US2343223A - Hydraulic turbine control system - Google Patents

Description

Feb. 29, 1944. PFAU AL 2,343,223

HYDRAULIC TURBINE CONTROL SYSTEM Filed April 25, 1942 c4 as/mr Patented Feb. 29, 1944 2,343,223 HYDRAULIC TURBINE CONTROL SYSTEM Arnold Pfau, Milwaukee, and Terry] B. Montgomery, Wauwatosa, Wis.,

assignors to Allis- Chalmers Manufacturing Company, Milwaukee,

Wis.,

a, corporation of Delaware Application April 25, 1942, Serial No. 440,562 Claims. (01. 137-158) This invention relates to improvements in control systems for hydraulic turbines and particularly to a turbine installation from which substantially the entire When a hydraulic turbine is used in a location where it is impossible to provide forebay or water storage space or when all of the water available for operating the turbine must be continuously available for use downstream from the turbine regardless of fluctuating loads on the turbine, it is necessary that means be provided which will bypass water around the turbine when the load on the turbine is not suflicient to require the full flow of the available water therethrough. The valve of such bypass must act synchronously with the turbine gate, that is, the area of the bypass opening must be varied simultaneously with gate opening variations so that the total water passage area remains substantially constant. When the turbine is to be operated up to its full capacity at which the gate vanes are fully opened, such full opening must of course correspond to the area required for passage of the available or desired quantity of water. And the total water bypass area must also at all times be suflicient to pass the desired quantity of water;

If there is only a small forebay water storage space, any downstream demand for water exceeding the flow into the intake of the turbine will result in emptying the storage space and drawing air into the turbine intake and bypass. Such entrance of air always has disturbing or destructive efiects in a hydraulic turbine installation and prevents the orderly delivery of power from the turbine. When the water is delivered to the turbine or penstock, theentry of the air into the penstock may prove disastrous. It is therefore necessary to provide a control quantity of water flowing tothe installation must be discharged at all times.

which Will limit by way of a long pipe line the total area of discharge opening to thatarea required to pass only the amount of water availbypass around the turbine is controlled responsive to the level of the water in the forebay.

Another object of the invention is to provide a control system for hydraulic turbines in which the operation of the normal load and speed responsive control means for the gate of the turbine is limited or controlled by means responsive only to the level of the water in the forebay.

Another object of the invention is to provide a control system for hydraulic turbines in which the load limiting means and the bypass control means are operated by increments only and are so interlocked as to prevent overrunning of either the turbine gate or bypass valve operating means.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing, which represents a diagrammatic illustration of the present improved system at high forebay level when the turbine is running at substantially no load with the turbine gate nearly closed and with the bypass valve nearly fully open.

Referring more particularly to the drawing by characters of reference, the reference numeral l designates a spiral casing extending about and directing the flow of Water to a hydraulic turbine wheel of the usual construction under the control of a gate made up of the usual gate vanes of which the stems 2 are connected with a shifting ring 3. Water passing through the turbine is discharged into a draft tube 4 and the power produced by the turbine is delivered by way of a shaft 6 to a suitable load. The opening area of the gate vanes is adjusted by movement of the shifting ring 3 by means responsive to the speed of the turbine and including a fluid pressure operated servomotor l, 8 to which pressure is admitted and from which pressure is discharged under the action of a pilot valve 9. The

; pilot valve 9 is actuated by a fiyball head I I of the able without draining any portion of the turbine Water passages and Without permitting entry of air thereinto.

It is therefore an object of the present inven- I tion to provide a control system for hydraulic turbines in which the total flow of water through the turbine and through the bypass around the turbine isautomatically maintained substantially constant.

Another object of the invention is to provide a control system for hydraulic turbines in which the turbine gate opening is responsive to loads imposed on the turbine while the valve of the usual construction, driven from the shaft 6 as by a belt l2, and acting on one end of a floating lever l3 having the other end connected with the stem of the valve. The floating lever I3 is movably fulcrumed on a rod l4 connected by way of a bellcrank IE to the piston 8 of the servomotor and the rod is adjustable in length by manual movement of a sleeve and wheel l1, thus providing means for starting and manually controlling the turbine gates.

