US2254918A - Voltage regulator - Google Patents

Description

Sept. 2, 1941- M. scHwAlGr-:R

VOLTAGE REGULATOR Filed June 24, 1938 2 Sheets-Sheet l W R. ww N 5./ vh mc 5 X W Sept 2, l941- M. sHwAxGER l2,254,918

VOLTAGE REGULATOR Filed June 24, 1938 2 Sheets-Sheet 2 Y /6 kl, XJ Lla I wlTNEssES: INVENTR WCM ax 5 wa/ge/ ff/#f7 vor synchronous condensers, and the like.

` Patented Sept. 2, 1941 VOLTAGE REGULATOR Max Schwaiger, Nuremberg, Germany, assignor to Westinghouse Electric & Manufacturing Com- Dany, East Pittsburgh,

Pennsylvania Pa., a corporation oi! Application June 24, 1938, Serial No. 215,553 In Germany August 27, 1937 -Yrelay 6 is provided with a shaft 'I that actuates 3 Claims.

This invention relates to a method of and apparatus for regulating the voltage of alternating-current system circuits. The system includes control mechanisms that are actuated in accordance with variations of the system voltage from the desired value, and govern the operation of the voltage adjusting mechanism, such as regulating transformers, field rheostats of generatorsv The moving parts of the voltage adjusting mechanism may be operated by a pilot motorof the ls'ynchronous, asynchronousor commutator type, or by control magnets.

According to the invention, the current drawn from the circuit by the primary relay or regulator control member is automatically adjusted by at least one self-regulating inductance device having movable magnetizable parts, or winding parts, connected in the circuit of the primary relay in such Vmanner that the primary relay is supplied with the necessary operating current only whenthe voltage to be regulated varies from the desired value in either direction by a.

a movable contact member 8 into engagement with the one or the otheroi two xed contact members 8 and I2 to complete motor operating circuits from the secondary winding I3' of a transformer, the primary winding I4 of which is shown connected between conductors I and 2. The movement of the contact member 8 into engagement with the contact member 9 completes amotor operating circuit through conductors I5, I6 and` I'I to operate the pilot motor Ii in one direction, and engagement of the contact member B with the contact member I2 completes a motor roperatllrig circuit through conductors I5, I8 and Il to operate the motor 5 in the opposite direction. The operation oi the motor 5 in one direction changes the relative position of the windings 3 and l of the induction regulator in predetermined amount. 'I'he self-regulating in-f ductance device that is connected in the circuit of the primary relay is itself adjustable with respect to its electric and magnetic characteristics. -4

My invention will be better understood from thefollowing description of certain prei'erredembodiments thereof, reference being had to the accompanying drawings illustrating the same, and in which:

Figure 1 illustrates an embodiment of a sel!- regulating lnductance device auch as used in the system of my invention; Fig. 2 illustrates characteristic curves explaining the operation oi' the self-regulating inductf ance device; c

Fig. 3 is a diagrammatic view of circuits and apparatus organized in accordance with one ernbodiment of the invention; Y

Fig. 4` is a diagrammatic view of the primary l relay circuits of another embodiment of the invention; and

;I|ig.k5"illustrates curves showing the characteristlcs y'ofthe control element illustrated in Fig. 4 as applied to a three-phase alternating-current circuit. y

Referring to Fig. 3, an alternating-current circuit is illustrated having conductors I and 2 leading from a source oi' supply at the right of theY figure to supply current at a regulated voltage to a load to the left of the figure. In this circuit is connected an induction regulator or regulating transformer having series and shunt windings 3 and 4, respectively, that are relatively movable, as .controlled by the operation of a pilot motor E which is controlled by the primary relay or voltage controlling element 6. The

such manner to increase the voltage supplied to the load, while operation of the motor in the opposite direction varies the relative position oi the windings 3 and 4 in such manner as to decrease the voltage supplied to the load in a well known manner.

For operating the shaft I of the primary relay device. two motor elements 2i and 22 are provided connected in opposition so that the motor 2l tends to rotate the shaft 1 in one direction, and the motor 22 tends to rotate the shaft 'I in the opposite direction. The motor 2l is provided with an armature 23 on the shaft 'I and windings 24 connected between conductors I and 2 through a network S1, the purpose of which will be later described. The motor 22 is provided with a similar armature 25 on the shaft 'I and windings 26 connected between conductors I and 2 through a network Szfsimilar to the network Si.

