The butterfly valves are operated by individual power units, each containing an oil tank, a set of hydraulic equipment, and a motor-driven grease pump. Electrical equipment for both control systems is housed in a single, independent electrical control center. All control equipment is located in the control house above the butterfly valves. The estimated weight of two power units, complete with external piping is 14, 500 pounds, and that of one electrical control center for two valves is 2, 750 pounds. (b) Design Valves. --The butterfly valves were designed to open or close normally under balanced, noflow conditions and to close, in an emergency under ruptured penstock conditions, with a flow of nearly 11,000 second-feet at a head of 295 feet. The bodies were designed to withstand a total head, including water hammer, of 485 feet, and the leaves were designed to withstand a total head of 350 feet, using normal safety factors. The 26-inch-inside-diameter cylinders for the operating units were designed for a maximum oil pressure of 3, 000 pounds per square inch with the cylinder wall stress limited to two-thirds of the yield point of the material. This maximum pressure would occur only with a ruptured penstock. The maximum oil pump pressure for normal operation or an ordinary emergency closure will not exceed 500 pounds per square inch. At this pressure, the operating units will develop approximately 572, 000 footpounds of torque at the drive shafts, which exceeds the torque requirement of 496, 000 foot-pounds for seating the leaves. The reactive forces from the operating units are transmitted directly to the bodies. The leaves were designed to limit the deflection angle at the trunnions to less than 6 minutes. The direction of rotation to the closed position was made so the slightly higher head on the lower half of the leaf would keep the valve closed. The leaf was designed to rotate 2° past the horizontal position to help hold the valve open with the small opening torque thereby developed. The valve bodies and the expander pieces connected to the upstream flanges were proportioned to provide a nearly uniform rate of acceleration of the flow through the valves; i.e., from a velocity of 16.5 feet per second at the 138-inch-diameter inlets to 19.75 feet per second at the 126-1/8-inch outlets. This acceleration minimizes valve losses and provides a smoother flow. The bulkhead load on the closed valve is transmitted to the upstream penstock. The weight of the valves, including water, is carried by the valve feet into the concrete pedestals. (c) Design Controls. --To provide the desired operating time of approximately 30 seconds for each butterfly valve, a pumping capacity of 200 gallons per minute is necessary for each valve. One hydraulic power unit containing two identical pumps driven by a single 40-horsepower, 1, 200-r. p. m., 440-volt, 3-phase, 60-cycle motor was selected for each power unit. Both pumps operate at pressures up to 200 pounds per square inch to obtain faster rotation of the leaf when only a normal torque is required. At 200 pounds per square inch, an unloading valve unloads one pump and the other continues to pump oil up to 500 pounds per square inch for seating the leaf at closure or when a high torque is required. This arrangement was used to reduce the size of the motor required and still obtain a closure time of 30 seconds. A single electrical control center (fig. 158) of the valve structure was designed to contain the control transformers and rectifiers which provide reduced-voltage alternating and direct current for the electrical control equipment. A separate source of power was provided to operate the butterfly valves in case of an interruption of the normal supply from Clear Creek Powerplant. The controls for each butterfly valve were designed to open or close the valves from either the valve structure electrical control center or the Clear Creek Powerplant control board. Emergency closure was designed to be initiated manually at the Clear Creek Powerplant control board or at Keswick Powerplant, or initiated automatically by protective devices in the Clear Creek Powerplant. Transfer switches in the electrical control center were provided to permit control of the butterfly valves from either the control center or the remote operating stations at Clear Creek or Keswick Powerplants. A pressure switch in each control circuit prevents the valve from being opened unless the water pressure on opposite sides of the leaf is balanced. A motor-driven grease pump was provided for each valve to grease the trunnions automatically, whenever the valve operates. The grease pumps may also be operated by separate pushbuttons in the electrical control center. To provide balanced heads on the butterfly