SHEET NO. 73

Type of draft tube Elbow with plate steel liner-two pier

Weight of runner. 38,500 Ibs. Weight of rotating parts. 70, 500

Weight of turbine parts including hydraulic thrust to be carried by generator
thrust bearing 220,000 lbs. New; 300,000

lbs. Worn rings.

60,

15

20

25

30

500

500

35

40
45
55
60
1000 HORSEPOWER AT DESIGN HEAD OF 426

50

65

Pipe size 5 inches.
Time element__5___seconds.
Weight.

MAX. HEAD 483 FT. HIGH HEAD RUNNER

475

475

Governor capacity in foot-lbs. 237,000
Gov. mfr. Woodward Governor Co.
Cost per unit f.o.b. factory $46, 470.00
Generator mfr. General Electric Co.

1000 HORSEPOWER

PREDICTED CHARACTERISTIC CURVES
FROM MANUFACTURER'S DATA

CURVES NO. 1094 & 1095
ISSUE "B"

REV. 6-18-63

HYDRAULIC TURBINE DATA
TRINITY POWER PLANT
U.S. DEPARTMENT OF THE INTERIOR
BUREAU OF RECLAMATION

Figure 101. --Trinity Powerplant hydraulic turbine data sheet.

The turbine gate operating mechanism is powered by two oil-pressure, double-acting, hydraulic servomotors having a total displacement of 12, 900 cubic inches, a designed piston stroke of 10.693 inches for full gate travel, and a cylinder diameter of 28 inches. The servomotors have a combined rated capacity of 237,000 foot-pounds at the minimum oil pressure of 220 pounds per square inch available at the pistons and are designed to move the wicket gates a full opening or closing stroke in a minimum time of 5 seconds under the maximum head of 710 feet, including water hammer, on the turbine with this minimum oil pressure.

An automatic mechanical gate lock is provided on one of the servomotors to secure the gates in the closed position upon shutdown of the unit. The gate lock is operated by oil pressure through the governor gate lock control valve. An interlock switch is provided to prevent starting the unit until the automatic gate lock is in the unlocked position. At heads above rated head, the output of the turbine can be limited to the rated output of the generator by an adjustable stop nut on one servomotor piston rod. The gates may be held in either the open or closed positions against maximum oil pressure by means of the manual operating arrangement provided on the automatic gate locking device. A horseshoe-shaped mechanical stop is also provided which will lock the gates in the closed position.

A depressor system is provided for lowering the water level in the draft tube below the bottom of the runner when the unit is being motored on the line. The unit is not to be motored unless the penstock butterfly valve is open and the spiral casing is full of water. Wicket gate leakage water is needed to cool the runner seals which otherwise would heat up and cause seizure of the runner. The depressor system consists of a main control mounted on the main control board, two pilot-operated 4-inch valves, two 2-inch solenoid valves, two float-operated switches for controlling the compressed air supply, and control switches operated by adjustable cams on the restoring mechanism in the governor actuator cabinet.

One of the 4-inch valves opens initially to admit compressed air through the turbine head cover for lowering the water level, and one 2-inch valve admits sufficient air through the shaft and runner snorkel to maintain the established water level below the runner. The other 4-inch valve is automatically opened to exhaust air to the atmosphere upon initiation of a shutdown while the unit is being motored. This permits the water level to rise so that its braking effect on the runner can be utilized to stop the unit. The 4-inch air vent valve is also controlled by means of a cam-operated switch in the governor. Initially, the cam is designed and set to open the air vent valve from 0 to 15 percent gate. Cams can be cut to open the valve at any desired range of gate positions in addition to the 0 to 15 percent range. The other 2-inch valve admits atmospheric air below the runner at certain gate openings to improve operation of the unit, if required. Opening of this valve is controlled by a cam-operated switch in the governor which is set initially to open the valve from 0.5 to 0.6 gate. Cams can be cut to open this valve over any desired portion of the full gate operating range.