Each of the networks Si and Sz consists of a' shown in Fig. 1 and explained by the curves in Fig. 2. f

Referring to Fig. l, an iron core JI is provided having an air gap 32 in which a rotatable armature 34 of magnetic material is provided mounted on the shaft 33. In order to reduce the stray or leakage ux as much as possible, the energizing windings 25 provided on the core member 3| on opposite sides or the air gap 32 are coneshaped, their adjacent ends approaching `each other and partially surrounding the armature member Il. The space 36 between the inner edges of the windings 35 is made small to provide space sumcient only for the shaft 33 so as to more easily attain the desired lcharacteristic curves of the self-regulating inductance device. The desired magnetic and electrical values of the self-regulating inductance device are determined by the special shape of the magnetic poles 8i and of the rotatable armature 315i. The rotatable armature 313 may be provided with a short-circuited damper winding S9, which creates a counter flux to oppose the magnetic ux penetrating the armature from the core member Si. This flux is of a variable nature, depending upon the position of the armature 3Q, so that the' inductance of the self-regulating device is variable and is a minimum when the amature @d is in its illustrated position.

As the energization of the Winding titi is varied in such manner as to rotate the armature ill in the direction shown by .the arrow do, the shaft v33 is moved against the bias of a spring il connected to a cam i2 carried on the shaft 38 through a strap 33. As the armature Sd moves in a counter-clockwise direction, the inductance of the self-'regulating inductance device increases in value until it reaches its maximum value. The

characteristic curve of the inductance ofthe device may be controlled within certain limits by the design of the spring di .and the shape of the cam i2 in such manner as to provide a. varyagencia ythe characteristic line L1' is connected in series with the two parallel connected elements, coming torque with varying position of the shaft 33. For example, the cam l2 may be stepped asv shown at til, thus increasing the torque arm through which the spring il operates. Also, the

winding @E may be provided with taps for varying the number of turns therein in the controlled circuit.

Fig. 2 illustrates characteristic curves of the self-regulating inductance device shown in Fig. l. As illustrated, the abscissa is plotted to show current I and the ordinate to show voltage E.

The self-regulating inductance device has the characteristic curve indicated by L1 in Fig. 2. Upon an increase in voltage from the value O to the' value H1, the current increases aiong a straight line curve to the point di. it this point, the armature wiil start to operate against the bias of the srring di, and the characteristic line of the device bends or taires e, dierent direction between the points il and is corresponding to A a voltage increase from the value Hi to the value H2, at which voltage value the inductance of the self-regulating inductance device reaches its maximum value. As the voltage is further increased, the current values increase along the line indicated above the point A2. The two horizontal lines H1 and Hzthereiore indicate the operating range ofthe particular self-regulating inductance device being considered. if a condenser is connected in parallel `with the selfregulating inductance device L1 corresponding to the condenser C1 of Fig.` 3, and having the characteristic curveiCi shown in Fig. 2. the characteristic curve of the two elements may be plotted as shown by the line Lr Ci.

If, however, in addition to the twoA elements Y between the voltage lines Ha and H4.

vides a small range oi voltage variation frompleting the network Si illustrated in Fig. 3, the

characteristic oi this whole network assumes the form indicated by the line L1 C14-L1' in the diagram of Fig. 2. By properly designing the values of the condenser C1 and the series inductance L1', a network may be provided having a sharp bend in its characteristic curve indicating a sharp current change along the line H2 with very little.

characteristic curves of the network correspond to that shown by the curve S2 in Fig. 2. 'Ihe curve of the circuit Sz is constructed vircrn the characteristic lines L2, VCiel-lie' in amanner similar to the curve S1. The characteristic curves are so plotted as to show that the network potential falls near the center of the dead range the desired value En in the center of this range for stabilizing the regulator, so that for trling potential variations from this value the regulatorA will not be brought into' operation.

Referring again to Fig. 3, in which the several 'parts of the networks S1 and S2 are indicated by the same identifying letters as the curves illustrated in Fig. 2 showing their characteristics, it will be noted from the curves in Fig. 2 that the motor 2l connected to the network Si .is supplied with current for values of voltage.A

less than the desired value of En, and that the meter-22 connected to the network S2 is supplied with current' only for values of voltage higher than the desired value oi En. For the desired voltage En, the self-reginating inductence device L1 will be operating on that part o itscharaeteristie curve above the point A2 showing that it has been moved from the position illustrated in l throughout its range of operation, that is, through the range between the points A1 and A2, or to its position ci maximum inductance.- The armature of the seiiregnlating inductance device is, on the other hand, is in a eld of operation below the value Di indicating that it is at rest at a position of minimum inductance velue or corresponding to the position shown in Fig. l.

if the voltage between conductors i and 3 increases above the desired value oi En, current Y will be supplied through the network S2 to the motor 2i, as indicated by the curve Savin Fig. 2,

Y It will -be noted that the characteristic curve ofthe. curofvar'iable inductance and xed capacity connected in parallel, another-inductance having Fig. 4 illustrates another embodiment of the' ca mi" the relay S to be operated in one direction to move the c ntact d into engagement with the appropriate contact 9 or it to operate the inotor Si to decrease the voltage-supplied to the load. if the voltage between the load conductors i and 2 drops below the value represented by En in Big. 2, the current supplied bei' 8 and the other of the two contact members d or. i2 to operate the motor 5 in a direc-V tion to decrease the voltage supplied to the load conductors i and 2.

