US2649526A - Liquid resistance electrical apparatus - Google Patents

Liquid resistance electrical apparatus Download PDF

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Publication number
US2649526A
US2649526A US302789A US30278952A US2649526A US 2649526 A US2649526 A US 2649526A US 302789 A US302789 A US 302789A US 30278952 A US30278952 A US 30278952A US 2649526 A US2649526 A US 2649526A
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United States
Prior art keywords
liquid
resistance
value
current
receptacle
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Expired - Lifetime
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US302789A
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English (en)
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Norbert R Benchemoul
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C10/00—Adjustable resistors
    • H01C10/02—Liquid resistors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
    • H02P1/34—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor by progressive reduction of impedance in secondary circuit
    • H02P1/36—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor by progressive reduction of impedance in secondary circuit the impedance being a liquid resistance
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
    • H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses

Definitions

  • the present invention relates to electrical apparatus which includes a liquid resistance and is capable of use in a variety of ways, e. g. as a rheostat, a means of limiting current strength or of generating current impulses or as a source of heat having inherent thermostatic control.
  • the action of theapparatus is based on the great dif,- ference in resistivity existing between a liquid (for instance water) and its vapour.
  • Electrical apparatus comprisesone or more enclosed spaces or Ycornf partments each in communication with a receptacle containing an electrically conducting liquid by means of one or more passages oiiering resistance to the flow of the liquid, there being in each compartment two or more electrodes so located as to make contact with liquid in ⁇ such compartment.
  • each compartment is provided with at least two passages, whereby circulation of liquid by means of thermo-Siphon action may take place.
  • the apparatus is dimensioned-insuch'amanner that, with a current equal to or exceeding a determined threshold value passing from one electrode to another through the liquid in the compartment orv each compartment, .evaporation of the liquid is produced, which is the more complete and rapid the smaller the volume ofthe liquid lying between the electrodes. This evaporation causes a considerable increase in the resistance of the apparatus and in consequence a drop in the value of the current.
  • the vapour thus generated in the compartment cannot be instantaneously replaced by liquid from the receptacle, because .of the hydraulic lresistance offered to its flow in the communicating passages.
  • the compartment is again lled with liquid, the resistance of the apparatus then falls and consequently the value of the current passing through its increases, assuming thata voltage across the electrodes is maintained. If this voltage is of such a value that the current passing through the compartment is equal to or'exceeds the threshold value Ydei-ined above, the phenomenon of evaporation of the. liquid .and its subsequent return tvill be repeated indefinitely, if desired with variations .corresponding yto the resistance and consequently the value of the current.
  • the apparatus functions as a generator of electric impulses of a determined frequency.
  • the latter may be modified, for instance, yby varying the effective cross section of the passage or pas- (cl. 201-57) Y* sages .connecting the lreceptacle with the compartment: ,adecreaseofthiscrosszsection causes adecrease ,ofz the frequency and vice versa.
  • the voltageatthe terminals of, the .apparatus has a. value below that, corre- Spending tothe .threshold value of the lcurrent causing evaporation .of the liquid, then the resistance o .f .the yapparat-usY willmaintain a relatively-low andsubstantiallv .constant value.
  • the resistance o .f .the yapparat-usY willmaintain a relatively-low andsubstantiallv .constant value.
  • .case-the currentpassing through the compartment causes heating of thev .liquid contained therein and, consequently, circulation by .convection or by thermo-Siphon action Withthat in .the receptacle. thusgraduallvraisins the temperature Gispen liquid; ⁇
  • the same device may be ntilisedmoresimply, as a current limiter.
  • the. current remains suiciently Weak, .circulationproeeedsnormally .as lone ⁇ as .the consumpton of enersvin the apparatus remains below the-critcal consumption.
  • the impulse device operates such .a manner as to limit the effective current to a well-determined quantity. No interruption ofthe V,current .occur-s.
  • ther apparatus may be used to ensureV the protection of -diierent electric circuits by limiting the value of the current pass- 111g.
  • the apparatus is applicable as a rheostat of inherently variable resistance.
  • liquid rheostats are known, which possess numerous advantages, but which frequently give rise to complaints about the instability of the resistance between the electrodes, the instability being due to variations in the concentration of the electrolyte with time.
  • Apparatus according to the present invention permits avoidance of these various inconveniences and production of an automatic starting device not expensive in its purchase price, extremely unsusceptible to deterioration and variations in the resistance of which are suiiiciently independent of possible alteration in the conductivity of the liquid.
