US2076499A - Voltage regulation - Google Patents

Description

H. c. GRANT, JR 2,076,499

VOLTAGE REGULATION April 6, 1937.

Filed Sept. 1, 1935 3 Sheets-Sheet l INVENTOR X/MLW C1, a

ATTORNEY April 1937- H. c. GRANT, JR 2,076,499

VOLTAGE REGULAT ION Filed Sept. 1, 1933 5 Sheets-Sheet 2 ENTOR INV Harry C'g mfibe/l Gra/mJI:

ATTQRNEY April 6, 1937. H. c. GRANT, JR

VOLTAGE REGULATION Filed Sept. 1, 1953 25 Sheets-Sheet 3 INVENTOR Haw/y C'am bbd/ G'rant J'.

' ATTORNEY Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE 2,016,499 vom'acn REGULATION Application September 1, 1933, Serial No. 687,835

19 Claims.

The present invention relates to electrical arrangements for controlling the voltage of current from a source of electric potential subject to fluctuations in voltage, whereby the fluctuations in voltage at the source will not be impressed across apparatus to be operated by such current.

There are many instances where a constant voltage is necessary for the operation of mechanlsm, such as fire detecting apparatus, smoke detecting apparatus, etc. yet the location of the apparatus frequently is such that a current supply of this character is not available. Thus, by way of example, in the use aboard ship, where wide variations in the voltage of the source of electric potential are known to be a common occurrence, of smoke detecting apparatus of the type employing a source of light directed upon a light-sensitive element with a current of air flowing along the path of the beam of light directed from the source of light upon the light-sensitive element and in which the presence of smoke in the current of air acts to decrease the intensity of the light falling upon the light-sensitive element and to thereby cause an alarm signal to be rendered, it has been found that if the light-sensitive element circuit has been adjusted to give detection for a reasonably light smoke density, it will also give false alarms for a drop in the line voltage as little as four volts, it being understood that a drop in the line voltage will cause a decrease in the intensity of the light emitted by the source of light. For this reason a well designed smoke detecting apparatus of the type referred to requires a voltage regulator to be used on the source of light to prevent fluctuations in the voltage applied thereto regardless of the changes in voltage at the source of electric potential.

It is accordingly the principal object of the present invention to provide means for controlling the voltage of current from a source of electric potential to maintain a constant value thereof across desired terminals, in spite of relatively great variations of the voltage at the source.

It is also an object of the invention to provide a constant voltage across desired terminals despite not only variations of the voltage at the source of electric potential but also variations in the load applied across the aforesaid terminals.

It is a further object of the invention to provide signalling means to indicate when the variations in the voltage at the source are so great that the apparatus of the present invention will not bring the load voltage back to normal, so that proper steps may be taken at once to correct the voltage directly at the source.

These, and other objects of the invention not specifically enumerated above, will be apparent as the invention is described in greater detail in connection with the accompanying drawings, where- Figure l is a conventional view showing the electrical circuits and connections of a complete voltage regulating arrangement constructed in accordance with the present invention.

Figure 2 is a conventional view showing in a somewhat more simplified manner the principal elements of the voltage regulating arrangement of Figure 1.

Figure 3 is a view similar to Figure 2 showing another arrangement of principal elements.

Figure 4 is a view similar to Figure 2 showing a further arrangement of principal elements.

Figure 5 is a view similar to Figure 2 showing still another arrangement of principal elements.

Figure 6 is a view similar to Figure 2 showing a still further arrangement of principal elements.

Figure 7 is a simplified conventional view showing an adaptation of the present invention to controlling the output voltage of an electric generator.

Figure 8 is a simplified conventional view showing an adaptation of the present invention to controlling the speed of an electric motor.

In order to simplify the explanation of the circult of the complete voltage regulating arrangement of Figure 1, reference will first of all be made to the simplified showing of Figure 2, in connection with which it should be noted that the regulator circuit is a special type of Wheatstone bridge in which, for example, two neon glow tubes are used instead of resistances. These are shown at G and T. These neon glow tubes have as an important characteristic the ability to automatically change their resistance so as to maintain the voltage constant across their terminals. Thus in the circuit shown in Figure '2, when the current is flowing from e through resistance X through glow tube G to O, the voltage across glow tube G remains constant regardless of changes in voltage across points 0 and 0 (within limits).

