US2178497A - Governor apparatus - Google Patents

Description

Oct. 31, 1939. A. F. SCHWENDNER 2,178,497

GOVERNOR APPARATUS Filed June 9, 1938 INVENTOR Humour F. Scuwsunnsn 'V B M ATTORNEY WITNESSES:

P atented Oct. 31, I939 li'fiii STATE GQVERNOR APPARATUS Anthony Schwendner, ssington, Pa, assignor to Westinghouse Electric &

Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylvania Application June 9, 1938, Serial No. 212,650

19 Claims.

My invention relates to a power plant installation where the power demand is met jointly by an electric supply line and a local prime mover and it has for an object to provide a control system effective to cause substantially all variations in power demand above a predetermined demand to be taken by prirnemover.

Another object oi my invention is to provide a plant installation where the power demand is met jointly by an electrical supply line and a local prime mover, together with a control system including governor controlling the prime mover and means responsive to change in electrical power when the latter exceeds a desired point to vary the speed setting of the governor so that variations in total power demand may then be largely taken by the prime mover.

A further object of my invention is to provide a power installation in which the power demand is met jointly by an electric supply line and a prime mover together with a control system including a governor for ti" e mover and means responsive to change electrical power for adjusting the governor to cause the prime mover to deliver more or less power together with means for changing over the governor from response entirely to its speed to joint response of the electrical power and the prime mover.

A further object of my invention is to provide a power pie it insteuation wherein the power demand met jointly by an electric supply circuit and prime mover together with control mechanism for ca variations in power demand to be largely by the prime mover and which is adjustable to vary the part of the demand met by the electric supply.

In many instances, the demand for electrical power may be more economically met if variations in power above a predetermined demand are carried. by a prime mover, for example, a steam turbine. In accordance with the present invention, automatic controlling mechanism is provided for securing this result, the control mechanism including a governor for the prime mover and responsive to change in power demand for ting the setting of the governor in order hat turbine may take substantially all changes above a predetermined point. control apparatus should provide for ready connection of the pr me mover in joint relation with the electrical supply; and, for this reason, the governor for the prime mover and the device responsive to change in power demand are so related that a characteristic of the governor and a characteristic of the device responsive to change The,

in power demand may be brought to the same value in order that the prime mover may have its governor shifted over from control entirely by the p" mover to joint control by the latter and electric supply. more particularly, the control apparatus for the prime mover includes a pressure responsive device controlling the admission of motive fiuid thereto and a first pressure transformer responsive to prime mover speed for delivering a reguletting pressure to the pressure responsive device together with a second transformer responsive to the electrical power of the supply circuit for delivering a controlling pressure to said apparatus for modifying the operation thereof. A further i ature is the adjustable power setting for the second transformer. A further object of my invention is to provide control mechanism having the foregoing advantageous features of construction and of operation.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which: 5

T is a view of a power installation and show 1g essential parts of the control system in section.

Referring now to the drawing, there is shown, at a local circuit for supplying the power of a plant and the like, power for the local circuit being supplied jointly by the supply line, at ii, and the generator 52, the latter being driven by the prime mover, for example, a steam turbine 53. A control system is associated with the supply line, at it, the prime mover it so that the power demand of the electrical supply circuit, at l i, may be kept substantially constant, any variations in the local power demand being largely taken. care of by the prime mover, that is, the total power demand of the local circuit, at It, is supplied partly by the supply circuit, at H, and by the prime mover it, the control system operating to maintain the part of the demand satisby the supply circuit substantially constant or within very narrow limits with variations in the demand carried largely by the prime mover.

Referring now more particularly to the control system, the prime mover i3 is provided with an 5 admission valve l l controlled by a servo-motor, at it, operated by means of a transformer governor, at it.

The prime mover or turbine provides fluid under primary pressure varying substantially as the square of its speed by means of a pressure developer of the reversed-flow impeller type, such as disclosed and claimed in the patent to Bryant 2,G35,689 granted March 31, 1936, the device comprising, in general, an impeller 58 driven by the turbine and constituting a source of pressure for supplying r'iuid through the orifice E9 to the pressure passage 29, the pressure in the latter varying substantially as the square of the speed of the turbine due to the cooperation of the inclined centrifugal escape passage 2i formed in the turbi e rotor and in communication with the passage 2d.

The control apparatus for the admission valve M includes the pressure developer delivering fluid under primary pressure to the transformer, at H, to operate the latter to supply, through the passage iiuid under regulating or secondary pressure to the pressure-responsive device, at it, for controlling the admission valve.

The supply circuit, at i i, has associated therewith a second pressure transformer, at 25, which functions, as hereinafter pointed out, tosupply a secondary or controlling pressure dependent upon the electrical power of the supply circuit, such controlling pressure being supplied to the aforesaid control apparatus to modify the latter so that variations in total power demand of the local circuit are carried very largely by the turbine, whereby a substantially constant load factor may be preserved for the supply circuit, at H.

