US1994953A - Regulating choke coil - Google Patents

Description

March 19, 1935. H. A. wl KLINKHAMER 1,994,953

REGULTING CHOKE COIL Filed May 28, 1932 3 Sheets-Sheet 1 a a fa /6 f# .fa

Ml'Ch 19, 1935 H, A. w. KLINKHAMER 1,994,953

REGULATING CHOKE COIL Filed May 28, 1952 3 Sheets-Sheet 2 March 19, 1935. H. A. w. KLINKHAMER REGULATING CHOKE COIL Filed May 28, 1932 3 Sheets-Sheet 3 Frfy Patented Mar. 19, 1935i UNlTi-:D sTATEs Y 1,994,953 aEGuLA'rnvG cnoirncon.

llendrik Abraham Wijnan hoven, Netherlands, assigner to N. V. Gloeilampenfabrieken, Eindhoven,

lands Application May 28,

In Germany d Klinkhamer, Eind- Philipe Nether- 1932, 'sa-m No. 614,216

rune z5, 1931 Claims# (Cl. 171-242) This invention relates to adjustable choke coils particularly adapted for controlling the current of a non-rotary welding device fed by polyphase current. In connection with suchdevices itis o known to control or regulate y'the current by modifying the reactance of a multi-phase choke coil 'which is inserted in the primary circuit of the welding transformer.

In such known devices a continuous control is obtained by providing theV iron core of the choke coil with a variable air gap. The great magnetic forces produced in said devices cause constructional diflicultiesand to obtain a satisfactory construction is comparatively expensive.

An intermittent regulation may be obtained by the simultaneous and stepwise change of the number of turns of the individual choke-coil phases, by providing these 'phases withl 'a plurality of taps. However, a sufficiently fine adjustment cannot be lobtained with such regulation, unless a large number of taps is provided and a cuordespondingly complicated switching device The invention has for its purpose to provide nmore simple and substantially continuous conv In the control device according to the invention the. choke coil winding comprises in each phase a plurality of taps, the taps being connected (and numbered) in a cyclical order of the phases and in the order of their distances from the starting point of the 'phase winding to a series of contacts of a switch device by means of which the different.

taps may be connected to the phase supply conductors or to a star point so as to obtain a series of control' stages. In any of the stages three successively numbered taps' are either connected to the preceding or succeeding phase supply conductor in order to obtain a polygon connection or are connected to the starpoint as to obtain afstar connection. In this manner, the number of stages obtained with a given number of taps v is much larger than obtainable with the known adjustable choke coils, since successive stagesA are obtained by merely adding or omitting a portion falling betweenrtwo successive taps of a single winding and furthermore by using the same taps and branches for a series of control stages obtained with star connection and a' series of control stages obtained with delta connection. r T'he adjustable choke coil above referred to may A beof quite small size and of a simple and cheap construction. In one embodiment oftheinvention this is obtained by providing in 'the switch device three series or rows of contacts, each having an equal number of contacts, the contacts of the middle row being connected to the taps of the choke coil, the contacts of one outer row being connected in a cyclical order to the phase supply conductors and the contacts of the` other outer row being all electrically interconnected. The Adiiiferent connections are obtained by connecting each time a number of successive contacts oithe middle row, which number corresponds to that of the phases, to the adjacent contacts of either 10 one of the outside rows.

Preferably the contact points of the switch device consist of contact sleeves, while. the connection between these sleeves is eiected by means lof a contact plug comprising two rows of three, pairwise interconnected, pins.

Circuit connections of the type above referred to, do not properly lend themselves for use with an ordinary multi-phase transformer or with a multi-phase choke coil, since in all or at least in some of the polygon switch positions the number of turns which the diiierentphases have'in the circuits is not equal, so that the sum of the magnetic fields of the individual choke coil cores, does not give zero in these cases. In order to'nevertheless obtain a compact assembly and a saving in material a three-,phase choke coil v construction may be advantageously used, which consists of'three single-phase shell type choke coils of the usual form, `but in which two yokes are omitted and in which one yoke, for instance the lower, of one of the choke coils serves at the same times as the other, for instance the upper yoke of the succeeding choke coll, and in which the coil of the intermediate choke cll is con- Vnected oppositely with respect to the outer choke coils.

