US2243225A - Anticipator apparatus - Google Patents

Description

May 27, 1941.

Filed Sept. 8, 1939 5 a mm N au mmm 3 am an 8 .3

3 QQ/ r u 3 Q 3 I 8 1% we o s &\g 1|! 0 0 I Patented May 27, v1941 ANTICIPATOR APPARATUS Anthony F. Schwendner, Bidley Park, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, 2a., a corporation of Pennsylvania Application September 8, 1939, Serial No. 293,883

10 Claims.

object to provide anticipating apparatus responsive to sudden load drop to close the prime mover admission valve to prevent overspeeding of the prime mover to such an extent that the emergency governor would be operated to close the throttle valve, the prime mover governing mechanism regaining control of the admission valve at the lower speed level.

In Grlscom et al. Patent No. 2,000,753, May 7, 1935, and assigned to the Westinghouse Electric 8: Manufacturing Company, there is disclosed and claimed apparatus of the watt-meter type which operates in an anticipatory manner to close the prime mover admission valve in case of sudden load drop to prevent overspeeding sufficient to operate the emergency governor and trip the throttle valve for closing. While thisapparatus may be timed to permit the governor to regain control of the turbine at the lower load level, it is desirable to supplement the performance of this function by hydraulic means, which, in response to sudden load drop, furnishes fluid pressure which supersedesthe governor control of the admission valve and brings about closing of the latter and which, independently off'the watt-meter device, provides for release oi' the anticipating fluid pressure after a predetermined time interval. Accordingly. a further object of my invention is to provide a hydraulic antich pating apparatus responsive to sudden. load drop for furnishing anticipating pressure to supersede the governor in control of the admission valve in order to close the latter, the anticipating ap paratus includingmeans providing." for release of the anticipating pressure after a predetermined short time interval in order that the gov ernor may regain control of the admission valve at the lower load level.

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

The figure isja longitudinal sectional view of a prime mover having my improved control mechanism applied thereto. a

Referring to the drawing more in detail, there is shown an electrical system including the leads.

ll of the generator ll driven by the turbine I2 having an admission valve 13 and a throttle valve ll. A is well known in the art and as shown on the drawing, the throttle valve normally 28 and it escapes from the chamber throng reduced, the supply being restricted by the or held open by fluid pressure acting on a piston it and opposed by a spring it, the fluid pressure being relieved in the event of overspeeding of the turbine by means of emergency governing mechanism, at ll, so that the spring or biasing means It is effective to close the throttle valve quickly. The present invention is concerned with governing mechanism, at l8, which normally controls the admission valve i3 and anticipating apparatus,'-at it, which supersedes the governor in control of the admission valve in case of sudden load drop.

Preferably, the governing mechanism, at it, and the anticipating apparatus, at H, exert their controlling efiects on the servo-motor, at 28, which operates the admission valve 53-.

Referring first to the servo-motor, this n cludes an operating cylinder 25 with an. open ing piston 22 therein, the operating piston haw ing a stem 23 whose upper end connr ted by means of the lever 24 to the ad ssicn valve is. Motive fluid is admitted and exhausted. apps site ends of the operating cylinder means a pilot valve 25.

The governing and anticipa x pressures are preferahl move the pilot valve means for effecting movemer motive means for purpose 26 acting upwardly against the lower e pilot valve and fluid pressure ie cl and whose force acts down end of the valve. Fluid an plied to the chamber through a.

restricted o annular orifice defined but-he cup valve 29 the upper end of the pilot valve and then p through the drain passage 3! formed in the l 0-- ter.

With this arrangement, if the cup valve 2 moved upwardly, pressure in chambe 2":

flce 28, and the spring 28 causes the piston v to follow the cup valve. On the other hand, the cup valve 29 is moved downwardly, thereby restricting the annular orifice area, the pressure builds up in the chamber 2! and causes the piston valve 25 to move downwardly., Thus, it will be seen, that the disturbance of fluid pressure in the chamber 2! brought about by movement of the cup valve is ensued by following movement of the piston valve in order to reestablish equilibrium of forces acting thereon.

The relay or cup valve 29 is operated by pressure-responsive-means, at I2, subject to governing and hydraulic pressures as will be herein-after pointed out.

The pressure-responsive means, at 32, is comprised by a chamber 33 formed in the housing structure 34, the chamber having the smaller and larger bellows 35 and 36 therein, the upper end of the smaller and the lower end of the larger bellows being attached to the structure 34 and the adjacent ends being connected to the movable abutment 38 presenting the annular pressure abutment or piston area 39. Thus, it will be seen that the bellows 35 and 36, the movable abutment 38, and interior walls of the chamber 33 provide a pressure chamber to which fluid under pressure is admitted from the governing mechanism, at l8, and the anticipating apparatus, at E9, the chamber having a small vent 4i for the escape of trapped air and gases.

