US1839154A - Mercury vapor rectifier - Google Patents

Description

fi 1931' M. A. E. LEBLANC 1,839,154

MERCURY VAPOR RECTIFIER Filed Aug. 15, 1927 lnven c01 MaL.u-ice A. E. LeBlanc,

byMM/M His Attorneg.

" with the constructional form of the movable Patented Dec. 29, 1931 v uNrrEosrA Esf rArsN'r OFFICE Manama aueusra zuemm anuxc, or suaasrus, FRANCE, assmuoa, BY 1mm assrommm's, 'ro 91mm morale comm, a CORPORATION or mm YORK Application filed A'lllultli, 1827, Serial" Io.-

This invention relates to mercur vapor rectifyingand the like apparatus an has for its main object to provide improved arrangements for starting or li htiug up apparatus of this character in whic a movable starting or lighting up electrode device is employed,

In order to start or light up mercury vapor rectifying apparatus, for example, a mov-' able electrode mounted at the extremity of a bimetallic element has been employed, the bi-' metallic element being arranged to be deformed when heated in any suitable manner so as to move the electrode out of, the mercury cathode of the apparatus, inzwhi'ch it, is immersed when at rest, and thereby start or light up the apparatus upon breaking contact between the mercury cathode and movable electrode, it being understood that a current is caused to flow between the cathode and movable electrode when it is required to start the apparatus.

The present invention is applicable essentially to this particular system of starting or lighting up and is concerned more especially electrode device and with the protection of the latter against various causes of deteri0-. ration on the one hand, and on the other hand. with various electrical circuit arrangements permitting he employment of the improved movable electrode device. r a

As regards the practical constructional form of the movable electrode device the bimetallic portion thereof is protected against direct contact with ionized vapor, soas to avoid all risk of deterioration this being at-- tained, for example, by meansof a screen or.

tungsten, which is not volatilizedunderflthe screens of insulating material and'the electrode portion itself, which. is arranged to'be immersed in the mercury cathode when at rest, consists of material, such forexample as auxiliary electrical 'systems, casings or lmncunx varoa 213,15 mi ln'irance s uam- :1, me.

I electrode device a .deviceis employed for preventing the flow of continuous current in the circuit of the starting or lighting up electrode device, in the event of the starting or lighting up arc being produced with the movable electrode. device as the cathode, on the one hand and on the other hand for placing the 'whole. of the movable, electrode at the same potential as the cathode when once the main ar c has been struck. This result can be attamed, either by employing a suitable relay for breaking the starting or' excitation circuit when the apparatus is started or lit up and consequently preventing the flow of continuous current which would tend to-be established in the starting or excitation circuit, or by inserting in this circuit a condenser alone or a condenser accompanied by an induction coil.- In the case where a relay is employed in'the starting or excitation circuit of apparatus of relatively great power a device isemployed for starting at low load and permltting the closing of the output circuit of the apparatus only when the main arc is struck. c The devices utilized for the purposessmentioned above may be constituted either by circuit breaking or, the like devices, or by g mgs provided'onthe exterior or in the Interior of the projecting "anode arms of theapp'aratus, these devices being controlled by systems of'suitablerelays in such manner as to prevent starting under load.

Inorder that the invention may be clearly,

understood it will'now be described by way of example, with reference to the accompanying drawings, in which Figure 1 ,is va view of an improved co nstru'ctional form of movable starting orlighting up electrode device applied to mercury vapor rectifying apparatus.

- Figure 2 is a diagrammatic view of improved circuitiarrangem'ents for starting rectifying apparatus for relatively smallcure rents atrelatively low pressure.

Figure 3 is'a diagrammatic view of modi- 'fied circuit arrangements suitable for rectifying apparatusof comparatively great capacity and provided with a maintaining circuit through a permanent shunt.

Figure 4 is a diagrammatic view of further modified circuit arrangements suitable for rectifying apparatus of comparatively great capacity and provided with a maintaming circuit through special electrodes, and

igure 5 is a view of a rectifying apparatus provided with a starting or excltation clrcuit having a condenser therein.