The invention will be more clearly understood by reference to the accompanying drawings, rep-L resenting, by way of example, one embodiment 40 thereof. Y l

Fig. 1 is a. circ t diagram of a direct current welding device in which the alternating current is rectified by means of gasfilled rectiei' tubes. and in which a choke coil according to the invention is used.

Fig. '2 is a diagrammatic showing of theconnection of the choke-coil winding for some of the control stages. I-

Fig. 3 is a graphical representation of the 50 welding current as measured in the `different positions Vof the contact plug.

. Fig. 4 is a schematic representation of the construction of the ironv core of an adjustable choke coil according to the invention.

Fig. 5 is a plan view and Fig. 6 is a side view of an adjustable welding 'apparatus comprising a regulating choke coil according to the invention.-

Referring to Fig. 1 the welding transformer 1 may be connected to the network through a switch 2 and a contact plug 3. Ihis also connects to the network the windings o the regulating choke coil 4, hereafter more fully described. By the insertion of plug 3 a heating transformer 5 is switched on at the same time. 'I'he secondary side of the welding transformer has three windings, which by'means' of center-taps form a 6- phase winding. These windings areconnected at their ends to the anodes of three full-wave rectier tubes 6, '1v and 8,'whose cathodes are connected across the secondary winding of the heating transformer 5. The middle tap of the secondary windingof transformer 5 is connected to a workpiece 9, and the center taps of the secondary windings of the welding transformer l. are connectedito a welding electrode 10.

'The regulating choke coil 4 coinprises three phase windings, the starting points or terminals A1, Ac and A3 o f which may be connected to the network through the welding current transformer; Each phase winding'of the regulating choke coil is provided with four taps, including the free ends of the windings. These taps are marked by the reference numerals l1`22 in the order o f their distance from the starting points or terminals Ai, A'z, and A3 of the respective windings. \Wl1eri going round the three phases always in the same sense the twelve taps are traversed in the order of the numbering.. Consequently of the optional three `successive taps there is each time one on-each phase.

A series of ten star-connected-control stagesl is obtained by interconnecting each time three successively numbered taps so as to form a star point.

obtained by connecting each of three successively numbered taps to the beginning of the p'e-y cedingv (or succeeding) phase winding.

The positionof the taps may be such that tlie ten star connected control stages join the ten delta-.connected control stages.

. The upper portion of Fig. l shows how the connections are established in the switch arrange- These contact sleeves'just referred-toconstitutevthe middle series or row ofthi'ee series of contact` sleeves. For the sake ofclarityy the connections between the contact sleeves and the taps are omitted from thef The twelvecontact sleeves -of the upper'v row are connected in groups of three in a cyclical order to the starting points A1,'A2 and A3 of the three phase windings and in such a. manner that opposing contact sleeves. of the two rows are always connected to diierent phases.

All oi the contact sleeves ofjthe lower row are inter-connected and form vthe .star-pointi for star-connection.

These contact sleeves cooperate 'with a contact plug provided with six pairwiseinter-connected pins. plug isfseparately'shown in-A Fig. 1 and denoted by-24. This arrangement of the contact sleeves per- A'series of ten delta-connected control stages l mits the above-referred to connections to be es tablished in a very simple manner. In order to obtain a star-connection each of three succeeding contact sleeves of the intermediate row is connected by means ot the plug to the corresponding contact sleeve of the lower row and for obtaining a delta-connection each oithem is .connected to the corresponding contact' sleeve of the upper row.

In,the drawings four indicated in dotted lines by way of example. These four positions correspond tothe four connectionI diagrams marked I, H, m, m of Fig. 2 and give corresponding adjustments of the welding current. i

. l in the position i, the windings of ihcregulting choke coil are connected in the manner indicated in Fig." 2, on the upper left. Invtbis case the full phase windings Ai-22, A2-20, iis- 21 are star-connected. The current fed from the welding transformer Lfyiz. the welding current, has its minimum value. l

When the plug is moved to the right in the position marked 1I so as to engage the succeeding positions of the plug are N contact sleeve, the full phase-winding A2-20 and .i3

A3-21 remain in the circuit, but from the phase-,L h

winding Ai-22 the portion 22-19 is cut out and only the portion Aie-19 remains in Ythe circuit; at the top and n the right of Fig. 2 are shown the circuit connections thus obtained. in this posio tion of the switch apparatus, the current is increased compared with position I.

