the lower winding of relay 445 from ground through contacts 493 at contacts 4| I, and opens points in the operating circuits to

relays

480 and 405 at contacts 4I2 and M3, respectively. Relay 4| 5 operates and extends conductor C2! through contacts 4H and M0 to relay 420. No further operations will take place in the runway light control relay group unless the number 21 is again dialed. Corresponding operations take place in the runway light indicating relay group under the control of selector switch !03 to cause lamp 540' to be energized.

The dispatcher now reoperates key Hill and dials 51 to cause selector switches I03 and 203 to step to the first contact on the fifth level and ground conductors Gill and C54, respectively. The ground extended over conductor C5I energizes relay 380 through contacts 3M and 3'. Relay 380 operates; closes a circuit from one side of the 110 v. A. C. supply over conductor 5' of cable 505, through contacts 38!, over conductor 5I2 of cable 505, and through contactor 5I0 to the other side of the 110 v. A. C. supply; closes a holding circuit to itself through the lower winding of relay 3T0 and'contacts 323 at contacts 382; and closes a circuit from ground through contacts 32!, 303 and 320, over conductor 441, and through contacts MI, 494 and 443 to relay 445. Relay 445 operates and closes a circuit to the lower winding of relay 440 at contacts 446. Relay 440 operates after a brief delay due to the slugging efiect of its short circuited upper winding, removes the short circuit from its upper winding at contacts 442, and opens the circuit to relay 445 and closes a looking circuit to itself at contacts 443. Relay 445 is rendered slow to release by a copper sleeve placed over its core. During the release time of relay 445, contactor 5I0 operates over the above traced circuit and connects winding 510a of transformer 510 across the secondary winding of transformer 580 at contacts 5. Relay 445 subsequently restores and closes a circuit to relay 435 through contacts 44I at contacts 440. Relay 435 operates and closes a circuit from one side of the 110 v. A. C. supply over conductor 510, through contacts 430, over conductor 502, and through contactor 500 to the other side of the 110 v. A. C. supply. Contactor 500 operates and closes a circuit to the primary winding of transformer 580 from the 2300 v. A. C. supply at contacts 56!. When the primary winding of transformer 580 is thus energized it produces a constant current in its secondary winding, which current flows through winding 510a of transformer 510. The current induced in windings 510b, c and d will be equal to that flowing in winding 510a. divided by the ratio between the total number of turns in windings 510b, c and d and the number of turns in winding 510a, since the primary and secondary ampere-turns of a transformer are practically equal. The lights associated with the first runway are thus energized at a low value of current flowing through windings 510b, c and d of transformer 57!! and contacts 55!, 56! and 5!!. The light intensity indicatin relay group responds to the ground extended over conductor C5! by selector switch N33 to energize lamp 510' in the same manner as light intensity control relays of Fig. 3 energized contactor 5I0.

The dispatcher restores key H]! to release the selector switches !03 and 203 as previously described. When selector switch 203 removes ground from conductor C5! a short circuit is removed from the lower winding of relay 310 causing it to be energized in series with relay 385. Relay 310 operates and closes a circuit to relay 3!!) from ground through contacts 384 at contacts 313. Relay 3!0 operates, locks to ground through contacts 328 at contacts 3! and opens points in the operating circuits to

relays

340, 360 and 380 and transfers conductors C53, C52 and C5! to relay 320 through contacts 321 at contacts 3!2, 3l3 and 3l4.