Neon glow tubes may be obtained for various voltages, but for the purpose of the present explanation it will be assumed that the voltage maintained by the glow tubes is in the order of 60 volts, varying slightly for difierent tubes due to manufacturing variations. Also the voltage at 0 will be considered the datum point of zero and all voltages are referred to the voltage at 0.

Therefore, in Figure 2, current flows from the positive unregulated line E through a rheostat W to point e, flowing to negative through resistance X and glow tube G, which is paralleled by a series of resistances Y, to 0. Current also flows from c through glow tube T, through resistance Z, to 0. Since the voltage drop across the glow tubes is 60 volts, the voltage at M will be 60 volts, while the voltage at F will be 60 volts less than that at e. As the unregulated voltage at E varies, the voltage at 0 will likewise vary, and due to the constant voltage drop across glow tube T the voltage at F will also vary the same amount. The voltage at M, however, will remain constant regardless of any variation of voltage E. Since the voltage at M is constant, the voltage at any point S of the series of resistances Y will also be constant. If it is desired to maintain a voltage at e of 90 volts, the voltage at F will be 30 volts. Since the voltage at S is constant, an adjustment may be made to cause this voltage to be 30 volts. If a galvanometer relay G. R. is now connected between S and F, there will be no voltage difference across G. R. and the galvanometer pointer will float clear of its contacts. If, however, the voltage at E rises, the voltage at 6 will also rise and the voltage at F will rise equally. Since the voltage at S remains constant, the galvanometer pointer will be deflected against one of its contacts, which action can be employed (as will be explained in connection with Figure 1) to effect increases or decreases in the amount of the resistance of the rheostat W in circuit. Therefore, upon the aforesaid rise in the voltage at E, the resistance W is increased and the voltage at e will decrease until the voltage at F is 30 volts, when the galvanometer will be neutral. When the voltage at F is 30 volts, the voltage at e will will be 90 volts, which is the desired regulated voltage. The reverse operation takes place when the unregulated voltage at E decreases.

By way of example (neglecting the small voltage drop caused by the fiow of current through the galvanometer relay when unbalanced), if the voltage at E were 110; at e, 90; at S, 30; and at F, 30; the galvanometer would be balanced. If the unregulated voltage then became 113 at E, the voltage at e would be 93 and at F, 33, the voltage at S remaining at 30. Consequently, the change in unregulated voltage of 3 volts from normal is transmitted directly to the galvanometer relay, resulting in the adjusting operation as just described.

Of course, with reference to Figure 2, the apparatus on which it is desired to maintain a constant voltage is connected across the terminals Li and L2.

