US2262561A - Governing apparatus - Google Patents

Description

Nov. 11, 1941. sc w D 2,262,561

GOVERNING APPARATUS Filed Oct. -l9, 1940 4 Sheets-Sheet 1 WITNESSES:

INVENTOR QWMXWMM Humour E Scnwsuonsn BY fi- ATTORNEY 1Q41. A. F. SCHWENDNER 2,262,561

GOVERNING APPARATUS I Filed 001; 19, 1940 4 Sheets-Sheet z M WITNESSES: 3 p INVENTOR )am Ik MW nn'rmmv FT Scnwsunum ATTORNEY Nov. 11, 1941.

A. F. SCHWENDNER GOVERNING APPARATUS Filed Oct. 19, 1940 4 Sheets-Sheet 3 INVENTOR NTHONYF SCHWENQNER.

BY (0. 0m;

ATTORNEY Nov. 11,1941.

A. F. SCHWENDNER 2,262,561

GOVERNING APPARATUS Filed Oct. 19, 1940 4 Sheets-Sheet 4 F'IQAL wnmzsszs; INVENTOR 9 M Humour E Scuwsnnnm BY @IWWM I41 ATTORNEY Patented Nov. 11, 1941 GOVERNING APPARATUS Anthony F. Schwendner, Ridley Park, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 19, 1940, Serial No. 361,849

18 Claims.

This application is a continuation in part of application Serial No. 225,272, filed August 17, 1938, for Governing apparatus. The invention relates to prime movers, more particularly to steam turbines, of the bleeder or extraction type and it has for an object to provide an improved control system for apparatus of this character.

Where a steam turbine has two or more bleeder points, compensation has heretofore been difiicult. With a single bleeder point, the associated pressure regulator may be used directly in connection with the governor for this purpose; however, with two or more bleeder points, this arrangement, without further additions, cannot be used because too many variables are involved. In one type of bleeder control mechanism for a turbine having a plurality of bleeder points and arranged for speed compensation, the impeller pressure of the governing mechanism is impressed on the admission valve regulating mechanism as well as on the regulating mechanisms of the bleeder valves, but, as the admission valve regulating mechanism is provided with a speed compensator, the impeller pressure would come back to the same value at different loads, and, therefore, be useless for the control of the bleeder regulators. Accordingly, it was necessary to incorporate pressure compensation to overcome this difficulty. In the preferred arrangement of the control system of the present invention, the regulating pressure may be utilized to operate both the admission valve and bleeder valve regulators for the reason that, with the isochronous arrangement of the system, the regulating pressure does not come back to the same value as in the case of, the impeller pressure, but it is maintained at a value determined by the load change. Accordingly, a further object of the invention is to provide control mechanism for a turbine having one or more bleeder points with means operating to secure a governing pressure which is compensated for load so that such pressure depends upon the load and may be used to operate the various regulators, each bleeder point regulator being also subject to the effect of steam pressure at its bleeder point so that the latter pressure may be maintained at a desired value.

Where a turbine is provided with the isochronous regulating system just referred to and is used to drive a generator, the latter being tied into a system, obviously the isochronous arrangement would not be suitable for maintaining the turbine at its proper load point, and, for this reason, the control system is shifted over from isochronous speed to load control.

steam turbine controlled by an isochronous control system wherein the system may be readily changed over from isochronous to load control in the event that the generator driven by the turbine is tied in to an electrical system,

A further object of the invention is to provide a steam turbine having one or more extraction points and driving a generator together with control mechanism provided for operation of the turbine as an isolated unit or for operation there-:

of in conjunction with a power system, the control mechanism operating, when the unit is isolated, to adjust the admission and extraction point valves in accordance with the load demand and steam flow demand at each extraction point, and, when connected to a system, at which time the turbine speed is fixed by the system independently of the governor, operating in response to change in load-carrying capacity induced by a change in extraction flow to bring about adjustment of the valves so as to maintain the load-carrying capacity within a narrow range of variation.

A further object of the invention is to provide an extraction type steam turbine driving a generator, which is connected to a power system, together with governor mechanism for the admission and extraction point valves and means responsive to a change in load-carrying capacity induced by flow change at an extraction point to effect adjustment of the governor in order that the valves may be adjusted to maintain the turbine load-carrying capacity at substantially a desired value.

A further object of the invention is to provide a steam turbine having two or more extraction points with a fluid pressure governing system wherein the governing pressure directly controls both the admission valve and the extraction or bleeder valves, the latter also being subject to the effect of pressure at each extraction or bleeder point, together with means responsive to load change to modify the governing pressure.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a view, partly in section and partly in elevation, showing a turbine installation with the improved governing system applied thereto;

Fig. 2 is a diagrammatic sectional view of the control system shown in Fig. 1;

Therefore, a further object of the invention is to provide a Fig. 3 is a view of an extraction turbine showing a different type of extraction pressure regulator in connection with load control features;

Fig. 4 shows the load control arrangement responsive to generator output; and,

Fig. 5 shows the load control arrangement responsive to local circuit input from a transmission system.

In accordance with the present invention, there is provided a prime mover or turbine having one or more extraction or bleeder points and controlled by governing apparatus of the general type disclosed and claimed in Patent No. 2,009,417, July 30, 1935, and in Patent No. 2,224,321, December 10, 1940, but which differs from the latter in the respect that the regulating pressure provided by the transformer governor is used directly, not only to control the main admission valve, but also each extraction or bleeder valve, the latter also being subject to the effect of bleeder pressure so that the pressure at each extraction or.bleeder point may be maintained at a predetermined value. While an isochronous system of the present type has aload-compensated governing pressure, making the latter peculiarly useful for all of the regulators, yet such a system would not be effective to make the turbine carry a predetermined load in the form of the ouput of its generator where the latter is tied into an electrical system. Accordingly, a further modification of the present invention contemplates an isochronous governing'arrangement for a turbine which may be readily changed over to load control so that the electrical output of the generator is maintained substantially constant.

Referring now to the drawings more in detail, there is shown a load or generator 9 driven by a turbine including a high-pressure section l0, an intermediate-pressure section II, and a low-pressure section l2, steam being supplied to the high-pressure section |8 through the admission valve I3 and, as shown, bleeder or extraction lines l4 and 5 are connected at the exhaust or discharge ends of the turbine sections In and II. Valves l6 and H are arranged in the path of steam flow along the turbine at the downstream sides of the extraction or bleeder lines l4 and 5 and serve, with the admission valve l3, to secure such admission and distribution of steam as to satisfy the power and bleeder demand, these valves being operated by the improved control system, which will now be described.

The turbine rotor carries an impeller providing oil under suitably high pressure for the supply passage 2|. The system is also provided with an exhaust or drain line indicated generally at 22.

Oil is supplied from the impeller, through an orifice 23, to the primary pressure passage 24, the pressure in which is maintained as a function of the turbine speed due to the centrifugal escape passage formed in the turbine rotor, this particular type of pressure developer being disclosed and claimed in the patent to O. N. Bryant, No. 2,035,689, March 31, 1936.