The first transformer, at H, is more particularly described and claimed in my application, Serial No. 193,487, filed March 1, 1938, and assigned to the Westinghouse Electric & Manufacturing Company. In general, this apparatus comprises a cylinder 26 formed in the body 26a having a pressure port 21, an exhaust port 28 and a regulating pressure port or chamber 29. The spinner piston 35, preferably being given spinning motion by means of a turbine element 32, has piston portion or lands 33 and 34 arranged to place the regulating pressure port 29 in communication either with the pressure port 2? or with the exhaust port 28; and, as the pressure port 2? is connected to a source of fluid under pressure by means of the conduit 35 supplied, for example, by means of the impeller IE, it will be apparent that the regulating pressure of the port 29 and the connected passage 23 may be varied.

The lower end of the spinner piston 35 has thrust bearing engagement, at 36, with respect to the pressure abutment 37 connected by the bellows 38 to the upper wall of the chamber 39, fluid under primary pressure being supplied to the latter by means of the passage 25 so that fluid under primary pressure may act on the pressure abutment 3?. to provide a primary pressure force acting on the spinner piston, such primary pressure force being opposed by the force of the spring it and by means of fluid pressure forces as will be immediately described.

The spinner piston valve 3| has upper and lower pressure abutment faces 52 and :23 forming closures for the pressure chambers Mi and respectively. The body structure 2611 is provided with a passage 46 for connecting the regulating pressure port 29 to the upper pressure chamber 4 with a passage ll which connects the regulating pressure port, for example, by Way of the chamber 44, with the lower pressure chamber 45, the passage i'l having an orifice i3 therein and an accumulator Q9 communicating with the passage M at the discharge side of the orifice. To compensate for leakage and consequent departures in pressure in the lower chamber 45 from those desired, the body 26a is preferably provided with a bleeder port or passage 45a and a valve 4%.

As pointed out in my application, aforesaid, the passages and accumulator provide for standard and isochronous operation. For ordinary or standard operation of the governor, only regulating pressure is applied to the upper chamber 44, the passage 'll being interrupted by closure of the valve lla; and, for isochronous operation, fiuid from the regulating source is supplied to the upper chamber it and is supplied to the lower chamber 45 through the passage ll and the orifice 48, the accumulator 49 exerting its effect at the downstream side of the orifice.

The regulating pressure is supplied by the passage 23 for controlling the servo-motor apparatus, at it, for example, as disclosed and claimed in my application, aforesaid, the servonnotor apparatus, at it, preferably using the regulating pressure supplied by the passage 23 for the operation of a relay, the latter in turn, securing operation of the pilot valve of the servo-motor. To this end the servo-motor apparatus, at it, includes a pilot valve 52 which controls communication of the pressure and drain lines and 53 with the upper and lower admission and exhaust ports 54 and 55 of the operating cylinder 56 having an operating piston ill therein, which is operatively connected to the valve i l by the rod 58 and the lever 59.

Preferably, the pilot valve 52 of the servo-motor is rendered efiective by means of a relay so that the regulating pressure supplied by the line 23 merely has to exert a controlling effect, the force for securing movement of the pilot valve being supplied by other means. To this end I show the cover structure 6% of the operating cylinder and the pilot valve cylinder provided with an expansible chamber El closed in a liquid-tight manner by a pressure abutment and upper and lower bellows elements 63 and G l, the bellows element 63 being smaller than the element 64 so as to provide a pressure abutment or piston area 65 subject to regulating pressure supplied by the line 23.

The force of pressure acting on the area 65 is resisted by the spring connected at its lower end to the upper end of the stem 61' of the pressure abutment {i2 and at its upper end to the floating lever 38 having one end fulcrumed at 69 and its other end pivotally connected to the rod 58. Thus, it will be seen that the pressure abutment G2 and its stem ill will occupy an equilibrium position where the force of regulating pressure applied to the area is balanced by the force of the spring Q6.

The lower end of the stem t! has a cup valve l2 arranged in the pressure chamber '53 and in covering relation with respect to the axial bore or passage i l formed in the pilot valve 52, the upper end of the pilot valve providing a pressure abutment face "it? exposed to pressure existing in the chamber Iii. Fluid under pressure is supplied to the chamber i3 from the pressure line 35 through an orifice '85 preferably formed in the pilot valve. The force of pressure in the chamber 13 acting on the piston area 75 of the pilot valve is resisted by means of a spring 'll abutting the lower end of the latter.

With the arrangement described, whenever the position of the cup valve is changed, the pilot valve 52 moves because its equilibrium position is determined by equilibrium of the force of fluid pressure acting on the area 15 with the force of the spring Tl.