Referring first to Figure 1, the lead 1 for the starting or excitation current is mounted in a prO ecting portion of the lateral wall of the mercury vapor rectifying apparatus, and is connected at 2 to one extremity of a bimetallic element 3 which is connected at its other extremity 4 to a tungsten starting electrode 5 covered with glass for a considerable portion of its length intermediate its extremities as illustrated. The lower uncovered portion 6 of the bimetallic element 3 is normally in contact with the mercury in the apparatus and it is the breaking of this contact which effects the striking of an are for starting or lighting up the apparatus. The whole of the bimetallic element to ther with its :onnections with the lead 1 an electrode 5 is protected from direct contact with the ionized vapor by an insulating tube 7, of glass for example, the lower extremity of WhlCh is supported by a flange 8 provided on the covering of the electrode 5. It will be evident that, if a current sufiicient for heating the element 3 is caused to flow in a circuit including the starting electrode 5 and the cathode of the apparatus, the element 3 will be deformed and the circuit will be broken down between the portion 6 and the mercury, thus striking an are for starting or lighting up the apparatus, it being understood that the play of the electrode 5 and insulating tube 7 as a whole is arranged to be sufficient to permit the deformation of the element 3 to the required extent. The general elevation of the temperature of the rectifying apparatus during operation also causes the element 3 to be heated and deformed so that the electrode 5 is raised but this deformation is not of importance. It is however, of advantage to adjust the element 3 so that when the rectifying apparatus is operating at a relatively small difference of potential, that is to say at a relatively low temperature, the portion 6 of the electrode 5 is just at the surface of the mercury, thus permitting the cathode glow to be fixed on the surface of the mercury and increase the stability of the main arc.

Before describing various electrical circuit arrangements (Figures 2 to 5) for use in connection with the bimetallic starting element, it should be observed that the starting or lighting up of the rectifymg apparatus is effected by breaking contact between the mercury and the electrode 5 and thus cutting off the current heating the bimetallic element, this current usually being alternating in character as the employment of continuous current for this purpose introduces complications. Contact is therefore broken sometimes with the mercury and sometimes with the electrode 5 as the cathode, and the circuit arrangements utilized should therefore be capable of selecting between these two cases, and main arc of the rectifying apparatus should only be able to be struck when the cathode glow is on the mercury. Moreover experience has shown that when the main arc 'of the rectifying apparatus has been struck the starting electrode 3 should be placed at the same potential as the cathode, if it is desired to avoid all danger of striking a cathode glow on the metallic portions of the starting electrode.

Circuit arrangements for use with rectifying apparatus for small currents at low pressure are illustrated in Fi ure 2 and referring now to this figure it will e observed that the anodes 10 of a mercur vapor lamp 9 are arranged to be energized by an autotransformer 11 which is itself energized through the leads 12. A winding 13 is provided on the core of the autotransformer 11, this winding being connected on one hand to the cathode 14 of the lamp and on the other hand to a bimetallic starting electrode device 15 through the two contacts 16 of a relay and througha resistance 17. The cathode 14 of the lamp 9 is moreover connected to a self inductance 18 arranged in series with the winding 19 of the relay. When the mercury vapor lamp is not operating and the autotransformer 11 is energized, alternating current is supplied to the circuit 13, 14, 15, 16, 17 and the bimetallic starting electrode device 15 is heated, thus causing contact between the electrode 15 and the mercury to be broken.

When the mercury is the cathode at the moment of breaking contact, and if the phase is favorable, the ,lamp 9 is started normally continuous current being supplied to the winding 19 of the relay with the result that the two contacts 16 are opened so as to cutoff the starting or lighting up current and permit the bimetallic starting electrode device 15 to assume the same potential as the cathode. The bimetallic starting electrode device 15 cools and comes into contact with the mercury and fixes the cathode glow. If on the contrary the phase is unfavorable, the bimetallic starting electrode 15 becomes cold, and comes into contact with the mercury, and the starting or excitation circuit being yet closed new break of contact is effected.

When however the electrode 15 is the oathode at the moment of breaking contact and if the phase is favorable, continuous current is supplied to the circuit 15, 17, 16, 13, 18, 19 but is cut off at the two contacts 16, which are closed at once, and the same process continues to be carried out until normal starting is eflected.

