US1931097A - Electrical regulating system - Google Patents

Description

Oct. 17, 1933. F. H WINTER 1,931,097

ELECTRICAL REGULATING SYSTEM Filed April 26, 1933 .n A J Y /2 .29 "75 *4- 5 "/3 Inventor" Fred H. Winter;

Patented Oct. 17, 1933 PATENT OFFICE I 1,931,091 ELECTRICAL REGULATING SYSTEM Fred H. Winter, Schenectady, N. Y., assignmto General Electric Company, a corporation or New York Application April 26, 1933. Serial No. 668,058

9 Claims. (CL 171-419) My invention relates to electrical regulating systems and more particularly to improvements in voltage regulating systems of the vibratory contact type.

Vibratory contact type regulators are usually, but not necessarily, used to control automatically the excitation of a dynamo-electric machine in such a manner as to maintain the voltage of the machine substantially constant. When so used, they have a pair of vibratory cooperating contacts which control the energization of an excita* tion controlling circuit for the regulated machine, usually indirectly through an auxiliary difierential relay which controls a regulating resistance in the field circuit of an exciter for the regulated machine. The auxiliary differential relay usually has a-pair of opposed windings, or coils, which are both energized from the exciter,

and the regulator contacts are connected in cirwhen the regulator contacts'open, only one relay winding is energized and the pull of this coil causes the relay contacts to open. It will thus be seen that the relay contacts open and close with the opening and closing of the regulator contacts.

I have found that the above relay arrangement produces an undesirable undercompounding effeet of the regulating system. This is brought about as follows: When the regulator acts to maintain constant voltage under adverse conditions, such for example, as under heavy load conditions on a generator, the voltage of the exciter or of the field winding of the regulated machine increases, and this means that the vibratory contacts of the relay must stay closed a greater proportion of the total time of this operating cycle. However, it is just as hard for the relay to open its contacts under highexcitation conditions as under low excitation conditions because as the 'exciter voltage increases the energization of the relay winding is equally increased. It would be desirable to make it more easy for the relay to close its contacts and to maintain these contactsclosed during high excitation conditions for under high excitation conditions it is desirable to have the relay contacts closed most of the time and. therefore an improved operation. results if the contacts will snap closed more quickly and if they tend to remain closed longer after the controlling contacts open.

Inaccordance with one feature of my invention I providean arrangement in which the relative energizaticn oi the relay windings automatically changes with changes in excitation of the regulated machine in such a manner as to render'it easier to close the relay contacts during high excitation conditions than at low excitation conto ditions.

This relative change may be such that the energization of the intermittently energized relay winding increases at the same time that the energization of the constantly energized relay g5 winding is decreased, or it may be such that the energization of the intermittently energized relay winding remains constant while the energization of the constantly energized coil is decreased, or the energization of the intermittently energized winding may be increased while the energization of the constantly energized coil is maintained constant. The common feature of all three methods is that as the excitation increases the strength of the intermittently energized coil in-. creases relatively to the strength of the constantly energized coil and consequently a closure of the regulator contacts during increasing excitation conditions produces a progressively stronger energ'ization of the intermittently energized coil 3 which consequently acts more powerfully to buck or cancel the effect of the constantly energized coil, whereby the relay contacts are more quickly clo ed.

object of my invention is to provide a new 35 and improved electrical regulating system.

Another object of my invention is to provide a new and improved system of connections for the auxiliary differential relay associated with vibratory contact type electrical regulators.

My invention will-be better understood from the following description taken in connection with the single figure of the accompanying diagrammatic drawing and its scope will be pointed out in the appended claims.

In the accompanying drawing I have illustrated an embodiment of my invention as applied to the regulation of a dynamo-electric machine which is shown by way of example, as a three phase synchronous generator 1, which is connected to a power circuit 2. Generator 1 has a field circuit 3 whose energization is controlled by an excitation controlling circuit 4 from a vibratory contact type voltage regulator 5 indirectly through an auxiliary differential relay 6 and an exciter '7.

As shown, exciter '7 is provided with a field winding 8 in series with which is a regulating resistance, or rheostat 9, which is adapted to be short circuited periodically by a set of contacts 110 10 on relay 6. Thus, when the relay contacts are closed rheostat 9 is short-circuited, full excitation is applied to exciter 7 whose voltage increases, thereby increasing the voltage and excitation of the field winding 3 and consequently oi' the generator 1. Conversely, when the contacts 10 open the regulating resistance 9 is inserted in the field circuit of the exciter 7, thereby reducing its voltage, which in turn causes a reduction in the excitation and voltage of the generator 1.

Regulator 5, which is of conventional construction, except for energization of its antihunting magnet, comprises a main control contact which is mounted on a pivotally supported main control lever 12, which in turn is actuated by a main control magnet 13 connected to be responsive to the voltage of power circuit 2. This magnet is so constructed that when the voltage of circuit 2 is normal the entire main control assembly will be balanced in any one of a suitable rangeof positions, while if the voltage rises above normal the contact 11 will move downwardly while if the voltage falls below normal the contact 11 will move upwardly. A dashpot,14 is provided for damping the motion of the main control assembly. Cooperating with main control contact 11 is a vibrator anti-hunting contact 15, which is fastened to a pivotally mounted anti-hunting lever 16, whose motion is controlled by an anti-hunting magnet 17. The pull of the anti-hunting magnet 17 is opposed by a spring 18.