Oil under primary pressure is supplied by the line 24 to the transformer, at 26, to derive oil under regulating pressure furnished by the line 28 to the servo-motor 21 for the admission valve and to the servo-motors 29 and 38 for the bleeder or extraction valves l6 and I1.

011 under regulating pressure supplied from the transformer, at 26, is the only controlling factor for the admission valve servo-motor 21 and it serves as a contributing factor for controlling the servo- motors 29 and 30, the latter also being responsive to pressures of the bleeder lines I4 and IS, the bleeder line pressures acting on the pressure-regulating transformers 3| and 32, Whose control pressures are impressed, by means of the lines 33 and 34, on the servomotors 29 and 30.

While the pressure-responsive arrangement or transformer governor, at 26, may be of any suitable type, one embodying the principles disclosed generally in the patents aforesaid is preferred. The one illustrated is similar to that disclosed and claimed in said Patent No. 2,224,321, that is, it is constructed and arranged to provide for different types of operation depending upon the requirements peculiar to each installation; but, with bleeder point control, in order that the governing or control pressure may be a function of the load, the apparatus is arranged for isochronous operation.

Preferably, the transformer governor, at 26, includes a body structure 35 having a cylinder 36 provided with an inlet pressure port 31, an

' exhaust port 38, and a regulating pressure port 39 arranged between the ports 31 and 38. A piston valve 48 is disposed in the cylinder 36 and it is turned, preferably by the turbine wheel 4|,

.. to avoid the effects of static friction. The piston valve has upper and lower lands 42 and 43 and an intermediate recessed or reduced portion 44 which cooperates with the interior of the cylinder 36 to provide a regulating pressure chamber 45 continuously in communication with the "port 39, the lands 42 and 43 being arranged just to lap the inlet and exhaust ports 31 and 38 with respect to the chamber 45.

The inlet pressure port 31 is connected to the high-pressure line 2|, the exhaust port is connected to the exhaust line or system 22, and the regulating pressure port 39, at the inner end of the passage 39a, communicates through the latter with the regulating pressure line 28.

If the piston valve 40 is moved axially to place the inlet pressure port 31 in communication with the regulating pressure chamber 45, then the regulating pressure increases. On the other hand, if the piston valve moves in the other disu rection to place the exhaust port 38 in communication with such chamber, then such pressure decreases.

Fluid under primary pressure is supplied by the line 24 to the chamber 46 closed by the bel- ,..l0Ws 41 and the first pressure abutment 48. A spring 50 exerts its force on the abutment 48 in opposition to the force of primary pressure exerted thereon. A thrust bearing 5| is arranged between the abutment 48 and the spinner piston 40. With this arrangement, if the primary pressure supplied to the chamber 46 increases,

the force thereof exerted onthe abutment 48 causes the latter to move upwardly against the force of the spring 50 until such time as'the fluid pressure and spring forces are in equilibrium. On the other hand, if the primary pressure decreases, movement occurs in the other direction until equilibrium of forces is established. Movements of the pressure abutment 48, in consequence of changes in primary pressure, are transmitted, through the thrust bearing 5|, to the spinner piston, causing the latter to place the regulating pressure chamber 45 in communicationeither with the inlet pressure port 31 or with the exhaust port 38, depending upon the direction of movement of the piston valve, to eflect change in regulating pressure.

Changes in primary pressure are accompanied by changes in secondary or regulating pressure and the latter are used to restore the piston valve to neutral position. Accordingly, it is necessary to apply to the piston valve a secondary or regulating pressure force in opposed relation to the primary pressure force. To this end, the cylinder 36 extends above the upper piston portion 42 to provide a pressure chamber 52 closed by the second pressure abutment face 53 at the upper end of the piston portion 42 and fluid is supplied to the pressure chamber 52 from the secondary or regulating pressure chamber 45 by a suitable passage, for example, the passage 54. If a change in primary pressure occurs due to change in prime mover speed, then the force applied to the first abutment face 48 changes and the piston valve moves to bring about a change insecondary or regulating pressure, this operation continuing until the regulating pressure attains such a value that the force thereof applied to the second pressure abutment face 53 balances the resultant of the primary pressure and spring forces applied to the abutment 48 with the piston valve restored to neutral position, it being apparent that, for a given change in primary pressure, the change in regulating pressure will depend upon the ratio of the first pressure abutment area 48 to the second pressure abutment area 53. To effect a change in speed setting of the governor, it is merely necessary to adjust the force of the spring 50 by means of suitable speed changing apparatus indicated at 55.

While the apparatus so far described would be satisfactory for ordinary governing operation, the governing or regulating pressure is a function of speed and it would be unsatisfactory for bleeder control unless the total speed change is greatly reduced. This may be readily done with this particular arrangement by the addition of an isochronous connection which causes the primary pressure to be restored to a constant value and the regulating pressure to assume a value dependent on the load.

With isochronous operation, transient speed changes do occur due to changes in load, but the governor operates to restore the speed to a normal value. Accordingly, the piston valve 40 is arranged so that it effects changes in secondary or regulating pressure but its equilibrium or cutoff position is determined entirely by the opposing forces of the spring 50 and of the primary pressure applied to the first abutment face 48, this being the condition for a constant speed as determined by the setting of the spring 50. If a change in load occurs, there is a concurrent but temporary change in speed, which change results in change in primary pressure supplied to the chamber 48. The change in force of primary pressure causes the piston valve to move to effect a change in secondary or regulating pressure, which is applied to the upper or second piston face 53; however, the change in secondary or regulating pressure is applied in a delayed manner to a lower pressure chamber 51 closed by the third pressure abutment face 58 formed at the lower end of the land 43. To this end, the body 35 is provided with a passage 59 affording communication between the upper and lower chambers 52 and 51, the passage having an orifice 60 and a Valve 5|, together with an accumulator or airbell 6 2 communicating with the pressure chamber 51. the temporary and consequent speed change causes the piston valve to move, the secondary or regulating pressure exerting its force on the upper or second pressure abutment face 53 and" tending to restore the piston valve to neutral position; however, if such piston valve were merely restored to neutral, with no additional adjustment, then the speed would be slightly differentdepending upon the regulation or operating range of the governor. passage 59, the orifice 60 and the accumulator is to cause a delayed application of pressure to the lower chamber 51, the pressure in the latter finally coming to equilibrium with that in the upper chamber 52, but, in so doing, the secondary or regulating pressure will be so modified as to effect speed compensation of the turbine at the new load, the speed setting being determined, as already pointed out, by the equilibrium of forces applied to the first pressure abutment 48 with the piston valve in neutral position, the opposed forces applied to the second and third pressure abutment faces 53. and 58: being in equilibrium.

Fluid under secondary or regulating pressure.

supplied to the line 28 is used directly, not only to control the admission valve servo-motor 21, but also the servo-motors 29 and 38 for the bleeder or extraction valves. 21, 29, and 30 are similar in structure and operation except that the servo- motors 29 and 30 are arranged to be subject to an additional. controlling pressure derived from steam pressure.

