US2080908A - Electric gaseous discharge device - Google Patents

Description

May 18, 1937. A.' BUNGER ET AL 2, 8

7 ELECTRIC GASEOUS DISCHARGE DEVICE v v Filed July 7, 193a r YINVENTORS Alberl: Burge KuHr Larcke gur' wiegjdnd.

ATTQRNEY "Patented May 18, 1937 UNITED STATES Neuendorf, Germanyd assigno'rs to- General Electric Company, a corporation of New York Application July 7,1936, Serial No. 89,412

I In Germany July 27, 1935 4 Claims. (01. l76-124) The present invention relates to electric gase ous discharge devices, and in particular to vapor are devices operating with a high vapor density.

A particular object of the invention is to reduce the time delay before a discharge in such a device can be restarted at the usual applied potential. A further object of the invention is to provide cooling means for such a device. Still another object of the invention is to provide a novel regulation of the cooling in accordance with the operation of the discharge device. Still other objects and advantages of the invention will appear from the following detailed specification or from an inspection of the accompanying drawing.

The invention consists in the new and novel combination of elements hereinafter set forth and claimed.

During the operation of vapor discharge devices, such as the high intensity mercury vapor arc lamp, the vapor density therein is raised to a relatively high value, as is well known, in order to attain the desired constricted discharge and high efficiency operation. As a result of this high density of the vapor the potential required to restart the lamp immediately after extinction of a discharge therein is extremely high, far in excess of that required when the device is at room temperature. The applied potential is ordinarily insufficient to restart the discharge under these conditions and hence the lamp remains extinguished, even though potential be applied thereto, until the lamp has cooled to such anextent that the discharge can be restarted on the the applied potential. This cooling period with the usual high intensity mercury vapor arc lamps amounts to from 2 ,to 10 minutes, depending upon their size, ambient temperature and the type of enclosure.

We have now found that this cooling time is materially shortened by a novel arrangement of our invention, wherein an electrically driven fan or blower is connected in parallel with the discharge device. With this novel arrangement the potential between the terminals of the discharge device is applied to the fan motor and determines the speed thereof. Thus at starting the discharge potential in a mercury vapor arc lamp of the high intensity type which is now going into extensive useis of the order of to 40 volts, and at this potential the fan will be rotated only slowly, if at all. During,continued operation the vapor density of the lamp increases. and the discharge voltage increases therewith to a potential of the order of 150 volts, whereupon the fan motor speeds up. The fan is still not particularly effec ivea th p d; however, and results o'nly'in a'steady moderate cooling whichserves toprotect the lamp against 5 excessive temperature rises. As soon as the discharge has been momentarily extinguished, how ever, it will not restart atthe applied potential,

' and hence practically the full 220 volt s which.

is usually applied to these" devices is impressed 10 across the terminalsofthe lamp, andlikewise across the fan motor, the current drawn by the fan motor producing but little voltage drop in the usual series'impedance. The fan is there? upon operated at full speed and thus rapidly l5 cools the discharge' tube to atemperature at which the discharge willagain-start on the ap pliedpotential. As soon asthe lampis thus restarted the speed of the fan motor is again drastically reduced, and the operation thereof 20 continues in the mannerhereinbefore described for normal operation of the lamp.

Since the potential required .to restart the lamp is determined by thecoldest spot on the lamp envelope, however. small, it is desirable to confine the cooling of the lamp to a small por-, tion thereof, so that the entire vessel will regain its operating temperature. asflsoon as possible after the dischargeihas been restarted. For this purpose the draft of the fan or blower is usually directed at a single spoton the lamp envelope,

preferably some point away from the electrodes,

and where desired heat insulating means are provided on the portions of the envelope adjacent the electrodes in order to keep the electrodes as hot as possible during the cooling period.

In some cases a special switching arrangement, including a delayed opening switch, is provided whereby the. fan motor iscaused to operate for a predetermined period after every extinguishment of the lamp, so as to insure rapid restarting of the lamp should its light be again desired. within a few minutes. I

For the purpose of illustrating our invention we have shown two embodiments thereof in the accompanying drawing in'which v Fig. 1 schematically shows the connection of the fan motor in the circuit of a high intensity mercury vapor arc lamp to produce the desired cooling, and i Fig. 2 shows a modification of the circuit of Fig. 1.

