US1499551A - Alternating-current system - Google Patents

Alternating-current system Download PDF

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Publication number
US1499551A
US1499551A US503369A US50336921A US1499551A US 1499551 A US1499551 A US 1499551A US 503369 A US503369 A US 503369A US 50336921 A US50336921 A US 50336921A US 1499551 A US1499551 A US 1499551A
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United States
Prior art keywords
current
voltage
value
transformer
resistor
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Expired - Lifetime
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US503369A
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English (en)
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Rieber Frank
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Individual
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Individual
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Priority to US503369A priority Critical patent/US1499551A/en
Priority to GB15462/24A priority patent/GB240238A/en
Priority to FR584964D priority patent/FR584964A/fr
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Publication of US1499551A publication Critical patent/US1499551A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/26—Measuring, controlling or protecting
    • H05G1/30—Controlling
    • H05G1/34—Anode current, heater current or heater voltage of X-ray tube

Definitions

  • This invention relates to an alternating current system, and more particularly to a system in which it is necessary that the cur rent supplied be maintained very nearly constant at any one of a number of optional values.
  • Such systems are required in connection with the heating of the filament in vacuum discharge tubes, such as Coolidge'or X-ray tubes.
  • the characteristics of tubes of that class are such that as the temperature of the heated filament varies a slight amount, the space current through the tube, which is a function of this temperature, varies to a considerable extent. The variation of this current is objectionable in many classes of work, as for instance in taking X-ray exposures. It is sometimes advantageous to adjust the temperature of the filament so as to obtain Varying effects, but no matter which optional value of temperature is chosen, it is essential that it be maintained constant at that value. Where a commercial alternating current source only is available, the fluctuations of voltage may be so great as to interfere materially with the adjust-- ment of the heated filament temperature which is dependent upon the current flowing through it and, therefore, the potential impressed upon it.
  • Another object of my, invention is to make it possible to set the value of the current supplied to the load at any one of selected for illustration in the specification.
  • Figure 1 indicates the wiring diagram of one form of my invention applied to an X-ray tube
  • Fig. 2 is a chart showing how the current companying and forming the load circuit
  • Fig.3 is a ,chart showing how the current in the heated filament varies under variations of supply voltage and of inductive reactances in the load;
  • v Fig. 4 is a chart showin how the current varies under varying con itions when that form of my invention is utilized which is illustrated in Fig. 1; and
  • Fig. 5 is a wiring diagram of another form of my invention.-
  • the leads 11 and, 12, in Fig. 1 are adapted to be connected to an alternatin current source of the ordinary commercia l sort.
  • an alternatin current source of the ordinary commercia l sort.
  • such sources do not maintain an absolutel uniform potential, so that if this source utilized immediately to supply a load, such as to heat the filament 13 of a vacuum or X-ray tube 14, variations in the temperature would be quite pronounced.
  • the heat generated in an electric circuit of constant resistance varies in proportion to the square of the impressed voltvoltage fluctuanullified for one current, is by the 1, in which a main tionscan be minimized or particular value of the means illustrated in Fig. transformer 15 and a bucking auxiliary transformer 16 are used.
  • the transformer 15 has a closed core 17 which is so proportioned that it is saturated at a voltage value somethe heated filament varies under var1- I ations of supply voltage and of resistance in 1 the core.
  • the primary coil 18 is supplied from the source, while the secondary coil 19 is used to supply the heated filament 13 with current. Even if no other means be utilized to minimize the voltage fluctuations, a large variation in the primary volts of transformer 15 causes a smaller variation in the secondary voltage, due to the saturation of However, the auxiliary transformer 16 may be so arranged that, for a certain isolated value of secondary current, it nullifies even this slight variation.
  • This auxiliary transformer has a primary coil 20 arranged in two sections, one on each limb of the core 21. These coils are fed from the source, in the present instance, in series with the primary coil 18 of the main transformer 15.