If the dispatcher wishes to increase the current flowing through the energized runway lights to a high value, he may do so by re-operating key and then dialing 53 to cause conductor C53 to be grounded by selector switch 203. The ground extended over conductor C53 energizes relay 320 through contacts 3!2 and 321. Relay 320 operates and opens the circuit to relay 440 and closes a circuit to relay 3!5 at contacts 32!. Relay 3I5 is a weighted spring relay of the type disclosed in Patent 1,641,256, issued September 6, 1927, to John Erickson. When this relay operates its weighted spring vibrates for several seconds, preventing immediate operation of relay 325. During this delay interval relay 440 restores and opens the circuit to relay 435 at contacts 44!. Relay 435 restores and opens the circuit to contactor 500 at contacts 436. Contactor 500 restores and disconnects the 2300 v. A. C. supply from transformer 580 at contacts 50!. As the amplitude of vibration of the weighted spring of relay 3l5 decreases, the average current flowing in relay 325 gradually increases until it is able to operate. When relay 325 operates it opens the circuit to relay 320 at contacts 321 and opens the holding circuit to relay 380 at contact 329. Relay 380 restores, opens the circuit to Contactor 510 at contacts 33!, and opens the operating circuit to relay 3H1 at contacts 384. Relay 31!} remains operated due to the energization of its upper winding from ground over conductor C53 and through contacts 3!2, 3M and 312. Contactor H3 restores. after a brief delay, opens the circuit to relay M5 at contacts 32!, and opens the lockin circuit to relay 3!!! at contacts 322. Relay 3! restores, opens the holding circuit to the upper winding of relay 310 at contacts 3!4, and ex- Relay 320 restores tends the ground on conductor C53 to relay 340 through contacts 33! at contacts 3!2. Relay 310 restores. Relay 340 operates, closes a circuit to contactor 530 over conductors 532 and 51! at contacts 34!, and closes a holding circuit to itself through the lower winding of relay 330 and contacts 322 at contacts 342, Relay 325 restores and closes a. previously traced circuit to relay 445 over conductor 441 at contacts 326.

Relays

445 and 440 operate, relay 445 restores and relay 435 operates as previously described to close a circuit to contactor 500 over

conductors

502 and 510 at contacts 436 after a predetermined time interval. During this interval contactor 530 will have operated to connect windings 510a, b and c of transformer 510 across the secondary of transformer 580 at contacts 53!. Contactor 500 subsequently operates to reclose the 2300 v. A. C. supply circuit to the primary of transformer 580 at contacts 50!. The current now flowing through the energized runway lights will be equal to the constant current output of transformer 580 multiplied by the ratio between the total number of turns in windings 510a b and c to the number of turns in winding 510d. A high value of current is thus produced in the circuit including winding 510d, runway lights RI, and contacts 55!, 56! and 53!. The operations which take place in the light intensity control relay group in response to the grounding of conductor C53 are duplicated in the light intensity indicating relay group !06 in response to the grounding of conductor C53 by selector switch !03. Lamp 5!0' is thus extinguished and lamp 530 is energiZ-ed.

When the dispatcher restores key !0! the selector switches I03 and 203 release, thereby removing grounds from conductors C53 and C53, respectively. The removal of ground from conductor C53 removes a short circuit from the lower winding of relay 330 causing it to be energized in series with relay 340. Relay 330 operates and closes a circuit to relay 3!!! from ground through contacts 344 at contacts 333. Relay 3 6 operates, locks to ground through contacts 328 at contacts 3! and extends conductors C5! to C53 to relay 320 through contacts 321 at contacts (M2 to 3!4.

It will next be assumed that the dispatcher wishes to illuminate runway Number 3. As previously noted, no runway may be illuminated while another is illuminated. Thus if the dispatcher proceeded to operate key ill! to the right and then dialed the number 23 corresponding to runway lights R3, conductor C23 would be grounded by selector switch 203 but without effect since the circuit between this conductor and relay 436 is open at contacts M2. Therefore the dispatcher first dials the number 21 to extinguish runway lights RI. When conductor C2! is grounded by selector switch 203 in response to the dialing of the number 21, circuits are completed from ground over conductor C2 through contacts 41! and 413 to the lower winding of relay 410, through contacts 41!, 4!!! and M6 to the upper winding of relay M5, and through contacts 41! and M9 to relay 420. Relay 420 operates, opens the circuit to relay 440 at contacts 42!, closes a circuit to relay 425 at contacts 422, and locks to ground through contacts 43! at contacts 423. Weighted spring relay 425 operates and closes an intermittent circuit to relay 436 at contacts 426. Relays 440 and 435 and contactor 500 restore as previously described to de-energize transformer 580. Relay 430 subsequently operates, opens the locking circuit to relay 420 at 9 contacts 43!, and opens th holding circuit to relay 490 through the upper winding of relay 4'!!! at contacts 432. Relay 490 restores, opens the circuit to contactor 540 at contacts 49 I, and opens the circuit to the lower winding of relay H5 at contacts 493. Contactor 54!! restores and shortcircuits runway lights R! at contacts 54 When selector switches H33 and 243 are released by the restoration of key ground is removed from conductor C2! thereby opening circuits to relay 420, the upper winding of relay 4 l 5, and the lower winding of relay 410. Relay 455 restores. Relay 470 restores and opens the circuit to relay M4 at contacts 474. Relay 424 restores and opens the circuit to relay 425 which restores and opens the circuit to relay 43B. Relay 4!!) restores and transfers conductors C2! to C23 to relays 49! 485 and 48!! at contacts 4M to M2, respectively. Relay 43E! restores.