When the cup valve 12 is moved, the pressure existing in the chamber 13 is immediately changed because of the restricted supply through the orifice l6 and the relatively greater change in escape resistance by the cup valve and through the bore 14.

If the cup valve moves upwardly, or in a di rection away from the pilot valve 52, then the pressure in the chamber 13 rapidly diminishes, with the result that the then preponderating force of the spring l'l is effective to move the pilot valve upwardly, such valve continuing to be moved until the escape of fluid by the cup valve and through the bore is reduced sufliciently to restore equilibrium pressure in the chamber 13.

On the other hand, if the cup valve should move downwardly, the pressure of fluid in the chamber 73 would build up and the force thereof preponderating over the spring Tl would result in downward movement of the pilot valve and increase of the force of the spring 'i due to compression thereof, the pilot valve coming to a stop with stopping of the cup valve because of the equilibrium condition of the forces of the pressure in the chamber 73 and of the spring 'il.

Thus, it will be seen that the pressure abutment 62 and the stem (il with the connected cup valve 72 move whenever the equilibrium of forces of the spring 65 and of regulating pressure acting on the area 65 is disturbed, this movement being immediately followed by movement of the pilot valve 52 in the same direction and to the same extent due to pressure forces acting thereon and controlled by movement of the cup valve.

Assuming a change in load and a consequent change in speed of the turbine, then the primary pressure in the passage 26 immediately changes, such change in primary pressure acting, through the transformer, at H, to secure a larger change in regulating pressure in the line 23, the changes in primary and regulating pressures being dependently related as determined by forces thereof acting on the spinner piston valve. If there is a change in primary pressure, since the piston area 3? is larger than the area 42, restoration of the spinner piston valve to neutral cut-ofi position will only occur when the fluid pressure forces acting on the spinner piston valve together with the spring lil are again in equilibrium, it being necessary for the regulating or secondary pressure to change until it bears such relation to the primary pressure that the value thereof times the piston area 42 shall be equal to the value of the primary pressure times the area of the piston face 3! minus the effect of the spring ill. In other words, the regulating or secondary pres sure is larger than the primary pressure in the ratio of the area of the piston face 3'1! to the area of the piston face 42.

Whenever change in regulating pressure in the line 23 occurs because of change in turbine load, the abutment 52 moves for reasons hereinbefore given, this movement of the abutment 62 and its connected cup valve 12 being followed by movement of the pilot valve 52 and connection of the passages 54 and 55 with the pressure and exhaust so that fluid under pressure is supplied to one side of the operating piston 5i and exhausted from the other. Due to the connection of the lever 68 with the piston rod 58, just as soon as the operating piston 57! starts to move, change in force of the spring 66 is initiated, the arrangement being such that the spring force is changed in such a direction as to restore the cup valve 12 to the position corresponding to the neutral or cut-off position of the pilot valve 52.

Referring to the transformer, at 2%, associated with the supply line, this includes a housing structure 88 having a cylinder 8| therein and a spinner piston 82 fits in the cylinder, the spinner piston having piston portions or lands 83 and 84 normally covering the exhaust port 85 and the pressure port 86, the spinner piston being recessed or reduced at 81 between the piston portions to provide a controlling pressure port 88 in communication with the controlling pressure line 7.5. If the spinner piston is moved, controlling pressure in the line 25 will change, upward movement of the piston resulting in decrease in pressure because of the port 88 being placed in communication with the exhaust port 85 and downward movement resulting in increase in pressure because of the controlling pressure port 88 being placed in communication with the pressure supply port 86. The lower end of the cylinder 8| is formed to provide a pressure chamber 89 in communication, by the passage 99, with the controlling pressure port 88 or the controlling pressure passage 25, and the lower piston portion 84 has its lower face 9! presenting a piston abutment or pressure area to the chamber 89.

The spinner piston is preferably turned by means of a turbine element 93 so as to avoid the effects of static friction.

The position of the spinner piston 82 is de pendent upon equilibrium of forces acting thereon, such forces being due to the magnetic pull of the watt meter device, at 95, acting on the core 95, the latter being attached to the upper end of the spinner piston, by the force of the tension spring 9'! operatively connected to the lower end of the spinner piston and by the force of controlling pressure acting on the piston area 9i.

Assuming a change in electrical power, then the magnetic force acting on the core 96 changes and equilibrium of forces on the spinner piston is disturbed and the spinner piston moves until restoration of equilibrium is obtained.