Referring to the servo-motor 21, this is shown as comprised by a structure or body 68 having" a. cylinder 69 for th operating piston 10 and a cylinder 11 for the piston valve 12, th cylinders 69 and 1| being closed by a cover structure 13. The piston valve cooperates with the pressure port 14 supplied by the line 2| and with the exhaust ports 15 and 16- connected to the drain line 22, the pilot valve 12 being moved to place the pressure and exhaust ports in communication with the cylinder ports 11 and 11a.

The pilot valve 12 is not moved directly by the governing pressure but by an interposed relay device, which, in turn, is controlled by the gover-ning pressure. To this end, the cover 13 has a pressure chamber 18 closed by the pressure abutment face 19, by the upper bellows and by the lower and larger bellows 8|, the force of pressure applied to the abutment face 19 being' resisted by means of the spring 82.

The abutment 19 is connected to a stem 83 whose lower end carries a cup valve 84 covering the axial bore 86 formed in the pilot valve 12, the cup valve 84 being arranged in the pressure chamber 81 into which the upper end of the pilot valve 12 extends so that its top surface provides a pressure abutment face subject to the pressure therein,

Fluid under pressure is preferably supplied to the chamber 81 from the line 2| by means of an orifice 88, preferably formed in the pilot valve. The downward force of pressure supplied to the chamber 81 and acting on the upper end of the pilot valve is opposed by the spring 90 acting on the lower end thereof.

Assuming a change in output pressure supplied by the line 28, then the first effect thereof is to secure movement of the stem 83 andthe cup valve 84, thereby changing the discharge resistance, either by restricting the discharge past the cup valve andthrough the bore 86 orpermit- With a change in load,-

The effect of the The servo-motors.

ting of greater discharge. With change in pressure brought about in this way in the chamber 81, in consequence of movement of the stem and the cup valve, the pilot valve moves in response to such change in pressure to follow the motion of the cup valve and the stem. Movement of the pilot valve establishes communication of the cylinder ports I1 and IIa with the pressure and exhaust ports to effect movement of the operating piston I0, and movement of the latter changes the force of the spring 82, this result being effected by means of the lever 9I pivot-ally connected to the operating piston and providing a support 9Ia for the upper end of the spring. If there is a change in secondary or regulating pressure followed by movement of the operating piston, it will be apparent that movement of the latter will be in such a direction as to change the spring force in such manner as to restore the cup valve 84 to .the position where the pilot valve will be in neutral or cut-off position, whereupon movement of the operating piston ceases.

The servo- motors 29 and 30 are similar to the servo-motor 21 except that the lower bellows elements 8I provide pressure chambers supplied by the transformer lines 33 and 34, so that the associated cup valves assume positions wherein the difference in forces of pressures supplied to the chambers 18 and 18a must be in equilibrium with the force of the spring 82 when the pilot valve is restored to neutral position incident to termination of movement of the operating piston, whereby these servo-motors respond both to the regulating pressure and to control pressures de pendent upon the respective bleeder line pressures.

Referring now to the pressure-regulating transformers, at 3I and 32, these devices are similar to that disclosed and claimed in Patent No. 2,009,418, July 30, 1935. Each of these transformers has a steam line 92 connected to its bleeder line, the steam line supplying steam to a pressure chamber 93 closed by an abutment 94 and a bellows 95, the abutment bearing on a stem 96 connected to the cup 91 having a flange 98 abutting the upper end of a spring 99, the lower end of the latter bearing against the abutment face I00 of the structure IIII.

The cup 91 engages, through the intermediary of a thrust bearing I02, with an upper end of a spinner piston valve I03 in the cylinder I030, and having lands I04 and I05, which just lap the exhaust port I06 and the pressure supply port IIII with respect to the control pressure chamber I08, formed by the reduced portion I09 between thelands and the interior of the cylinder, thev chamber I08 being continuously in communication with the control pressure line 33 or 34.

The secondary or control pressure chamber I08 also communicates, by way of passage III], with the lower pressure chamber I I I closed by the piston abutment face I I2 provided by the lower end of the land I05. The spinner piston I93 is given spinning motion by means of the turbine element II3. The lower end of the spinner piston engages with an abutment II4 through the intermediary of a thrust bearing M, th abutment being sustained by a spring 4b with which cooperates an adjustable abutment 40.

In operation, each pressure-regulating transformer 3I and 32, therefore, receives steam pressure through itsline 92 from the bleeder line and such pressure is transformed into a controlling fluid pressure dependent thereon, the controlling pressure being supplied to the pressure chambers 18a of the servo-motors 29 and 39 and'the trans: formers, at 3I and 32, serving to bring about such control as to maintain the bleeder line sure at a predetermined value.

With the apparatus so far described, it will be apparent that the governor mechanism not only serves to control the admission and distribution of steam in such manner as to maintain the pressure at each bleeder point at a predetermined value with variation in bleeder demand,

presbut also serves to maintain the power developoccurs, the extent of speed change being a measure of the change in load, and the governor' mechanism operates to secure such admission and distribution of steam as will meet the new load condition with the turbine operating at the normal speed. Since, in this way, the governing mechanism is compensated for speed change due to load change, it will be apparent that the secondary or regulating pressure is dependent upon load and may, therefore, be used for controlling all of the regulators.

If it is desired to have the power output of the turbine held at a substantially constant value, as may be the case where the generator of the turbine is tied into an electrical system and it is desired to have the generator carry a definite part of the system load, then the isochronous control arrangement would be ineffective; and, for this reason, provision is made for changing the governing system from the speed compensation type to the load compensation type.

, To this end, a load responsive device is associated with the turbine and it exerts its effect on the governing system in such manner that the latter causes steam to be admitted to the turbine to cause the latterv to deliver a desired power. Accordingly, the generator 9 driven by the turbine has its supply line II5 operating a device, at I'I6, which responds to the power of the generator, thev device being associated with the transformer, at II'I, so as to provide a secondary or load-responsive control pressure supplied by the line I I8 to the transformer, at 26, to secure modification of the operation thereof, as will be immediately pointed out. Therefore, the transformer, at III, responds to a change in electrical output of the generator in such manner as to oppose the change, whereby the electrical output is maintained at substantially a constant value. This arrangement is necessary where the generator is tied into an electrical system and it is desired to have the generator deliver a predetermined output to the system, for, if the governing system were maintained isochronous, then the tendency of the generator to operate synchronously with the system would cause such erratic operation as to result in highly variable electrical output of the generator. With a slight change of the system frequency the generator load would change from no load to full load or vice versa.