When the gate shuts off the flow of Water through the turbine, the water in the spiral casing l flows through a bypass including a con- .called house-power 2 necting pipe 2| and through a relief valve 22, discharging the water into the discharge pit from the turbine. The valve 22 is enclosed in an elbowlike casing 23 with the valve stem Zfl guided in and passing through one wall of the elbow to a cylindrical chamber formed by an extension 26 from the casing. The valve stem 24 "1s joined'to a piston 21 movable in a cylinder 25 for closing the valve upon the admission of fluid pressure below the piston. The valve stem is hollow and forms a passage for fluid pressure taken from the valve casing by way of apertures 28 and 25' and delivered below the piston 2-'| by way of apassageway 3| when a seat. Water is discharged from 21 by way of the piston passage 3|, 2. port 33 above the Valve 32 and a drain pipe 34. The gate and the control valve are connected by a levercontrol valve 32 is raised from its below the pi v age including a rod 36 with one end of a float- 31 having the other end comiected by way of a rod 38, a bellcrank 39 and a linkrdll with the shifting ring 3. The floating lever 37 is fulcrumed. on a rod 4| which screw-threadedly engages a nut 42 engaging or formed as a part of a hand wheel portion 53 and a worm wheel portion 46. The hand wheel 43 provides means by which the bypass may be initially manually opened or may be adjusted to meet conditions occurring during operation of the unit.

Rotation of the nut 42 raises andlowers the rod 4| and causes movement of the control valve 32 to control the opening and closing of the relief Valve 22. Rotation of the nut may be by means of the hand wheel 43 or by means of the worm wheel 44 upon movement of the worm it into engagement therewith. The worm it is driven through suitable connections with a re versibleelectric motor 4! having two fields ining lever dicated at 48 and 49. The armature of the motor 4'! is connected with the armature of a reversible motor 5| also having two fieldsindicated at 52 and 53. The motor 5| drives a screwthreaded spindle 56 having movable thereon a nut with a finger 51, rotation of the nut being prevented by guides 58 and travel .of the nut being limited by stops 59. The finger 51 extends into the path of movement of the flyball H and limits or reduces the movement of such flyball in one direction only, that is, when the load imposed on the tubine exceeds the limit allowable due .to the'level of the water in the forebay. The fields 48 and 49 of the motor 41 are controlled in part by limit switches 6| and 62 respectively, which are normally-spring held in, closed positicn and are movable into open .position by a flange 63 on the threaded rod 4| which acts as the fulcrum for the floating lever 31. And fields 52 and 53 of the motor 5| are controlled in part by limit switches 66 and 61, respectively, which are normally spring held in closed position and are movable into open position by a flange 68 on the rod 38 connecting one endof the floating lever 31' with the gate operating-shifting ring 3. The draining cfthe penstocl; and the turbine water passages which would permit dangerous entry of'air is prevented if a sufficiently high water level is retainedin the forebay. Such water level is controlled by a float counterbalanced by a weight l2 and carrying a contact finger 13 by which electric circuits are closed either by way of a pair of contacts M or a pair of contacts 15.

Motors 51 and 5| are energized from a soline 8i! supplied from an independent source and supplying energy to the switch 81.

motors intermittently under the control of a so-called notching circuit which intermittently closes and interrupts the motor supply circuits. The notching circuit includes relays 8| and 82 which are energized upon bridging of the contacts T5 or M, respectively. The actuation of relays 8| and 82 being precisely the same, only the circuits resulting from the energization of relay 8| will be described. The coil of relay 8| is energized when control contacts T5 are bridged and the energized circuit includes a switch 84. The relay 8| closes its lower contacts which complete a circuit placing the switch 85 in parallel-with a switch 84 and the upper contacts of relay 8| close simultaneously and complete the circuit through contacts of switch 84 to the coil of a time delay relay 83 and also complete a circuit to the coil of relay 9| through contacts of switches 85, 81 and the upper contacts of relay B.|,.and the switch 8 2-. Relay 9| thenlifts and was upper contacts connects both the motors 4! and 5| to one conductor of line at. 'A power impulseis then given to the motors if their respective limit switches 6|, E2 and 68, 67 are closed and if the proper one of a plurality of'interlocking switches 96, 91, 98 are in the proper positions and if the proper float switch contacts 14 or 15 are closed. Relay 9| when energized, by its lower contacts, bypasses the contacts of switch 81, whichprevents the deenergization of its co-il upon subsequent opening of During the time the motors are operating, relay 83 is rising to the top of its stroke where it opens switches 85, 86 interrupting the circuit to both relays 8| and 9| which interrupt the flow of power to the motors 41 and 5|, and also interrupt the circuits to the relay 83. The relay .83 drops at a delayed rate until it closes the switches 85 and 81, whereupon relays 8| and .9! are again energized to r'eclose the circuits by which another impulse is sent to the motors 41 and 5|. Such impulse or intermittent supplies of energy are. continued until either the rod 38 or rod 4| moves sufilciently to cause en gagement of the flanges thereon with the limit switches adjacent either of the rods and thus opens such switches. v The plurality of interlocking switches 88, 8?, 9B are mounted on the casing of the bypass for operation by the rod of the bypass to limit the independent movement of both the motors i] and 5| by interlocking the circuits of such motors. Without such interlocks it would be possible for either motor to overrun to the detriment of the gate or bypass operation by the other motor. Switches 96 91 and 93 enter into one or more of the circuits driving the motors 41 and 5|. and thus control the operation .of such motors in both directions of operation.