Referring now to the circuit of the complete voltage regulating arrangement shown in Figure 1, the same reference characters as were employed in connection with Figure 2 have been used wherever possible. However, the resistances A, B, C and D together comprise the series of resistances shown in Figure 2 as Y. The unregulated voltage is applied from the positive PQS. of the source of electric potential to the terminal line E and from the negative NEG. to the terminal line 0. The regulated positive voltage is obtained from terminal line L1, the negative line being shown at L2. When the voltage across terminals E and 0 drops, galvanometer relay G. R. deflects I to the left, causing the relay I to operate through a circuit from negative terminal line 0, through resistance 2, through the now closed contact 3, through the relay I, through the normally closed contact 4, and through wires 5, 6 and 1 to the positive terminal line E, causing the relay I to operate. The operation of the relay I closes the contact 8, permitting a current to flow from the positive terminal line E, through wires 1, 6 and 9, through contact 8, through armature I0, through wires II and I2, through the field I3 of the voltage regulator motor I4, through wires I5, I6 and I1 to the negative terminal line 0. Closing of the contact I8 of the relay I permits current to flow from positive terminal line E, through wires 7, 6, 5 and I9, through armature 20, through contact I8, through the relay 2|, through the resistance 22, and through wire I1 to the negative terminal line 0, causing the relay 2| to operate. Current then flows from the positive terminal line E, through wires 1, 6 and 8, through contact 8 of the relay I, through armature I0, through wires I and 23, through armature 24 of the relay 2|, through the now closed contact 25, through resistance 26, through wire 21, through the armature of the voltage regulator motor I4, through the wire 28, through the now closed contact 23 01' the relay 2|, through the armature 30, and through wires I6 and I! to the negative terminal line 0. Since both the armature and the field I3 of the voltage regulator motor I4 are now connected to positive and negative, this motor causes the motor driven rheostat W to turn so as to reduce its resistance and bring the regulated voltage at terminal L1 (e) to its proper value. When the voltage at terminal L1 (e) is correct, the contacts of the galvanometer relay G. R. clear, releasing the relay I and the relay 2|, permitting the voltage regulator motor I4 to stop. When the voltage across terminals E and 0 increases, the galvanometer relay G. R. deflects to the right, causing the relay 3| to operate through a circuit from the negative terminal line 0, through resistance 2, through the now closed contact 32, through the relay 3 I, through the normally closed contact 33, through wires 34 and l to the positive terminal line E. The operation of the relay 3| closes the contact 35, permitting a current to flow from positive terminal line E, through wires 1, 34 and 36, through armature 31 of the relay 3|, through contact 35, through wire I2, through field I3 of the voltage regulator motor I4, and through wires I5, I6 and I1 to negative terminal line 0, thus energizing the field I3 in exactly the same sense as it is energized by operation of the relay I. However, the relay 2| is not energized upon operation of the relay 3| (as it is upon operation of the relay I), so that the direction of the current through the armature of the voltage regulator motor I4 is reversed, causing the motor to turn in the opposite direction and to bring the regulated voltage at terminal L1 (e) to its proper value. In accomplishing this, the connection from the positive terminal line E is through the contact 38 of the relay 2I to the wire 28 connecting to one side of the armature of the motor I4, instead of through contact 25 of the relay 2| to the wire 27 connecting to the other side of the armature of the motor I4.

It should be noted that resistance 26 is provided to reduce the speed of the voltage regulator motor I4 and to prevent arcing of the contacts of the relay 2I.

It will be noted that the relay 3| operates when the unregulated voltage increases. Operation of this relay not only causes the contact at 35 to be closed, as already explained, but at the same time causes the contact 39 to open, removing the short-circuit normally existing across resistance B. This short-circuited resistance B is provided electric potential varying over a to compensate for the voltage drop caused by the sudden connection or the voltage regulator motor |4 upon operation of the relay 3|. For example, it the unregulated voltage increases very slightly but sufllcient to cause the relay 8| to be operated, the consequent connection or the voltage regulator motor |4 would increase the load sufllciently to cause a line drop in voltage equal to or greater than the initial increase, so that the regulator would be automatically rebalanced without any adjustment of the motor driven rheostat W. This would permit the release of the relay 3| and the disconnecting of the voltage regulator motor l4 which, upon removal or its load, would permit the line voltage to return to its initially increased amount. Consequently, for a slight increase in voltage, the only action would be a chattering of the relay 3| and the galvanometer G. R. without eflecting any permanent adjusting. The sudden insertion of the resistance B by operation of the relay 3| causes the voltage at the terminal of the galvanometer relay connected to the point S to decrease an amount equal to the drop which would be caused by connection of the voltage regulator motor l4, so that the voltage difference across the galvanometer relay will be very nearly that which would be obtained if no load were put on the line by the voltage regulator motor l4.

It will also be noted that if the voltage changes sufllciently the motor driven rheostat W will reach its limit in one direction or another. While the regulator as described is operable to produce a constant regulated voltage fro a source pf de range, it will not regulate over the entire range, and it is accordingly necessary to provide means for preventing mechanical injury to the rheostat and its driving mechanism. Limit switches are accordingly provided on the rheostat and arranged in such a manner that their circuits are opened before the mechanical limit of the rheostat is reached. These limit switches are shown at 40 and 4| for the relays and 3| respectively.