When the turbine operates independently of However, when there is a change in load, a temporary speed change an outside power system, two variables are encountered, first load demand, and, second, steam flow demand at the extraction points. Load changes are cared for with no changes in speed, the governing valve and the extraction valves moving in order to maintain the extraction pressures with practically no corrections from the extraction point regulators. Flow changes at either of the extraction points will change the pressure at that particular point which will position the control valve, through the action of the regulator at that point, and the change in steam flow will. change the load-carrying capacity of the turbine and consequently its speed. The governor, with its isochronous device, will position, not only the governor valve, but also the extraction valves to correct the load capacity and also the speed without a secondary correction required from the extraction regulator.

When the installation is connected to an outside power system or to other units in the same plant when the turbine speed is controlled by a characteristic of the system such as a synchronous electrical correction, changes in extraction flow would change the load carried by the turbine. The load regulating device then changes the position of all the valves to enable the unit to carry the same load as before without a secondary resetting action from the extraction pressure regulator.

When the load regulator is used, the pressure responsive to speed changes is constant due to the reasonably constant frequency of a power system. Transformed pressure variations then depend on the pressure from the load-responsive device. An increased load-responsive control pressure will increase the regulating pressure the same amount and move the valves in the closing direction. Therefore, if the steam demand, for example, in the high-pressure extraction line, decreases, the pressure in that line will increase and open the extraction valve and the steam will flow through that part of the turbine and it will pick up load. The low-pressure extraction .point will receive more steam, and, due to the increase in its pressure, will open the grid valve, thereby further increasing the turbine load. The increase in load will increase the load-responsive control pressure of the load regulator and the resultant regulating pressure will close all of the valves until the load is reduced almost to its previous value. A certain amount of load change, due to extraction steam changes, will have to be allowed in order to increase the stability of the system.

The transformer, at H1, is comprised by a body structure II9 having a cylinder I within which is arranged the spinner piston I2I turned by means of a turbine element I22. The cylinder I20 has a pressure port I23 connected to the pressure supply line 2|, an exhaust port I24, and a secondary or control pressure port I25 arranged between the ports I23 and I24. The spinner piston has lands I26 and I2! which just lap the pressure and exhaust ports I23 and I24 with respect to the secondary or control pressure chamber I23 formed by the reduced portion I29 and the interior of the cylinder I20, the chamber I28 being continuously in communicat ion with th control pressure port I25. The upper land I25 has a top pressure abutment face I30 exposed to pressure in the chamber I3I supplied by the branch passage I 32 from the control pressure chamber I20. The force of the spring I34 is exerted on the lower end of the spinner piston, the spring force being varied by the mechanism, at I35. The watt-meter device, at I I6, exerts a magnetic force on the core I36 connected to the spinner piston.

Thus, it will be seen that the spinner piston is subject to opposing forces, an increase in output or power results in increase in the upward force or pull of the core I36 resisted by the spring I34 and the consequent upward movement of the spinner piston causes increase in secondary or control pressure and consequently of the force thereof acting on the piston face I30. This increase in control pressure continues until such time as the force thereof acting on the piston face I30 is sufficient to permit the spring I34 to restore the spinner piston valve to its neutral position. In the event of decrease in magnetic pull, the spring I34 causes the spinner piston to move downwardly bringing about a decrease in load-responsive control pressure and the latter will decrease until the force thereof acting on the abutment face I30 is sufficient to compensate for the change in magnetic force and to restore the spinner piston to neutral or cut-off position.

If the turbine is being operated in a speed compensated manner, without the load-responsive device, at IIG, being effective, any changes in load being first manifested as speed changes and these bringing about readjustments in steam admission and distribution to secure isochronous operation, and, if it is desired to render the loadresponsive device, at IIS, effective, the spring I34 is varied until such time as th pressure in the line I I8, and indicated by the pressure gauge I31, is the same as the regulating pressure indicated by the gauge I38, at which time the valve I39 in the line H8 is opened and the valve BI is closed so that the lower pressure face 58 of the transformer governor is subject to a fluid pressure, which is a function of the setting of the load control device.

To slow up the motion of any of the operating mechanisms 21, 29 and 30 in relation to each other or to the transformer governor, at 26, there are shown needle valves I4I providing restricted communication of the regulating pressure line or header 28 with the pressure chambers I8 of the operating mechanisms, air bells or accumulators I42 being in communication with the chambers I8. Likewise, if desired, a similar arrangement of needle valves I43 and accumulators I44 may be used with the steam pressure responsive regulators 3I and 32 and the pressure chambers 78a of the operating mechanisms 29 and 30, the air bells or accumulators communicating with the chambers 18a. Any or all of these delay devices may be rendered ineffective by suitable opening of the needle valves MI and I43, or relative retarding effects thereof may be secured by appropriate adjustment of the needle valves.

The improved controlling arrangement for a turbine having one or more extraction points operates as follows: Where the turbine is isolated, it is operated isochronously, or with very little speed change due to load change, the regulating pressure or effect from the governor being applied to the admission valve as well as to each extraction point control valve with the result that load changes are cared for with no changes in turbine speed, all of the valves being adjusted by the regulating pressure furnished by the governor with whatever adjustment may be required by such pressure to maintain the predetermined extraction point pressure. A change in flow at an extraction point will change the steam pressure thereat, thereby resulting in operation of the associated regulator to adjust its'control valve and the resulting change in steam flow will change the load-carrying capacity of the 'turbineand consequently speed with the result that the governor response will adjust all of the valves to correct the load-carrying capacity and the speed. When the turbine drives a generator connected to an electrical system and has its speed fixed by a characteristic of the latter, the governor no longer controls the speed but determines the load carrying capacity of the turbine. As long as the flow conditions of the turbine remain unaltered, the load capacity may be changed by adjustment of the speed changer; however, as flow conditions may undergo wide variation with the present type of turbine, it is necessary that the regulating pressure provided by the governor be modified by change in loadcarrying capacity induced by change in extraction flow so as to maintain a narrow range of variation of load-carrying capacity with changes in extraction flow. Therefore, the load control device or regulator, at III, is employed, the latter being sensitive to changes in turbine load capacity to maintain the latter within a small range of variation with the result that wide variations in extraction flow may occur with small changes in load-carrying capacity. The loadcarrying capacity of the turbine is, dependent upon adjustment given to the spring I34 of the load regulator, the force of this spring being subject to variation by the mechanism, at I 35, the spring and the mechanism constituting an arrangement operating as a speed changer to vary the load-carrying capacity of the turbine. As before, the extraction point regulators respond to changes in steam pressure at each extraction point to adjust the control valve thereat; and, in consequence of such adjustment, the load capacity is changed, causing the load regulator to operate to modify the regulating pressure to adjust the valve suitably to the extraction and turbine load capacity requirements with the turbine operating at the same or synchronous speed.

The control system is arranged to provide for change-over from isolated and isochronous operation to synchronous operation or vice versa without stopping the turbine. Assuming that the turbine is operating isochronously and it is desired to change over for load control or synchronous operation, the spring I34 and load regulator is adjusted to change the load control pressure in the passage H8 until it is equalized, with the regulating pressure in the passage 28, the gauges I31 and I38 being provided to indicate these two pressures; and, when the pressures are equalized, the valve I39 in the passage H8 is opened and the valve BI is closed so as to subject the lower pressure abutment or piston face 58 to load control pressure instead of to the isochronous connection lagging pressure.

