US2760117A - Mercury vapor lighting system - Google Patents

Description

Aug 21, 1956 A. VAN RYAN 2,760,117

MERCURY VAPOR LIGHTING SYSTEM Filed May 2l, 1953 5 Sheets-Sheet. 2

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INVENTOR. Am'Hcwwl VAN RYAN Flex 3 y 'ATTQZM Aug. 21, 1956 A. VAN RYAN 2,760,117

MERCURY VAPOR LIGHTING SYSTEM Filed May 21, 1955 5 sheetssheet :s

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INVENTOR. ANTH oNY VAN RYAN am. @WM

A-r-roawav ug- 21, 1956 A. vAN RYAN 2,760,117

MERCURY VAPOR LIGHTING SYSTEM Filed May 21, 1955 5 Sheets-Sheet 4 IH l a@ L l INVENTOR. ANTHo'NY VAN RYAN e. 5

A-r-rosvmvr Aug. 21, 1956 A. VAN RYAN 2,7605117 MERCURY VAPOR LIGHTING SYSTEM Filed May 21, 1955 Y 5 Sheets-Sheet 5 CQ. 7 lMa-rm. 251 Mill JNVENTOR. F\ C1. 8 'ANTHONY VAN RYAN United States Paten-t O MERCURY VAPOR LIGHTING SYSTEM Anthony Van Ryan, South Milwaukee, Wis., assignor to McGraw Electric Company,l Milwaukee, Wis., a 'corporation of Delaware Application May 21, 1953 Serial No. 356,535 5 Claims. (Cl. 315-122) This invention relates to a series system of mercury vapor lightning,

lMercuryy vapor lamps are frequently connected in a series circuit. The lamps have a relativelyl low internal resistance due to the relatively low pressure when the lamp is cold. Whenl the lamps are rst started, therefore, only a relatively safe Voltage isy required toV strike or initiate the arc. During the normal operation of the lamps the pressure rises but the arcv is not interrupted as there is continuousl ionization. However, when the circuit is interrupted thelamp is extinguished; and consequently ionization ceases but the pressure remains for several minutes and the internal resistance ofthe lamp isrelatively high.l The arc cannot now be restarted and if an attempt is made to start the mercury vapor lamp by increasingl the voltage', it will result merely in a destructive flash-over. lf lm cut-outs are provided in shunt to eachy of the lamps, one or more of ythese film cut-outs will be puncturedr if the circuit is opened and subsequently reclosed before the lamps have had time to cool down.

This invention is designed to provide a systems of series lighting for mercury vaporlamps and objects of this invention are to provide a system in` which eachl mercury vapor lamp is bridged or shunted. by a film` cut-out which will allow punctu'ring of the. corresponding vllm cut-out in theevent a mercury vapor lamp fails, to thus protect against the hazards of very high voltage and flashfover at the defective lamp, but which is` so arranged that although the system may be cut-off Vand turned. on as. desiredfthere isno danger of puncturing thefcut-outs-orof dangerous and destructive Hash-overs as there is a predetermined time delay each time an attempt is 1 made -tov close the circuitimmediately after the operator has opened it, thusl allowing time for the mercuryvapor latnpsztoy cool dow'n.

Attempts have been made to4 use film cut-outs shunting the mercury Vapor lampsl asrthis is. a desirable feature in seriesv lighting, but. these attemptsr have not beenl satisfactory asthe iilrncut-outs were punctured each time the series circuit wasfreclosed immediately after the mercury vapor lamps werein operation.v As. pointed out above, the internal resistance of the mercury Vapor lampsnis` very high immediately after using thelamps anddoes not drop to -a low enough value fora lreasonable and safestarting voltage forAs'everal minutesA after the lamps have been extinguished. Withthe present system even ifitheoperator recloses the control switchy immediately after eX- tinguisliing the mercury vapor lamps no damage results and no cut-outs are punctured. Thisvinvention, therefore, allows the fre use ofiilm cut-outswith assurance that theyhcannot be punctured except upon failure of the corresponding mercury vapor lamp.. Y'

Embodiments of the invention are shown in the accompanyingdrawings in which:

Figure l is a diagrammatic view'showing therswitch when employed in one 'type of circuit.

Figure 2 is a view showing the switch when used with another type of circuit.

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Figure 3 is a sectional view with parts broken away showing the switch in normal position when not in use and when cold and showing in dotted lines the position of the thermal element when heated.