  • apparatus according to the invention in all its applications, operates automatically, i. e. without actuation of any movable member, thermo-dynamic and hydraulic phenomena alone ensuring its operation. It is possible to provide movable members for making a preliminary adjustment, but subsequent operation of the device is not dependent on movement of such members.
  • Figure 1 is a longitudinal section of one form of the apparatus
  • Figure 2 is a cross-section on the line II-II of Figure l
  • FIG. 3 illustrates the control plate for the passages
  • Figures 4 and 5 show the character of the curves of variation in the resistance vof the apparatus as a function of time for two different cases.
  • Figure 6 illustrates in longitudinal section a modified construction of apparatus, showing diagrammatically connections thereof to a threephase asynchronous motor, and
  • Figure '7 is a section on the line VII-VII of Figure 6.
  • the rheostat represented in Figures 1, 2 and .3 comprises a cylindrical case I of insulating material pierced by a number of radial ports 2. This case is closed at one end by a base Ia and is open at the other end. Let into its wall so as to be flush therewith are three electrodes 3 having the shape of cylindrical segments occupying about 60 and having the same internal radius as the cylindrical cavity of the case. These electrodes are mutually displaced at and are connected respectively to current-carrying terminals 4 xed to the outside of the base Ia.
  • a cylindrical rotor 5 also made of insulating material, following generally the shape of the cavity of the case and provided with three electrodes 6 of substantially the same span and disposed angularly in the same way as the electrodes 3.
  • These electrodes 6 are placed at the bottom of shallow recesses 1 provided on the surface of the rotor.
  • the electrodes 6 are situated respectively at a slight distance from the electrode 3 and, with the latter, form the sides of spaces ⁇ or compartments 8 having a relatively small volume.
  • the rotor 5 is traversed by a series of ducts 9 parallel to the axis of rotation and communicating at one end 9a with the compartments 8.
  • the rotor 5 is integral with a shaft I0 which passes through the base Ia of the case, a sealing gasket II being clamped around the shaft I0 by means of a threaded collar I2 screwed into the base.
  • a control knob fixed on the shaft I0 by means of a screw I4, allows adjustment of the angular position of the rotor.
  • the open end of the case I is closed by a circular plate I5 provided with two rows of holes: the holes I6 are in line with the compartments 8 on the one hand, whilst the holes I1 may be brought opposite the ends Sib of the ducts 9 on the other hand, the holes Il being substantially of the same diameter as the ducts 9.
  • the perforated plate I5 which is provided with an adjusting knob t8, is retained over the mouth of the case l by means of a threaded ring I9.
  • the whole assembly described above is arranged in a receptacle or expansion vessel 29, into which it is inserted through a circular opening 20a arranged in the wall of this vessel.
  • the case I which is provided with a flange Ib, is fixed to the receptacle 20 by means of a clamping ring 22 screwed on to a threaded nipple 23 which is integral with the receptacle 2li, a sealing washer 2
  • a hood 24 is arranged between the control knob I3 and the base la of the case; its purpose is, on the one hand, to prevent axial displacement of the shaft IB and, on the other hand, to prevent any accidental contact with the current-carrying terminals 4.
  • the receptacle 20 has in its upper part a neck 25 closed by a threaded plug 26 for the introduction by a conducting liquid 21. In addition it is provided with cooling ribs 28.
  • the conducting liquid 2l lls the compartments 8, which are in communication with the receptacle 20 through the ports 2, the holes I6, the ducts 9 and the holes I1. If a three-phase voltage is applied to the terminals 4, a current will pass through the electrolyte contained in the compartments 8, causing heating, which will be a function of the square of the value of this current. If this value is sunciently high, the liquid contained in the compartments 8, or a part of it, evaporates, causing the expulsion of the remainder of the liquid into the receptacle 20. Thereby the resistance between the electrodes rises considerably, thus reducing the current.
  • the liquid returns gradually to the compartments 8 at a rate which, in view of the frictional loss of head taking place in the various passages connecting these compartments with the receptacle, depends largely upon the eilective cross section of these passages; it is therefore possible to regulate this rate by modifying this cross section.
  • the passages 2 and I6 have a constant cross section; as against this the effective cross section of the ducts 9 may be adjusted by means of the perforated plate i5, the holes I1 of which may be brought to a greater or less degree opposite the ends 9b of these ducts.
  • the same phenomenon repeats itself, if the current when the compartments are full has a value exceeding the threshold value. If on the contrary the voltage applied to the terminals 4 decreases and the current then drops to a value below the threshold value at which the evaporation of the liquid takes place, the resistance of the apparatus will remain relatively low.
  • the rheostat maybe short-circuited by any known automatic means, which preferably should re-i-nsert the rheostat into the circuit in case of an excessive increase of the opposing torque and, consequently, of slip. In that case the increase of slip results a corresponding increase of the rotor voltage, and the current passing through the rheostat becomes higher than the evaporation threshold value, so that the phenomena described above reproduce themselves.