In this drawing, with particular reference to Fig. 1, there is shown a high intensity mercury vapor arc lamp I of any usual type containing the usual gas and mercury filling. and having thermionic electrodes. This lamp isconnecte'd in series through an inductance 2, which serves to stabilize the discharge, and switch 3 across the inserted between the terminal I of the lamp I and the connection point 8 to the fan motor,

whereby the lamp can be extinguished without interrupting the operation of the fan motor.

In the operation of this device, switch 9 being closed, the lamp is started into operation byclosing' the switch 3, the cold lamp having a starting potential below that applied. The lamp voltage immediately falls to from 20 to 40-volts, and hence the voltage applied to the motor of the fan 6 is thus so lowthat this motor either idles along or fails to operate at all. As'the temperature of the lamp increases the voltage drop therein likewise increases to the normal operating voltage of the order of 150 volts, with a resultant moderate speeding up of the fan; The cooling produced thereby is still relatively small, however, and serves only to protect the lamp against an excessive temperature rise; If the lamp is now extinguished by opening the switch 3 and directly afterward, for example one second later, the

.switch is again closed, the lamp will not restart at the applied potential due to the high vapor density existing within the lamp at the normal operating temperature. Heretofore, it has been necessary to await the natural cooling of the lamp beforethe'flanifctiuld be restarted, but with our rinew arrangement the fan 6 is operated at this time at full speed since the entire line voltage, with the, exception of the relatively small voltage drop in the inductance 2 as a result of the motor current, is impressed upon the fan motor. As a result the lamp, and particularly a small area near the center thereof, is rapidly cooled to the temperature at which'the lamp will again start on the applied potential. As soon as the lamp restarts the voltage across the fan motor is'of course, drastically reduced,so that the fan again rotates at a greatly reduced speed.

The lamp I can also be extinguished by opening the switch 9, in which case the fan 6 continues to operate at full speed, rapidly cooling the lamp I, until the switch 3 is opened at some later time. In this manner provision is made to restart the lamp as soon as possible after it is its light is again position the line terminal is connected over the contact I3 with the lamp I and also over the contact l2 with the'motor of the fan 6; the otherlineterminal 4"is connected over the con- 2,oso,9oa i I ftact II with both the lamp and the fan motor through the inductance 2. In this position of the switch I D it is therefore obvious that the lamp I and the fan 6 are connected in parallel, this 'beingthe position of the switch for operation of the lamp. In order to extinguish the lamp the switch III is moved to its other work position.

In' this position the line terminals 4 and 5 are connected with the contacts I I', I2 which lead to the fan motor over the conductors I4, I5, the time-switch I6 and the conductors I4, I5. The time switch I8 is so constructed that after an adjus'table time, for example 2 minutes, it disconnects the fan 6 from the supply line.

With this arrangement when the lamp I is extinguished by operation of the switch III the fan 6 issimultaneously connected directly to the line and thus left in full operation for the period determined'by the time switch I G, with the result that the lamp is rapidly cooled off and will immediately restart if the light of the lamp is again desired after even a brief interval.

While we have described our invention by reference to certain specific embodiments thereof it' is to be understood that it is not limited thereto but that various changes, omissions and substitutions, within the scope of the appended claims, may be made therein without departing from the spirit thereof.

What we claim as new and desire .to secure by Letters Patentof the United States, is:

1. In combination, a vapor discharge device of the high intensity'type and a fan arranged to direct a blast of air upon said lamp, the motor for said fan being connected in parallel with said discharge device, whereby the cooling effect of said fanis determined by the condition of said discharge device. v

2. In combination, a vapor discharge .device of the high intensity type, a fan so disposed with respect to said device that it selectively cools the central portion thereof, the motor for said fan being connected in parallel with said discharge device, whereby the cooling effect of said fan is determined by the condition of said discharge device.

. 3. In combination, a vapor discharge device of the high intensity type, a fan arranged to direct a blast of air upon said lamp, the motor for said fan being connected in parallel with said dis-'- charge device, whereby the cooling effect of said .fan is determined by the condition of said discharge device, and means to open the circuit through said lamp without opening the circuit through said motor.

4. In combination, a vapor discharge device of the high intensity type, a fan arranged to direct a blast of'air upon said lamp, the motor for said fan being connected in parallel with said discharge device, whereby the cooling efiect of said fan is determined by the condition of said discharge device, means to open the circuit through said device, and means including a delayed opening switch to continue the operation of said fan for a predetermined period after the circuit through said device has been opened.

- ALBERT BUNGER.

KURT LARCHE. KURT WIEGAND.

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