The tailwater depressing system was designed on the basis of supplying an air volume of 200 percent of the water displaced if water in the draft tube is lowered to 3 feet below the bottom of the runner. The time for lowering the water level was set at 30 seconds and the designed back pressure was 125 percent of the final pressure under the runner.

The turbine spiral case is made of welded plate steel which is shop welded to the welded plate steel stay ring. The spiral casing and stay ring was made in four sections with field-welded joints in the spiral casing and bolted joints in the stay ring. The spiral casing is designed so that, with a flow of 2, 150 second-feet through the turbine, the velocity of the water at the centerline of the unit normal to the inlet section is approximately 27.6 feet per second, which is 16.7 percent of spouting at the design head of 426 feet for the high-head runner, or 19.3 percent of spouting velocity at the design head of 315 feet for the low-head runner. The casing and the stay ring are designed for an internal hydrostatic pressure of 310 pounds per square inch which is the maximum pressure head, including water hammer, that would result from a full gate closure in 10 seconds with reservoir water surface at maximum elevation and both units shut down simultaneously. A thrust collar is provided on the spiral case inlet section which is designed to carry the 4, 000, 000-pound thrust from the closed butterfly valve into the concrete foundation.

The spiral casing was tested in the field to a pressure of 465 pounds per square inch. A hydrostatic pressure of 185 pounds per square inch, corresponding to normal operating pressure with high-head runner installed, was maintained in the casing while the concrete surrounding it was placed. The method employed to support and secure the spiral case and stay ring preparatory to and while placing concrete consisted of jacks and turnbuckle tie rods attached to the casing and stay ring at various points (fig. 102). Prior to encasement of the casing in concrete, all tie rods were prestressed and securely welded after a final check of the alinement. Sufficient cooling water was circulated through the spiral case during placement of concrete, to control the heat of hydration in the surrounding concrete so that the temperature of the metal did not rise more than 5° F. above the temperature at the beginning.

The draft tube is the elbow type with two intermediate piers. The welded plate steel draft tube liner extends downward to and includes the pier noses. That portion of the liner which extends from the discharge ring to a point 15 feet below the centerline of the unit is not embedded in concrete, but is fabricated from 1-inch plate steel and is made in two removable sections to permit exchange of runners. The remainder of the liner is 3/4-inch plate steel embedded in concrete. The liner is designed to withstand full external hydrostatic pressure with tailwater at elevation 1911.00 and an absolute pressure of one-half atmosphere inside. Each pier nose is designed to support a load of 650, 000 pounds. Two opposed 24- by 30-inch mandoors are provided for access into the draft tube liner for inspection and repair.

The turbine pit liner is made of 1/2-inch plate steel and extends to floor elevation 1913.00. Openings are provided for servomotors, unit piping, and stairways.

PROCEDURE NOTES
See completion specifications for division of work

· Erect the elbow section of the draft fube liner on the supports
and jacks and make boited connections of field joints Aline to
elevation and centerline position and secure liner in place by
means of the hoiddown rods Weld the field joints and check
olinement taking speciol care that the fienge at Section 3
is accurately alined at El 1889 25

2 bastoll stay ring anchors that are located in draft tube access
pessages and plece second stage concrete embedding the iner
to Ei 1883 25. Spray inner surface of liner with cooling
water during placing and initial setting of concrete.

3. Place second stage concrete to El 1896 50 and piers to E
1899 50 installing all remaming anchors for the stay ring.
and spiral casing

• Assemble the upper section of the draft tube liner, spirol
casing and stay ring sections, and the inlet section in
position. Place and pre-stress stay ring fienge bolts in
occordance with turbae manufacturer's instructions Aline
the assembly and weld the spiral case sections Adjust jocks
and tie rods to aline and level complete assembly offer
welding is complete