The governing mechanism, at [8, and the anticipating apparatus, at i9, have fluid passages 43 and 44 for furnishing fluid under regulating and anticipating pressures, respectively, to the pressure chamber 33 of the pressureresponsive device, at 32, pressure changes being applied to the pressure abutment 38 connected, by means of the stem 45, to the cup valve 29. If there is an increase in pressure to the chamber 33, the cup valve 29 is moved downwardly, bringing about downward movement of the pilot valve 25, upward movement of the operating piston 22 and movement in a closing direction of the admission valve 13. If the pressure decreases, movements take place in the opposite direction and the admission valve I3 is opened Wider.

Movement of the operating piston 22 is also utilized by the follow-up mechanism, including the lever 46 and the link spring 4'! between the lever and the upper end of the stem 45, to restore the cup valve 29 to such a position that the pilot valve 25 will be brought to neutral to terminate movement of the operating piston 22 and the admission valve, that is, assuming a change in load and a consequent change in regulating pressure supplied by the passa e 43 to the chamber 33, with movements of the piston valve, the operating piston, and the admission valve, as just pointed out, such movements occm with change in the force of the spring 41 and they will continue until the force of the latter is in equilibrium with the force of the changed fluid pressure acting on the abutment 38 with the cup valve 29 in a position conresponding to neutral of the piston valve in order to terminate valve adjusting operation.

The fluid pressure passages 43 and 44 are connected, by automatic valve means, to the pressure chamber 33, such valve means providing for communication of the passage of higher pressure with such chamber. As shown, the valve means is comprised by an elongated chamber 5| whose upper and lower ends communicate with the passages 43 and 44 and whose intermediate portion is connected, by means of the passage 52, with the pressure chamber 33 and a ball valve 53 is arranged in the elongated chamber. With this arrangement, it will be apparent that, in the absence of pressure supplied to the passage 44, or if the pressure in the passage 44 is below the regulating pressure furnished by the governor, at l8, to the passage 43, the ball valve 53 will occupy its lowermost position, closing the discharge end of the passage 44 and eiiecting communication between the passage 43 and 52; on the other hand, if anticipating pressure is developed, such pressure being normally substantially greater than the maximum regulating pressure, the ball valve will be lifted, interrupting communication of the passage 43 with the'chamber 33 and placing the passage 44 in communication with the latter chamber, whereby the relatively large anticipating pressure acts on the pressure-responsive relay, at 32, to render the servo-motor, at 20, effective to close the admission valve l3.

Referring now to the governor, at 18, for furnishing fluid under regulating pressure to the passage 43, this is preferably of the pressure transformer type, that is, it responds to a primary or controlling force dependent on prime mover speed to provide a regulating pressure having definite relation with respect thereto. For example, the means for securing the primary or controlling force is shown as comprising a pressure chamber defined in part by the movable abutment 56 and the bellows 51 and to which fluid under pressure varying substantially as the square of the speed of the prime mover turbine is supplied from the reverse-flow impeller, at 58, the force of such pressure acting on the abutment 56 abainst the force of the spring 59 whose tension may be adjusted by the speed changer 60.

A member Bl has its lower end arranged in abutting relation with respect to the abutment 56 and it cooperates with suitably arranged ports to provide the regulating pressure. For example, the member 8! may take the form of a spinner piston, the spinner piston valve having spaced lands 62 and $3 fitting in the cylinder 54 and normally just lapping pressure and exhaust ports 65 and 66, respectively, so as to interrupt communication thereof with the regulating pressure port 61, the regulating pressure port communicating with the conduit or passage 43 and also communicating, by way of the branch passage 68, with the upper end of the cylinder 84 so that regulating pressure acts on the upper piston area 69 provided by the upper land 62.

With this arrangement, if there is a change in speed, the governing pressure supplied to the chamber 55 changes and the abutment 56 moves to move the spinner piston valve; however, just as soon as the latter moves a very slight amount, depending upon the direction of movement, either the pressure port 65 or the drain port 66 is placed in communication with the regulating pressure port 61 to increase or decrease the regulatin pressure and the regulating pressure will change until the force thereof acting on the piston area 69 may restore the spinner piston valve to neutral position, that is, until the force of regulating pressure acting on the piston area 69 is brought into equilibrium with the force of governing pressure acting on the piston area 56,'a change in governing pressure being accompanied by a relatively larger change in regulating pressure in the ratio of the area 55 to the area 69.