Figure 4 shows the switch open with the thermal element still heated rbefore it has had an opportunity to cool down.

Figure 5 is a sectional View with parts broken away on the line 5-5 of Figure 3.

Figure 6 is a sectional view with parts broken away on the line 6-6 of Figure 3.

Figure 7 is a fragmentary sectional view on the line 7-7 of Figure 3.

Figure 8 is a fragmentary sectional View on the line 8-8 of Figure 3.

In both Figures l and 2, the switch has been shown in a very diagrammatic manner.

In Figure l, the switch is indicated generally yby the reference character 1 and comprises a bimetal unit indicated generally by the reference character 2. This bimetal unit has a portion thereof heated by means of current passing through one element thereof, but which for simplicity of disclosure, is shown diagrammatically as being heated by means of the heater 3 supplied from the secondary 4 of a stepdown transformer 5*. As the description proceeds, the `bimetal unit, as actually constructed, will be fully described. The primary 6 of the transformer 5 is fed from the mains 7 and the operation of the switch is controlled by a main control switch 8. The mains 7 are preferably low voltage mains sucht as the usual mains furnishing current to dwellings and so forth. A source of high. voltage indicated generally at 9l is controlled by means of a circuit interrupter generally indicated at lll. This circuit interrupter comprises the movable contacts l1 which are permanently biased open and*y which are closed when the operating coil l2 is-energized thus drawing the plunger 113 upwardly and closing,- the circuit interrupter.

The high voltage line passes through a constant our.-

rent statictype transformer indicated at ldland to a series of mercury vapor lamps indicated at l5. Each of the mercury vapor lamps is bridged or shuntedby means of a film cut-out indicated generally by the reference` character 1.6. The film cut-out has, a sufficiently high breakdown voltage to withstand a Voltage which is in excess of the startingvoltage of the individual lamp across which.

necessary to heat the bimetal sufficiently, an opening.

should occur in any part of the seriesmercury vapor lighting circuit, the bimetal unit indicated generally. at 2 will be released and will move upwardly thus opening the circuit of the closing coil or holdingcoil 12 ofthe circuit interrupter 1t).

Also it is to be noted that the switch l0 cannot be closed unless the control switch 3 is closed.

If, for. example, the circuit should be interrupted-andA an attempt was made to restart the mercury vapor lamps immediately after opening the circuit, the bimetal unit indicated generally at 2 would hold the control'circuit open as long as the bimetal member remained sufficiently heated. This will become clearer when the actual structure` of the bimetal member is described .in detailA asxhevv description proceeds. Consequently, there is a time delay provided so that if an attempt to restart the mercury vapor lamps is made, voltage will not be applied to the mercury vapor lamps until the mercury vapor lamps have had sufiicient time to cool down. in this way, puncturing of the film cut-outs 16 is prevented. On the other hand if it were possible to immediately close the series circuit through the mercury vapor lamps before they had cooled down, the film cut-outs would be punctured due to the excessive voltage across one or more of the lamps. It is a well-known fact that when the lamps heated the pressure rises and the striking voltage for initiating the arc is thus extremely high, more than enough to puncture the film cut-outs and sufcient to cause flash-over with consequent damage to the lamps or other equipment. However, as will be seen from the preceding description, this characteristic of mercury vapor lamps has been tal-Len care of.

Figure 2 shows substantially the same construction as that previously described and the same reference characters will be used wherever possible to indicate the same parts.

The differences between the systems shown in Figure l and that shown in Figure 2 resides in the fact that Figure 2 shows a protective relay indicated generally by the reference character i8. This protective relay indicated by reference character 1S has two switch elements or means indicated at 19 and 2@ which are normally closed. The switch 19 is held open whenever the magnet coil 2l is energized, such coil being connected in the high voltage circuit of the mercury vapor lamps l5. The switch 9 controls the energization of the magnet coil 2i which controls the switch 2t). Whenever the coil 2l is energized the switch 2t] is urged to move in a direction against a time delay means 22. T he time delay means 22 is provided to prevent false operation of the protective relay as a result of a transient or momentary fault. it will be seen therefore from reference to Figure 2 that normally the switch unit or bimetal unit generally indicated at 2 is closed and the switches 19 and 20 are closed. When the control switch 8 is closed the coil 2i is momentarily energized but as soon as the lamps 1.5 light the coil 21 is energized and the circuit to the coil 2f is broken before the switch can be opened.