  • the secondary coil 22 of the auxiliary transformer 16 is likewise shown as made up of two sections, one on each limb, and is connected in series with the secondary coil 19 of the main transformer 15 and in such a way that these two coils buck
  • the voltage produced in the secondary coil 22 is made to be of such value that it substantially nullifies the change in Volta e in the main secondary coil 19 due to a c ange in the supply voltage.
  • This is made possible since the magnetization of the main core is always at such a stage that it is above the knee of saturation, and beyond that point the magnetization, as the voltage increases, increases as if there were a large air gap in the core.
  • a transformer properly constructed an having a lar e air gap it is possible to-balance exact y this increase in potential beyond the knee of saturation, for a particular value of secondary current.
  • the temperature of the heated filament 13 may be adjusted by varying the" current flowing therethrough which in turn may be accomplished by varying the poten-' tial applied to it.
  • the .secondary current is conducted through a controlling device '24, to the rimary 25 of an insulator transformer 26, t e secondary 27 of which is directly connected to the heated filament 13.
  • the insulator transformer 26 serves to insulate the alternating current system from the high otential system 28, 29, connected across t e electrodes of the tube 14. If it be attempted to vary the current in the filament 13 by simply a resistance in series with it or with the secondary 19, the result would be that variations in the supply voltage would no longer be nullified. This effect may be best appreciated from a study of the chart in Fig. 2.
  • the abscissae represent the supply potential in volts and the ordinates represent filament current in amperes.
  • Curve #1 may representthe relation between current and volts when there is a minimum resistance in the circuit. It is seen that. between 90 and 140 volts the current remains constant at 5 amperes. The normal voltage in this case is 110.
  • Curve #2 represents an attempt to set the current value to 4.5 amperes with the aid of additional resistance in the circuit. It is seen that the currentnow varies between about 4 amperes and about 5 amperes as the supply potential varies from 90 to 140 volts.
  • the current Upon a further increase in the resistance, the current behaves as shown in curve #3, and varies between about 3.3 amperes and 4.5 amperes for a variation in supply voltage from 90 to 140 volts. It is thus seen that any attempt at choosing any one of a number of optional values of the heating current by means .of resistance control fails, since the current does not stay at the chosen value as the supply potential fluctuates.
  • Curve #2 shows what happens when the value of the inductive reactance is increased.
  • the filament current now varies between 4.5 and 4 amperes for the limits of 90 and 140 volts of the source of supply. With the use of reactance, however, the effect is to give the curve a. downward slope. Upon a furtherincrease in reactance, the current behaves as shown by curve #3 and varies from about 4 amperes to about 3.2
  • the controlling device 24 is utilized for this purranged as to be simultaneously variable by means of a dial switch arm 32 and the two series of contacts 33 and. 34, disposed around a circle in the path of the extremities of the arm 3.2.
  • the values of the resistor and of the inductor are made greater, and there is a reverse elfect when the arm 32 moves in the opposite direction.
  • Other arrangements may 0 viously be utilized.
  • a chart shows how this current varies as the supply potential varies.
  • Curve #1 in this figure shows that the current stays substantially constant at 5 amperes when the supply voltage varies between 90 and 140 volts.
  • Curve #2 shows the current values after both the resistor and inductor 31 had been increased somewhat. This current stays at about 4.7 amperes for the usual variation in the supply potential.
  • a further increase in the resistor 30 and in- 1 ductor 31 carries the current down to the "34. To do this,
  • Fig. 5 I show a somewhat different form of controlling device 35.
  • two variable resistors 36 and 37 are used, one in series in th'efilament supply circuit, and the other parallel to it.
  • the dial arm 38 is so arranged that as one is increased, the
  • One end 40 of the resistor 36 is connected to the primary 25 of the insulator transformer 26, so that that section of resistor 36 between the contact portion of the upper end of arm 38, and the end 40, is in series in the main circuit.
  • a parallel circuit to the main circuit is completed by lead 41 connecting to the lower insulated portion of arm 38, and that portion of resistor 37 which is between the contact of the lower end of arm 38 and the point 42. It is evident that as arm 38 is turned to the right, the series resistor 36 is decreased and the parallel resistor 37 is increased. By properly proportioning the steps in these resistors, a constant load may be drawn from the source irrespective of the value of the heating current. Thus, it is merely necessary to construct the stabilizer to take care of but one current value.