Referring now' to the anticipating device, at l9, responsive to a predetermined rate of change in decline or drop in load, the generator outlet leads l0 have associated therewith a watt-meter control device 12 of well-known construction, such as shown and described more in detail in said patent to Griscom et al., which serves to open and to close the D. C. circuit 13 including the winding '14, the operation being such that the circuit is closed when the rate of change of decline in load of the generator exceeds a predetermined value; and, it such rateof change is suilioiently great, as in the case of load drop, then the D. C. circuit is closed and the winding or solenoid 14 is energized to pull the core 18 downwardly for the purposes to be immediately described.

The core 15 is connected to a lever 18 having one end fulcrumed, at 11, and its other end pivoted, at 18, to the upper endoi the rod 18 connected to the piston valve 88 in the piston valve cylinder II of the body 82. A spring 83 exerts an upward force on the rod 18 opposing the downward magnetic pull of the solenoid". The structure 82 has a port 84 communicating with the cylinder 8| and connected to the pressure supply line' 85and with a port 88 spaced a suitable distance from the port 84 and communicating withthe drain passage 81.

The structure 82 also has a port 88 having one end communicating with the cylinder 8| between the ports 84 and 88 and having its other end communicating with the lower annular enlargement 88'of the piston valve cylinder 88, the piston valve cylinder having an intermediate enlargement 82 arranged above the enlargement 88 and a,- top enlargement 83. The lower end of the piston valve cylinder 88 communicates with the cylinder 84.

A piston 85 is arranged in the cylinder84and it is connected to a piston'valve 88 having upper and lower lands 81 and 88. A spring 88 acts downwardly on the piston 85 to move the latter and .the piston valve downwardly if unopposed. The passage 88 is connected by a branch .passage' L88 with the space of the cylinder below the piston 85, the passagehav-ing an adjustable In the event of generator load drop, the solenoid' '14 pulls the piston valve 88 to:place the pressure supply port 84 in communication with the passage 88; and, with the-piston valve 88 in the position shown, fluid'will pass from the lower enlargement 88 to the intermediate enlargement 82 and then past the check valve I82 to the passage 44, the anticipating pressure so developed superseding theregulating pressure and causing the servo-motor, at 28, to close the ad- Y mission valve.

Just as soon as anticipating pressure is appliedin the passages 88 and 44 in this manner, it is also effective in the passage I88 and gradually builds up in the cylinder 84 beneath the piston 85, as determined by the setting of the orifice |8I the efiect of pressure building up underneath the piston 85 being to move the piston valve 88 upwardly until the land 88 interrupts communication of the enlargement 88 with the enlargement 82, whereupon, due to cut-oi! of the passage 44 from the passage 88, the supply of pressure to the passage 44 is terminated and the regulating pressure furnished by the governing mechanism, at l8, regains control of the pressure-responsive servo-motor, at 28.

When the rate of change declines to a pre determined small or zero value, that is, when the lower load level is reached, the spring 83 moves the pilot valve 88 back to its normal position shown on the drawing, and, in which position, it interrupts communication of the pressure port 84 with the passage 88.

'I'he'pilot valve 88 has a bore I85 and radial ports I88 providing for the escape of oil accumulating in the lower end of the cylinder 8| and which would otherwise impede movement of sure or force acting on the pressure-responsive servo-motor, at 28, to control the position of the admission valve I3, so that, with an increase in load, opening of the valve is increased and vice versa. In the event of sudden load drop such that the governing mechanism, at I8, would not move the admission valve I3 in a closing direction quick enough to prevent overspeeding of the turbine l2 and consequent tripping of the emergency governing apparatus, resulting in stoppage of the turbine and requiring restarting of the latter and reconnection of its generator to the line, the anticipating apparatus, at I8, is employed to close the admission valve l3 just as soon as a predetermined rate of change or decline in 'loaddr'op occurs. The watt-meter device 12 responds immediately to load drop, bringing about completion of the D. C. circuit 18 to provide an anticipating forcefwhich supersedes the governing force and closes the admission valve. Preferably, the circuit 13, when closed, energizes the solenoid 14, in consequence of which the. device, at I8, is rendered eifective to supply fluid under anticipating pressure through the passage 44 to the lower end of the valve chamber 5|, such pressure moving the ball valve 58 upwardly and entering the pressure chamber 33 to render the servo-motor, at 28, ef-