If the electrical power of the line, at H, increases, the upward force acting on the core 96 increases and the spinner piston moves upwardly against the force of the spring 9'1, thereby placing the controlling pressure port 88 in communication with the exhaust port 85 and reducing the controlling pressure, this reduction in output pressure continuing until the force thereof acting on the piston area 9! is reduced sufficiently to restore equilibrium of forces acting on the spinner piston, at which time the latter will occupy its neutral cut-off position. On the other hand, if there is a decrease in electrical power the contrary operation will take place, the spinner piston moving downwardly because of decreased magnetic force and causing an increase in controlling pressure, the movement continuing until the controlling pressure reaches such a value that equilibrium of forces acting on the spinner piston is restored with the latter in neutral cut-off position.

Assuming that the local circuit, at It, is being supplied both by the supply line, at H, and by the turbine l2 then the effect of the transformer, at 2 is as follows: The spinner piston of the primary pressure transformer, at IT, is maintained in equilibrium by forces acting thereon including the force of the controlling pressure supplied by the line 25 to the chamber 45. There fore, if the controlling pressure'in' the controlling pressure line 25 should change, then equilibrium of forces acting on the spinner piston of the transformer, at IT, is disturbed and such spinner piston moves in such a manner as to restore the equilibrium of forces acting thereon.

If the electrical power should increase, bringing about reduction in controlling pressure in the line 25, then the upward force acting on the spinner piston 3| would be reduced to the extent of the change in pressure acting on the piston area 43, in consequence of which the spinner piston 3| would move downwardly to place the regulating pressure port 20 in communication with the exhaust port 28, thereby bringing about reduction in regulating pressure in the line 23 and consequent operation of the servo-motor, at I8, to open the valve I4 wider, whereby a slight increase in electrical power is followed by a relatively much greater increase in prime mover power. On the contrary, if the total power de mand should decrease, then the decrease is very largely taken by the prime mover. Thus, it will be seen that the change in electrical power is only that required to secure operation of the control mechanism, that is, the total change in electrical power amounts merely to a regulating range.

The effect of increase in pressure in the supply line 25 of the transformer, at 24, is to decrease the speed setting of the transformer governor, at I I. As long as the power demand of the local circuit I0 is less than that for which the transformer, at 24, is set, the pressure in the line 25 will be kept sufficiently high to maintain the speed setting of the transformer governor, at H, such that the latter operates to provide for minimum steam admission to the turbine, if the latter is in operation, the pressure in the line 25 decreasing as the power demand increases; and, when the power demand reaches a predetermined point, determined by the setting of the spring 9! of the transformer, at 24, the pressure in the line 25 will be reduced to such a value and consequently the speed setting of the transformer governor, at IT, will be decreased to such a point, that the transformer governor then becomes effective to control the turbine such that further increases in power demand are largely carried by the turbo-generator, there being only such small increases in power from the supply line, at. II, as are necessary to exert a controlling effect through the line 24 on the transformer governor, at H, to continue decreasing the speed setting of the latter, with increases in power demand, until the turbo-generator is operating at maximum load. Thus, it will be seen that, aside from the part of power demand of the local circuit I0 that is carried by the turbo-generator, increases in power demand of the latter are carried by the supply circuit II until the power supplied by the latter is effective to reduce the pressure in the line 25 and to decrease the speed setting of the transformer governor, at Ill, such that the latter is then effective to cause the turbine to carry the major portion of any increase in load demand, the supply circuit II then carrying only such part of the increase in load demand as is necessary to operate the transformer at 24, to continue de reasing the speed setting of the governor, at I'I, such that the turbine continues to carry the major portion of increase in power demand until the latter is operating at maximum capacity. I

To make the application of the apparatus somewhat clearer, assume that it is desired to hold the electrical load, for example, approximately at 10,000 kw., that the maximum local load demand is about 20,000 kw., and that the base load for minimum steam admission of the turbine is 2,000 kw., the turbine having the capacity of about 10,000 kw. For local load demands of, say 9,500 kw. or less, the supply line, at II, would be relied upon; on the other hand, if the local demand should exceed this figure, as is the usual case intended with this arrangement, then both the supply line, at II, and the steam turbine It would have to be depended upon. With the turbine in operation and its generator properly connected, then there would be a supply of approximately 9,500 kw., on the line II and 2,000 kw. from the turbine, making a total of 11,500 kw., and, at the maximum load, there would be a supply of 10,000 kw. on the line, at II, and 10,000 kw. from the turbine. In other words, in the example given, a change of 500 kw. in electrical load is sufficient to bring about adjustment in the turbine from its minimum or base condition to its maximum power output condition.

The change in electrical power of the supply line, at II, for the entire power change depends upon the characteristics of the transformer and of the watt meter device, the only effect in change of force of the spring 9'! being to determine the point at which the transformer, at 24, becomes effective. Under the conditions above referred to, it is assumed that the transformer starts to operate whenever the electrical load in the line, at H, exceeds 9,500 kw. By adjustment of the spring 9'l, the point at which the transformer, at 20, becomes effective may be changed, but the necessary range of electrical load or power, namely, 500 kw., for the entire range of control by the transformer remains the same. For example, the spring 91 might be adjusted so that the transformer becomes eifective at any other value than 9,500 kw.

