US1849820A - Combination electrical regulator - Google Patents

Description

March 15, 1932. T. A. E. BELT 1,849,820

COMBINATION ELECTRICAL REGULATOR Filed April 29. 1930 F'i l.

Inventor: Thomas A.E.Be It,

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H is Attorney.

Patented Mar. l5, i932 @TFEQE THOMAS A. E. BELlj; 0F SGMNEU'IADY, NEW YORK ASSIGNQR T0 GEBT'FRAL ELECTEIG COM?ANY, A COR-EOEATIQN 035 NEW YORK GOMBINATION ELECTRKGAE EEG-FLATUR V Application filed April 29, 1980.

My invention relates to the regulation of electric circuits or electrical apparatus and particularly to the voltage regulation of alternating current feeder circuits.

It is well known that the sudden application of a comparatively large inductive load to an alternating current feeder circuit, such as the starting of oil burner, refrigerator or washing machine motors from house lighting circuits, causes a sudden dip in voltage on such circuits which in the cases mentioned manifests itself in an unpleasant momentary flicker in the lights or in a momentary disturbance in the reception from radio broadcast receiving sets which are energized from such circuits. Such dips in voltage are due to the fact that the comparatively large low power factor lagging starting current of load devices of the above mentioned type when' drawn through the inductive reactance of the circuit produces a reactance voltage drop which is almost in phase opposition to the voltage impressed on the circuit. Thus the vector sum of these voltages is approximately equal to their arithmetical difference. In ac cordance with one feature of a preferred embodiment of my invention I provide means in the form of a series capacitor for producing a voltage rise in said circuit as a result of the fiow'of lagging current therethrough.

As the magnitude of the current taken by motor operated domestic load devices decreases as they get up to speed and as, at the same time. their power factor improves, the effect of the reactance drop in the line does not become as important, from the point of view of load voltage regulation, as does the resistance drop in the line. However, as it is important that incandescent lamps should operate at substantially constant voltage it is customary to provide means for regulating the voltage of said circuits. My invention, therefore. contemplates-a simple and novel comparatively slow acting voltage regulator for regulating the voltage of alternating current circuits under steady conditions com bined with instantaneously acting means for regulating the voltage of such circuits upon the sudden application of lower power factor inductive loads.

Serial No. nearer.

An object of my invention is to provide means for reducing the voltage dips in alternating current circuits when inductive loads are suddenly applied thereto.

Another object of my invention is to pro- 555 vide means for eliminating the flicker in lamps fed from alternating current feeder circuits to which motor operated loads are suddenly and intermittently applied.

A further object of my invention is to proon vide a novel voltage regulator for alternating current circuits which operates on the principle of flux control.

An additional object of my invention is I toprovide a voltage regulating system, for ca alternating current circuits, including ins. stantaneously operating means for minimizing voltage dips on feeder circuits when inductive loads are suddenly applied thereto combined with relatively slow acting means an vention, while Fig. 2 is a vector diagram for explaining the operation of one of the features of my invention. Referring now to Fig. 1 wherein if have shown by way of illustration an embodiment of my invention as applied to the regulation of the voltage of an alternating current feedor circuit which supplies energy to a typical domestic house load and in which 1 is an alternating current power supply circuit to which is connected an alternating current 90 secondary distribution or feeder circuit 2 through a distribution transformer 3. The load on circuit 2 is shown as comprising a plurality of unity power factor load devices, such as incandescent electric lamps i and a plurality of intermittently applied low power factor loads. such as a motor operated electric refrigerator 5 and an oil burner 7. The latter is shown associated with a furnace 8 and is driven by a motor 9 under the control of the usual room temperature thermostat 10. Such motor operated loads draw a relatively large lagging current at low power factor when starting. The series capacitor, which may be connected in either circuit 1 0r circuit 2, is shown as a variable condenser 11. This condenser may be connected directly in either of the circuits if desired, although considerations of physical size make it desirable in most cases when connecting it in circuit 2 to connect it therein through a transformer, such as the series transformer 13 shown. A variable resistance 12 is preferably connected to series with the capacitor 11 for preventing har- -monic saturation of the series transformer under heavy surges of current. As one feature of my regulator depends for its operation upon the magnetic saturation or flux control of a portion of a transformer core to secure the desired changes in voltage, means may be associated with the distribution transformer 3, for controlling the magnetic flux linking its windings, without departing from my invention in its broader aspects. However, as this would involve mak-' ing changes in existing distribution transformers which have already been installed, if my invention were to be applied to circuits associated therewith, I have shown a separate transformer 14 in the form of a booster autotransformer and it is the saturation or flux control of a portion of the core of this transformer which is varied for regulatorypurposes. p