  • the motor can deliver a higher driving torque and this prevents the motor from falling out of step.
  • the stability of the motor is greatly increased, even down to very low speeds.
  • a rheostat in practice, maires it possible to substitute for the usnal slip-torque characteristics' of asynchronous motors with reduced stability ranges and corresponding each to a given rotor resistance, a single characteristic with a relatively wide stabilityrange. This allows, in particular, satisfactory utilisation of asynchronous motors for driving machines subject to jerks' (for instance traction machines, rolling mills,- etc.)
  • TheconsequenceV ofthis is important.
  • a decrease of the resistance will correspond to a decrease of voltage, i. e. to an increase of the speed of the motor.
  • Figures 6 and 7 show the apparatus as ap- 8. plied to an asynchronous motor having a wound rotor for starting purposes.
  • the motor indicated as a whole at 30, consists of stator windings 3l connected in delta to terminals 32 and rotor windings 33 connected in start and, at their outer extremities, to slip rings.
  • the rotor windings are connected to the terminals 4 of a liquid resistance apparatus according to the invention-
  • This apparatus comprises, as in that above described, a receptacle 20 into which there project three conducting rods 35 which constitute extensions of the terminals 4.
  • the lower extremities 35a of these rods extend into cylindrical cavities 36a of a conducting member 36 immersed in electrically conducting liquid 21 which is contained in the receptacle 20.
  • This member is supported by the conducting wall of thel receptacle 23, which is earthed at 40.
  • the lower extremities 35a of the rods 35 and the walls of cavities 36u constitute respectively the two electrodes, whereas free spaces respectively subsist between the extremities 35a and the walls of the cavities 36a, forming the compartments 8.
  • each of these compartments communicates with the liquid space in the receptacle 20, so that the liquid 21 may circulate through the compartments by convection or by thermo-Siphon action.
  • each of the rods 35 there is threaded a tube 38 of insulating material preventing passage of current between the upper portions of the rods via the liquid 21.
  • Each of these insulating tubes is enlarged at its lower end to constitute insulating bush 39 fitting into one of the cavities 35a and is screwed on to a rod 35 so as to permit the longitudinal displacement of each bush relatively to its rod.
  • the bushes 39 are perforated by small channels 4
  • An electrical apparatus comprising at least one small volume compartment, a larger volume receptacle adapted to contain an electrically conducting liquid, connecting means between said compartment and said receptacle including at least two passages located at different levels and adapted to offer resistance to the ilow of the liquid, and at least one pair of opposed electrodes 1n said compartment, so located as to make -contact with liquid in such compartment.
  • means for adjusting the cross includes, at its uppermost part, an exhaust passage.
  • An electrical apparatus further comprising a stationary hollow cylinder of insulating material and an inner rotary cylinder also of insulating material bearing on the inner surface of the hollow cylinder, the compartment being constituted by a recess in that surface of one of the cylinders by means of which it bears on the other cylinder and the electrodes being Xed respectively to the two cylinders.
  • An electrical apparatus further comprising an insulated stem having an electrically conducting extremity located inside said receptacle and forming one of said electrodes, and an electrically condu-cting member located inside said receptacle and having a, recessed wall surrounding the conducting extremity of said stem and constituting the other one of said electrodes.
  • An electrical apparatus having a plurality of pairs of electrodes and further comprising a plurality of electrically insulated terminals on said receptacles, electrically connecting means respectively between one electrode of each of said pairs and one of said terminals, and interconnecting means between the other electrodes of each of said pairs.
  • An electrica1 apparatus having a plurality of pairs of electrodes and further comprising a plurality of electrically insulated stems having each an electrically conducting extremity located inside said receptacle and forming each one electrode of said pairs, and an electrically conducting member located inside said receptacle and including a wall having a plurality of recesses surrounding each the conducting extremity of one of said stems and constituting each the other electrode of said pairs.
  • An electrical apparatus further comprising a hollow electrically insulating plug movable along said stem and adapted to fill the space between said stem and said recessed wall.
  • An electrical apparatus according to claim 9, further comprising narrow duct means located inside said plug, parallel to said stem.
  • An electrical apparatus further comprising at least two ducts located at dii-ferent levels and with different inclinations inside said Iconducting member for connecting the inner part of said recessed wall to said receptacle.
  • An electrical apparatus according to claim 1, further comprising means for hermetically sealing said receptacle containing conducting liquid.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Adjustable Resistors (AREA)
  • Cell Electrode Carriers And Collectors (AREA)
  • Control Of Ac Motors In General (AREA)
US302789A 1951-08-07 1952-08-05 Liquid resistance electrical apparatus Expired - Lifetime US2649526A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR1088565T 1951-08-07