The force of the spring 91 is adjusted by means of the threaded rod 98 engaged by a worm gear 99 operated by a worm I00 or the spring may be adjusted by means of the hand wheel IOI, which has the effect of turning the stem 98 and causing the latter to screw up or down in the worm wheel 90.

If the turbine and the generator are in oper- D ation and it is desired to connect the generator to the local circuit without shock or load disturbance and have the turbine under controlof the load responsive transformer, at 24, than the latter must be coordinated to the governor transformer, at IT. To this end, the regulating pressure space of. the transformer, at IT, is provided with a pressure gauge I03 and the controlling pressure passage 25 of the transformer, at 24, is provided with a pressure gauge I04. The passage 41 of the governor transformer is opened and closed by the valve Na and communication of the passage 25 with the chamber 45 is opened and closed by a valve I00.

Assuming that the turbine is operating and being controlled, either standard or isochronously, dependent upon the nature of local conditions, and it is desired to subject the transformer governor, at IT, to load control, then the operator ad-' justs the spring 0? until the pressure gauges I03 and I04 have the same indication and then the valve I06 is opened to supply fiuid under the controlling pressure of the load control transformer, at 24, to the lower chamber 45 of the first transformer, the pressure in the latter chamber being zero, if operating standard, or at a value dependent upon instantaneous load conditions, if operating isochronously. lI'he valve l'la is closed after the valve tilt is opened.

From the foregoing, it will be apparent that I have provided, for a power installation in which the power demand is met jointly by a local prime mover and by an electrical supply circuit, controlling mecha ism for the prime mover which operates to cause changes in power demand to be largely takenby the prime mover. The control mechanism includes apparatus responsive to speed of the prime mover for controlling the ad-' mission of motive fluid thereto together with means responsive to a power characteristic for modifying the apparatus so that changes in power demand may be largely taken by the prime mover. Preferably, there is provided means responsive to the electrical power input for applying an impulse to the apparatus to secure this result.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various modifications and changes without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

I. In a power plant installation, means for supplying electrical power to meet part of the power demand of the installation, a prime mover for meeting the remainder of the power demand, a governor for controlling the admission of motive fluid to the prime mover, means responsive to power supplied by said electrical supply means to the installation for obtaining a controlling eiiect, and means utilizing the controlling efifect to control the speed responsiveness of the governor.

2. In a power plant installation, means for supplying electrical power to meet part of the power demand of the installation, a prime mover for meeting the remainder of the power demand, a governor for controlling the ission of motive fluid to the prime mover, means responsive to power supplied by said electrical supply means to the installation for obtaining a controlling effect, means for securing variation in the controlling eifect in relation to the supplied electrical power, and means utilizing the controlling effect to control the speed responsiveness of the governor.

3. In a power installation, means for supply ing electrical power to the installation for meeting part of a power demand or the latter, prime mover apparatus for supplying the remainder of the power demand, means for controlling the prime mover apparatus comprising means providing fluid pressure varying as a function of the speed of the apparatus, means for controlling the admission of motive fluid to said apparatus in response to said fluid pressure, and means responsive to electrical power supplied to the installation for providing a fluid pressure that is variable in accordance with variation in the demand and for modifying the action of said control means in response thereto, whereby, until a predetermined load demand is reached, variations in demand are carried by the electrical supply means, and, at and above the predetermined demand, variations in demand are carried by the prime mover apparatus with only such small "the admission of motive fluid to the prime mover, means responsive to power supplied by said electrical supply means for obtaining a controlling effect, and means utilizing the controlling eiTect to control the speed responsiveness of the governor.

5. In a power plant installation, a local circuit, means for supplying alternating electrical power to the circuit to meet a part of the power demand of the installation, means for meeting the remainder of power demand of the installation includ an alternating current generator connected said circuit and a print-e mo or driving the generator, a governor for controlling the admission of motive fluid to the prime mover, means including a ring acting in opposition to electrical power supplied by the electrical supply means to obtain a controlling effect, means utilizing the controlling effect to control the speed responsiveness of the governor, and means providing for adjustment of the spring,

6. In a power plant installation, means for supplying electrical power to meet part of the power demand of the installation, a prime mover for meeting the remainder of the power demand of the installation, pressure-responsive means for controlling the admission of motive fluid to the prime mover, means for obtaining a governing force dependent upon the speed of the prime mover, means for obtaining a controlling force dependent upon electrical power supplied by said electrical supply means to the installation, means utilizing said forces to obtain a regulating pres sure, and means for applying the regulating pres sure to said pressure-responsive means.