valve leaves during remote operation, the motor-operated bypass valves were designed to open automatically when the butterfly valve is opened from the powerplant control board, and close automatically when the butterfly valve is fully open. Separate pushbuttons were provided to open the bypass valves when the butterfly valves are opened from the electrical control center. (d) Design Stresses. --The maximum stresses used for design were based in general on the following criteria: (1) Tensile. --The allowable design stress in tension used for the following materials were the smaller value of the percentages of the yield and ultimate strength of the following material: (2) Compression. --The allowable design stresses in compression used for the materials listed above were the same as for tension. (3) Bearing. --The allowable design stresses used for crosshead or trunnion bearing were limited to 3, 500 pounds per square inch. (4) Shear. --Allowable design stresses in shear were not more than 0.6 the allowable design stresses in tension. (5) Hoist cylinders. --Allowable design stresses for hoist cylinders were based on the recommendations of the ASME Boiler and Pressure Vessels Code--Unfired Pressure Vessels--Section VIII. 194. Intake Structure Electrical System. Electric service for operation of electrical and lighting system equipment at the Clear Creek Tunnel intake structure is provided at a power distribution panel in the pump chamber of the structure by means of a service circuit in a conduit extending from a service pole located near the roadway abutment end of the structure access bridge. Lewiston Powerplant provides the source for the electrical service (fig. 121). Service is nominally 115/230 volts, 3-phase, 4-wire (groundedneutral), 60 cycles providing 230-volt, 3-phase service for operation of motors and 115/230-volt service for operation of the structure lighting system. Motor-driven equipment served includes a fishscreen wash pump, a screen hoist unit, and 10 slide gate lifts. The wash pump motor and the power and lighting system distribution panels are located in the pump chamber of the structure, and the screen hoist and the slide gate lifts are located on the hoist deck of the structure. The lighting system provides illumination in the pump chamber and on the hoist deck area; and 115-volt convenience outlets served by lighting system circuits are provided in the pump chamber and at the hoist deck area. Motors, the lighting distribution panel, and a 230-volt power outlet are served by branch circuits emanating from the power panel. Lighting fixtures and convenience outlets are served by branch circuits emanating from the lighting panel. Branch circuits are afforded overcurrent protection by automatic-trip molded-case-type circuit breakers grouped in the respective power and lighting system distribution panels. The main service circuit to the structure is afforded overcurrent protection by a fused main service switch located on the service pole. The magnetic motor starters for the water pump and slide gate lifts are controlled by pushbutton station units. The various motors are afforded thermal overload protection by their associated starters. Pump chamber and hoist deck lights are controlled by lighting circuit switches located at the hoist deck. 195. Clear Creek Penstock Valve Structure Electrical System. Electric service for operation of butterfly valve equipment and lighting equipment in the penstock valve structure is provided nominally at 480 volts, 3-phase, 60 cycles, from two sources. The emergency source is obtained from the distribution system of the Pacific Gas and Electric Co. The normal source originates at a circuit breaker located at power board M1A in Clear Creek Powerplant. Both the normal and emergency service circuits enter the valve structure via conduits and terminate at an automatic transfer switch contained in butterfly valve control center HJA located in the structure. A All electrical equipment in the valve structure is usually supplied from the normal source through the transfer switch. Failure or loss of normal source voltage will cause the switch to transfer automatically the electrical equipment load from the normal source to the emergency source. Restoration of voltage to normal source will cause the switch to retransfer the load to the normal source. The switch is such that it will not transfer load to a dead or unenergized source. Also, loss of normal source voltage for approximately 30 cycles or less will not initiate transfer of load to the emergency source. Lighting system voltage for operation of valve structure lights is provided by a 480- to 120/240-volt, 5-kv. -a., single-phase, 60-cycle transformer located in control center HJA. The transformer serves a circuit