  • a variable inductor and a variable resistor in the circuit for selecting the value of the current supplied to the load, and means for causin this current value to be independent of Euctuations in the supply voltage.
  • an inductor in the circuit for supplying current to a load in such a way that the current stays substantially constant at any one of a number of optional Values
  • an inductor in the circuit for supplying current to a load in such a way that the current stays substantially constant at any one of a number of optional Values
  • a resistor in the circuit means for simultaneously varying the value of the inductorand the resistor whereby the value of the current supplied to the load is determined
  • this current value to be uctuations in the supply simultaneously varying both the inductor and the resistor whereby the valueof the current supplied to the load is determined, and means for causing this current value to be independent of fluctuations in the supply voltage.
  • a transformer having a closed core, a primary coil adapted to be connected to a source of supply, and a secondary coil, the core being so proportioned that it is saturated when the voltage of the source is somewhat below normal, an auxiliary transformer adapted to be supplied from the same source having a primary and a secondary coil, this transformer being so proportioned that for variations from normal of the supply voltage, the secondary potential stays substantially proportional to the primary potential, the secondary coils of the main and auxiliary transformers being connected in series to the load, a resistor and an inductor in the load circuit, and means for simultaneously varying the resistor and inductor, whereby the value of the current supplied is determined.
  • a main transformer adapted to operate with its core above the knee of saturation so that variations in the supply voltage cause relatively small and substantially proportional changes in the secondary voltage
  • an auxiliary transformer having a large air gap in its magnetic circuit and connected in series bucking relation with the main transformer, said auxiliary transformer being proportioned so that its secondary voltage substantially entirely neutralizes the proportional changes in the secondary voltage of the main-transformer for a definite value of current consumption
  • a device utilizing electrical energy derived from the secondaries of the transformers, and means for varying the current supplied-to the device 9.
  • a main transformer adapted to operate with its core above the knee of saturation so that fluctuations in the supply voltage cause relatively small and substantially proportional changes in the secondary voltage
  • an auxiliary transformer having a large air gap in its magnetic circuit and connected in series bucking relation with the main transformer, said auxiliary transformer being proportioned so that its secondary voltage substantially entirely neutralizes the proportional changes in the secondary voltage of the main transformer for a definite value of current consumption
  • a device utilizing electrical energy'derived from the secondaries of the transformers, andmeans for varying the current supplied to the device while maintaining the voltage fluctuation neutralizing effect of the transformers, comprising a resistor, an inductor, both in series'relation with the secondaries of the transformers, and means for simultaneously adjusting the resistor and the inductor.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • X-Ray Techniques (AREA)
US503369A 1921-09-26 1921-09-26 Alternating-current system Expired - Lifetime US1499551A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US503369A US1499551A (en) 1921-09-26 1921-09-26 Alternating-current system
GB15462/24A GB240238A (en) 1921-09-26 1924-06-26 Improvements in or relating to alternating current systems
FR584964D FR584964A (fr) 1921-09-26 1924-06-30 Installation à courant alternatif

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US503369A US1499551A (en) 1921-09-26 1921-09-26 Alternating-current system

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US1499551A true US1499551A (en) 1924-07-01

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US (1) US1499551A (fr)
FR (1) FR584964A (fr)
GB (1) GB240238A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2845590A (en) * 1955-04-18 1958-07-29 Westinghouse Electric Corp Voltage reference devices

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2845590A (en) * 1955-04-18 1958-07-29 Westinghouse Electric Corp Voltage reference devices

Also Published As

Publication number Publication date
FR584964A (fr) 1925-02-19
GB240238A (en) 1925-09-28

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