The control system contemplates a multiplicity of fluid pressures. Primary pressure, which is a function of turbine speed, is supplied to the governor transformer, at 26, and the latter delivers a regulating pressure to the servo-motors, at 21, 29 and 30. The bleeder line transformers, at 3| and 32', each delivers a control pressure, dependent upon bleeder line steam pressure to the servo-motors, at 29 and 30. The load control transformer, at IILdelivers a load-responsivefiuid pressure. As already pointed out, when operating isochronously with the load control transformer, at II'I, isolated from the main governing transformer, the regulating pressure is not a proportional amplification of first or primary pressure but it depends upon load. If there is a change in load, there immediately follows a temporary change in speed and in primary pressure, the change in primary pressure bringing about a change in regulating pressure and the latter change is used to secure such further change or modification of regulating pressure that the admission and extraction valves will be positioned to secure such admission and distribution of steam at the new load condition as to restore the turbine speed to its normal value. When the turbine drives a generator tied into an electrical system and is subjected to load control, a change in turbine power is accompanied by a change in load-responsive control pressure and the latter change acts on the governing apparatus with the result that changes in extraction flow are accompanied by a narrow range of variation in turbine loading capacity; and, as already pointed out, the load capacity may be altered by suitable adjustment of the spring I34 of the load regulator.

While the load-control function achieved by the watt-meter device, at H5, and the associated pressure transformer, at 1, operating in conjunction with the transformer'governor, at 26, is shown applied to a turbine having two extraction lines, two extraction valves, and a pressure regulator for each extraction line, with the admission and extraction valves subject to the load-control modified transformer pressure and with each extraction valve subject to a controlling pressure provided by the associated regulator, it will be obvious that the transformer governor providing load-control modified transformer pressure is applicable just as well to a turbine having a single extraction valve and regulator.

Furthermore, while in Figs. 1 and 2, the pressure regulators each provide a single fluid pressure for the associated extraction valve servomotor, the extraction valves being operated thereby to hold each extraction pressure within narrow limits of variation, any tendency to change in power of the turbine produced by such valve adjustment causing the turbine speed to change in consequence of which the transformer governor adjusts all of the valves for turbine steam flow to maintain the turbine power, adjustment of the valves to maintain the turbine power need not involve turbine speed change to operate the governor to adjust the valves for this purpose. Accordingly, in Fig. 3, there is shown a pressure regulator, for example, the pressure regulator 3Ia, which, instead of providing a single pressure applied only to the servomotor 29a, provides an additional fluid pressure for application to the admission valve servo-motor 21a so that the latter is caused to adjust the steam flow to maintain the carried load without involving speed change and governor operation for this purpose.

In Fig. 3, there is shown an extraction turbine having two extraction lines Ma and I5a, an admission valve I3a, and extraction valves Mia and Fla, with all of the valves controlled jointly by oil under pressure supplied from the transformer, at 26a, and by controlling fluid pressures supplied by the extraction regulators 3Ia and 32a.

In Fig. 3, the transformer governor, at 26c, as Well as the load-responsive transformer, at II'Ia,

suitable pressure source.

cup valve I62 is in covering relation with reare the same as those already described; .how-

ever, the servo-motors 21a, 29a and 30a for .the valves, the extraction regulators .3Ia and 32a and the connections of the latter with respect to the servo-motors differ to provide at least for the regulator 3Ia supplying a fluid pressure acting with the transformer governor to control the ad mission valve servo-motor 21a.

Referring to the admission valve servo-motor, this has the upper and lower bellows elements 80a and BIa differently disposed so as to provide, in addition to the pressure chamber 191) to which the pressure area 19a is exposed, a lower pressure chamber I40 to which the pressure area 1 9b is exposed.

Referring to the extraction valve servo-motors 29a and 3011, the piston valves I4'I thereof have depending rods I42 carrying abutments I43 and having their lower ends connected by springs I44 to the servo-motor follow-up levers I45. Each servo-motor housing or body structure I46, the abutment I43, and the inner and outer bellows elements I41 and I48 provide pressure chambers I49 and I50 to which the pressure or piston areas II and I52 are exposed. Transformed fluid pressure from the transformer governor is supplied to the chambers I49 and the chambers I50 are supplied from the pressure regulators, as will be described.

The pressure regulator 3Ia comprises a pressure chamber I54 connected by a pipe I55 to the extraction line Mr; and is covered by a diaphragm I56 connected to the lever I51 fulcrumed at I58.

,At opposite sides of the fulcrum, springs I59 and I60 are arranged between the lever I51 and relief valves I6I and I62,

The relief or cup valve :IBI is in covering relation with respect to the escape port I63 of the enclosed space provided by the conduit I64 and by the space I40 of the pressure-sensitive element of the admission valve servo-motor, the enclosed space so defined being furnished with oil by means of an orifice I65 from any In like manner, the

spect to the escape port I66 of the enclosed space defined by the conduit I61 connected to the space I49 of the pressure-sensitive element of the extraction valve servo-motor 29a and this enclosed space being supplied by means of an orifice I68 with oil from any suitable pressure source.

From the structure of the regulator 3Ia so far described, it will be apparent that, upon an increase in extraction steam pressure in the line 14a in consequence of a decrease in extraction demand, the diaphragm I56 will be moved upwardly to rock the lever I51 in a clockwise direction, thereby decreasing the force of the spring I59 and increasing that of the spring I60 to decrease the pressure in the conduit I64 and to increase that in the conduit I61, the decrease in pressure in the conduit I64 operating on the admission valve servo-motor 21a to move the admission valve in a closing direction and the increase in pressure in the conduit I61 operating on the extraction valve servo-motor 29a to move the extraction valve I6a in an opening direction in order to maintain the extraction pressure in the extraction line I4a within narrow limits of variation. If the extraction pressure should decrease in consequence of increased extraction demand, then the contrary operation would take place, the admission valve I3a moving in an opening direction and the extraction valve I6a moving in a closing direction.

As the valves I3a and I6a are operated in opposite directions to hold the extraction pressure in the line I4a substantially constant, it will be apparent that this result is obtained with the aggregate power developed by the sections of the turbine to which steam is admitted by the valves I3a and I6a also held substantially constant, any reduction in power of the first turbine section in consequence of movement of the admission valve I3a in a closing direction being compensated for by increased power of the second turbine section to which steam is admitted by the valve I6a and vice versa.