1 Opening of the limit switch 40 when the rheostat W has reached one limit of its motion disconnects the relay by breaking its energizing circuit at the contact 4 of the limit switch, causing the voltage regulator motor M to stop. Similarly, opening of the limit switch 4| when the rheostat W has reached the other limit of its motion disconnects the relay 3| by breaking its energizing circuit at the contact 33 of the limit switch, likewise causing the voltage regulator motor |4 to stop. At the same time that the contact 4 of the limit switch 40 is opened, the contact 42 of the limit switch is closed, thus completing a circuit from positive terminal line E, through wires 1, 6 and 5, through contact 42, through wire 43, through a trouble bell 44 and a trouble lamp 45 in parallel, and through the wire 46 to negative line terminal 0. Similarly, at the same time that the contact 33 of the limit switch 4| is opened, the contact .41 of the limit switch is closed, thus completing a circuit from positive terminal line E, through wires 1 and 34, through contact 41, through wires 48 and 43, through a trouble bell 44 and a trouble lamp 45 in parallel, and through the wire 46 to negative line terminal 0. It will therefore be seen that trouble signals are given when the unregulated line voltage is too high or too low, i. e., beyond the adjusting range of the regulator, so that proper steps may be taken at once to correct the voltage directly at the source. A switch 49 is provided in the circuit or the trouble bell 44 so that the trouble bell may be stopped, but the trouble lamp 45 remains lighted until the trouble has been corrected.

The condensers 50 and 5| shown connected across the relays I and 3| respectively are used to reduce arcing of the contacts of the galvanometer relay G. R.

The resistance C of the voltage regulator is provided with an adjustable tap to compensate for difierences in resistance of the commercially wound resistors A and B and also to permit adjustment of the regulating voltage due to differences in the voltage produced across each of the glow tubes G and T.

It will, of course, be understood that it the unregulated line voltage across the terminal lines E and 0 remains constant, and if the load connected across the terminals L1 and L2 of the regulated voltage changes sufiiciently to alter the regulated voltage itself, the regulator arrangement will become unbalanced, and the regulator will operate to adjust the value of the resistance W so as to return the regulated voltage to its proper value.

It will accordingly be seen that the present invention not only provides a constant voltage across desired terminals despite variations of the voltage at the source of electric potential, but also despite variations in the load applied across said terminals.

Referring now to Figure 3, the arrangement here shown is similar to that shown in Figure 2, but the arrangement of Figure 3 will act to regulate a voltage only of a magnitude equal to the sum of the regulating voltages of the glow tubes G and T.

The arrangement of Figure 2, on the other hand, can be employed to produce a regulated voltage of a magnitude greater than the regulating voltage of one glow tube and less than the sum of the regulating voltages of two glow tubes. With this arrangement limited changes in the range of the regulated voltage are obtainable in view of the limited range of adjustment of the point S of the series of resistances V.

Figure 4 shows another arrangement in accordance with the present invention, this arrangement being similar to that of Figure 2, but employing only a single glow tube T. With this arrangement it is possible to produce a regulated voltage of any magnitude greater than the regulating voltage of the glow tube but less than the unregulated line voltage. rangement is not quite as sensitive as that of Figure 2, because in Figure 4 the voltage at the point S changes with changes in the unregulated line voltage, whereas in Figure 2 the voltage at the point S remains absolutely constant despite changes in the unregulated line voltage, as already explained in connection with Figure 2. Limited changes in the range of the voltage to be regulated are also obtainable with the arrangement of Figure 4.

Figure 5 shows an arrangement for obtaining regulated voltages of a magnitude less than the regulating voltage of the glow tube with limited changes in the range of the voltage to be regulated, the resistance R connected across the glow tubeN being suitably tapped to produce a regulating voltage less than the regulating voltage of the glow tube.

Figure 6 also shows an arrangement for obtaining regulated voltages of a magnitude less However, this arthan the regulating voltage or the glow tube but with wide changes in the range of the voltage to be regulated. As in Figure 5, the resistance R connected across the glow tube N is suitably tapped to produce a regulating voltage less than the regulating voltage of the glow tube.