'7. In a power plant installation, a local circuit, means for supplying alternating electrical power to said circuit to meet part of the power demand or" the installation, means for meeting the remainder of the power demand of the installation and including an alternating current generator connected to said circuit and driven by a p ne mover, pressure-responsive means for conti ng the admission of motive fluid to the prime mover, means providing a first fluid pressure dependent upon prime mover speed, means includspring acting in opposition to a force dependent upon the power supplied by said electrical supply means to obtain a second fluid pressure, means utilizing said first and second fluid pressures to obtain a regulating pressure and for apply the latter to the pressure-responsive means, and means providing for adjustment or" the force of said spring.

8. In a power plant installation, a local circuit, means for supplying alternating current electrical power to the circuit to meet part of the power of the installation, means for meeting the remainder of the power demand of the instaln and includin a generator connected to the circuit a prime mover for driving the generator, pressure-responsive means for controlling the admission of motive fluid to the prime mover such that with an increase in pressure the supply of motive fluid is restricted and Vice versa, means for obtaining a first fluid pressure dependent upon prime mover speed, means including a spring acting in opposition to a force dependent upon power supplied by said electrical supply means to the installation to obtain a second fluid pressure such that the second fluid pressure decreases as the electrical power increases and vice versa, means including piston areas facing in the same direction and acted on by said first and second fluid pressures to provide a regulating pressure such that with an increase in the resultant force of first and second pressures applied to said piston areas the regulating pressure increases and vice versa, and means providing for adjustment of the force of said spring.

9. In a power plant installation, a local circuit, a generator supplying the local circuit, a prime mover driving the generator, a governor controlling the admission of motive fluid to the prime mover, means providing for standard operation of the governor wherein a small percentage of speed regulation occurs from no load to full load of the prime mover or for isochronous operation thereof, a supply circuit for supplying electrical power to the local circuit, means responsive to power supplied from the supply circuit to the local circuit to develop a controlling effect, and means for applying said controlling effect to said governor with the latter operating standard or isochronously.

10. In a power plant installation, a local circuit; a supply circuit connected to the local circuit for meeting at least part of the power demand of the latter; means for meeting the remainder of the power demand of the local circuit including a generator connected to the local circuit and a prime mover driving the generator; an admission valve for the prime mover; apparatus for controlling the admission valve including pressure-responsive actuating means for the latter, a first transformer including an element movable to provide a regulating fluid pressure, and a conduit for conducting fluid under regulating pressure to the actuating means; means for developing and applying governing force to said movable transformer element; means for applying a force to said element in opposition to the governing force and dependent upon said regulating pressure; a second transformer including an element movable to provide a controlling pressure; a conduit for conducting fluid under controlling pres sure to said controlling apparatus to modify the action thereof; means for applying force to the second transformer movable element dependent upon electrical power supplied by said supply circuit; a spring exerting its force on the second transformer movable element in opposition to the force dependent upon supplied electrical power; and means for applying to the second transformer movable element a force dependent upon controlling pressure and acting in opposition to the force of said spring.

11. In a power plant installation, a local circuit; a supply circuit connected to the local circuit for meeting at least part of the power demand of the latter; means for meeting the remainder of the power demand of the local circuit including a generator connected to the local circuit and a prime mover driving the generator; an admission valve for the prime mover; apparatus for controlling the admission valve including pressure responsive actuating means for the latter, a first transformer including an element movable to provide a regulating fluid pressure, and a conduit for conducting fluid under regulating pressure to the actuating means; means for applying force to said element and. dependent upon the prime mover speed; a spring having its force applied to said element in opposition to the first force; means for applying to said element a force opposed to the first force and dependent upon regulating pressure; a second transformer including an element movable to provide a controlling pressure; a conduit for conducting fluid under controlling pressure to said controlling apparatus to modify the action thereof; means for applying force to the second transformer movable element dependent upon electrical power supplied by said supply circuit; a spring exerting its force on the second transformer movable element in opposition to the supplied electrical power force; means for applying to the second transformer movable element a force dependent upon controlling pressure and acting in opposition to said spring; and means for adjusting the setting of the last-named spring.

12. In a power plant installation, a local circuit; a supply circuit connected to the local circuit for meeting at least part of the power demand of the latter; means for meeting the remainder of the power demand of the local circuit including a generator connected to the local circuit and a prime mover driving the generator; an admission valve for the prime mover; apparatus for controlling the admission valve including pressure responsive actuating means for the latter, a first transformer including an element movable to provide a regulating fluid pressure, and a conduit for conducting fluid under regulating pressure to the actuating means; means for applying force to said element and dependent upon the prime mover speed; a spring having its force applied to said element in opposition to the first force; means for applying to said element a force opposed to the first force and dependent upon regulating pressure; a second transformer including an element movable to provide a controlling pressure; a conduit for conducting fluid under controlling pressure to said controlling apparatus to modify the action thereof; means for applying force to the second transformer movable element dependent upon electrical power supplied by said supply circuit; a spring exerting its force on the second transformer movable element in opposition to the supplied electrical power force; means for applying to the second transformer movable element a force dependent upon controlling pressure and acting in opposition to that of said spring; and means for adjusting the settings of the first and second transformer springs.