This proinvention in which a single motor 50 is employed for operating the contact making relay in place of the two motors 2| and 22 of the form of the invention illustrated in Fig. 3. The motor 50 is shown as a two-phase motor having one phase winding 5l connected to the circuit to be regulated through a network S corresponding in nature to the networks S1 and Sz of Fig. 3, and a second phase winding 52 connected to the circuit through means which displaces the phase of the current drawn by this winding with respect tothe phase of the current in the winding For this purpose, a. condenser 53 is provided. 'I'he nature of operation of the motor 50 does not require that the two phase circuit currents be displaced by exactly 90. Other phase displacements providing sufdcient torque may be employed. This arrangement may also be used in three-phase networks in which the phase voltages varying by 60 are available. When the neutral point of a three-phase system is accessible, one of the phase windings 5l may be connected between two phase conductors, and the other phase winding 52 between the remaining phase conductor and the neutral point. In this way, the desired 90 displacement between the voltages in the two windings is obtainable.

The value of the series inductance L' in the I circuit S of Fig. 5 and the value of the parallel connected condenser C and the regulating inductance device L are so dimensioned that the characteristic curve of the network corresponds to that shown in Fig. 5. The curve of the selfregulating inductance device varies slightly between the points A1 and A2 from that shown in Fig. 2, in that it includes a step in the center of its operating range that is attained by the design of the armature of the device. The curve Lo follows from combining the two curves C and L, and the curve'S is attained if the ihdctance L is added in series with the twio parallel elements of the network.

If it is desirable that the motor element of the primary relay employ only a single-phase motor with a single winding circuit, the two control networks Si and S2 may be connected in series with the winding. The two control circuits must have characteristic curves that are similar to those of S1 and Se in Fig. 2, and will operate `to control the flow of current through the single-motor winding varying its phase angle from leading to lagging and vice versa as the voltage of the circuit varies in the one to the other direction from its desired value, to cause operation of the relay in the appropriate direction to effect the. desired correction in voltage.

It will be noted that a regulating system organized in accordance with this invention results in small losses to the primary relay or controlling mechanism, since this mechanism does not take current from the line continuously but only when the regulated quantity varies in the one or the other direction from its desired value. Since, also, upon a slight variation in the regulated voltage from its desired value in the one direction or the other, the current change is quite abrupt, it is not necessary that the motor elements of the contact making primary relay be large. f

Since many modifications will occur to those skilled in the art within the spirit oi' my inl ll by some value, such, for example, as 90. V

vention, I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention:

1. In a. regulating system for governing the voltage of alternating-current circuits, means for adjusting the voltage of said circuit, control means therefor energized to be operated in accordance with variations in the regulated quantity from its desired value comprising two motor elements coupled together in opposition and having their energizing circuits separately connected across the circuit to be regulated in series with separate networks comprising a variable inductance and a fixed capacitance connected in parallel circuit relation to each other and in series with a xed inductance, the variable inductance comprising an automatically regulated variable inductance device operable for eiIecting a sudden variation in inductance for permitting the required operating current to iiow to the control means only upon variation in the regulated quantity from its desired Value and to prevent the ilow of operating current when the regulated quantity is substantially at its desired value.

2. In a regulating system for governing the vvoltage of alternating-current circuits, means for adjusting the voltage of said circuit, control means therefor energized to be operated in accordance with variations in the regulated quantity' from its desired value and comprising two motor elements coupled together in opposition and having their energizing circuits separately connected across the circuit to be regulated, and networks connected in each motor element circuit and each including an automatically regulated variable inductance device operable from a minimum to a maximum value over a predetermined voltage range, and a condenser con-I nected in parallel circuit relation thereto, the two regulating inductance devices and associated condensers being so dimensioned electrically and adjusted that their operation causes the two motors to carry substantially no current when the regulated voltage is at its desired value and that one only of them only to carry current when the regulated voltage is above its desired value and the other only to carry current when the regulated voltage is below its desired value.

3. In a. regulating system for governing the voltage lof* alternating-current circuits, means for adjusting the voltage of said circuit, control means therefor energized to be operated in accordance with variations in the regulated quantity from its desired value comprising two motor elements coupled together in opposition and having their energizing circuits separately connected across the circuit to be regulated, and automatically regulated variable inductance devices connected in each motor element circuit and operable over a predetermined voltage range for permitting the required operating current to flow to the control means upon variation in the regulated quantity from its desired value and to prevent the flow of operating current when the regulated quantity is substantially at its desired value, said two automatically regulated inductance devices being so dimensioned electrically that when the regulated voltage is at its desired value the inductance value of one inductance device is a minimum and the inductance value of the other device is a maximum.

MAX BCHWAIGER.

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