It will be observed that the relay 16, 19 effects the selection between the normal and reverse starting or lighting up and on the other hand places the electrode 15 at the same potential as the cathode when normal starting is effected.

It is to be observed that the contacts 16 of the relay shouldbe on the one hand capable of cutting off all the continuous current load on the one hand and on the other hand of offering a resistance to the passage of current which is sufliciently small so as not to limit the starting or excitation current even if a winding 13 of very low pressure is employed.

It has been assumed until now that the relay 16, 19 and self inductance 18, are separate from one another but they could be constructed as a single device by utilizing the flux due to self inductance 18 to move the contacts 16 which may be of any desired form.

The circuit arrangement illustrated in Figure 2 which is applicable to rectifying apparatus for small currents at low pressure fails in the case of rectifying apparatus of comparatively great capacity. In fact, if it were used in the latter case without modification, and the cathode glow were formed on the starting electrode 15 when starting, the total current supplied by the rectifying apparatus would be liable to flow through the starting electrode 15 and this current would have to be cut oil by the contacts 16, wherebv rapid deterioration of both the contacts 16 and electrode 15 would be caused.

It is therefore necessary, in the case of apparatus of comparatively great capacity, to effect the striking of the arc of comparatively small difl'erence of potential through an auxiliary circuit, and to permit the closure of the continuous current circuit only after having normally obtained the striking of the arc.

In Figures 3 and 4 two circuit arrangements of this character are illustrated as applied to rectifying apparatus provided with a maintaining circuit through a permanent shunt (Figure 3) and on the other hand to rectifying apparatus provided with maintaining electrodes.

In Figure 3, the autotransformer 20, which is illustrated as a monophase transformer, is arranged to energize the two anodes of the mercury vapor lamp 21. A winding 22 is provided on the core of the tran'sformer 20 for energizing the cathode and starting electrode circuit through a resistance 23 and a relay provided with two opening contacts 24.

A resistance 25, serving as a shunt for maintaining the main arc, is connected across the apparatus and is arranged in series with a winding 26 provided for actuating the contacts 24.

In the output circuit of the rectifying apparatus a circuit breaking device 27 is inserted which is adapted to beactuated upon the passage of alternating current at a difference of potential equal to the difference of pressure between the anodes and the neutral point of the transformer 20. The actuating circuit of the circuit breaking device 27 may be closed either by the contacts 28 of a maximum current relay arranged in series in the output circuit or by the opening contacts 29 controlled by the winding 26. It will be observed that with this circuit arrangement the starting or lighting up process is similar to that described with reference to Figure 2 but, owing to the contacts 29, it is impossible to close the circuit breaking device 27 when the rectifying apparatus is not suitably started on its shunt.

Moreover, in case of the failure of the supply of alternating current, the first effect of the re-establishment of the pressure is to actuate the circuit breaking device 27, thus rendering impossible the starting of the apparatus on load.

In Figure 4 the rectifying apparatus is illustrated as being provided with a maintaining circuit having special electrodes. A three-phase transformer 30 is arranged to supply the main anodes 31 of the lamp, and

a separate transformer having double Winding 32 has its primary winding energized for example from two of the supply terminals of the transformer 30. The secondary winding of the transformer 32 is connected at its extremities to the maintaining anodes 33 of the apparatus through two induction coils 34 which maycooperate with the same magnetic circuit if desired, the neutral point of the secondary winding being connected to the cathode 35 through an induction coil 36 controlling two pairs of contacts; an opening pair 37 and a closing pair 38.

The pair of contacts 37 areincluded in the starting or excitation circuit comprising a winding 39 mounted on the maintaining transformer 32 and a resistance 40.

On the other hand, included in the output circuit are a maximum relay 41 and a contact device 42 provided with a closing auxiliary contact 43. The contact device 42 is provided with a controlling circuit comprising a resistance 44 and two push buttons, one 45 for closing the other 46 for opening.