While the pressure regulator 3Ia and the transformer governor, at 26a, are adequate to meet variable power and extraction demands if the turbine is of the single extraction type, that is, has only the single extraction line I4a, the pressure regulator 3la providing oppositely varying fluid pressures with one pressure imposed on the admission valve servo-motor pressure-sensitive element and the other pressure imposed on the extraction valve servo-motor pressure-sensitive element, where the turbine is of the doubleextraction type, as illustrated, if, assuming the external load of the turbine to be constant, a variation in extraction demand of the first extraction line I4a should tend to change the extraction pressure in the second extraction line I5a, the regulator 32a would respond to change in pressure in the second extraction line to bring about modification of flow conditions in the turbine to maintain the power developed and delivered thereby substantially constant and to keep the second extraction pressure within a very narrow range of variation.

While the pressure regulator 32a might be of the same type as the regulator 3Ia, in which event both regulators would mutually contribute to controlling the servo-motors for the valves Ifia and [1a, as disclosed in Patent No. 2,262,559, dated November 11, 1941, and assigned to the Westinghouse Electric & Manufacturing Company, such regulator is shown as providing only a single hydraulic pressure which is supplied only to the servo-motor 30a for controlling the sec- .ond extraction valve Ila.

The pressure regulator 320: includes a pressure chamber I10 having a conduit I'II connected to the second extraction line I5a and closed by a ,the enclosed space including the conduit I10 and the pressure space I49 of the pressure-responsive device of the servo-motor 30a, the other pressure space I53 thereof being supplied with fluid under transformed pressure from the transformer governor, at Thus, it will be seen that the servo-motor 3% is controlled in response to the opposing eiiects of operation of the pressure regulator 32a and of the transformer governor, at 26a.

Assuming that the external load of the turbine is held constant and that the extraction demand of the second extraction line 15a should increase, thereby causing decrease in extraction pressure, such decrease will bring about decrease in fluid pressure in the conduit I'i8 and the space I 50, whereupon the valve I10, will be moved in a closing direction so as to increase the flow to the second extraction line I5a to minimize any change in pressure therein. On the other hand,

if the extraction demand should decrease in the second extraction line I5a, the contrary operation would take place, the servo-motor 30a being caused to operate to open the extraction valve IIa so as to limit any increase in the extraction pressure.

While operation of the second extraction valve IIa in this way to minimize variation in extraction pressure in the second extraction line I5a causes the flow in the third or final section of the turbine to vary, and consequently the power developed thereby to vary, any tendency of this variation to vary the total power of the turbine will result in operation of the transformer governor, at 26a, to cause all of the valves to be operated to maintain the power without disturbing the pressure in either extraction line.

As already described in connection with Figs.

1 and 2, in Fig. 3, the apparatus is also provided with the wattmeter device, at IIIia, for controlling the operation of a second transformer, at Illa, to provide for load control of the transformer governor, at 25a.

While the wattmeter devices, at H and Ilfia,

and the associated pressure transformers, at H! and Ta, have been described as being responsive to the output of the generator 9, it will be obvious that such wattmeter device and its transformer may be connected in Various ways to maintain the total power of a local circuit sub- .very narrow range of variation irrespective of the power demand of the region, at I8I, variations in the latter being cared for by variations in power supplied from the system I82.

In Fig. 5, instead of the wattmeter device and the associated pressure transformer exerting its effect on the governor transformer to keep the generator output substantially constant, it is arranged in the local circuit I80 and acts on the transformer I I! to exert a controlling effect on the transformer governor 26 so as to vary the turbine and generator output such that the input to the local circuit I80 from the system I82 is held substantially constant.

Thus, the arrangements in Figs. 4 and 5 provide for satisfying the power requirements of the plant or region I8I in opposite ways. In Fig. 4, the turbine and generator output is held substantially constant and variations in power demand are provided for by variations in input to the local circuit from the system I82, while, in Fig. 5, the input from the electrical system to the local circuit I80 is held substantially constant and the output of the generator is varied to meet the power demand.

While the invention has been shown in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

I claim:

1. The combination with a steam turbine driving agenerator, the turbine including one or more extraction points, an admission'valve, and a control valve at each extraction point; of a governor operated by the turbine for controlling all of said valves, means responsive to change in generator output induced by change in flow at an extraction point to modify th efiect of said governor in order to minimize the range of variation in generator output with variations in extraction flow, and means providing for adjustment of the last-named means to vary the generator output.

2. The'combination with a steam turbine driving a generator, the turbine having one or more extraction points and provided with an admission valve and a control valve at each extraction point; of operating devices for the valves, a governor for controlling the operation of the operating devices, means responsive to steam pressure at each extraction point to effect operation of the associated control valve operating devices so as to maintain the extraction point pressure substantially constant, means responsive to change in generator output induced by extraction flow change to adjust the governor to effect operation of said operating devices to effect adjustment of the valves in order to maintain the generator output within a small range of variation with changes in extraction flow, and means providing for adjustment of the lastnamed means to vary the generator output.

3. The combination with a steam turbine provided with one or more extraction points, an admission valve and a control valve at each extraction point; of a governor providing a regulating effect for adjusting all of said valves, means responsive to steam pressure at each extraction point to regulate the control valve thereat, means effective when the governor determines the turbine speed to modify the regulating effect to correct'the speed of the turbine for changes in load so that the turbine operates substantially at the same speed for different loads, means effective when the turbine speed is controlled independently of the governor to modify the regulating effect incident to change in load-carrying capacity of the turbine induced by change in extraction point flow to minimize the range of variation in load-carrying capacity with variations in extraction point flow, and means for rendering either of said modifying means effective.

4. The combination with a steam turbine having one or more extraction points and provided with an admission valve and a control valve at each extraction point; of pressure-responsive devices for adjusting said valves, a governor providing a regulating pressure for said devices, a speed changer for the governor and operative to adjust said regulating pressure, means effective when the governor determines the turbine speed to modify the regulating pressure to effect speed correction with changes in turbine load, means effective when the turbine speed is controlled independently of the governor to modify the regulating pressure incident to change in load-carrying capacity of the turbine induced by change in extraction point flow to minimize the range of variation in load-carrying capacity with variations in extraction point flow, and means for rendering either of said modifying means effective.

5. The combination with a steam turbinehaving one or more extraction points and provided with an admission valve and a control valve at each extraction point; of pressure-responsive operating devices for the valves, a governor providing a regulating pressure for said operating devices, first means effective when the turbine speed is controlled by the governor to modify the regulating pressure so as to effect speed correction with load changes, second means effective when the turbine speed is controlled in dependently of the governor to modify the regulating pressure in response to changes in turbine load-carrying capacity to secure operation of the control devices to adjust the valves in order to maintain the load-carrying capacity of the turbine Within a narrow range of variation, means for rendering either said first or second means effective, and means providing for adjustment of said second means to vary the turbine load-carrying capacity.

6. In a steam-operated prime mover having one or more extraction points, an admission valve, a valve for controlling the flow of steam along the prime mover at each extraction point, means providing a first fluid pressure dependent upon prime mover speed, means responsive to said first fluid pressure to provide a second fluid pressure, means providing a third fluid pressure for each extraction point and dependent upon the steam pressure thereat, means responsive to prime mover power to provide a fourth fluid pressure, means utilizing said fourth pressure to secure modification of the second pressure, means responsive to modified second pressure for controlling the admission valve, and means responsive to the joint effect of modified second pressure and of the third pressure of each extraction point for controlling the valve associated with the latter.