preferably accomplished by the hydraulic timing arrangement forming a part of the device, at |8. As soon as the pressure source is placed in communication with the anticipating pressure passage including the passages 88 and 44, to supply fluid under anticipating pressure to the chamber 33 to close the admission valve I3, such pressure is also supplied through the branch passage I88 and the adjustable orifice |8| to the cylinder space below the piston 85, the latter moving upwardly at a speed determined by the setting of the orifice |8|. As soon as the piston valve 88 moves a sufiicient distance that the lower land 88 interrupts communication of the passages 88 and 44, then, irrespective of the condition or position of the watt-meter device 12 and the piston valve 88, the supply of fluid under anticipating pressure to the pressure-responsive device, at 32, will cease, the bleeder port 4| for venting the pressure chamber 33 of air and gases providing slow leakage or bleeding of liquid so that the pressure in the passage 44 declines rapidly and the governing mechanism, at

I8, regains control of the turbine. Not only may the orifice |8| be adjusted to time the antici pating apparatus, at I8, so that the governing mechanism, at I8, regains control of the tursuitable time in relation to electrical characteristics of the system so as to minimize surges.

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 changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. The combination with an electric generator driven by a prime mover and the prime mover having an admission valve, of pressureresponsive means for operating the admission valve; a governor providing a regulating pressure varying as a function of speed of the prime mover; means responsive to sudden generator load drop to provide an anticipating impulse;

means responsive to the anticipating impulse to provide an anticipating fluid pressure; means effective, when fluid under regulating pressure is developed and there is absence of fluid under anticipating pressure, to supply fluid under regulating pressure to the pressure-responsive 5 means to control the admission valve in accordance with the load and eifective, when fluid under anticipating pressure is developed, to supply the latter to the pressure-responsive means to effect movement of the admission valve in a closing direction; and means responsive to initiation of supply of fluid under anticipating pressure for terminating the latter a predetermined time interval after it becomes effective.

ply the latter to the pressure-responsive means to efiect movement of the admission valve in a closing direction; means responsive to fluid under anticipating pressure for terminating the supply of the latter to the pressure-responsive means; means including an orifice for supplying fluid under anticipating pressure to the lastnamed means; and means providing for variation in the flow area of the orifice.

4. The combination with an electric generator driven by a prime mover and the prime mover having an admission valve, of pressureresponsive means for operating the admission valve, a governor providing a regulating pressure varying as a function of speed of the prime mover, means responsive to sudden generator mined time interval after it becomes effective.

2. Ihe combination with an electric generator driven by a prime mover and the prime v mover having an admission valve, of pressureresponsive means for operating the admission valve; a governor providing a regulating pressure varying as a function of speed of the prime mover; means responsive to sudden generator load drop to provide an anticipating impulse; means responsive to the anticipating impulse to provide an anticipating fluid pressure; means efiective, when fluid under regulating pressure is developed and there is absence of fluid under anticipating pressure, to supply fluid under regulating pressure to the pressure-responsive means to control the admission valve in accordance with the load and efiective, when fluid under anticipating pressure is developed, to supply the latter to the pressure-responsive means to efiect movement of the admission valve in a closing direction; means responsive to fluid under anticipating pressure for terminating the supply of the latter to the pressure-responsive means; and means for varying the time required for the last-named means to act.

3. The combination with an electric generator driven by a prime mover and the prime mover having an admission valve, of pressureresponsive means for operating the admission valve; a governor providing a regulating pressure varying as a function of speed of the prime mover; means responsive to sudden generator load drop to provide an anticipating impulse; means responsive to the anticipating impulse to provide an anticipating fluid pressure; means efiective, when fluid under regulating pressure is developed and there is absence of fluid under anticipating pressure, to supply fluid under r'egulating pressure to the pressure-responsive means to control the admission valve in accordance with the load and effective, when fluid under anticipating pressure is developed, to sup- 5. The combination with an electric generator driven by a turbine and the turbine having an admission valve, of pressure-responsive means for operating the admission valve, a governor providing a regulating pressure varying as a function of speed of the prime mover, means responsive to sudden generator load drop to provide an anticipating impulse, means responsive to the anticipating impulse to provide an anticipatingfluid pressure, first and second conduits for supplying fluid'under regulating and anticipating pressures, respectively, to the pressureresponsive means, valve means responsive to regulating pressure when the anticipating pressure is ineiiective to connect the first conduit to the pressure-responsive means and responsive to anticipating pressure to connect the second conduit to the pressure-responsive. means, a normally-open valve movable to interrupt the supply of fluid under anticipating pressure to the second conduit, and timing means rendered effective upon establishment or fluid under anticipating pressure for controlling the duration of time interval required for closing of the last-named valve.