The operation of the apparatus illustrated in Figure 4 is as follows The process of starting or lighting is carried out as before by means of the maintaining circuit, and when the apparatus is suitably started, the Winding 36 opens the contacts 37, consequently insulating the starting electrode device, and closes the contacts 38, thus permitting the closing of the contact device and it is suflicient for this purpose to press the button 45. The closing coil attracts the armature, which closes the auxiliary contact 43 shunting the push button and inserting the resistance 44 in the circuit. The circuit may be broken, either by actuating the push button 46, or, in case of too great acurrent, bfy the action of the maximum relay 41. I the supply current fails, the contact device 42 opens, as is also the case when the maintaining circuit is accidentally broken. In any event the apparatus cannot be started while the continuous current circuit is closed. y

In the case of two or more rectifying a paratus arranged in parallel with their cat odes interconnected if it is desired to employ one contact device only for protective purposes each rectifying apparatus may be .provided with similar starting devices, but

it is then necessary to interpose in series in the closing circuit of the single contact device all the contacts corresponding to 38. All the lamps should be lighted up so that the contact device can be closed on the external circuit.

It will be evident that the contact device can be operated by an automatic device, on condition always, that such a device, only permits the contact device to close when all the maintaining circuits are in operation.

It was supposed above that the closing winding of the contact device was employed in shunt with the continuous current circuit, but a closing winding in series with the maintaining circuit, may be employed which permits the omission of the contacts 38, the latter arrangement being recommended in certain cases, in particular where a variable pressure is employed.

An external casing device or internal grating device may still be employed in the apparatus forpreventing starting under load it being sufiicient to provide each projecting anode arm of the apparatus either with an external or internal grating.

In order to prevent starting under load it is sufficient to employ a system of relays similar to those described above in order to place the casings or gratings at the same potential as the cathode so that the maintaining circuit is not energized and to the potential of the correspondinglanodes as soon as the maintaining circuit is energized. This arrangement is a plicable in particular to high tension recti ylng apparatus which always function at a low temperature, a circumstance favoring the employment of casings and gratings.

The arrangements described above render impossible the closure of the continuous current circuit, when the starting of the rectifying apparatus is not suitable. An arran-gement for permitting starting under load'i without permitting continuous current to traverse the starting electrode may also be provided, it being sufficient for this purpose to interpose in the startin circuit a condenser in series with a self mductance in order to diminish its impedance.

Figure 5 illustrates such an arrangement. The autotransformer for supplying current to the lamp 47 is provided with a starting winding 48 connected to the starting electrode through a winding 50 and condenser 49. It will be observed that in these conditions, the starting electrode will be operated until continuous current is established in the cathode circuit, inasmuch as it cannot be established in the lighting circuit because of the condenser. A relay (not illustrated in Figure 5) may be employed for breaking the starting circuit and for placing the starting electrode at the same potential as the cathode.

It will be evident that the invention is not limited to the particular arrangements hereinabove described which may be varied as required to suit particular requirements.

Claims:

1. In va or rectifying apparatus, the combmation 0 an auxiliary electrode, bi-metallic means for actuating said electrode and means including a tubular member for protecting said electrode and said bi-metallic means from the action of the ionized vaporwithin the apparatus, said tubular member being mountedto permit deformation of said bimetallic means.

2. In vapor rectifying apparatus, the combination 0 an auxiliary electrode, bi-metallic means for actuating said electrode and insulating means including a tubular member surrounding said electrode and said bi-metalhe means and protecting same from the ionized vapor within the apparatus, said tubular member bein mounted to permit deformation of said bimetallic means.

3. In vapor rectifying apparatus, the combination of an auxiliary electrode composed of tungsten, bi-metallic means arranged to support and actuate said electrode, an insulating casing surrounding said bi-metallic means all mounted to permit deformation of said bi-metallic means and an insulating covering for a portion of said electrode.

4. In vapor rectifying apparatus, the combination of an auxiliary electrode made of tungsten, bi-metallic means 'for supporting and actuating said electrode, and insulating covering for said electrode and insulating means surrounding said bi-metallic means.

In testimony whereof I affix my signature.

MAURICE AUGUSTE EUGENE LEBLANC.

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