Figure '7 shows an adaptation of the present invention to controlling the output voltage of an electric generator, so as to maintain it constant. In Figure '7 the generator is shown at 52 and its output terminals at 53 and 54. The field 55 of the generator is connected to be energized from the output of the generator. At the same time a voltage regulating arrangement in accordanc with the present invention is connected across the output of the generator, and the galvanometer relay of the voltage regulating arrangement is connected to control the resistance of the field 55, so that any change in the magnitude of the output voltage of the generator is communicated to the voltage regulating arrangement, which then causes the resistance of the field 55 to change in the proper direction for returning the output voltage of the generator to its desired constant value, it being understood that the value of the output voltage of the generator is determined by the strength of its field, which in turn is determined by the field resistance.

In connection with Figure 7 it will be noted that batteries 56 have been shown as voltage regulators instead of the voltage regulating neon glow tubes described in connection with the previous figures. It will, of course, be understood that batteries act to maintain a practically constant voltage and therefore may be employed interchangeably with the neon glow tubes or any other type of voltage regulating element, it being, of course, apparent that the regulating effect of the present invention is based upon the use of a constant voltage regulating element.

It should, of course, be further understood that commercially obtainable voltage regulating elements, such as neon glow tubes, pass only small currents, and will not act to regulate the voltage when connected directly across apparatus drawing a relatively large current.

Figure 8 shows an adaptation of the present invention to controlling the speed of an electric motor, so as to maintain a constant speed. In Figure 8 the motor is shown at 51, and the motor field at 58, the motor field being connected to be energized by a source of electric potential subject to fluctuations in voltage. There is also shown a relatively small output generator 59 connected to be driven by the motor 57, the arrangement constituting a motor-generator set. Across the output terminals of the generator 59 is connected a. voltage regulating arrangement in accordance with the present invention, the voltage regulating arrangement being connected to vary the resistance of the motor field 58. Asstuning that the motor has been operating at a desired constant speed, and that the voltage regulating arrangement has been balanced at the resulting output voltage of the generator, any change in the voltage energizing the motor, resulting in a change in speed of the motor, will result in a change in the output voltage of the generator, which change will be communicated to the voltage regulating arrangement. The voltage regulating arrangement will then act to vary the resistance of the field of the motor in such a direction as to return the speed of the motor to its desired constant value,

at which time the output voltage of the generator will return to its desired constant value, resulting in a return to normal oi! the voltage regulating arrangement.

From the foregoing detailed description of various embodiments and applications of the present invention, it will be seen that I have produced decided improvements in electrical arrangements for obtaining a constant voltage from a source of electric potential subject to fluctuations in voltage, and that I have accomplished the various objects set out at the beginning of this specification. understood from the foregoing description that my invention is not only capable of wide application, but that it can be carried out in various styles of execution, and Y accordingly do not wish my invention to be limited save as defined in the appended claims.

1. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance, and means to control the resistance varying means upon unbalance of the bridge following a voltage variation for causing a change in the value of the resistance, whereby to reestablish the balance of the bridge, the desired regulated load voltage being obtained from at least one arm of the bridge.

2. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subjcct to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a variable resistance forming another arm of the bridge, means to connect the bridge so as to be subject to the voltage capable of fluctuating, means to vary the value of said resistance, and means to control the resistance varying means upon unbalance of the bridge following a voltage variation for causing a change in the value v of the resistance, whereby to reestablish the balance of the bridge, the desired regulated load voltage being obtained from that arm of the bridge which is in series with said variable resistance.

3. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a resistance forming one parallel side of the bridge and having means associated therewith for varying the proportion of resistance in the two arms forming said parallel side of the bridge, means to connect the bridge so as to be subject to the voltage capable of fluctuating, and means to control the resistance varying means upon unbalance of the bridge following a voltage variation for causing a change in proportion of the resistance in said two arms of the bridge, whereby to reestablish the balance of the bridge, the desired regulated voltage being obtained from It will also be that portion of the resistance which directly parallels the constant voltage element.

4. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential sub- Ject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge,

a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance, and means to control the resistance varying means upon unbalance of the bridge following a voltage variation for causing a change in the value of the resistance, whereby to reestablish the balance of the bridge, the desired regulated load voltage being maintained across and obtainable from the bridge.

5. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having constant voltage elements in diagonally opposite parallel arms thereof, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance, and means to control the resistance varying means upon unbalance of the bridge following a voltage variation for causing a change in the value of the resistance, whereby to reestablish the balance of the bridge, the desired regulated voltage being maintained across and obtainable from the bridge.

6. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance comprising a two-way driving mechanism, and a pair of electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbalance of the bridge following a voltage change in the other direction, one of said contacts serving to control the driving mechanism to cause it to vary the value of said resistance in one direction and the other of said contacts serving to control the driving mechanism to cause it to vary the value of said resistance in the opposite direction, whereby to reestablish the balance of the bridge, the desired regulated voltage being obtained from at least one arm of the bridge.

7. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential sublect to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance comprising a two-direction electric motor having the usual field and armature, a relay having contacts adapted to effect energization of the motor armature in one sense when the relay is deenergized and to effect energization of the motor armature in the opposite sense when the relay is energized; a second relay having a pair of contacts, one of which is adapted to effect energization of the motor field in one certain sense, and the other of which is adapted to effect energization of the first named relay; a third relay having a contact adapted to effect energization of the motor field in the same certain sense as before mentioned; a pair of electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbalance of the bridge following a voltage change in the other direction; one of said contacts serving to effect energization of the second named relay to cause it to effect operation of the motor in one direction to effect variation in the value of said resistance in one direction, and the other of said contacts serving to effect energization of the third named relay to cause it to effect operation of the motor in the opposite direction to eifect variation in the value of said resistance in the opposite direction, whereby to reestablish the balance of the bridge; the

desired regulated voltage being obtained from at least one arm of the bridge.

:3. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance comprising a two-way driving mechanism, a. relay having contacts adapted to effect operation of the driving mechanism in one direction to cause it to vary the value of said resistance in one direction, a second relay adapted to effect operation of the driv ing mechanism in the other direction to cause it to vary the value of said resistance in the opposite direction, means to effect deenergization of the first named relay and of the driving mechanism when said resistance reaches the limit of its adjustment in one direction; means to effect deenergization of the second named relay and of the driving mechanism when said resistance reaches the limit of its adjustment in the opposite direction; and a pair of electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbalance of the bridge following a voltage change in the other direction; one of said contacts serving to control the first named relay to cause it to effect operation of the driving mechanism to effect variation in the value of said resistance in one direction, and the other of said contacts serving to control the second named relay to cause it to effect operation of the driving mechanism to effect variation in the value of said resistance in the opposite direction, whereby to reestablish the balance of the bridge; the desired regulated voltage being obtained from at least one arm of the bridge.

9. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm of the bridge, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance comprising a twoway driving mechanism, a relay having contacts adapted to effect operation of the driving mechanism in one direction to cause it to vary the value of said resistance in one direction, a second relay adapted to efiect operation of the driving mechanism in the other direction to cause it to vary the value of said resistance in the opposite direction, a limit switch having a normal- 1y closed contact in the energizing circuit of the first named relay, a second limit switch having a normally closed contact in the energizing circult of the second relay; means to effect opening of the normally closed contact of the first named limit switch when said resistance reaches the limit of its adjustment in one direction, so as to effect deenergization of the first named relay and of the driving mechanism; means to effect opening of the normally closed contact of the second named limit switch when said resistance reaches the limit of its adjustment in the opposite direction, so as to effect deenergization of the second named relay and of the driving mechanism; and a pair of electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbal-. ance of the bridge following a voltage change in the other direction; one of said contacts serving to control the first named relay to cause it to effect operation of the driving mechanism to efiect variation in the value of said resistance in one direction, and the other of said contacts serving to control the second named relay to cause it to efi'ect operation of the driving mechanism to efiect variation in the value of said resistance in the opposite direction, whereby to reestablish the balance of the bridge; the desired regulated voltage being obtained from at least one arm of the bridge.