7. In a steam-operated prime mover having one or more extraction points, an admission valve, a valve for controlling the flow of steam along the prime mover at each extraction point, means providing a first fluid pressure dependent upon prime mover speed, means responsive to said first fluid pressure to provide a second fluid pressure and opposed by a spring, means for varying the force of the spring, means providing a third fluid pressure for each extraction point and dependent upon the steam pressure thereat, apparatus responsive to prime mover power to provide a fourth fluid pressure, means utilizing said fourth pressure to secure modification of the second pressure, means responsive to modified second pressure for controlling the admission valve, means responsive to the joint effect of modified second pressure and of the third pressure of each extraction point for controlling the valve associated with the latter, and means providing for adjustment of said apparatus to vary the relation of power to fourth pressure.

8. In a steam turbine having one or more extraction points, an admission valve; a valve for controlling the flow of steam along the turbine at each extraction point; a pressure-responsive device for controlling each valve; means providing fluid under first pressure varying as a function of the turbine speed; means providing a second fluid pressure including a piston valve movable in one direction to increase the second pressure and in the other direction to decrease such pressure; means providing a third fluid pressure dependent upon steam pressure at each extraction point; means for subjecting the admission valve pressure-responsive device to the influence of second pressure and each extraction valve pressure-responsive device to the joint in fluence of second pressure and the corresponding third pressure; means for exerting force on said piston valve to secure axial movements thereof to vary the second pressure and including first, second and third pressure abutment faces and a spring; means for supplying fluid under first pressure for action on the first pressure abutment face; means for supplying fluid under second pressure for action on the second pressure abutment face; means responsive to power output of the turbine to provide fluid under fourth pressure; and means for supplying fluid under fourth pressure to said third abutment face.

9. In a steam turbine having one or more extraction points, an admission valve; a valve for controlling the flow of steam along the turbine from each extraction point; pressure-responsive devices controlling said valves; means providing fluid under first pressure varying as a function of the turbine speed; a pressure transformer providing fluid under second pressure and including a piston valve movable in one direction to increase the second pressure and in the other direction to decrease the latter; means providing a third fluid pressure dependent upon the steam pressure at each extraction point; means for rendering all of the pressure-responsive devices responsive to second pressure and also each extraction point valve pressure-responsive device responsive to the corresponding third fluid pressure; means for moving said transformer piston valve and including first, second, and third pressure abutment faces and a spring; said second and third pressure abutment face being so disposed that the forces of fluid pressure applied thereto are in opposed relation, said first and third pressure abutment faces being so disposed that the forces of fluid pressures applied thereto are in like directions, and the spring being so disposed that the force thereof opposes the force of pressure applied to the first abutment face; means for supplying fluid under first pressure for action on the first pressure abutment face; means for supplying fluid under second pressure for action on the second pressure abutment face; apparatus for maintaining the power output of the turbine within a desired range of variation and including means responsive to turbine power to provide fluid under fourth pressure; means for supplying fluid under fourth pressure for action on said third pressure abutment face and including a passage with a valve for opening and closing the latter; and means providing for adjustment of said apparatus to vary the relation of turbine power to fourth pressure so that the latter may have a desired value immediately before opening said valve and so that the turbine power output may be varied after said transformer is made responsive to fourth pressure.

10. In a steam turbine having one or more extraction points, an admission valve; a valve controlling the flow of steam along the turbine from each extraction point; pressure-responsive devices controlling said valves; means providing fiuid under first pressure varying as a function of the turbine speed; a pressure transformer providing fluid under second pressure and including a piston valve movable in one direction to increase the second pressure and in the other direction to decrease the latter; means providing a third fluid pressure dependent upon the steam pressure at each extraction point; means for rendering all of the pressure-responsive devices responsive to second pressure and also each extraction point valve pressure-responsive device responsive to the corresponding third fluid pressure;-meansfor moving saidtransformerpi-ston valve and including first, second, and third pressure abutment facesand a spring; said second andthird pressure: abutment face being so dis- -posed that the forces of fluid pressure applied thereto are in opposed relation, said first and thirdpressure abutment faces being so disposed that the forces of fluid pressures applied thereto are in like directions, and the spring'being so disposed-that the force thereof opposes the force. of pressure applied to the first abutment face;

means for supplying fluid under first pressure for action on the first pressure abutment face; mean for supplying fluid under second pressure for action on the second pressure abutment face; i means including a first passage provided with an orifice forsupplying fluid under second'pressure for action on thethird abutment face; an

- accumulator in communication with said passage between'the orificeand the third abutment face;

apparatus for maintaining the power output of the turbine within'a desired range of variation and including meansresponsive to turbine power to provide fluid -.under fourth pressure; means forsupplyingnfluid under fourth pressure for action on sai'd'third pressure abutment face and including a second passage; and valves provided for opening and closing of the first and second passage.

ILQInasteam turbine having one or more extraction points, an admission valve; a valve controlling the flow of steam along theturbine from eachextraction point; pressure-responsive devices controlling said valves; means'providing fluid under first pressure varying as a function r of 'the turbine speed; a pressure transformer providing 'fluidunder second-pressure and including apiston valve-movable in-one direction to increase the-second pressure and in the'other direction to decrease the latter; meansproviding a thirdfiuid pressure dependent upon the steam pressure at each extraction point; means for rendering all of the pressure-responsive devices responsive to second pressure and also eachextraction point valve pressure-responsive device responsive tothe corresponding third fluid pressure; means for --moving said transformer piston valve and including first,'second, and third'pres- -sure abutment faces and -a spring; said second and third pressure abutment face being of equal areas and so disposed that the forces of fluid pressure applied thereto are in opposed relation,

said first and third pressure abutment faces being so disposed that the fonces of fluid pressures ap-l pliedjthereto are in like directions, and the spring .being so disposed that the force thereof opposes thefforce of pressureapplied to the first abutment face; means for supplying fluid under second pressurejfor action on the second pressure abutment face; means including a first passage prorvidedlwith. an orifice'for supplying fluid under secondpressure to the third abutment face; an

. accumulatoriin communication with said passage .between theorifi'ce and the third abutment face: apparatus for-maintaining the power output of .the turbine within a desired range of variation 4. and including means-responsive to turbine power .t provide fluid under fourthlpressure; means for rsupplyingifluidgunder fourth pressure for action on said I third pressure abutment face and in- "cluding a secoridpassage; valves for opening and closing of the -first-and second vpassages; and

means providing-for adjustmentof said apparatus to 'vary the r-elation of turbine power to fourthpressure so that the latter may be equal- 'ized' with second pressure before ithev valve for the second passage is opened.