In the form of the invention shown in Figure 2, on the occurrence of an interruption after the delay period, the bimetal unit 2 opens faster than the switch 20 and the effect is just the same as though the switch 3 had been opened. It is to be noted that the bimetal heating circuit is also interrupted. Thus, after the time delay bimetal unit 2 recloses, if power is again available at 9 the lamps make a normal start, but if the power at 9, is still off, the switch 19 stays closed, the coil 2l is energized, if power at 7 is still available, and the switch 20 opens, and the circuit interrupter 1l opens. The bimetal unit 2 does not reheat because the switch 20 is open and the lamps are disconnected until manually restarted.

In Figures 3 through 8 the actual physical structure of the switch employed in the system is shown.

The switch is normally housed within a metal casing 23 provided with a removable cover or top 24 from which the switch is suspended. The switch consists of a lower insulating base portion 25 and an intermediate insulating portion or transverse member 26. The member 26 carries the electromagnet 27 whose coil is the coil i7 previously described. This electromagnet is provided with an armature 28 which when the switch is in closed position as shown in Figure 3 is held against the electromagnet 27. The bimetal unit, indicated generally by the reference character 2, consists of an operating bimetal member 29 and a compensating bimetal member 3d which latter corrects for ambient temperature variations. The members 29 and 30 are rigidly joined at their outer ends by means of the insulating members 3i which are rigid with the members 29 and 3i). The member 29, it will be seen from reference to Figure 7, consists of a pair of arms whose terminals 32 are connected to the secondary 4 of the transformer 5. The transformer 5 as will be seen from Figure 6 is carried by the lower or base plate 2S. The inner end of the bimetal member 30 is connected by means of a link 33, see Figures 3 and 4, with the movable element 34 of a snap switch which has a switch arm indicated at 35. The arms or elements 34 and 35 are joined by means of tension springs 36, see Figures 3, 4, and 6. The inner ends or adjacent ends of the members 34 and 35 are seated in notched arms 37 of a pivotal support. The upper limit of stroke of the link 33 is limited by the upper stop 37 and the lower limit is determined by means of the lower adjustable stop 38, see Figures 3 and 4. The movable contact is indicated at 39 and is carried by the arm 35 and cooperates with a stationary contact indicated by the reference character 4i) carried by the contact 41. An operating handle 42', see Figure 5, is secured to a shaft 42. The lever 43 is connected by means of a link 44 with the pivot pin 45 which joins the links 46 to the armature 28. Links 44 and 46 are formed of insulating material and it is to be noted that the link 44 is slotted so as to allow independent motion of the links 46 but the construction is such as to cause operation of the links 46 when the shaft 42 is manually rotated.

It is to be noted that the insulating platforms or transverse members 25 and 26 are supported by insulating pillars 47 and 48 which in turn are supported from the top 24 so that the entire switch may be lifted from the casing when the top is removed. The top is held clamped to the casing by any suitable means, not shown. It is to be understood also that suitable bushings extend throughout the top and carry the outwardly extending connecting conductors of the switch in accordance with the usual construction for this type of apparatus. Also it is to be understood that it is preferable to provide a shielding insulating sheet 49 immediately inwardly of the casing 23, see Figures 3 and 4.

It can now be explained that, as previously stated, he diagrammatic showing of Figures l and 2 of the time delay switch indicated generally at 1 does not actually show the physical structure of this time delay switch which physical structure is shown in the remaining Figures 3 through 8.

The operation of the apparatus is as follows:

Normally the switch is in closed position as shown in Figure 3. The dotted lines show the position of the bimetal unit indicated generally at 2 when the bimetal unit has its member 29 heated due to passage of current through its arms, such current being furnished by the secondary of the transformer 5. When the bimetal unit is heated the parts distort to the dotted line position shown in Figure 3 and bias the switch towards open position so that the link 33 is urged upwardly or biased upwardly by means of the bimetal unit. This upward motion of the link, however, is resisted by the downward pull upon the armature 28 exerted by the electromagnet due to energization of its coil 17.

However, when the circuit is interrupted in any of the ways previously described, the electromagnet is deenergized and the switch moves to open position as shown in Figure 4. The switch cannot now be closed until the thermal unit has cooled down. These units are so designed that the time delay provided before closing is permitted is more than suicient to allow the mercury vapor lamps to cool. The particular construction of the mercury vapor lamps forms no part of this invention. As a matter of fact the actual mercury vapor lamps employed by applicant are known in the trade as E-Hl manufactured by Westinghouse Electric Corporation, Lamp Division, Bloomfield, New Jersey. These lamps have an operating pressure of 2.5 atmospheres. A further characteristic is that their starting time is four minutes and their restriking time is four minutes. The time delay of the switch shown in Figures 3 and 4 is greater than the restriking time of the mercury vapor lamps so as to insure suflicient cooling of the lamps and suicient reduction of internal pressure before the time delay switch can be reclosed.