10. An electrical arrangement for maintaining at a. regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electrical potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm thereof and a constant voltage element paralleling the diagonally opposite arm and a portion of the directly opposite arm, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance comprising a two-way driving mechanism, a relay having contacts adapted to efiect operation of the driving mechanism in one direction to cause it to vary the value of said resistance in one direction, a second relay adapted to effect operation of the driving mechanism in the other direction to cause it to vary the value of said resistance in the opposite direction; a pair oi electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbalance oi the bridge following a voltage change in the other direction, one of said contacts serving to control the first named relay to cause it to effect operation of the driving mechanism to effectvariation in the value of said resistance in one'direction, and the other of said contacts serving to control the second named relay to cause it to effect operation of the driving mechanism to effect variation in the value of said resistance in the opposite direction, whereby to reestablish the balance of the bridge, the desired regulated voltage being maintained across and obtainable from the bridge; and means to prevent undesired balancing of the bridge upon an increase in voltage of such a magnitude that it would be balanced by reason of an equivalent decrease in voltage occasioned by connection of the driving mechanism to the voltage source, comprising means normally short-circuiting a portion of the aforesaid arm directly paralleling the first named constant voltage element, comprising a normally closed contact 01' the second named relay, the short-circuit being removed upon operation of the second named relay when it acts to eflect operation of the driving mechanism to effect variation in the value of the first named resistance, upon an increase in voltage as before mentioned, to restore the regulated voltage to its proper value.

11. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is supplied from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement having a constant voltage element as one arm thereof and a constant voltage element paralleling the diagonally opposite arm and a portion of the directly opposite arm, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means to vary the value of said resistance, means to control the resistance varying means upon unbalance of the bridge following a voltage variation for causing a change in the value of the resistance, whereby to reestablish the balance of the bridge, the desired regulated voltage being maintained across and obtainable from the bridge; and means to prevent undesired balancing of the bridge upon an increase in voltage of such a magnitude that it would be balanced by reason of an equivalent decrease in voltage occasioned by connection of the resistance varying means to the voltage source, comprising means normally short-circuiting a portion of the aforesaid arm directly paralleling the first named constant voltage element, the short-circuit being removed upon operation of the resistance varying means to effect variation in the value of the first named resistance, upon an increase in voltage as before mentioned, to restore the regulated volt age to its proper value.

12. An electrical arrangement for maintainting at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement, means to connect the bridge so as to be directly subjected to at I least a portion of the voltage subject to fluctuations, means comprising a constant voltage element for maintaining a constant voltage drop in one arm of the bridge, said bridge being initially balanced to give a desired regulated voltage drop in at least one arm of the bridge, and means controlled by unbalance of the bridge to reestablish the balance of the bridge and the desired regulated voltage.

13. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means comprising a constant voltage element for maintaining a constant voltage drop in one arm of the bridge, said bridge being initially balanced so as to give a desired voltage drop in at least one arm of the bridge, and means controlled by unbalance oi! the bridge to vary the value oi! said variable resistance in consonance with variations in voltage of the source of voltage to reestablish the balance 01 the bridge and the desired regulated voltage.

14. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electric potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement, means to connect the bridge so as to be subjected to at least a portion of the voltage subject to fluctuations, means comprising a constant voltage element for maintaining a constant voltage drop in one arm of the bridge, said bridge being initially balanced to give a desired regulated voltage drop in at least one arm of the bridge, and means controlled by unbalance of the bridge to vary the resistance of at least one arm of the bridge in consonance with variations in voltage of the source 0! voltage to reestablish the balance of the bridge and the desired regulated voltage.

15. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electrical potential subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement, a variable resistance, means to connect the bridge and said variable resistance in series with each other and with said source, means comprising a constant voltage element for maintaining a constant voltage drop in one arm of the bridge, said bridge being initially balanced to give the desired regulated voltage drop in at least one arm of the bridge, and means controlled by unbalance of the bridge to vary the value of said variable resistance in consonance with variations in voltage of the source of voltage to reestablish the balance of the bridge and the desired regulated voltage, said last named means comprising a two-way driving mechanism, and a pair of electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbalance of the bridge following a, voltage change in the other direction, one of said contacts serving to control the driving mechanism to'cause it to vary the value of said variable resistance in one direction and the other of said contacts serving to control the driving mechanism to cause it to vary the value of said variable resistance in the opposite direction.

16. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electric potential-subject to fluctuations in voltage, which comprises a Wheatstone bridge arrangement, means to connect the bridge so as to be subjected to at least a portion of the voltage subject to fluctuations, means comprising a constant voltage element for maintaining a constant voltage drop in one arm of the bridge, said bridge being initially balanced to give a desired regulated voltage drop in at least one arm of the bridge, and means controlled by unbalance of the bridge to vary the resistance of at least one arm of the bridge in consonance with variations in voltage of the source of voltage to reestablish the balance of the bridge and the desired regulated voltage, said last named means comprising a two-way driving mechanism, and a pair of electrical contacts controlled by the bridge galvanometer, one of which contacts is controlled by the galvanometer upon unbalance of the bridge following a voltage change in one direction and the other of which is controlled by the galvanometer upon unbalance of the bridge following a voltage change in the other direction, one or saig contacts serving to control the driving mechanism to cause it to vary the value of said resistance in one direction and the other of said contacts serving to control the driving mechanism to cause it to vary the value of said resist ance in the opposite direction.

17. In the art of maintaining at a regulated value the voltage across aload, which may be subject to variation and which is energized from a source of electric potential subject to fluctuations in voltage, the steps consisting in connecting a Wheatstone bridge arrangement so as to be directly subjected to at least a portion of the voltage subject to fluctuations, maintaining a constant voltage drop in one arm of the bridge despite the fluctuations in voltage to which the bridge is subjected, initially balancing the bridge to give a desired regulated voltage drop in at least one arm of the bridge, from which the desired load voltage is derived, and utilizing the unbalance of the bridge upon a variation in voltage to which the bridge is subjected to control means to reestablish the balance of the bridge, whereby to reestablish the desired regulated load voltage.

18. An electrical arrangement for maintaining at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electric potential subject to fluctuations in voltage, which comprises voltage changing means connected so as to control the voltage across the load, an electrical device connected so as to be responsive to changes in the voltage across the load, said electrical device being initially balanced when the load voltage is at its desired regulated value, means controlled by the electrical device upon increases and decreases of the voltage across the load to actuate the voltage changing means to reestablish the balance of the electrical device and the desired regulated load voltage, and means to prevent undesired balancing of the electrical device upon an increase in voltage of such magnitude that it would be balanced by reason of an equivalent decrease in voltage occasioned by actuation of the means controlled by the electrical device, comprising means operable upon actuation of the means controlled the electrical device to cause a rise in voltage across the elec trlcal device substantially numerically equal to drop which would otherwise occur upon actuation of the means controlled by the electrical device, whereby to restore the unbalanced condition of the electrical device occurring upon an increase in voltage to thereby enable the desired balanced condition to be effected by the intended 0 eration of the means controlled by the electricol device.

19. An electrical arrangement for maiutaining at a regulated value the voltage across a load which may be subject to variation and which is energized from a source of electric potential subject to fluctuations in voltage, which cornprises a Wheatstone bridge arrangement, means to connect the blclge so as to be directly subjected to at least a portion of the voltage subject to fluctuations, means comprising a constant voltage element for maintaining a constant voltage drop in one arm of the bridge, said bridge being initially balanced to give a desired regulated voltage drop in at least one arm of the bridge, means controlled by the bridge galvanorneter upon unbalance of the bridge to reestablish the balance of the bridge and the desired regulated voltage, and means to prevent undesired balancing of the bridge upon an increase in voltage of such magnitude that it Would be balanced by reason of an equivalent decrease in voltage occasioned by connection of the balance reestablishing means to the voltage source, comprising means operable upon connection of the balance reestablishing' means to the voltage source to vary the resistance of at least one arm of the Wheatstone bridge to cause a rise in volt age across the bridge galvanometer substantially numerically equal to the drop Which would otherwise occur upon connection of the balance reestablishing means to the voltage source, whereby to restore the unbalanced condition occurring upon an increase in voltage to thereby enable the desired balanced condition to be effected by the intended operation of the balance reestablishing means.

HARRY CAMPBELL GRANT, J a.

Images