Publications (1)

Publication Number Publication Date
US2649526A true US2649526A (en) 1953-08-18

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ID=9613894

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Application Number Title Priority Date Filing Date
US302789A Expired - Lifetime US2649526A (en) 1951-08-07 1952-08-05 Liquid resistance electrical apparatus

Country Status (6)

Country Link
US (1) US2649526A (de)
BE (1) BE513344A (de)
CH (1) CH305239A (de)
DE (1) DE937533C (de)
FR (1) FR1088565A (de)
GB (1) GB718320A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2748232A (en) * 1955-03-15 1956-05-29 Rubega Robert Liquid potentiometer
US2855545A (en) * 1952-05-07 1958-10-07 Norbert R Beyrard Circuit breaker devices
US3003130A (en) * 1960-07-27 1961-10-03 Gen Electric Liquid rheostat
US3935554A (en) * 1974-03-28 1976-01-27 Siemens Aktiengesellschaft Polyphase liquid rheostat
US3978313A (en) * 1974-03-05 1976-08-31 Albert Curchod Power regulating arrangement for a three phase electrode-type water heater
CN106849759A (zh) * 2015-02-28 2017-06-13 朱蕾 一种电机启动缓冲的方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2855545A (en) * 1952-05-07 1958-10-07 Norbert R Beyrard Circuit breaker devices
US2748232A (en) * 1955-03-15 1956-05-29 Rubega Robert Liquid potentiometer
US3003130A (en) * 1960-07-27 1961-10-03 Gen Electric Liquid rheostat
US3978313A (en) * 1974-03-05 1976-08-31 Albert Curchod Power regulating arrangement for a three phase electrode-type water heater
US3935554A (en) * 1974-03-28 1976-01-27 Siemens Aktiengesellschaft Polyphase liquid rheostat
CN106849759A (zh) * 2015-02-28 2017-06-13 朱蕾 一种电机启动缓冲的方法
CN106849759B (zh) * 2015-02-28 2019-10-18 台州市黄岩热恒注塑科技有限公司 一种电机启动缓冲的方法

Also Published As

Publication number Publication date
FR1088565A (fr) 1955-03-08
DE937533C (de) 1956-01-12
BE513344A (de) 1954-04-02
GB718320A (de) 1954-11-10
CH305239A (fr) 1955-02-15

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