5 After installation of all items to be embedded in the concrete
surrounding the turbine such as drains, piezometer lines, etc.
install the test ring and test head with their gaskets
install the necessary grout Diping with or vents, and the
pressure water cooling systems for use in testing and
embedding the spiral case

between turbine and completion contractors

Erect pit timer in place Reset or replace the relief valve for
pressure relief of 194 par Bring hydrostatic pressure withe
cesing to normal operating pressure of 185 psi and check
alinement

9 While maintaining 185 psi within casing, wold

teop ends of tie rods and pre stress all tie rods Care
should be taken in pre-stressing rods to prevent movement
of turbine cosing

10. Make final olinement check, weld jack supports in place and
place second stage concrete to El 1913.0 es continuously as
feasible During concreting operations and for a period of
not less than 7 days after the concrete has been placed,
montam a pressure of 185 psi in the casing. Throughout this
entire period, circulate a sufficient quantity of cooling water
through the casing to montem the temperature of the cass
metol within 5°F above that determined at the beginning
of concreting operations, and spray the inside of the draft
tube and pit liners during initial setting of the concrete.

casing

Pressure gage.

Thermometer

-2" Air bleed

4° Cooling water outlet.

-Close space between stay ring and
test ring to insure circulation of
Cooling water

Pressure goge

Install piezometer lines.

See Dwg No 416-0-2022

Positive type relief valve
with capacity equal to
supply and set to 490 psi
for pressure test and

194 psi for placing concrete

4" Drain
connection

2" Drain

ELEVATION C-C

Figure 102.--Trinity Powerplant turbines and auxiliaries--Procedure for erecting and embedding turbines.

416-D-822

109. Governors. The governors for regulating the speed of the main generating units are located on the generator floor downstream of the generators and are of the oil-pressure, actuator-cabinet type with electric-driven, speed-responsive elements. Each governor is a self-contained unit, the principal parts consisting of the actuator with its distribution (relay) valve, indicators and controls, restoring connections, two motor-driven pumping units, sump tank, separate pressure tank, piping, independent alternatingcurrent generator for supplying power to the motor driving the speed-sensitive element, and other miscellaneous accessories required for regulating the speed of the unit. The pressure tanks are located below the actuator cabinets on the turbine floor and the pumps are located inside of the actuator cabinets. The pressure tank and pumps for each unit are connected so as to permit repair or removal of one pump without interrupting the operation of the unit. The governor oil system is designed for an operating pressure of 300 pounds per square inch and operates between 270 and 300 pounds per square inch pressure. In order to prevent deterioration of the oil by exposure to moisture and oxygen, nitrogen rather than air was initially provided for the cushioning medium in the governor pressure system. Later, the system was revised to use compressed air for the cushioning medium.

The rated capacity of each governor at 270 pounds per square inch oil pressure is 237,000 foot-pounds as recommended by the turbine contractor. The governor is designed to supply an adequate quantity of oil to allow the servomotors to operate the turbine wicket gates through a complete opening or closing stroke, under a maximum head including water hammer of 710 feet, in 5 seconds with an oil pressure of not more than 270 pounds per square inch in the pressure tank. Each governor has two 20-horsepower, 80-g. p.m., motor-driven oil pumps. The pumping units are complete with echelon controls, unloader valves, check valves, safety valves, and pilot valves.

The speed responsive element of each governor is driven by an alternating-current motor receiving its power supply from a permanent-magnet alternating-current generator. The independent generator is used exclusively for this purpose and is direct-connected to the exciter shaft of the main generating unit. Provision is made in the design of the independent generator to allow a limited amount of vertical movement of the main generator shaft without disassembly of any part of the independent generator.

The enclosure for the independent generator contains two overspeed and two underspeed switches as well as a device for operating lamps to indicate dead stop and breakaway. The motors, generator, and speed devices are designed to satisfactorily withstand the maximum runaway speed of the turbine of 383 revolutions per minute. Each governor is equipped with means for adjusting the rate of movement of the turbine gates to any rate between 5 and 15 seconds for a full gate opening or gate closing stroke. The adjustment positively restricts the oil flow to the servomotors and is so arranged that the operation of the gate limit mechanism, control solenoid, or any other device cannot cause the rate of movement of the turbine gates to exceed the maximum rate for which they are adjusted. The governors were set at the factory for 12-second operation. The speed-responsive elements are capable of causing the governor relay valves to pass oil in the direction to effect corrective movement of the turbine gates in consequence of speed variations of the turbines of two-hundredths of one percent.