Relay 6 has a spring 19 for urging its contacts 10 to close and a pair of opposed operating windings, or coils, 20 and 21. Coil 21 is the continuously energized coil and this coil is preferably connected to be energized in a uniform or constant manner from any suitable source of constant voltage. By way of example, it is connected across one of the phases of circuit 2 which, due to the fact that this circuit is energized by a generator whose voltage is maintained constant by a voltage regulator, will have a substantially constant voltage. As shown, coil 21 'is connected across one of the phases of circuit 2 through a rectifier 22, a conductor 23 and a return conductor 24. A suitable current limiting resistor 25 is shown connected in this circuit. Relay winding 20 is the intermittently energized winding of the relay and this coil is connected in a circuit including one of the phases of the power circuit 2; a means for producing a variable voltage which varies in accordance with the voltage of exciter '7, or the voltage of field winding 3, both of which voltages are substantially equal, and the contacts 11 and 15 of the regulator 5. Thus, beginning with rectifier 22 the energizing circuit for coil 20 may be traced as follows: Through conductor 23, the coil 20, a conductor 26, the contacts 11 and 15, an adjustable potentiometer circuit 27, responsive to the voltage or the excitation controlling circuit 4, and back to the other side of one of the phases of the power circuit 2 through resistor 25.

With the above described arrangement, relay winding 21 will be continuously energized by a substantially constant voltage source of current supply, while relay winding 20, which OpDOSes winding 21 when the former is energized, will be intermittently energized, because of the vibratory action of the regulator contacts, by a voltage which is proportionate to the sum of the voltage of power circuit 2 and the voltage of the excitation controlling circuit 4. By adjusting potentiometer 27 the total voltage energizing the circuit including the relay winding 20 may be made such that under minimum excitation conditions, that is to say, when the voltage of the exciter 7 is a minimum, the energization of relay winding 20 when the contacts of the regulator 5 are closed, will just be sufiicient to produce an effect which cancels or neutralizes the effect of the uniformly and constantly energized winding 21. Consequently, when the regulator contacts close under these conditions, the spring 19 will close the contacts 10 of the regulator. It is, of course, not necessary that coils 20 and 21 should exactly neutralize each other, but all that is necessary is that under minimum excitation conditions the differential pull produced by the two coils when they are both energized will be insufiicient to overcome the pull of spring 19, so that under these conditions the relay will close its contact 10. If now the voltage of the exciter increases, as will be the action produced by the voltage regulator 5 in case the load on generator 1 is increased, the voltage of the circuit energizing winding 20 will also increase so that every time the contacts 'of the regulator 5 close, the energization of the winding 20 will be progressively stronger as the voltage of the exciter 7 increases, and this is desirable because in order to increase the excitation of the exciter, it is necessary that the contacts 10 remain closed in a greater proportion of their operating cycle. Thus, the higher the voltage of exciter '7 the more easily and the'more quickly will the closure of the regulator contacts cause the closure of the relay contacts 10. The reason the winding 20 of the relay is energized by the variable voltage of the exciter and also by a series voltage which is substantially constant is because the normal range of exciter voltage is so great, typically 4 to 1, as to produce an undesirably wide range in energization of winding 20, if this winding were energized by a voltage propoitional to the exciter voltage only. However, by providing a base excitation for winding 20 which is substantially constant, and by adding to'this base voltage a variable voltage which varies with the voltage of the exciter, the total over-all range in voltage applied to the winding 20 may be reduced to any desired value.

Anti-hunting'magnet 17 comprises 2 cumulative, or additive, windings 28 and 29. Winding 28 corresponds to the usual winding of the antihunting magnet but instead of energizing this winding directly from across the exciter as is the usual practice, it is energized by two voltages in a manner similar to the energization of relay winding 20. Thus, anti-hunting winding 28 is energized through rectifier 22 and potentiometer 27 in series. The purpose of this is the same as the purpose of energizing relay winding 20 from the two voltages, namely, to reduce the range of energization of this winding. This is very desirable because the pull of a winding usually varies substantially as the square of its applied voltage so that with a 4 to 1 voltage range, a 16 to 1 pull range will be produced and this has usually necessitated the use of a special restraining spring arrangement for the anti-hunting assembly whereby a plurality of springs are provided which successively come into action as the pull of the anti-hunting coil increases. However, by the use of the connections illustrated it is only necessary to provide a simple single spring for restraining the anti-hunting assembly.