When through successive displacement of the plug to the right so as to engage successive sleeves been trav- 30 all of the star-connected stages have ersed, the plug is returned to the left,` but now in the position to interconnect the sleeves of the upper. and middle rows for delta-connection. After a number of these stages. have been trav-d' ersed theplug occupies fori instance the position4 XIX, to provide for the delta-connection shown in Fig. 2 at the bottom on the left. If it is desired to still further increase the current, the plug is moved further to the iight so as to occupy the position XX thus cutting outthe portion 11-14 in the corresponding winding of the regulating choke coil. 'I'he connection thus obtained is shown in Fig. 2 at the bottom on the right.v

This position corresponds tothe last stage and gives the maximum current strength obtainable.` 50

stantially a straight line, shows that the percentage of current increase with the transition from any stage to the succeeding stage is the same throughout. C Thus the device makes` it possible to obtain V 'twenty diierent stages ,or adjustments inthe welding current strength and requires only four taps per phase, -including the free end terminals arithmic Scale. The .fact'that the curve is sub- "0 of the phases. At the-same time the maximum 65;

current carried bythe conductors connecting the choke coil-to the switch apparatus and by Y pins and sleevesof the switching apparatus amounts only to The transitign from one connection to another l 7%."-

ed at the upper and at the lower end by means by the switching apparatus amounts only to times the no-load current of the transformer.

The regulating apparatusis small, simple and cheap and the control in twenty stages allows a practically continuous control. Of course, the number of stages may be increased in a simple manner.

In case the taps of the different phase windings are provided at equal distances from the starting point, in certain stages the different phases will be symmetrically loaded, while in other stages will be asymmetrically loaded, as appears from Fig. 2. However, the last stage will be a symmetrical one so that the maximum power of the ywelding apparatus is not decreased by the controldevice.

In one embodiment of the invention the distance between the starting points of the windings and the successive taps increase toward the free end terminals of the phase windings. Such a division has the advajntage that the maximum load diiference betweenthe individual phases is materially smaller than in the case of an equal spacing of the taps.

As has already been stated it is not ad ble\to use the regulating arrangement referred to with a normal three-phase transformer or a threephase choke coil. In fact, since these haveonly three cores which are magnetically interconnectof yokes, the sum of the fields is zero. Consequently the sum of the electro-motive forces in-fducedl by the ilelds in the three windings is not zero for those connections in which the number of turns are unequal. Due to this, unduly large compensating currents would occur in the asymj metrical delta-connections. This also holds good for themulti-phase constructions having a phase number other than three.

The arrangement according to the invention may be also used if instead of ya combined m phase core, m separate single phase cores are provided. However, the combined core has `the advantage of a saving in materials and of greater compactness. This advantage is also partially lost when the multi-phase construction is provided with an additional unwound core by which the yokes are magnetically interconnected. However, the construction in which the compensating currentis suppressed has other drawbacks.

The same important saving in material obtained with the standard three-leg construction can, however, also be obtained by means of a construction of the multi-phase core as shown in Fig. 4, which construction has several further .practical advantages. l y

'I'he device illustrated may be regarded as consisting of an assembly of three single-phase shell type cores 25, 26 and 27 in which two yokes are omitted. When denoting the magnetic fleldsof the three cores by Fi, Fn, andF-i, the yokes 28, 29, l 30 and 31 carry the following fields:

tsm, 5m-F1), str1-Fn, ma The fields F1, Fa, and Fa are assumed to be positive in the directions indicated by arrows in the drawings. Should the three coils vbe wound and connected in the same sense, each of the two mid- `diey yokes would" in accordance with the above terms, carry a ileld having a value which is proximately times that of the ileld of the end yokes. However, when the coil of the middle winding of the three single-phase windings is oppositely connected, insteadv of the usual relation existing between the core ilelds namely:

When inserting vthe so found value of Fi in the above terms for the yoke fields, the latter become lFi; VgFa; -vmz -yFz Fromthisit appears thatinthiscasethefour yoke ilelds are equal. Consequently the two middle yokes need not be thicker than the terminal yokes. 'Ihus with this construction the amount of material required is practically the same as that required for the normal combined three-phase construction. Furthermore the above arrangement has the following advantages:

1. The mutual inductance due to the leakage elds are practically zero. Consequently, the troublesome effect due to unequal mutual inductances is absent, whereas this is quite pronotmced in the case of a standard three-legged choke coil and results in unequal loading of the rectifying valves, which drawback also manifests itself even when the number of turns on each of the three cores is the same.

2. 'lhe air gap of veach choke coll core may be adjusted separatelyfin contradistinction to the three-leg construction, thus making it possible tocompensate for differences which mayA exist for some reasons between the three phases.

3. The same type of stamps and punches may be used as for single-phase choke coils.

4. Instead of clamping the yokes between angle bars the side cores are' clamped between brass strips. For this purpose the bolt apertures already normally provided in the core sheets may be used. When using common strips for the three choke coils they are assembled so as to form a unit. The strips must be provided with oblong apertures so that the air gaps may be adjusted. There is no danger of the brass strips being heated by Foucault currents as may be the case with angle bars.

5. The core sheets need not be wound into the coils but the coils may be slipped over previously formed-cores.

Figs. 5 and 6 show the arrangement of the regulating choke coil 4 in a welding apparatus comprising wheels.

In Fig. 5 the rectifier tubes 6, 'I and 8 are shown as disposed in a separate space. Furthermore this figure shows the plate 23 together with the contact sleeves and the plug 24 in plan view.

Fig. 6 shows vthe switch device arranged centrally above the choke coil 4 so that the twelve connecting wires are as short as possible while the assembly remains clear.

The regulating device is mounted on the top .of the casing. thus at a readily accessible and properly illuminated place. A hinged cover may be provided above this regulating device. I

A ventilator (not shown). may serve for coolingthe rectifyingvalves,andmaybeplacedat the bottom ofthe case, whereby it also coolsthe choke coil and other parts of the apparatus.

` sulting from the combined construction are not obtained.

WhatI claim iszl. A control device for the control of a'polyphase current comprising an adjustable chokecoil to regulate said current, said choke-coil having a plurality or phase windings, andv each winding having a plurality of taps, a conductor -for each phase and connected to one end oi its respective phase winding, a switching device having a. series of contacts, the taps of said windings being connected to said contacts in a cyclical order of the phases and in the order of their disconductor to obtain a tance from the starting point of their respective phase, said switchingdevice comprising means to connect successive taps, one of each phase, to the preceding or succeeding phase conductor to obtain a :Milligan` connection of said phases.

2. A control device tor the control oi a threephase current comprising an adjustable choke coil to Aregulate said current, said choke coil having three phase windings each having a plurality oi taps, a conductor for each phase and connected- .to one end ot its. respective phase winding, ,a

switching device having a series of 'contacts, the taps of said windings being connected to said contacts in a cyclical order of the phases and in the order of their distance from the starting point oi'- their respective phase winding, said switching device'comprising means to connect three successive taps tolthepreceding or phase polygon connection o! said phase windings.

3. A control device for the control of threephase current comprising anl adjustable choke coil to reguiatesaid current, said choke coil having three phase windings. each phase winding having amlurality of taps,` -a switching device having a series of contacts. the tails of said windings being connected tosaid contacts in a cyclical order of the phases and in vthe ,orderv of their distances vfrom the starting point ot theirrespective phase,

said vswitching device comprising means to conl nect three successivetaps to a cominonpoint, to

-obtain a connection of said phase windings.

4. 'A controldevice. i'or three-phase current comprising an adjustable choke ,coil to regulatesaidcurrent, saidchoke coilh'aving three fphase wlndings, eachphase'windin'g having a plurality o! taps, a Supply conductor i'or each phase and connected to one end of its respective phase winding, a switchingapparatus comprising aseriesofcontactathetapsofsaidwindingsbeing connected to said contacts in a cyclical order ci the phases and in the order of their distance from the'starting'point of their respective phase winding, said switching device comprising means to alternatively connect three successive taps to thev preceding or succeeding phase supply conductor Ato obtain a'polygon connection of said phase ,windinsadtoconnectthreevetapcto 'a toobtainastar connection oi s. A contrai device, for the control of a polynosaecs phase current comprising, a chokecoil to regu' late said current, said choke coil having a plurality of phase windings and each phase winding having a plurality oftaps, asupply conductor for each phase and connected to one end ofits respective phase winding, a switching i apparatus having a series oi contacts connected to the taps of said windings in a cyclical order of the phases and in the order of the distance of the taps from. the starting point of their respective phase windings, said switching device having a second seriesof contacts connected in a cyclical order to the phase supply conductors, the numbers ot the contacts of each series being equal to the total number of taps, and means to interconnect the contacts of the two series to`connect three successive taps of the phase windings to the phase supply conductors to obtain a polygon connection of said phases.

6. A jcontrol device for the control of threephase current comprising, an adjustable choke coil to regulate said current, a4 Supply conductor for each phase and connected to one end of its respective phase winding, said choke coil having three phase-windings, the starting .pointof each phase winding being connectedgto one off said phase supply conductors. each phase winding having a plurality of taps, a 'switching device having a series of co tacts, the taps of said windings being connected vsaid contacts in a cyclical order of the phases and in the order o! their distance from the starting point oi' their respective phase winding, and a second series of contacts on said switching device connected in cyclical order to said phase supply conductors.and means to connect three successive taps to. the phase supply conductor so that the taps are connected to'diii'erent supply conductors as are the starting point ot their respective phase-winding.

7. A control device for the control o! three phase current comprising an adjustable -choke coil to regulate said current, said choke coil hav.

ing three phase-windings and each a plurality ot taps, a S'uIply conductor for' each phase and connected to one end of its respective phase winding, a switching device having a se' ries o! contacts the number ot which equals the total number of taps, said taps being connected to said contacts in a cyclical order ofthe phases and the order of the distance of the taps from the starting point of their respective windings, a second series of contacts connected in a cyclical order to the phase supply conductors@I third series of electrically interconnected contacts, Yand means to alternatively connect three successive contacts of the intermediate series with thethree v phase supply -conductors to obtain a polygon connection of said vphase-windings and to connect them with said` third series ,ot'ccntacts to obtain a star connection oi' said phase-windings.

.8. A control device for the control of polyphone current comprising an adjustable choke coil to .regulate said current, said choke-coil having a plurality of phase windings and each phase windinghavingaplurality-oftap s,aswitchingde-v vice having three series of eachseries having a number o! contacts euualjto number oi taps, one seriesot contacts beim xediv connected tothe tops. and

io alternatively conn'cctzone each phase with the cocontactolthe second series to obtaino Deinen', and with the correspcndingcontactotthethird series?.

to obtains star connection.

; s. A conn-o1 device for ure current comprising an adjustable choke coil to regulate said current -and having a plurality ot phase windings, a supply conductor for each phase and connected to one end of its respective phase winding, said phase windings being connected with their starting point to one of. said phase supply` conductors,A each phase winding having a plurality of taps, a switching device having v vummm; plug having pairs of Contact pms the number of which equals the number oi.' phases three rows of contact sleeves, the vcontact sleeves of the intermediate row being tlxedly connected with the taps oi said windings in a `cyclical order of the phases and in order ot the distance of the taps from 'the starting point of their respective phase, one outer row of contact sleeves being connectedin a cyclical order to the phase supply conductorsand the other outer row of contact sleeves being electrically interconnected, and a movable and so as to be adapted to engage opposing contact sleeves of the middle row and either one of the outer rows toalternatively establish a polygon connection and a star connection o! the choke-coil windings. f

10. A control device for the control of threephase current comprising a choke-coil having three-phase windings, and a conductor for each phase and connected to one end of its respective phase winding, each phase winding having a plurality of taps and being connected with its startingpoint to one of said conductors, and a switching device adapted to provide a plurality of polygon connections of said phases, the number of which is equal to the number of phases multiplied by the number of taps less two, and to provide a plurality o! star connections of said phases, the number oi which is equal to the number of phases multiplied by the number o! taps, minus two, the

transition from successive connections causinga substantially uniform increase of the current, so that the change of the current through the whole range oi' control is substantially linear.

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