6. The combination with an electric generator driven by a turbine and the turbine having an admission valve, of pressure-responsive means for operating the admission valve, a governor providing a regulating pressure varying as a function of speed of the prime mover, means responsive to sudden generator load drop to provide an anticipating impulse, means responsive to the anticipating impulse to provide an anticipating fluid pressure, first and second conduits for supplying fluid under regulating and I anticipating pressures, respectively, to the presopposition to the tion oi the first conduit with the pressure-responsive means and to open communication of the second conduit with the latter, a normally-open valve movable to interrupt the supply of fluid under anticipating pressure to the second conduit, means for biasing the valve to open position, a piston connected to the valve, and means including an adjustable orifice for supplying fluid under anticipating pressure for action on the piston in opposition to the biasing means to overcome the latter and close the valve.

7. The combination with an electric generator driven by a turbine and the turbine having an admission valve, of pressure-responsive means for operating the admission valve such that increases in pressure supplied thereto move the valve in a closing direction and vice versa, a governor providing a regulating pressure varying as a function of speed of the prime mover, means responsive to sudden generator load drop to provide an anticipating impulse, means responsive to the anticipating impulse to provide an anticipating fluid pressure which is larger than the maximum regulating pressure, first and second conduits for supplying fluid under regulating and anticipating pressures, respectively, to the pressure responsive means, valve means responsive to regulating pressure when the anticipating pressure is inefiective to open communication of the first conduit with the pressure-responsive means and to interrupt communication of the second conduit with the latter and responsive to regulating pressure to open communication of the second conduit with the pressure-responsive means and to interrupt communication of the first conduit with the latter, a normally-open piston valve having a range of movement to interrupt the supply of fluid under anticipating pressure to the second conduit, a spring for biasing the piston valve to open position, a piston connected to the piston valve, and means including an adjustable orifice for supplying fluid under anticipating pressure for action on the piston in spring to close the piston valve.

8. The combination with an electric generator driven by a turbine and the turbine having an admission valve, of pressure-responsive means for operating the admission valve such that increases in pressure supplied thereto move the valve in a closing direction and vice versa, a governor providing a regulating pressure which increases with decrease in load and vice versa, meansincluding a control circuit and a wattmeter device responsive tosudden generator load drop toclose the control circuit, means energized by electio current flowing in the control circuit to provide an anticipating fluid pressure which is larger than-the maximum regulating pressure, first and second conduits for supplyin fluid under regulating and anticipating pressures, re-

spectively, to the pressure-responsive means, valve means responsive to regulating and anticipating pressures to establish communication of the first conduit with the pressure-responsive means when the anticipating pressure is ineffective and to establish communication of the second conduit with the pressure-responsive means when the-anticipating pressure is effective, and means responsive to the initiation of supply of fluid under anticipating pressure for terminating the latter a predetermined time interval after it becomes effective.

9. The combination with an electric generator connected to an electrical system and driven by a turbine having an admission valve, of governor mechanism providing a regulating pressure which increaseswith increase in turbine speed and decrease in load and vice versa; means responsive to a predetermined rate of change of generator load to provide an anticipating pressure; pressure-responsive means tor controlling the admission valve such that with an increase in pressure the valve is moved in a closing direction and vice versa; connections for supplying fluid under regulating and anticipating pressures to the pressure-responsive means so that normally the latter is operated in accordance with the magnitude of regulating pressure and, when the ing pressure becomes effective, it is operated to close the admission valve; and means rendered eflective by the anticipating pressure to limit duration of action of the latter on the pressureresponsive means in order that the regulating pressure may regain control oi! the latter.

10. The combination with an electric generator connected to an electrical system and driven by a turbine having an admission valve, of governor mechanism providing a regulating pressure which increases with increase in turbine speed and decrease in load and vice versa; means responsive to a predetermined rate of change of generator load to providean anticipating pressure; pressure-responsive means for controlling :the admission valve such that with an increase in pressure the valve is moved in a closing direction and vice versa; connections for supplying fluid under regulating and anticipating pressures to the pressure-responsive means so that normally the latter is operated in accordance with the magnitude or regulating pressure and, when the anticipating pressure becomes efiective, it is operated to close the admission valve; means rendered eflfective by the anticipating pressure to limit duration of action. of the latter on the pressure-responsive means in order that the regulating pressure may regain control of the latter; and means for adjusting the last-named means to vary the duration of action of the anticipating pressure.

ANTHONY F. SCHWENDNER.

anticipat-

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