The operation of the electrical portions of the control system will be bestunderstood if the conditions andpositions of the several elements are traced through a number of conditions which the system is required to meet. The circuits will therefore be traced through the sequence of operations when (a) the forebay is filled to a high level with the bypass open to discharge all .of the water possible and with the turbine gates closed and to be opened following backing ofi of the load limit device, (b) the iorebay is at low level with the bypass closed and the gate is to be closed and (c) the forebay level is rising to the high level with both the bypass, and the gates closed and to be opened.

Under condition (a), the bypass 22 is fully open, the turbine gate is closed, the fulcrum 4| is lowered to open switch 62 and the high forebay level has raised the float 1| to the position at which the contact finger 13 bridges the contacts 15. The so-called notching circuit then is completed to cause intermittent energization of motor 5| for backing off the load limit to permit the turbine to take on load. A circuit is completed to .the coil of relay 8| and closes its lower and its upper contacts simultaneously. Closure of the lower contact of the relay 8| places switches 84 and 85 in parallel and closure of the upper contact of the relay 8| closes the circuit to the coil of the relay 83 through the switch 84 and also closes the circuit of the relay 9| through the switches 86 and 81. The relay 9| then closes the circuit to the armature of the motor 5| and its winding 53 through the switches 61, 91 and the contacts 15. An impulse is thus given to motor 5| to back ofi the load limit and allow the gate to open. As the gate opens, the floating lever 31 is mechanically shifted by the gate opening so that bypass 22 is closedtothe degree required to cause the water to flowthrough the turbine to supply load as it comes on-the turbine. Since switch 62 is held open bysflange 63, winding 49 of the motor 41 will not be energized. As the turbine takes on load and the turbine gate opens, the bypass valve will be moved toward closed position through the action of mechanical linkage.

The rising of relay 93 allows switches 84 and 81 to open without effect on the above circuit. At the top of its stroke the relay 83 opens the switches 85 and 86 which interrupt the circuit to the relays 8| and 9|. Such interruption of the relay circuits continues until the relay 83 has dropped back to the position shown. As long as the contacts are bridged, the relay 8| is kept intermittently energized and causes repetitious opening and closing of the above circuits until the gate is fully opened after the load limit is fully backed oil. The flange 68 on the rod 38 then opens the switch 61 to interrupt the circuit to the motor 5|. It will be understood that each opening impulse to the gate produces a closing impulse on the bypass because of the mechanical relay action by way of link 40, bellcrank 39 and rod 38. Complete closing of the bypass can occur only when the load on the turbine is suflicient to require all of the water flowing into the forebay. When the turbine is at low load only, the gate will be positioned to pass only a portion of the water while the remaining water must flow through the bypass. The mechanical connection between the gate and the bypass alone adjusts the position of the bypass so long as the forebay level remains between the predetermined high and low level points.

When condition (b) is present in which the forebay level has dropped while the bypass valve 22 is closed, and it is desired to close the turbine gate to preventqthe entrance of air into the turbine passages,- th e float 1| drops to the position at which theflnger 13 bridges the contact's' 14. The bypass valve 1-22 being closed by mechanical action as above stated, the flanges on the bypass rod 36 have opened the switches 96 and 9'! and have closed the switch 98. Opening of the gate and closure of the bypass valve has moved the rod 38 to the position where the flange 68 hasallowed switch 66 to close. The circuit is then completed to the coil of the relay 62 over. the switch 84. The relay 82 closes and completesthe circuit to the relay 9| and the other circuits described above as a part of the notching circuit.