When the dispatcher reoperates key I!!! and dials 23 selector switch 243 grounds conductor C23 thereby completing a circuit to relay 489 through contacts 447, 4l2, 4!! and 452. Relay 48!) operates, closes a circuit to contactor 566 over conductors 562 and Elli at contacts 44!, closes a holding circuit to itself through the upper winding of relay 450 and contacts 432 at contacts 482, and-closes a circuit to relay 445 from ground over conductor 44'! at contacts 484. Relays 444 and 440 operate, relay 445 restores, and relay 435 operates to close a circuit to contactor 5!!!! over conductors 502 and 51%! at contacts 435 after a predetermined time interval, as previously described. During, this time interval contactor 54!! operates to remove a short circuit from runway lights R3 at contacts 35!. Contactor 5% subsequently operates to energize transformer 546 from the 2,340 v. A. C. supply to illuminate the runway lights R3. When selector switch 243 is released by the restoration of key llll, ground is removed from conductor C23 resulting in the energization of the upper winding of relay 454 in series with relay 44!). Relay 459 operates, closes a circuit to relay' llll at contacts 454, and opens a point in the operating circuit to relay 445 at contacts 455-. Relay 4! t operates and closes a circuit to the lower winding of relay 4l5 from ground through contacts 433 at contacts 4i Relay 4l5 operates and extends conductor C243 through contacts 447, 45! and 4!! to relay 4%.

The system is arranged to permit concurrent illumination of runway lights R2 and R3 since the second and third runways are non-interfer ing. To energize runway lights R2 and R3 simultaneously the dispatcher first dials the number corresponding to the runway lights which are energized, in this case number 23, in order to extinguish them in the previously described manner, and then dials the number corresponding to the combination of runway lights R2 and R3. The runway light control relays will have been restored to normal when the previously energized runway lights were extinguished so that when conductor C2!) is grounded by selector switch 243 in response to the dialing of number 20 a circuit is completed through contacts 455 and to the lower winding of relay Relay 445 operates, shunts

contacts

455 and 455 at contacts 444, extends conductor C24! to relay 484 through contacts 499, 44?, 4422, 4!! and 452, and extends conductor C24 to relay 4% through contacts 449, 408, M3, 4! and 452. Relays 444 and 445 operate, close multiple circuits to the upper winding of relay 445 through contacts 444 at

contacts

483 and 488, and close multiple circuits to relay 10 445 from ground over conductor 44'! at

contacts

484 and 489.. Relay 480 also closes a circuit to contactor 560 over conductors 562 and 51!) at contacts 48!, and closes a holding circuit to itself through the upper winding of relay 459 and contacts 432 at contacts 482. Relay 4% also closes a circuit to contactor 554 over conductors 552 and 5'!!! at contacts 486, and closes a holding circuit to itself through the upper winding of relay 464 and contacts 432 at contacts 48?.

tactor 54! overconductors 542 and 574 at contacts 435 after a predetermined time interval during which contactors 554 and 56!! operate to remove short circuits from runway lights R2 and R3 at contacts 55! and 56!, respectively. When transformer 580 is energized in response to the operation of contactor 544, runway lights R2 and R3 are energized in series with each other and contacts 54! and 53! and winding 574d of transformer 570. When ground is removed from conductor C24 in response to the restoration of key 4! a short circuit is removed from the upper windings of relays 458 and 464 causing them to be energized in series with relays 484i 2111:1484 in multiple with the lower winding of relay 445. Relays 454 and 444 operate, open circuits to the lower winding of relay 445 at contacts 452and 442, and close multiple circuits to relay M4 at contacts 454 and 444. Relay 4M3 operates, closes a circuit to the lower winding of relay 4N? at contacts 4! from ground through contacts 433 and 484 in multiple, and opens a point in the circuit to relay 494 at contact-s 4l4. Relay 4B5 operates and extends multiple circuits from conductor C20 to relay 424 through contacts 449, and 444, !and46!,and4!'!and4!li.