13. In a power plant installation; a local circuit; a supply circuit connected to the local circuit for meeting at least part of the power demand of the latter; means for meeting the remainder of the power demand of the local circuit including a generator connected to the local circuit and a prime mover driving the generator; an admission valve for the prime mover; apparatus for controlling the admission valve including pressure responsive actuating means therefor, means developing a governing force, a first pressure transformer responsive to said governing force to provide a regulating fluid pressure, and a conduit for furnishing fluid under regulating pressure from the transformer to the pressure responsive actuating means, said first transformer including a cylinder having a pressure port connected to a source of fluid under pressure, an exhaust port, a regulating pressure port connected to said. conduit, and a piston valve for placing the latter port in communication either with the pressure port or with the exhaust port to provide the regulating pressure; said piston valve having an abutment area arranged so that the force of pressure applied thereto is in opposition to said governing force and said cylinder providing a pressure chamber for the abutment area; a passage for supplying fiuid under regulating pressure to said chamber; a second transformer including a cylinder having a pressure port connected to a source of fluid under pressure, an exhaust port, a controlling pressure port, and a piston valve for placing the latter port in communication either with the pressure port or with the exhaust port to provide for a controlling pressure; means responsive to electrical power supplied by said sup ply circuit for applying a force to the piston valve of the second transformer; said piston valve of the second transformer having a pressure abutment face and the second transformer cylinder providing a pressure chamber for the pressure abutment face; a passage for supplying fluid under controlling pressure to the last-named pressure chamber: a spring acting on the second transformer piston valve so that its force balances the resultant of the electrical load and controlling pressure applied thereto; and a conduit for supplying fluid under controlling pressure to said apparatus to modify the action thereof.

14. In a power plant installation: a local circuit; a supply circuit connected to the local circuit for meeting at least part of the power demand of the latter; means for meeting the remainder of the power demand of the local circuit including a generator connected to the local circuit and a prime mover driving the generator; an admission valve for the prime mover: apparatus for controlling the admission valve including pressure responsive actuating meons therefor, means for developing a governin: force. first pressure transformer responsive to governing force to provide fiuid under regulating pressure, and a conduit for furnishin fluid under regulating pressure from the transformer to the pressure responsive actuating means: said first transformer including a cylinder having a pressure port, an exhaust port: a regulatin pressure port connected to said conduit, and a piston. valve for placing the latter port in communication either with the pressure port or with the exhaust port to provide the regulating pressure; said pi."- ton valve having an abutment area arranged so that the force of pressure applied thereto in opposition to said governing force and said cylinder providing a pressure chamber for the abutment area; a passage for connecting said regulating pressure port and the chamber; a sec nd transformer including a cylinder having a pressure port connected to a source of fluid under pressure, an exhaust port, a controlling pressure port, and a piston valve for placing the latter port in communication either with the pressure port or with the exhaust port to provide for the controlling pressure; means responsive to electrical power supplied by said supply circuit for applying a force to the piston valve of the second transformer; said piston valve of the second transformer having a pressure abutment face and the second transformer cylinder providing a pressure chamber for the pressure abutment face; a passage for supplying fluid under controlling pressure to the last-named chamber; a spring acting on the second trans-former piston valve so that its force balances the resultant of the electrical load and controlling pressure force; means for varying the force of the spring; a conduit for supplying fluid under controlling pressure to said apparatus to modify the action thereof; and means providing for said pressure responsive means responding either to the regulating pressure or to the resultant effect of the regulating and controlling pressures.