- the switches 61, 91

Circuits are then completed through the contacts 14,- switches 98 and 66, the Winding 52 and the armature of the motor 5| to raise the load limit finger into engagement with the fiyballs I which raises the pilot valve 9 to admit fluid pressure for closing the turbine gates. While the bypass valve is closed, switch 96 is held open by a flange on rod 36 so that, at such time, winding 48 will not be energized and operation of motor 41 will not result. However, as soon as the turbine gate begins to close, the bypass will begin to open slightly by mechanical action and thereby open switch 98 and permit switch 96 to close. Wind: ing 48 of motor 41 is energized by way of the switch 6| to lift the fulcrum 4| and to close the bypass 22 against the mechanical opening of the bypass as the gates are closed. Lifting of the fulcrum and closing of the bypass interrupts the circuit to the motor 5| intermittently and mechanical opening of the-bypass restarts the motor 5| so that the gate is closed by increments. Each closing movement of the gate causing opening movement of the bypass, is superposed on the closing movement of the bypass clue to raising of the fulcrum and the bypass therefore also closes by increments until the gate is fully closed. The circuits of motors 41 and 5| are then interrupted by switches 96 and 98 respectively.

When condition (c) prevails the forebay level is rising so that the bypass or the gate should be opened. No action takes place until the float 1| has risen sufliciently to cause bridging of the contacts 15 by the finger 13. The relay BI is then energized and the above described notching circuit including the relay 9| are energized. Circuits are therefore completed to the bypass motor 41 and its winding 49 over the switch 62 and the contacts 15. The fulcrum rod 4| then moves down intermittently and causes movement of the bypass 22 downwardly until the flange 63 on the fulcrum rod opens the switch 62. As soon as the flange on the bypass rod allows switch 91 to close, circuits are also completed by the relay 9| to the armature of the motor 5| and itswinding 53 over and the contacts 15 to move the load limit finger away from the fiyballs to allow the turbine gate to be opened either manually or under the control of the flyball head When the fulcrum 4| has been lowered to fully open the bypass, the flange 63 opens the switch 62 and the circuit to the winding 49 of the motor 41 is interrupted. Load coming on the turbine opens the gates and the flange 68 on rod 38 opens the switch 61 to interrupt the circuit to the winding 53 of the motor 5|. The action of opening the gates causes mechanical closing of the bypass as required by the load to be supplied by the turbine.

It will be seen from the above, that the gate of the turbine is responsive to the load on the turbine under the control of the flyball head excepting that the load limit blocks movement of the fiyballs when the forebay level is low. Indirectly, therefore, the gates of --the turbine are responsive to low level in the forebay as well as respone sive to turbine load. The bypass is'responsive to high and low levels in the forebay but between such high and low levels the bypass is regulated only by mechanical relaying action from the turbine gates. Both the turbine gates and the bypass can, of course, be manually actuated if desired.

Although but one embodiment of the present invention has been illustrated and described, it will be apparentto those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a control system for hydraulic turbines supplied with Water from a. forebay under control of a gate, means responsive to increase and decrease in the speed of the turbine for respectively closing and opening said gate, electrically operated means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustableiulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, electrically operated means for moving the fulcrum setting of said leverag for controlling operation of the valve of said bypass regardless of' the movement of said gate, and circuits for energizing both of said electrically operated means, said circuits bein so arranged that at low forebay level-said'gate openin limit means moves in the direction of decreased load setting and the fulcrum of said leverage moves into the position to cause closing of said bypass while at highforebay level said limit means and the fulcrum of said leverage move in the direction of increased load setting and into position to cause opening'of said bypass respectively, said circuits includin a plurality of pairs of contacts bridged responsive respectively to high and low levels of water in the forebay for controlling completion of said circuits.

2. In a control system for hydraulic turbines supplied with water from a'forebay under control of a gate, means responsive to increase and decrease in the speed of the turbine for respectively closing and opening said gate, electrically operated means movable for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustable fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, electrically operated means for moving the fulcrum setting of said leverage for controlling operation of the valve of said bypass regardless of the movement of said gate, and circuits for energizing both of said electrically operated means, said circuits being so arranged that at low forebay level said gat opening limit means moves in the direction of decreased load setting and the fulcrum of said leverage moves into the position to cause closing of said bypass while at high forebay level said limit means and the fulcrum of said leverage move in the direction of increased load setting or said load limit means and into the position to cause opening of said bypass, respectively, said circuits including, a plurality of pairs of contacts bridged responsive respectively to high and low levels of water in the forebay for controlling completion of said circuits, and switch means operated by said leverage for stopping both of said electrically operated means when said means severally reach predetermined settings in the direction of opening and closing said gate and of opening and closing said bypass.