If the dispatcher wishes toextinguish one of the two energized groups of runway lights, he

must first dial 20 to extinguish both groups of lights and. must then dial the number corresponding to the group which it is desired shall remain energized. Selector switch 293 grounds conductor C29, in response to the dialing of the number 20, thereby closing holding circuits to the lower winding of relay 495 through contacts 499, to the lower windings of

relays

454 and 464 through contacts 4B9, 40?, 45! and 453 and through contacts 459, 408, 46! and 463, and to the upper Winding of relay 415 through contacts 449, 44'! and 488, 45! and 46!, 4!! and M8, and 4H5. Relay 42!? is energized in multiple with the upper winding of relay 4l5. When rela 424 operates it opens the circuit to relay 444 at contacts 44!, closes a circuit to relay 425 at contacts 422, and locks to ground through contacts 43! at contacts 423. Weighted spring relay 425 operates and closes an intermittent circuit to relay can at contacts 4245. Relays 444 and 435 restore to release contactor 54!] and thereby de-energize transformer 589. Relay 43! subsequently operates, opens the locking circuit to relay 42!] at contacts 43!, and opens the holding circuits to

relays

484 and 485 through the upper windings of

relays

454 and 454 at contacts 432.

Relays

484 and 485 rostore, open the circuits to contactors 564 and 556 l at contacts 48! and 486, respectively, and open the circuits to the upper winding of relay 4% and the lower winding of relay 4 5 at contacts 483 and 48B. Contactors 454 and 46!! restore. When selector 203 is released by the restoration of key it! ground is removed from conductor C24 thereby releasing relays 4!5, 424, 454 and 46B. Relays 454 and 4t!) restore and open multiple circuits to Relays 445, 444 and 435 operate as 7 previously described to close the circuit to conrelay M at

contacts

454 and 464. Relays 4H! and M5 restore. Relay 420 restores and opens the circuit to relay 425 which restores and opens the circuit to relay 430 at contacts 426. Relay 430 restores after a brief delay. The operation of the runway light control relays in response to the dialing of the number corresponding to the runway lights which it is desired shall remain energized should be apparent from the preceding description.

It should be apparent that additional pairs of relays, such as 410 and 490, may be added to control additional runway lights; and that, if there are more than two non-interfering runways, additional relays, such as 405, may be provided to permit simultaneous con-tro1 of the runway lights in different combinations.

In order to test the operation of the apparatus located at the switching station, the key 20I and impulse transmitter 202 are provided thereat. By operating key 20I to the right the circuit to relay 220 is transferred from conductors I08 and I09 to the 110 v. A. C. supply through the impulse transmitter 202. Selector 203 may then be controlled by the impulse transmitter 202 independently of the control station. If the test man at the switching station wishes to converse with the dispatcher, key 20! is momentarily operated to the left thereby completing a circuit from the 110 v. A. C. source over conductors I08 and I09 to relay I40 in series with condenser H0 and contacts of key IOI. Relay I40 operated momentarily, connects the 110 v. A. C. supply at the control station to the ringer I04 at contacts I42, and opens a point in the circuit to the handset I00 and locks to conductor I09 independently of the talk ke I0! at contacts MI. The dispatcher responds by operating key lIlI to the left thereby connecting the handset I00 through contacts of key IIII, contacts I4I, over conductors I08 and I09, through contacts of key 20!, and through contacts MI and 22'! to the handset 200 for two way conversation. Each handset is equipped with a non-locking switch which must be operated to complete a circuit to the transmitter and receiver therein.

In the event of a failure of the direct current power supply (not shown) used to operate the relays at the switching station, relay 245 will be de-energized. Relay 245 restores, transfers conductor I08 from rectifier 209 to one side of the 110 v. A. C. supply at contacts 246, connects con- .ductor I09 to the other side of the 110 v. A. C.

supply at contacts 241, and connects alarm lamp 249 across the 110 v. A. C. supply at contacts 248. The connection of the 110 v. A. C. supply to conductors I08 and I09 causes relay I40 to operate and continuously energize ringer I05 at the control station from the 110 v. A. C. supply thereat to notify the dispatcher of the failure.