15. In a power plant installation, a local circuit; a supply circuit connected to the local circuit for meeting at least part of the power demand of the latter; means for meeting the remainder or" the power demand of the local circuit including a generator connected to the local circuit and a prime mover driving the generator; pressure responsive means for controlling the prime mover; means operated by the prime mover for developing a force which is a function of its speed; a first transformer including a cylinder having a pressure port connected to a source of fluid under pressure, an exhaust port, a regulating pressure port, and a piston valve for placing the latter port in communication either with the pressure port or with the exhaust port to provide fluid under regulating pressure; means for applying said iorce to the piston valve; said piston valve having first and second opposed pressure abutment areas and the first area being arranged so that the force of pressure applied thereto is in opposition to said first force and said cylinder providing first and second pressure chambers for the areas; first and second passages for connecting said regulating pressure port and said first and second chambers and the second passage having an orifice therein; accumulator communicating with the second passage and the second chamber at the second-chamber side of the orifice; means including a spring and the resultant of pressure forces acting on said first and second pressure abutment areas of the piston for opposing said first force; a second transformer including a cylinder having a pressure port connected to a source of fluid under pressure, an exhaust port, a controlling pressure port, and a piston valve for placing the latter port in communication either with. the pressure port or with the exhaust port to provide for a controlling pressure; means responsive to electrical power supplied by said supply circuit for applying a force to the piston of the second transformer; said piston of the second transformer having a pressure abutment face and the second transformer cylinder providing a pressure chamber for the pressure abutment face; means acting on the piston valve of the second transformer in opposition to the electrical power force and including a spring and a passage for supplying fluid under controlling pressure to said pressure chamber of the second transformer; means for adjusting the force of the last-named. spring; a first conduit connecting the regulating pressure port of the first transformer and said pressure responsive device; a second conduit for connecting the controlling pressure port of the second transformer with said second chamber; and valves providing for opening and closing of said second passage and said second conduit.

16. The combination as claimed in claim 15 with pressure gauges for the second passage and the second conduit.

17. In a power plant installation, a local circuit; a generator supplying the local circuit; a prime mover driving the generator; means operated by said prime mover for developing a governing force; means for transforming said governing force to fluid under regulating pressure and providing a source of fiuid under such pressure; the last-named means including a cylinder having supply, exhaust and regulating pressure ports and a piston valve having piston portions cooperating with said ports; means responsive to regulating pressure to control the admission of motive fluid to the prime mover; said piston valve having opposed first and second piston areas with the first area disposed so that the force of pressure applied thereto opposes the governing force; means cooperating with said first and second piston areas to provide first and second expansible and contractible chambers; a first passage for supplying fluid under regulating pressure to said first chamber; a second passage connecting said regulating pressure source and the second chamber; means providing an orifice in said second passage; an accumulator communicating with the second. chamber; a supply circuit for supplying electrical power to the local circuit; means responsive to power supplied from the supply circuit to the local circuit for developing a controlling fluid pressure; a conduit for supplying fluid under controlling pressure to said second chamber; and valves providing for the opening and closing of said second passage and the conduit.

18. In a power plant installation, a local circuit; a generator supplying the local circuit; a prime mover driving the generator; means operated by said prime mover for developing a governing force; means for transforming said governing force into a regulating pressure and providing a source of fluid under regulating pressure; the lastnamed means including a cylinder having supply, exhaust and regulating pressure ports and a piston valve having piston portions cooperating with said ports; means responsive to regulating pressure to control the admission of motive fluid to the prime mover; said piston valve having opposed first and second piston areas with the first area so disposed that the force of pressure applied thereto opposes the governing force; means cooperating with said first and second piston areas to provide first and second expansible and contractible chambers; a first passage for supplying fluid under regulating pressure to said first chamber; a second passage connecting said regulating pressure source and the second chamber; means providing an orifice in said second passage; an accumulator communicating with the second chamber; a supply circuit for supplying electrical power to the local circuit; means responsive to power supplied from the supply circuit to the local circuit for developing a controlling fluid pressure; means for adjusting the lastnamed means to secure variation of the controlling pressure with reierence to the power supplied; a conduit for supplying fluid under controlling pressure to said second chamber; and valves for opening and closing said second passage and said conduit.

19. In a power plant installation; a local circuit; a generator supplying the local circuit; a prime mover driving the generator; means operated by said prime mover for developing a governing force; means for transforming said governing force into a regulating pressure and providing a source of fluid under regulating pressure; the last-named means including a cylinder having supply, exhaust and regulating pressure ports and a piston valve having piston portions cooperating with said ports; means responsive to regulating pressure to control the admission of motive fiuid to the prime mover; said piston valve having opposed first and second piston areas with the first area so disposed that the force of pressure applied thereto opposes the governing force; means cooperating with said first and second piston areas to provide first and second expansible and contractible chambers, a first passage ior supplying fluid under regulating pressure to said first chamber; a second passage connecting said regulating pressure source and the second chamber; means providing an orifice in said second passage; an accumulator communicating with the second chamber; a supply circuit for supplying electrical power to the local circuit; means responsive to power supplied from the supply circuit to the local circuit for developing a controlling fluid pressure; means for adjusting the last-named means to secure variation of the controlling pressure With reference tothe power supply; a conduit for supplying fluid under controlling pressure to said second chamber; pressure gauges associated with said regulating pressure source and with said conduit for indicating regulating and controlling pressure values; and valves for opening and closing said second passage and the conduit and so arranged as not to interfere with the operation of said pressure gauges in response to regulating and controlling pressures.

ANTHONY F. SCHWENDNER.

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