3. In a control system for hydraulic turbines supplied with water from a forebay under controlof a gate, means responsiveto increase and decrease in the speed of the turbine for respectively closing and opening said gate, electrically operated means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water fromthe forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustable fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, electrically operated means for moving the fulcrumsetting of said leverage for controlling operation of the valve of said bypass regardless of the movement of said gate, and circuits for energizing both of said electrically operated means, said circuits bein so arranged that at'low forebay level said gate opening limit means moves in the direction of decreased load setting and the fulcrum of said leverage moves into the position to cause closing of said bypas's'while at high forebay level said limit means and the fulcrum of said leverage move in the direction of increased load setting of said load limit means and into the position to cause opening of said bypass, respectively, said circuits including, a plurality of pairs of contacts bridged responsive respectively to high and low levels of water in the forebay for controlling completion of said circuit, switch means operated by said leverage for stopping both of said electrically operated means when said means severally reach predetermined settings in the direction of opening and closing said gate and of opening and closing said bypass, and switches actuated by the stern of said bypass valve for interlocking the circuits of said electrically operated means to prevent simultaneous closing and opening of said gate'and said'bypass.

v 4. In a control system for hydraulic turbines supplied with water from a'forebay under control of a gate, means responsive to increase and decrease in the speed of the turbine for respectivley closing and openin said gate, reversible electrically operated means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustable fulcrum, said leverage openin said bypass upon closing-of said gate and vice versa responsive to changes in load on the turbine, reversible electrically operated means for moving the fulcrum'setting of said leverage for controlling operation of the valve of said bypass regardless of the movement of said' gate, the imcrum being lowered at high water levels tendin to move the bypass valve to open position when said gate is closed and being raised at low water levels tending to move the bypass valve to closed position, and circuits for intermittently energizing both of said'electrically operated means in either direction of operation, said circuits including a plurality of pairs of contacts for severally controlling completion or said circuits upon the several bridging of said pairs of contacts re-' sponsive to high and low levels of water in the forebay, bridging of said pairs of contacts at high level completing the circuit for backing of]? said load limit means and bridging of said pairs'of contacts at low level completing the circuit for moving said load limit means into load limit position. I

5.-In a control system for hydraulic turbines supplied with water from a forebayunder control of a gate, means crease in the speed of the turbine for respecresponsive to increase and detively closing and opening said gate, electric movtor drivenmeans for limiting gate opening movement of said speed responsive means, avalved bypass for conducting water from the forebay and around the turbine, aleverage mechanically interconnecting said gate and the valve ofsaid bypass and pivoted on an adjustable fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, electric motor driven means for. moving the fulcrum setting of said leverage for controlling operation of the valve of said bypass regardless of the action of said gate on said leverage, thefulcrum being loweredat high water levels valve to open position when said gate is'closed tending to move the. bypass and being raised at low water levels tending .to move the bypassvalveto closed position, and

circuits for energizing both of said motors and including a plurality of pairs of contacts bridged responsive to high and low water levels in the forebay for controllingcompletion of said cir- ;trol of a gate, meansresponsive. to increase and decrease in the speed of thetturbine for respectively closing and opening said gate, electric motor driven means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the forebay and around th turbine, 43, leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustable fulcrum, said leverage openin said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, electric motor driven means for moving the fulcrum setting of said leverage for controlling operation of the valve of said bypass regardless of the action of said gate on said leverage, the fulcrum being lowered at high water levels tending to move the bypass valve to open position when said gate is closed and being raised at low water levels tending to move the bypass valve to closed position, and circuits for energizing both of said motors, said circuits including a plurality of pairs of contacts bridged responsive to the water level in the forebay for controlling completion of said circuits, bridging of said pairs of contacts at high level completing the circuit for backing 01? said load limit means and bridging of said pairs of con tacts at low level completing the circuit for moving said load limit means into load limit position, and switch means operated by said leverage for stopping both of said electrically operated means when said means severally reach predetermined settings in the direction of opening and closing said gate and of opening and closing said bypass.