12. In a steam turbine having one or more extraction points, an admission valve; a valve .con-

trolling the flow of steam along the turbine from each extraction point; pressure-responsive devices controlling said valves; means providing fluid under first pressure varying as a function of the turbine speed; a pressure transformer providing fluid under-second pressure and including. a: piston valve movablein one direction to increasethe second pressure and in the other direction todecrease the latter; means providing a thirdfluid' pressure dependent upon the steam pressure at each extraction point; "means for rendering all of the vpressure-responsive idevices responsive to second pressurean'd also each .extraction point valve pressure-responsive device responsive to the corresponding third fluid pressure? means for moving said transformer piston valve and including first, second. and third. pressure abutment faces and a spring; said second and third pressure abutmentface being of equal areas and'so disposed that the forces'of fluid pressure applied thereto are in opposed-relation,

said first andthird pressure abutment faces being so disposed that the forces of fluid pressures appliedthereto are in' like directions, andthe spring being so disposed that the force thereof opposes theforce of pressure applied to the'firstabutment face; means for supplying fluid under'first pressure for action on the'flrst pressure-abutment face; means for supplying fluid under second pressure for action on the second pressure abutment face; means including a first passage provided with an orifice for'supplying fluid'under second pressure for action on thethird abutment face; an accumulator in communication with said passage between the orifice and the third abutment face; apparatus for maintaining the power output of the turbine within a desired range of variation and including means responsive to turbine power to provide fluid under fourth pressure; means for supplying fluid under fourth pressure for action on said third pressure abutment face and including a second passage; valves for opening and closing of the first and second passages; pressure gauges for indicating second and fourth pressures; and means providing for adjustment of said apparatus to vary the relation of turbinepower to fourth pressure so that the latter may be equalized with second pressure before'the valve for the second passage is opened.

13. In a steam turbine having one or more extraction points, anadmission' valve; a valve controlling the flow of steam along the turbine from each extraction point; pressure-"responsive devices controllingsaid valves; means providing fluidunder firstpressure varying as a function of theiturbinespeed; afirst pressuretransformer 7 providing fluid under second pressureand'including a piston valve movable in one direction to invcrease the second pressure andin the other di- Hrection-to decreasethe latter; means providing a 5 l third fluid pressure dependent upon the steam pressure at each extraction point means for rendering all ofthe pressure-responsive devices responsive to second pressure and also-each extraction point valve pressure-responsive device responsive to the corresponding third fluid pressure; means for moving said transformer piston-valve and including first second, and third pressure abutment faces and a spring; said secondand third pressure abutment face being of equal areas and so disposedithatcthe forces of fluid pressure applied thereto are in opposed relation, said first and third pressure abutment faces being so disposed that the forces of fluid pressures applied thereto are in like directions, and the spring being so disposed that the force thereof opposes the force of pressure applied to the first abutment face; means for supplying fluid under first pressure for action on the first pressure abutment face; means for supplying fluid under second pressure for action on the second pressure abutment face; means including a passage provided with an orifice for supplying fluid under second pressure for action on the third abutment face; an accumulator communicating with said passage between the orifice and the third abutment face; a second transformer providing fluid under fourth pressure and including a piston valve movable in one direction to increase the fourth pressure and in the other direction to decrease the latter; apparatus for moving the second piston valve including means responsive to turbine power and a spring; means for adjusting the force of said lastnamed spring; means for supplying fluid under fourth pressure for action on said third pressure abutment face and including a second passage; and valves providing for opening and closing of said first and second passages.

14. The combination with an electrical system connected to a local circuit and a generator connected to the local circuit, of a steam turbine having one or more extraction points, an admission valve, an extraction valve at each extraction point, means operated by the turbine to provide a force dependent upon turbine speed, means for transforming changes in said force into changes in fluid pressure, means for operating the admission and extractionvalves in response to transformed fluid pressure and for operating each extraction valve in response to extraction steam pressure, and means for modifying the transformed fluid pressure including a device responsive to the power transmitted in a portion of said local circuit to secure such development and de livery of power to the local circuit by the connected turbine and generator that the power transmitted by said portion of the local circuit is held within a narrow range of variation.

15. The combination with an electrical system connected to a local circuit and a generator; connected to the local circuit, of a steam turbine having one or more extraction points, admission and extraction valves, means operated by the turbine to provide a force dependent upon turbine speed, means for transforming changes in said force into changes in fluid pressure, means responsive to extraction steam pressure to provide fluid under pressure, means responsive to transformed fluid pressure and to fluid pressure provided in response to abstraction steam pressure to operate each of said valves, means for modifying the transformed fluid pressure including a watt-meter device responsive to the power transmitted in a portion of said local circuit to secure such development and delivery of power to the local circuit by the connected turbine and generator that the power transmitted by said portion of the local circuit is held within a narrow range of variation.

16. The combination with an electrical system connected to a local circuit and a generator connected to the local circuit, of a steam turbine having one or more extraction points, admission and extraction valves, means operated by the turbine to provide a force dependent upon turbine speed, means for transforming changes in said force into changes in fluid pressure, means responsive to extraction steam pressure to provide controlling fluid pressures for the respective valves, means responsive to fluid under transformed pressure and to fluid under a controlling pressure to control the operation of each of said valves, a device connected to a portion of the local circuit and operative to provide a force dependent upon the power transmitted thereby, means for transforming changes in the lastnamed force into changes in fluid pressure, and means for applying changes in the last-named transformed fluid pressure to said first transformer means to modify the transformed fluid pressure delivered thereby.

17. The combination with an electrical system connected to a local circuit and a generator connected to the local circuit, of a steam turbine having one or more extraction points, admission and extraction valves, means operated by the turbine to provide a force dependent upon turbine speed, a first transformer for transforming changes in said force into changes in fluid pressure, means responsive to extraction steam pressure to provide controlling fluid pressures for the respective valves, means responsive to fluid under transformed pressure and to fluid under a controlling pressure to control the operation of each of said valves, a second transformer for transforming force changes into fluid pressure changes, a device connected to a portion of said local circuit for exerting force on the second transformer, a spring exerting its force on the second transformer in opposition to that of the device, and means for applying the last-named fluid pressure and changes therein to said first transformer to modify the transformed fluid pressure delivered by the latter.

18. The combination with an electrical system connected to a local circuit and a generator connected to the local circuit, of a steam turbine having one or more extraction points, admission and extraction valves, means operated by the turbine to provide a force dependent upon turbine speed, a first transformer for transforming changes in said force into changes in fluid pressure, means responsive to extraction steam pressure to provide controlling fluid pressures for the respective valves, means responsive to fluid under transformed pressure and to fluid under a controlling pressure to control the operation of each of said valves, a second transformer for transforming force changes into fluid pressure changes, a Wattmeter device connected to a portion of said local circuit for exerting force on the second transformer, a spring exerting its force on the second transformer in opposition to that of the wattmeter device, means for applying the last-named fluid pressure and changes therein to said first transformer to modify the transformed fluid pressure delivered by the latter, and means providing for adjustment of said spring to vary the force exerted thereby on the second transformer.

ANTHONY F. SCHWENDNER.

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