In general terms, the variations in the voltage boost produced by transformer 14 are secured by varying the mutual flux threading its primary and secondary windings, thus causing variations in its ratio of transformation. This result is secured by providing what may be referred to as a variable reluctance short circuit path for a portion of the primary winding flux. In the specific embodiment of my invention illustrated this transformer comprises a four-legged core member having a primary'winding 15, which is connected across circuit 2, wound on two of its legs 16 and 17 a secondary ,or Voltage boost producing winding 18, which is connected in circuit 2, wound on leg 16 and a regulating winding 19 wound on leg 17. Leg 17 forms a portion ofthe short circuit path for a part ofthe primary winding flux, the rest of this path being the remaining right hand portion of the core. Regulating winding 19 may receive its energization from any suitable source ofcurrent and in the embodiment shown it is energized from circuit 2 W through a rectifier 20. It is thus a saturating winding whose degree of-energization controls the-'rreluctance of leg 17 However, it will be obvious to those skilled in the art that the same result may be obtained by omitting the rectifier solong as the magneto-motive force of winding 19 bucks that of primary winding 15, for in such case variations in the energization of winding 19 will vary the effective reluctance of leg 17 because of its duced voltage impressed across them, as by connecting them across a part of shunt winding 16. For varying the current through regulating winding 19, I employ a variable impedance device which may be of any type and which in the embodiment shown is a car bon pile rheostat 21. For controlling rheostat 21 I provide a variable force producing means which operates in accordance with variations in the voltage of circuit 2, such as av small induction disc type torque producing motor 22. This motor, which operates on a well known principle, has an operating magnet 23 connectedto be responsive to the voltage of circuit 2. Magnet 23 has a core '26 provided with a split pole portion on one of the split parts of which is the usual short icircuited shading coil 27. The torque of such trolled by the former. A suitable spring 25 serves to oppose the torque of motor 22 and thus to increase the pressure on the carbon pile 21 upon a decrease in voltage on circuit 2.

The operation of the illustrated embodiment of my invention is as follows. Assume that power supply circuit 1 is connected to a suitable source of alternating current (not shown) and that one or more lamps 4 are being energized from circuit 2 and that one or the other, or both, of the motor operated load devices 5 and 7 has just started to operate. The sudden rush of comparatively large lagging current'required by the operating motors of these devices willordinarily produce a considerable dip, in the voltage of circuit 2 which would be attended by the well known flicker of the lamps connected to the circuit. This is illustrated in Fig. 2 where V represents the voltage at the terminals of the load devices. I the current taken by the load devices, IR the resistance drop in lines 2 and 1, IX the voltage drop through the inductive reactance of lines 1,2 and transformers 3 and 14, and V the voltage of the source of energy connected to circuit 1. The difi'erence between V and V indicates the magnitude of this dip in voltage. However, as I have provided a capacitance through which its reaaeao the lagging current must pass a Volta e drop is produced therein which, due to the fact that the current is lagging, is in reality a voltage boost. I have therefore been able to eliminate or greatly minimize this voltage dip. Thus, referring again to Fig. 2, IX, represents the voltage drop through the capacitance which is of course opposite in phase to the voltagedrop through the inductive reactance of the lines. As shown, capacitance 11 is of such a value that this drop is equal in magnitude to the dro through the inductance of the circuit. fiowever, by changing the magnitude of the capacitance it may be made either greater or less than the drop through the inductance of the circuit. When the voltage drop IX, is added to the other drops the vector V represents a much smaller voltage of the source applied to circuit 1 for the same load voltage or, in other words, the addition of the capacitor greatly reduces the difierence between the load voltage at light loads and at times when loads 5 and 6 have just been connected to the circuit for any given voltage applied to circuit 1.