It is to be distinctly understood that these specific facts are given merely as an illustration and are not to be understood as in any way limiting.

If desired, the protective relay 1S may require manual resetting after having once been opened or may be set from the circuit interrupter in any of the usual ways.

It will be seen that a novel system of series lighting employing mercury vapor lamps has been provided in which iilm cut-outs bridged around the mercury vapor lamps are used and in which the system is so constructed that no harm can come to the lm cuts-outs in restarting, but in which the full value of the film cut outs is obtained.

Although this invention has been described in considerable detail, it is to be understood that such description is intended to be illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. A series system of mercury vapor lighting comprising a plurality of mercury vapor lamps connected in series, a cut-out shunted across each mercury vapor lamps connected in series, a cut-out shunted across each mercury vapor lamp for shorting out any lamp upon failure thereof, a substantially constant current high voltage source, a circuit interrupter for connecting said series circuit to said source, and time delay switch means controlling said circuit interrupter and delaying the reclosing of said circuit interrupter for a length of time at least equal to the cooling time of said mercury vapor lamps, whereby excessive voltage is prevented from building up across any mercury vapor lamp when an attempt is made to restart the lamps before said mercury vapor lamps have cooled.

2. A series system of mercury vapor lighting comprising a plurality of mercury vapor lamps connected in series, a cut-out shunted across each mercury vapor lamp for shorting out any lamp upon failure thereof, a source of high voltage, a constant current transformer between said source and said series circuit, a circuit interrupter for connecting said series circuit to said source through said constant current transformen, and time delay switch means controlling the operation of said circuit interrupter and delaying the closing of said circuit interrupter after said lamps have been extinguished for a length of time at least equal to the cooling time of said mercury vapor lamps, whereby excessive voltage is prevented from building up acros any mercury vapor lamp when an attempt is made to restart the mercury vapor lamps before said lamps have cooled.

3. A series system of mercury vapor lighting comprising a plurality of mercury vapor lamps connected in series, a cut-out shunted across each mercury vapor lamp for shorting out any lamp upon failure thereof, a source of high voltage, a constant current static type transformer between said source and said series circuit, a circuit interrupter for connecting said series circuit to said source through said constant current transformer, and time delay switch means controlling the operation of said circuit interrupter and delaying the closing of said circuit interrupter after said lamps have been extinguished for a length of time at least equal to the cooling time of said mercury vapor lamps, whereby excessive voltage is prevented from building up across any mercury vapor lamp when an attempt is made to restart the mercury vapor lamps before said lamps have cooled.

4. A series system of mercury vapor lighting comprising a plurality of mercury vapor lamps connected in series, a film cut-out shunted across each mercury vapor lamp for shorting out any lamp upon failure thereof, a source of high voltage, a constant current transformer between said source and said series circuit, a circuit interrupter for connecting said series circuit to said source through said constant current transformer, and time delap switch means controlling the operation of said circuit interrupter and delaying the closing of said circuit interrupter after said lamps have been extinguished for a length of time at least equal to the cooling time of said mercury vapor lamps, whereby excessive voltage is prevented from building up across any mercury vapor lamp when an attempt is made to restart the mercury vapor lamps before said lamps have cooled.

5. A series system of mercury vapor lighting comprising a plurality of mercury vapor lamps connected in series, a lm cut-out shunted across `each mercury vapor lamp for shorting out any lamp upon failure thereof, a source of high voltage, a constant current static type transformer between said source and said series circuit, a circuit interrupter for connecting said series circuit to said source through said constant current transformer, and time delay switch means controlling the operation of said circuit interrupter and delaying the closing of said circuit interrupter after said lamps have been extinguished for a length of time at least equal to the cooling time of said mercury vapor lamps, whereby excessive voltage is prevented from building up across any mercury vapor lamp when an attempt is made to restart the mercury vapor lamps before said lamps have cooled.

References Cited in the le of this patent UNTED STATES PATENTS 1,057,041 Dempster Mar. 25, 1913 2,310,149 McDermott Feb. 2, 1943 2,479,179 Newbill Aug. 16, 1949

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