The additional anti-hunting winding 29 isvoltage of said normally constant voltage source,, and the other of said windings being energized energized from across one of the phases of circuit 2 through rectifier 22, the return conductor being a conductor 30. With this arrangement the regulator is made more responsive to voltage changes because as both windings 28 and 29 are cumulative, a sudden decrease in line voltage will decrease the total pull of the anti-hunting magnet, whereby the spring 18 will tend to cause contact 15 to engage contact 11, whereby the relay 6 will close its contacts and cause the excitation controlling element to increase the voltage of generator 1. Similarly, a sudden increase in voltage on circuit 2 will produce an opposite efiect in that it will strengthen the pull of the anti hunting magnet, thus separating the contacts of the regulator and causing a decrease in excitation.

The general operation of vibratory contact regulators of the type illustrated by regulator 5 is believed to be so well understood that a detailed description thereof is thought unnecessary. Briefly described, the action is such that contact 11 moves upward toward contact 15 when the line voltage tends to drop and moves downward away from'contact 15 when the line voltage increases. If the contact 11 moves upward toward contact 15, these contacts will, in effect, stay in engagement, thereby increasing the voltage. of the exciter 7 to a new and higher value which will finally produce an energization of the anti-hunting magnet 28 sufficient to cause a separation of the contacts. Contact 15 will then vibrate intermittently in relation to contact 11, which latter contact will come to rest as soon as the voltage has been restored to normal. Similarly, when contact 11 moves downwardly in response to a decrease in line voltage the contacts will separate and they-will, in effect, stay separated until the voltage has fallen to a value low enough to cause a resultant weakening of the anti-hunting I :nagnet sufficient to allow spring 18 to again close the contacts. The contact 15 will then vibrate in its new position. Actually, it should be understood that when contact 11 moves upwardly or downwardly the action is usually not such as to produce a continuous and direct change in excitation, but the action will be intermittent, although the eifect will be to produce an increase or decrease in excitation until the voltage is re.

stored to normal at which time the, contact 11 will come to rest in the new position.

The vibratory action of the contacts is usually so rapid under normal conditions that the field current of the regulated machine is substantially constant and consequently the voltage of circuit 2 is substantially constant. Therefore, under normal conditions, the energization of coil 29 is constant which results in an additional base energization-of the anti-hunting coil.

While I have shown and described a particular embodiment of my invention, it will be obvious to those skilled inthe art that changes and modifications maybe made without departing from in accordance with the sumof the voltages of said source and said excitation controlling circuit.

2. An auxiliary differential relay for vibratory contact regulators for variably excited dynamoelectric machines, said relay having two oppo sitely acting windings one of which is substantially constantly energized and the other of which is energized through the contacts of said regulator from a source whose voltage varies in accordance with the degree of excitation of the regulated machine.

3. In combination, a'dynamo-electric machine having an excitation controlling circuit, a regulator therefor having a pair of'relatively vibratory cooperating contacts, a relay for controlling said excitation controlling circuit, said relay having a pair of opposed windings, means for giving one of said relay windings a substantially constant energization, and means for energizing the other relay winding through the contacts of said regulator in accordance with the energization of said excitation controlling circuit.

4. In combination, a dynamo-electric machine having an excitation controlling circuit, a regulator therefor having a pair of relatively vibratory cooperating contacts, a relay for controlling said excitation controlling circuit, said relay having a pair of opposed windings, means for giving one of said relay windings a substantially constant energization, and means for energizing the other relay winding through the contacts of said regulator in accordance with the sum of two voltages one of which is substantially constant and the other of which varies in accordance with the voltage of said excitation controlling circuit.

5. In combination, an electric generator, an exciter therefor, a vibratory contact voltage regulator for said generator, an auxiliary relay controlled by said regulator for varyingthe excitation of said exciter, said relay having two opposed coils, one of said coils being energized in accordance with the voltage of-said generator, the other of said coils being energized in accordance with the sum of the voltages of said generator and said exciter.

6. In combination, a dynamo-electric machine having an excitation controlling circuit, a vibratory contact voltage regulator therefor having an anti-hunting coil, and an energizing circuit for said coil, said energizing circuit being energized by two voltages in series, one voltage being proportional to the voltage of said machine and the other voltage being proportional to the voltage of said, excitation controlling circuit.

'7. In combination, a dynamo-'electric-generator having a field winding, a vibratory contact voltage regulator therefor, said regulator having an anti-hunting magnet with two cumulative windings, one of said magnet windings being connected to be energized in accordance with the voltage of said generator and the other of said magnet windings being connected to be energized in accordance with a voltage which varies as the sum of the voltages of said generator and said field winding.

8. In combination, an alternating current generator having a'direct current field winding, a vibratory contact voltage regulator therefor, said regulator having an anti-hunting magnet with two cumulative windings, a rectifier, circuit connections for energizing one of said magnet windings from across said generator through said reetifler, and circuit connections for energizing the other magnet winding from across both said generator and said field winding through said rectifier, the voltages of said generator and field winding being additive with respect to said last mentioned magnet winding. I

9. A voltage regulating system comprising, in ombination, an alternating current generator, an exciter therefor, a vibratory contact regulator connected to be responsive to the voltage of said generator, a differential relay controlled by said regulator for controlling the excitation of said exciter, said relay having two opposed windings

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