7. In a control system for hydraulic turbines supplied with water from a forebay under control of a gate, means responsive to increase and decrease in the speed of th turbine for respectively closing and opening said gate, electric motor driven means for limiting gate opening movehigh water levels tending circuits for energizing both off saicl load limit means ment of said speedresponsive means, a valved bypass for conducting water from the forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustable fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, electric motor driven means for moving the fulcrum setting of said leverage for controlling operation of the valve of said bypass regardless of the action of said gate on said leverage, the fulcrum bein lowered at to move the bypass valve to open position when said gate is closed and being raised at low water levels tending to move the bypass valve to closed position, and of said motors, said circuits including a plurality of pairs of contacts bridged responsive to high and low levels of water level in the forebay for controlling completion of said circuits, bridging of said pairs of contacts at high level completing the circuit for backing and bridging of said pairs of contacts at low level completing the circuit for moving said load limit means into load limit position, switch means operated by said leverage forstopping both of said electrically operated means when said means severally reach predetermined settings in the direction of opening and closing said gate and of opening and closing said bypass, and switches interlocking the circuits of said motors and actuated by the stem of said bypass valve to secure synchronous opening and closing of said gate and said bypass respectively.

8. In a, control system for hydraulic turbines of a gate, means responsive to increase and decrease in the speed of the turbine for respectively closing and opening said gate, reversible electric motor'driven means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass an pivoted on an adiust able fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, reversible electric motor driven means for moving the fulcrum setting of said leverage for control ling operation of the valve of said bypass regardless of the action of said gate on said leverage, the fulcrum being lowered at high water levels tending to move the bypass valve to open position when said gate is closed and being raised at low water levels tending to move the bypass valve to closed position, and circuits for intermittently energizing both of said motors in either direction of operation and including a plurality of pairs of contacts for severally controlling completion of said circuits upon the several bridging of said pairs of contacts responsive to high and low levels of Water in the forebay, bridging of said pairs of contacts at high level completing the circuit for backing 01f said load limit means and bridging of said pairs of contacts at low level completing the circuit for moving said load limit means into load limit position.

9. In a control system for hydraulic turbines supplied with water from a forebay under control of a gate, means responsive to increase and deturbine for respectively closing and opening said gate, reversible electric motor driven means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the iorebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass and pivoted on an adjustable fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in load on the turbine, reversible electric motor driven means for moving the fulcrum setting of said leverage for controlling operation of the valve of said bypass regardless of the action of said gate on said leverage, the fulcrum being lowered at high water levels tending to move the bypass valve to open position when said gate is closed and being raised at low water levels tending to move the bypass valve to closed position, and circuits for intermittently energizing both of said "motors in either direction of operation, said circuits including a pluralityof pairs of contacts for severally controllingcompletion of said circuits upon the several bridging of said pairs of contacts responsive to high and low levels of water in the forebay, bridging of said pairs of contacts at high level completing the circuit for backing off said load limit means and bridging of said pairs of contacts at low level completing the circuit for moving said load limit means into load limit position, and switch means operated by said leverage for stopping both of said electrically operated means when said means severally reach predetermined settings in the direction of opening and closing said gate and of opening and closing said bypass.

10. In a control system for hydraulic turbines supplied with water from a forebay under control of a gate, means responsive to increase and decrease in the speed of the turbine for respectively closing and opening said gate, reversible electric motor driven means for limiting gate opening movement of said speed responsive means, a valved bypass for conducting water from the forebay and around the turbine, a leverage mechanically interconnecting said gate and the valve of said bypass andpivoted on an adjustable fulcrum, said leverage opening said bypass upon closing of said gate and vice versa responsive to changes in loadon the turbine, reversible electric motor driven means for moving the fulcrum setting of said leverage for controlling operation of the valve of said bypass regardless of the action of said gate on said leverage, the fulcrum being lowered at high water levels tending to move the bypass Valve to open position when said gate is closed and being raised at low water levels tending to move the bypass valve to closed position, and circuits for intermittently energizing bothof said motors in either direction of operation, said circuits including a plurality of pairs of contacts for severally controlling completion of said circuits upon the several bridging of said pairs of contacts responsive to high and-low levelsof water in the forebay, bridging of said-pairs of contacts at high level completing the-circuit for backing off said load limit means and bridging of said pairs of contacts at low level completing the circuit for moving said load limit means'into load limit position, switch means operated by said leverage for stopping both of said electrically operated means when said means severally reach predetermined settings in the direction of opening and closing said gate and of opening and closing said bypass and switches interlocking the circuits of said motors and actuated by the stem of said bypass valve to securesynchronous opening and closing of said gate and said bypass respectively.

' "ARNOLD PFAU.

TERRYL B. MONTGOMERY.

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