However, as the power output of the motors operating the load devices increase as they come up to speed the power factor of the load improves so thatthe resistance drop in the lines now becomes the predominating factor in reducing the load voltage and it is for regulating the load voltage under these conditions that the variable ratio transformer and its associated apparatus are employed. Thus, if the voltage cit circuit 1 falls the torque of motor 22 decreases, thereby allowing spring 25 to compress the carbon pile through the medium of arm 24, with the result that the resistance of the circuit including the saturating winding 19 decreases and the saturating current therethrough increases. lhe increase in saturation of leg 17 results in an increase in its effective reluctance, thus causing more of the primary winding flux to thread the secondary winding with the result that a higher voltage boost is induced in the secondary winding. in this manner the voltage drop in the circuit may be compensated for. Similarly, an increase in voltage on circuit 2 increases the torque of motor 22, thereby decreasing the excitation of winding 19 with the result that more of the primary winding flux is diverted from the secondary winding and consequently the voltage boost of this transformer is reduced. it

should be noted that my regulator is not only operative to regulate the voltage of circuit 2 in accordance with changes in load thereon.

but that it is also capable of regulating the voltage of the circuit as a result of changes in the voltage impressed on it.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as-new and desire to secure by Letters Patent of the United States is:

1. In combination, an alternating current circuit, transformer means for supplying a voltage boost to said circuit, a regulating winding for varying the ratio or" the fluxes threading the primary winding and the secondary winding of said transformer, a variable current limiting means in series with said regulating winding, and means responsive to the voltage of said circuit for varying said current limiting means.

2.. In combination, an alternating current circuit, a booster transformer including a voltage boosting series winding connected in said circuit and a shunt windingw connected across said circuit, a saturating winding on said transformer, means connecting said winding across said circuit through a rectifier, a rheostat in series with said winding, and means including a torque producing motor for varying the resistance of said rheostat in accordance with variations in the voltage of said circuit.

8. in combination, an alternating current circuit, transformer means for producing avoltage boost in said circuit, and means, responsive to the V0 tage of said circuit, for varying the saturation of a portion of the magneticcircuit or the primary winding of said transformer means inversely with variations in the voltage of aid circuit and in dependently of the condition of the magnetic circuit of the secondary winding of said transformer.

i. In a system of distribution, in combination, an a rnating current power supply cult, o. transformer connecting said circuits, a variable load connected to said distribution cir- Cult, a booster transformer including a voltage boosting series winding connected in said distribution circuit and a shunt winding con nected across said distribution circuit, a magnetic circuit common to both said windings, a separate magnetic circuit for diverting a portion of the flux of said primary winding from said secondary winding, a saturating winding associated with said second magnetic circuit, means connecting said saturating winding across said distribution circuit through a rectifier, a carbon pile rheostat connected in series with said saturating winding, an induction disc torque producing motor connected across said distribution circuit, and mechanical means connecting the rotor of said motor to said carbon pile rheostat.

5. In a voltage regulating system, a variable ratio transformer comprising a four legged core of magnetic material, a primary stribution circuit, a distribution winding linking two of the legs of said core, a secondary winding linking one ofthe legs linked by said primary winding and a regulating winding-linking the other leg linked by said primary winding.

6. In combination, an alternating current circuit, one or more intermittently applied load devices connected to said circuit, said last mentioned load devices drawing an initial relatively large lagging current, a capacitor connected to said circuit so that the current flow therethrough is directly proportional to the current flow through said circuit, and means having a time delay for regulating the voltage of said circuit.

7 In combination, an alternating current circuit, one or more incandescent lamps connected thereto, one or more intermittently applied motor operated load devices connected thereto, a capacitor, means including a series transformer connecting said capacitor in said circuit, and voltage regulating means including a magnetically regulable variable ratio booster transformer and a voltage responsive element for regulating the voltage of said circuit.

8. In a system of distribution, in combination, an alternating current power supply circuit, an alternating current distribution circuit, a distribution transformer connecting said circuits, one or more incandescent lamps connected to said distribution circuit, one or more intermittently suddenly applied motor operated loads connected to said distribution circuit, a capacitor, means including a series transformer connecting said capacitor in said distribution circuit, a booster transformer connected to said circuit, a saturating winding for varying the reluctance of a portion of the magnetic circuit of the primary winding of said transformer, means for energizing said winding through a rectifier from said distribution circuit, a rheostat in the circuit of said saturating winding, and means for producmg a force which varies in accordance-with variations in the voltage of said distribution circuit for operating said rheostat. v

In witness whereof, I hereunto set my hand this 22nd day of April, 1930.

A 5 THOMAS A. E.

aseaeao BELT,

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