(a) Control Plan. --Trinity Powerplant is an unattended plant, with basic control centered at the main control boards in the control rooms of Trinity and Keswick Powerplants. A unit can be started, brought up to speed and synchronized, loaded as required, and stopped from the control room of either plant. The auxiliaries such as the generator air cooling water pumps and the bearing cooling water supply can be started remotely. Other auxiliaries such as the lubricating oil pumps, governor oil pumps, and air compressors are started locally. The mechanical controls and remotely operated indicators provided in the main control room at Trinity Powerplant to achieve above operations are: (1) gate-limit control, (2) gate-position and gate-limit indicators, (3) speed-changer control, (4) speed-changer indicator, (5) speed-droop adjustment mechanism, (6) speed-droop setting indicator, (7) start-stop indicating lamp, (8) electrically operated tachometer, (9) normal and complete shutdown controls, and (10) draft tube water-level depressor control. The mechanical controls and remotely operated indicators provided at Keswick Powerplant are: (1) gate-limit control, (2) gate-limit indicator, (3) speed-level control, and (4) normal and complete shutdown controls.

(b) Speed Control. --The governor head is the speed responsive element of the governor, and through its flyballs, effects a corrective gate movement when the speed deviates from the desired speed level. The speed level can be varied from 85 percent of rated speed at no load and zero speed droop to 105 percent of rated speed at rated load and maximum speed droop, and is primarily used to synchronize the unit on the line and to load the unit while still under control of the flyballs. This speed changer can be adjusted manually at the governor or electrically from the control board at Trinity Powerplant or from Keswick Powerplant. An electrically operated tachometer is mounted on the governor and another one is mounted on the main control board. The speed droop causes the unit to reduce speed as the load increases. The speed-droop control adjusts this droop from 0 to 5 percent below the speed level and can be controlled manually at the governor or electrically from the main control board. This speed-droop control in combination with the speed-changer mechanism can be used to adjust the turbine output to the system demand with the plant normally operating under a baseload.

(c) Gate Position and Limit Control. --The turbine wicket gates are normally positioned by the interaction of the governor head and restoring mechanism but are limited in their opening stroke by the gate limit mechanism, without interfering with the possibility of automatic shutdown in case of emergency. The gate limit may be set anywhere between 0 and 100 percent gate, manually at the governor, or electrically from the main control board or from Keswick Powerplant. The gate position and limit indicator on the governor is provided with a dual selsyn-type transmitter, and the receiver on the control board indicates the fixed gate limit and actual gate position. The electrical setting of the gate limit is made through a 125-volt direct-current reversing motor controlled from the control room.

(d) Auxiliary Gate Controls. --In addition to the normal control of the turbine wicket gates through the governor head, they are directly operated by the normal and complete shutdown mechanisms, and the hydraulic-type hand control.

Opening the electrical contacts of a master relay by means of the local start control switch or the supervisory start control relay deenergizes the normal shutdown solenoid. This operation disconnects the unit from the line and causes the wicket gates to close, the brakes to be applied, and setting of the automatic gate lock without lockout of the unit. The normal shutdown solenoid does not require manual resetting before the unit can be restarted manually or automatically when the solenoid is reenergized by closing the electrical contacts of a master relay.