The dispatcher may signal the test man at the switching station by operating key Iii! to the right and dialing the number 01. Selector switch 203 operates in the previously described manner to extend ground through wiper 231 and the first contact on the tenth level to relay 240. Relay 24%! operates, opens a point in the circuit to handset 200 at contacts 2M, and connects the 110 v. A. C. supply to ringer 204 at contacts 242. Contacts 24I prevent the application of the the 110 v. A. C. signaling current to the transmitter and receiver of handset 200 in the event that the test man operates the handset switch to answer before the circuit to relay 220 is interrupted in response to the restoration of key MI. Shortly after dialing 01 the dispatcher operates key IOI from the right to the left, thereby interrupting the operating circuit to relay 220 which restores to release the selector switch 203 and relay 240. When relays 240 and 225 restore the previously traced communicating circuit between handsets I00 and 200 is completed.

What is claimed is:

1. An airport comprising a flying field having a plurality of airplane runways thereon, illuminating means individually associated with said runways, a control circuit corresponding to each of said runways for controlling the illuminating means individually associated therewith, a selector switch having access to said control circuits, an electric supply circuit for energizing said illuminating means, means common to said control circuits operated in response to selection thereof for automatically rendering said electric supply circuit inactive, said means automatically operated to activate said electric supply circuit after a predetermined time interval.

2. An airport comprising a flying field having a plurality of airplane runways thereon, illuminating means individually associated with said runways, an electric supply circuit for energizing said illuminating means, a plurality of circuits for changing the intensity of said illuminating means, a control circuit individual to each of said intensity changing circuits and to each of said illuminating means, a selector switch having access to each of said control circuits, means operated in response to the selection of any of said control circuits by said selector switch for automatically rendering said electric supply circuit inactive, said means automatically operated after a predetermined time to activate said electric suppliy circuit.

3. In an airport lighting system for an airport having a plurality of runways, a group of lamps individually associated with each of said runways, a control circuit for each of said groups, each control circuit including a control relay, an auxiliary relay, and a control lead, means operated to select any one of said control leads and to apply a control potential thereto, a circuit completed responsive to the selection and application of said potential to said selected control lead for operating said control relay associated therewith, switching means operated in response to the operation of said control relay for illuminating a corresponding group of said lamps, means for removing the control potential from said selected control lead in response to the release of said first means, an auxiliary relay in said selected control circuit operated in response to the removal of said control potential, a relay common to said control circuits operated in response to the operation of any one of said auxiliary relays to disable all of said control circuits except said selected control circuit, thereby, to prevent the operation of other of said control relays, means responsive to the reapplication of said control potential to said selected control lead for releasing said operated control relay, thereby, to control said switching means to extinguish said illuminated group of lamps.

4. In an airport lighting system as claimed in claim 3 including circuit means for releasing said operated auxiliary relay and said common relay in response to the removal of the reapplied control potential from said selected control lead by the subsequent release of said first means, the releasing of said common relay 13 conditioning each one of said control circuits for subsequent individual operation.

5. In an airport lighting system having a group of lamps for marking a runway, means for illuminating said lamps, a selector switch, a plurality of intensity control circuits, each having a control lead individually accessible to said selector switch, each one of said control circuits operable individually in. response to the selection of the corresponding control lead by said switch to determine a different degree of brilliance for said lamps, and any operated one of said control circuits remaining effective to determine the degree of brilliance until a subsequent selection of any one of said control leads by said switch, a relay common to said control circuits, circuits for operating said relay in response to the release of said selector switch, circuit releasing means, contacts on said relay operated to disconnect all of said control leads from their corresponding control circuits and for connecting all of said control leads to said circuit releasing means, said circuit releasing means operated in response to the subsequent selection of a different one of said control leads by said switch to release any operated one of said control circuits, said common relay released in response to the releasing of saidoperated control circuit to reconnect each one of said control leads to its corresponding control circuit, and said control circuitcorresponding to the last selected one of said control leads operated to determine a difi'erent degree of brilliance for said illuminated lamps.

6. In an airport lighting system for illuminatinga plurality of runways, a group of lamps for each of said runways, a selector switch, a control circuit for each of said groups, each control circuit connected to an individual control lead accessible to said selector switch, means to operate said selector switch to select any one of said control circuits, any selected one of said control circuits operated individually in response to its selection to illuminate a corresponding group of said lamps, relay means having a common control lead accessible to said selector switch, said relay means operated in response to the selection of said common control lead to disconnect a plurality of said individual control leads that correspond to noneconflicting runways from their control circuits and to connect said common control lead to said disconnected control circuits, said disconnected control circuits operated in response to their connection to said selected common control lead to illuminate the corresponding groups of lamps concurrently.

HARRY N. NEWSTEDT.

REFERENCES CITED The following references are of record in the file of this patent: