US1715215A - Means for regulating the voltage of electrical transformers - Google Patents

Description

May 28, 1929. I H 1,115,215

MEANS FOR REGULATING THE VOLTAGE OF ELECTRICAL TRANSFORMERS Filed Oct. 15, 1928 2 Sheets-Sheet l Y t 1 F a May 28, 1929.- c, w s 1,715,215

MEANS FOR REGULATI NG THE VOLTAGE OF ELECTRIGAL'TRANSFORMERS Filed Oct. 15, 1928 2 Sheets-Sheet 2 Patented May 28, p

UNITED STATES ,PATENTTOFFICE.

' ALBALN JCECIL wmsn, or HAYES, E GLAND. means m REGULATING mm volumes or nnncrarcar. ramsroaimas.

Application filed. October 15, 1928, Serial No. 812,607, and in Great Britain June 30, 1927.

This invention relates to voltage regulating ta-nce apart that when they are moved tomeans of the kind whereby the voltage of an wards the next adjacent tapping plate for b insulated. from c other; so as ping points and five tapping plates, it is posf electrical transformer, for instance an oil voltage regulatingpurposes, one of them can immersed transformer, can be regulated bear against the next adjacent tapping plate whilst the transformer is under load, and 7 before the other leaves the first tapping plate. particularly to voltage regulating means of The two movable contacts are 'res ectively the type in which for the purpose mentioned, connected through two separate sw1tches,=to sections of a transformer winding connected the opposite ends of an auto-transformer, or to successive tapping points can be' cut in or a choke coil (both hereinafter included for out of action successively, at will, by causing brevity in the term auto-transformer) the a pair of insulated contacts connected through middle point of which is connected to a secswitching means to an output terminal or 0nd or output terminal for connection to an lead, to pass over the successive stationary output lead. The arrangement is such that contacts connected to the successive tapping when the two movable contacts bear upon one f points of the said transformer winding. only of the tapping plates, the current flowing The present invention has reference to through the transformer winding, divides and improvements in voltage regulating means passes in parallel through both movable conof the type referred to, and it has for its tacts to the two switches and then through chief object to provide voltage regulating the two halves and middle point of the automeans of simple construction, whereby any transformer tothe output terminal. When, desired number of voltage regulating steps for reducing or increasing'the voltage of the or stages can be obtained and used'for any winding, the two movable contacts aresimul- V I desired, time with a less number of tapping taneously moved in one or'other direction topoints connected to stationary tapping con-- wards the nextadjacent tapping plate, one

tacts or plates than has heretofore been the of the movable contacts will bear against the case in voltage regulating means of the type second tapping plate while the other movable above referred to, and without the voltage contact still bears on the first tappingplate regulating means itself causing any objecand current willfiow through the two movtionable reduction. of voltage or los of elec able contacts and switches to the two ends of tric energy. It also has for its object to the auto-transformer and thence to the middle enable the movable contacts which co-act point thereof to the output terminal. gIn this with the said stationary tapping contacts or position of the parts, a virtual tapping point plates to be operated in a simpler manner is obtained midway of the section of the windthan heretofore. It also has for its object to ing between the two tapping points connected enable the current normally passing from the to the two tapping plates upon which the two tapped winding to the output terminal or, movable contacts are then hearing. The curlead,-to pass through the two movable contacts rent then flowing through the two halves of connected inparallel, so thatsuch contacts the auto-transformer balance each other so can be made of smaller cross section than is that th-ere is no appreciable drop of voltage practicable in the case where the whole of the caused by the inclusion -of the auto-trans said current has normally to pass through former in circuit and no objectionable loss of one or other of the two movable contacts.

For this purpose, in voltage regulating be allowed to remain in. the position menmeans according to the present invention, tioned for any desired length of time with-I there is associated with the successive tapout disadvantage, to constitute an additional ping points of a transformer winding which running position; Consequently, for any is connected at one end to an input terminal given number of stages of voltage regulation, or lead, a control switch comprising a row the number of tapping points on the winding of successive fixed contacts (hereinafter and "the number of tapping plates, can be called tappingplates) connected to,the succonsiderably reduced as compared With-voltsv energy. The movable contacts can therefore cessi've tapping points, and two movable conage regulating means of the kind hereinbel I tacts that are mechanically connected tofore referred to. a For instance, with five tapto form-one movable device and are adapted sible, by the present invention, to obtain nine to bear simultaneously upon-one only of the running positions of the voltage regulating tapping plates but. arranged at such a dismeans. -Inthe known arrangement of the the two movable contacts are moved simul-.

. taining the transformer. By the present inkind hereinbeforereferred to, to obtain nine running positions, it would be necessary to use nine tapping points and nine tapping plates. Whenit be desired to cut out or cut in the'section of winding included between two tapping points and tapping plates and movable contacts in the present arrangement,

ventionjt will be seen that only one operating device is necessary for movingb th of the movable contacts simultaneously, each movable contact carries only one half ofthe current flowing from the transformer winding to the output terminal through the twoswitches and auto-transformer; no objectionable reduction of voltage, or loss of elec tric energy will be caused by the auto-transformer when the two movable contacts are on one tapping plate, or when they connect two adjacent tapping plates through the two halves of-the auto-transformer to the outputv terminal, andfor any given number of running voltage regulating'steps, the number of tapping points and plates is considerably less than the number required in voltage-regulating means of the type hereinhefore referred to.

' The two movable contacts can be connected to the two switches through flexible'connec- .tions. It is however preferred to connect them to the two switches through two sta tionary contact bars that are insulated from each other, are arranged parallel to the row of tapping plates, and are electrically con nected to the two switches, and against which the said movable contacts are arranged to 1 slide. The. middle point ofthe auto-transformer may .be connected direct to the outgo-.

'ing terminal, or it may be connected to cm H --end of a second winding that, in elfect,-forms part of; the winding providedwith the tap 'pingpoints' and which is connected at its other end't o the said output. terminal. In the accompanying illustrative Q'r'aw-ings,

:Fig. 1 shows, diagrammatically, one construe;

Fig. -1 showin T 3. shows in tion of voltage regulating means according to theqinvention'. Fig. 2 is a similar View to a modified construction. Fig. e elevation and'Fig.. 4 in end elevation, a modified construction of control r switch. Fig. 5shows a further modified form of'control switch.

In these drawings, A and areQt-hetwo This windings of a transformer. The winding A, say the primary winding, is connected to in' put and output terminals A and A winding B, say the secondary-winding, may, as shown in Fi 1, be divided into two portions connected together in series through the aforesaid control switch, oil switches and auto-transformer, and its ends to input and output terminals B and B Or, as shown in Fig.2, the winding B maybe undivided and be connected at one end to the input terminal B and at its other .end portion to the output terminal B through the said control switch, oil switches and auto-transformer direct. In each case, C, C, C are tapping pointson the secondary winding 13 connectedby conductors to insulated tapping plates D,

The-

D 1) with whichthe control switch co-acts,

and which are arranged in a single row.

In the example shown in Fig. 1, the control switch comprises a pair of parallel movable contact bars 1 and 2 which are rigidly connected together but insulated from each other, and a pair of stationary parallel contact bars.

3 and 4 arranged at right angles to the movable contact bars. 1 The movable contact bar 1 'is arranged to'bridge the stationary contactf bar 3 and one or other of the tapping plates D, D D according to its position, and the movable contact bar 2 is arranged to bridge the contact bar 4 only and one -or other,

of the said tapping plates according to its adapted to bear simultaneously upon any 'one. of the tapping plates. Thesai'd pair of mov able contact bars are moved, as. for instance 1 as by a rod E, in a direction at right angles to their length for cutting in and out sections of the transformer winding B located between the tapping points C, 0 C and corresponding tapping plates D, D ,'D The relative position of the movable contact bars 1 and 2 and tappingplates D, D, D is such that position, the two movable contact bars being.

when the bars aremoving in either direction,

the leading contact bar makes contact with the next tapping plate before the trailing contact bar leaves. the preceding tapping plate. The stationary contact bars 3 and 4, which are also insulated from eachothe'r, are connected through oil switches, indicated at 5 and 6, to the opposite ends of an auto-transformer 7. Each oil switch 5 and 6 comprises, in the example now being described;two staati nary contacts 10,- 10' an a movable conta lt- 11. The stationary co tact,.10 of the oil switch at MS. connected to contact bar'3, and

the stationary contact 10 of the switch is connected to one-end. of the auto trans'formerj, the stationary contact 10 of the second oil switch at 6 being connected to the contact bar Aandthe other stationary contact 10 of the sameswiteh being connected to the opposite end of the auto-transformer .7. The. movable contact 11 of each oil switchis adapted to be actuated by suitableoperating means, comacircuit betweenits associated pair of stationary contacts at therequired times. The

middle point 7 of the auto-transformer 7 is connected by a conductor 8 to the second portion of the winding B.

When the parts in the position shown in Fig. 1, the upper portion of the wind-ing B is connected at the tapping point C through the movable and stationary contact bars; 1, 2, 3, 4 and closed oil switches at 5 and 6 to the opposite ends of the auto-transformer 7 and thence from the mid-point 7 thereof and conductor 8 to the second portion of the winding B, the sections of the winding B between the tapping points 0, C and C being cut out. The current'then flowing in opposite directions through the two halves of the auto k transformer, balance each others action, so

that there is no appreciable drop of voltage caused'by the inclusion of the auto-trans former in the circuit. When it is desiredto cut-m the section of the transformer winding B between the tapping points 0 and C the movable contacts 1 and 2 are moved overthe' contact bars 3 and 4 in the directionof the arrow and pass successively from the tapping plate D to the tapping plate D the section of-winding between the two plates being cut 1nto circuit when both of the movable bars bear on-the tapping plate D. When, during this movement, the movable contact bar 2 has moved on to the contact plate D andwhile the movable contact bar 1 is still on the contact plate D, as shown in dotted'linesin Fig. 1, the auto-transformer 7 is connected in parallel across the section of winding B between the tapping points G and C the current then passing through the conductor 8 to the second portio'nof the winding B, being drawn half from the tapping point C and half from tapping point G With the parts 1n the position mentioned, the midpoint 7 of the auto-transformer becomes electrically equivalent to a tapping pointon the winding B midway between tapping points C and C To prevent sparking between each movable contact bar 2 and 1 and the tapping plate D,

when it leaves that plate, the correspondlng Oll switch at 6 or 5 is opened before the contactbar 2 or 1 leaves the said tapping plate, so

that any sparking that takes place when breakingithe'circuit between the tapping plate D and one or other end of the auto-trans former 7, willtake place in the oil switch and not, in the oil tank containing the trans former, if the controlswitch be placed in the tank as is usually preferable. When each contact bar 2 and 1 reaches the tapping plate D its corresponding switch 6 or 5 is closed. The next section of winding B can be similarlv cut-in by continuing the movement of swears 1 and 2 untilthey both bear on tapping plates D'-, the switches 6 and 5 being alternately open and closed at the required former time for the purpose mentioned. revers- 4 ing the movement of the contact bars 1 and'2 and opening and closing the oil switches in the properorder and at the required times, the cut out sections of-windings can again be successively cutin. In each case a virtual midway tapping point on the winding between the actual tapping points, is obtained when the movable contact bars11 and 2are v on adjacent tapping plates. Also, the mov-' able contact bars 1 and 2 can be left for any desired time on any two adjacent tapping to constitute an additional running :voltage position without any plates,

reduction of voltage "or lossof electrical energy being caused by the auto-transformer.

objectionable Thus it will be seen that at no time during the cutting in or out of sections of the winding B, is the circuit of the winding opened, so that regulation of the voltage of the transformer can be made whilst the transformer seen thflt l10 sparking can take placeat the is under load. .Also, it will be control switch. 1

The operation of the ,inovable' contacts 1 and -2 of the control switch and of the movable switch contacts 11 ot the 'oil SW1l3Ch6S,

can be effected at the required times by hand actuated means, or by motor operated actuatnext one, owing to one half-only of the auto transformer winding :7 being then in iICtlOIl= and such half acting as a reactance or choke.

In order to minimize the time during which the slight fall of potential can take place,

switch at 5 and 6 may be adapted, on its acting to disconnect one half of the autotransformer winding 7 from its associated stationary contact bar 3 or 4, immediately to short circuit such half of the auto-transformer winding, so that it will then serve to counteract the efiect of the current then flowing through former winding through the other contact bar and oil switch.

This result can conveniently be attained, as shown in Fig; 2, by providing each of the the movable contact 11 in each oil the other half of the'auto-transtwo oil' switches at 5 and 6, comprising the pair of stationary contacts 10, 10 and the co-actlng movable contact 11, as hereinbefore' described, with an additional pair of station'- ary contacts, 12, l2 'with which 'the associated movable contact 11 can co -act, one of the additional contacts, namely 12, of each oil switch being connected to the said mid point 7. of the auto-transformer 7 and the other additional stationary contacts 12 of the two switches being connected respectively" to the opposite ends of the auto-trans- 7. The movable cont act 11 of each oil switch and 6 is adapted to bear against one or otherof its associated pairs of stationary contacts 10, 10 or 12,12. In this case, immediately either movable contact 11 is moved from its stationary contacts 10 and 10f to'disconnect one or other end of the auto-transformer winding 7 from the corresponding contact bar 3 or 4,'as h'ereinbef ore vdescribed,'it is immediately caused to bear against the additional pair of stationary contacts 12 and 12 and short circuit the corresponding'half of the auto-transformer windmovable contact of each oil switch to move ing,"for the purpose mentioned. By this means drop of voltage, whilst regulating the -voltage of the transformer, will be limited to the moment of time that is necessary for the from one of its pair of stationary contacts to theopposite pair of stationary contacts.

Figs. 3 and 4 show a modified construction of control switch wherein the stationary tapping plates, C, C C are arranged in a single row above and transversely to the stationary insulated contact bars 3 and 4, and the "two movable contact devices are arranged to be moved longitudinally and simultaneously I between the tapping plates and contact bars.

In this example, one of the movable contact devices comprlses upper and lower contacts 1, 1 that are pressed apart and into contact with one or other of the tapping plates C, C C and the contact bar 3, by a spring 13, are connected together electrically by a flexible strip14of metal and are carried by two arms .15 and 16pivoted on a pin 17 fixed to acarrier 18 ofv insulating material. The other mov able contact device comprises upper'and lower contacts 2 and 2 that are pressed apart and into, contact with one or. other of the tapping plates, C, C C and the other contact bar 4 by a spring 13 are connected together electrically by a flexible strip 1 1* of metal and are carried by two arms 15 and 16 pivoted on a pin 17 fixed to 'the said carrier 18. The said carrier is adapted to be moved to and fro inlthe direction of the tapping plates and contact bars by any convenient means, as; for instance, by a longitudinal screw'19,jadapted to be rotated in one or other direction and at the required times but which is prevented from moving 'endways.

The control switch instead of being con- .structed with movable contact devices arshown at 1" and'2 in Fig. 5, be radially ar-' ranged so that they-can be rotated in relation.

ranged'to slide in a rectilinear direction in relation to straight stationary tapping-plates and contact bars 3 and 4, asfhereinbefore described, mayjotherwise be arranged.

Thus, the movable, contact devices may, as

to stationary arcshaped stationary ta'pping plates 0,0 C and contact bars 3 and? m.

V a' manner that will readily be understood.

In each case it wilLbe seen that each inovable contact device is at all times inelectrical connection with oneterminal, say 10, of its corresponding oil switch 5 or 6, and could if desired be directly connected to such terminal by a movable conductor and the'corresponding stationary contact bar.3 or 4 dispensed with. It is however preferred-to use the fixed contact bars 3.and-4. I

. Usually it will be preferable, as hereinbefore mentioned, to arrange the control switch within an oil filled tank containing the main transformenbut it and its associated tapping plates may be. arranged outside the tank if desired. The auto-transformer may be arranged inside or outside the tank. The two oil switches will be. arranged external to the tank, so as to avoid sparking therein.

The said winding 13 may be divided at any point of its length, as hereinbefore described with reference to Fig. 1, so that the tapping points can be arranged in any desired posi:

tion on thelwinding. Or the tapping points may be at one end portion of the winding, as in the example shown in Fig. 2.

With voltage regulating means accordingwhether such transformers I tionsof voltage regulating means and no claim is herein broadly made for the use of 'an auto-transformer or choke coil in voltage regulating means.

What I claim is i 1. For re ulating the voltage of an elec-' trical transformer, the combination with a winding of the transformer connected at one a plurality of tapping points, of a control swltch comprising a plurality of stationary insulated tapping contadts connected 'tothe respective tapping points and two movable contact devices mechanically connected together but insulated from each otheryand adapted to" bear simultaneously on any one.

tapping contact, or upon two adjacent'tapping 'conta'c-ts duringmovement from one tappingcontact to an adjacent one, an autotransformer the middle point of. which is in electrical connection with the second-terminal, two separate circuit opening. and closing switches normally connecting the 'two movablecontact devices to the opposite'ends.

of said auto-transformer whereby each movable contact device can, ulation be disconnected during voltage 'regfrom its correspon'dingend of the said auto-transformer. before 1 10 end to one of a pair of terminals and having tact device from one-half of the auto-transformer and immediately afterwards to shortcircuit the said half of the auto-transformer.

2. For regulating the voltage of an electrical transformer, the combination with a winding of the transformer connected at one end to one of a pair of terminals-and having a plurality of tapping points, of a control switch comprising a plurality of stationary insulated tapping contacts connected to the respective tapping points and two movable contact devices. mechanically connected together but insulated from each other and adapted to bear simultaneously on any one tapping contact, or upon two adjacent tapping contacts during movement from one.

tapping contact'to an adjacent one, an auto- I transformer the middle point" of which is in electrical connection with the second terminal, and two separate circuit opening and closing switches, normally connecting the two movable contact devices to the opposite ends of the said auto-transformer and whereby each movable contact device can, during voltage regulation, be disconnected from its corresponding end of the said auto-transformer before it leaves the tapping contact upon which it is hearing and be reconnected to the auto-transformer when it reaches the next tapping contact, each of the two circuit opening and closing switches comprising two pairs ofstationar'y insulated contacts and a movable contact adapted to co-act alternately with each pair of said contacts, one

of the contacts of one pair of contacts of one switch being connected to one of the movable contact devices of the control switch and the other contact of the pair being connected to one end of the auto-transformer, and the two contacts of one pair of contacts of the other switch being similarly connected to the other movable contact device of the control switch and to the other end of the auto-transformer,

and the other two contacts of each switch being connected respectively to the mid-point and corresponding end of the auto-transformer.

Signed at London, England, this fifth day of October, 1928.

ALBAN, CECIL WHISH.

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