The complete shutdown mechanism disconnects the unit from the line, closes the wicket gates, and applies the brakes, bringing the unit to a stop and sets the automatic gate lock upon operation of any of the following: manual tripping of complete shutdown solenoid, emergency shutdown control switch, supervisory emergency shutdown relay, overspeed switch, low governor oil pressure switch, low governor oil level switch, generator thrust bearing and upper and lower guide bearing temperature relays, generator air thermal relay, generator air-cooling water pressure switch, generator overvoltage relays, generator ground relay, split-phase generator differential relay, generator carbon dioxide manual or thermal-operated discharge switches, overcurrent relay, loss of field relay, turbine guide bearing and packing box thermal relays, turbine bearing low oil level switch, bearing cooling water pressure switch, transformer winding differential relay, transformer differential relay, transformer fault pressure relay, incomplete sequence relay, penstock low-pressure switch, drainage and unwatering sump high-level relay, and other devices. Operation of the complete shutdown solenoid requires manual resetting before the unit can be restarted.

When the wicket gates are closed, and the speed has dropped to approximately 50 revolutions per minute, the low-speed switch in the governor drive generator housing will close and set the brakes on the generator. The brakes remain on until a short period of time after the unit comes to rest. The braking system is designed to bring the rotating parts of the generator and turbine to a stop from one-half normal operating speed within 5 minutes after the brakes are applied, with a brake air pressure of 60 pounds per square inch, without field excitation on the generator and with leakage through the turbine gates not exceeding an amount which will produce 1 percent of the rated generator torque.

The hydraulic type hand control operates the wicket gates through the auxiliary valve by oil pressure, after the transfer valve is moved to the manual position. This permits movement of the gates when the unit is at rest.

The brake control can be taken off automatic operation by moving the control from "Automatic" through "Off" to "Manual" and then released. Manual operation of the brakes occurs each time the control is shifted to "Manual" and held. The brakes can also be applied by means of an auxiliary handle located inside of the actuator cabinet.

(e) Oil-Pressure System. --Two motor-driven oil pumps of the rotary type, each having a capacity of 72 gallons per minute, are provided in each governor cabinet. The pumps are self-priming. The 20-horsepower motors are direct connected to the pumps and are of the squirrel-cage, low-startingcurrent, induction type, designed for full-voltage starting on a 440-volt, 3-phase, 60-cycle circuit. Automatic controls are provided to start one of the pumps when the oil pressure in the pressure tank drops to a predetermined point, and to start the other pump should the pressure drop to some lower predetermined pressure. Echelon controls are provided to change the order of starting the pump motors. The pumps can be operated independently of each other and either one may be taken out of service without interfering with the operation of the other. Each unit is provided with motor overload protection, unloader valve, check valve, safety valve, and control valves, making it a complete unit.

Each governor is provided with a pressure tank, located in the turbine gallery. The pressure tank has a volume of approximately 198 cubic feet and it is designed for a working pressure of 330 pounds per square inch. The tank is equipped with an oil level sight gage, a manually operated air-release valve, a float valve to prevent air entering the piping, a manhole, three low oil pressure switches, and three low oil level switches. The oil level gage is provided with both manual and automatic means for shutting off air and oil discharge from the pressure tank in the event of breakage of the gage glass. All connections to the pressure tank, except the upper gage glass connection and air-release connection, are below the low oil level.

Each governor is provided with a sump tank, located in the base of the governor cabinet. The sump tank has a capacity of 778 gallons and is provided with an oil level gage, a manhole for access to the interior of the tank, a strainer, a breather with oil-vapor filter, pipe connections for filling and draining the sump tank, and a filling valve located inside of the actuator cabinet.

4. Turbine and Governor Unit Auxiliaries

110. Generator and Turbine Bearing Lubrication. The generator combined thrust and upper guide bearing is a self-lubricated type immersed in an oil bath, with a coil-type water cooler provided in the oil reservoir. A high-pressure oil system is provided for the thrust bearing to be used when the unit is started after a complete shutdown and below approximately 25 percent normal speed when the unit is stopped. The generator lower guide bearing is also of the self-lubricated type with its own oil reservoir and coil-type water cooling. The babbitt-lined turbine guide bearing is lubricated by a combination pumpcirculated, gravity return system as described in section 114.