breaker type load center distribution panel located adjacent to the control center. From the breakers in the load center panel, circuits emanate to serve lights and convenience outlets in and on the valve structure. Exterior lights on the structure are controlled by a time switch located near the load center panel. The control room lights are controlled by a single-pole switch located near the access door. The remainder of lights in the structure are controlled by circuit breakers in the load center panel. The penstock valve structure is provided with a grounding system to which the electrical equipment enclosures, electrical conduits, and other metalwork items are connected. GENERAL OPERATING INFORMATION The two 156-inch butterfly valves are operated by separate and 2 The butterfly valves are normally to be opened or closed with volve -Penstock water pressure switch ---Oil pressure goge System relief -Oil pressure Angle check Oil pump Unloading 4. The valves may be opened or closed locally from the electrical control 5 Emergency closure, which overrides all opposing signals, may be a. Loss of governor actuator oil pressure or level b. Incomplete sequence of operations on shutdown of generating unit. e Continued ratation of turbine runner after unit should have stopped 7 The grease pumps will operate automatically whenever the butterfly JIC HYDRAULIC SCHEMATIC Angle check volve 3. During inspection or repair of o turbine, close Valves D and E of 4 The butterfly valves may be closed during the opening cycle by 5. When the opening or closing cycle is initiated the leaf will rotote opens to stop the motor-pumps automatically 6 The butterfly valve will not open until the downstream penstock to actuate penstock water pressure switch. After putting valve 7 Coution: After completion of any local operation from the valve C OPERATING INSTRUCTIONS: 1. Operation from local electrical control center Set oppropriate transfer (10 Open by-pass valves, by pressing appropriate OPEN push (2) When filling is complete, press butterfly valve OPEN (3) When the butterfly valve is fully open, as indicated by the red indicator light, press the by-pass valve CLOSE push button b Closing--Press CLOSE push buffon Stopping-Press STOP push button. d. Return transfer switch to REMOTE position. 2 Operation from moin control board. Appropriate transfer switch, 438V1 or 2, at local control center a. To open valve, operate appropriate butterfly valve control b To close valve, operate appropriate butterfly valve control 3. Operation from Keswick Power Plant. Set appropriate transfer switch, 438V1 or 2, of the local electrical a To close valve, operate appropriate keyed switch handle, b Valves cannot be opened from Keswick. 416 0-2302 TEST GAGE ADDED PICTORIAL #TORAULIC SCHEMATIC PARAGRAPH AZ FLOW AND HEAD CORRECTED Figure 158. --Clear Creek Powerplant--Controls and operating diagrams for 156-inch butterfly valve. (Sheet 1 of 2.) INSTALLATION AND SERVICING INSTRUCTIONS All adjusting and testing procedures, except the emergency close test and A. GREASE PUMPS: 1. Fill grease pump crankcase to the proper level with SAE 20 oil. 3 Fill grease lines and butterfly valve covities by removing grease B. FILLING THE SYSTEM WITH OIL: The pressure devices have been shop set and should require no 2 Approximately 285 gallons of new, clean, light, hydraulic oil will be 3. Physically place the butterfly leaf in the open position and close 4 Provide and install auxiliary piping and volve C suitable for 1000 • Remove solenoid wiring access plate on 4-way valve and temporarily 9. Open Valves Q. v, and R. Press either the CLOSE or the OPEN push 10 Press CLOSE push button, the piston will raise and the butterfly IL Press OPEN push-button when the butterfly valve is fully opened b Valve open--Adjust screws to operate four upper switches simultaneously which actuate as follows (1) Two switches apen to turn green lights off at local control center, power plant control board, and supervisory control board at Keswick (2) One switch closes to actuate by pass valve closure D. CHECK REMOTE OPERATION: From main control board (See Operating Instructions Porograph C-2) b When butterfly valve is fully open, check that by-pass valves c. initiate closing cycle from main control board and check for proper closure of butterfly valve. 4 Initiate opening cycle and interrupt it by initiating closing cycle Check that valve closes 2. From Keswick control board (See Operating Instructions Paragraph C-3). a. With butterfly valve fully open, initiate closing cycle from Keswick control board and check for proper closure of butterfly valve E PRESSURE DEVICE FUNCTIONS, SETTINGS, AND ADJUSTMENTS: e Place a jumper wire across terminals of pressure switch c. Adjust relief volve as quickly as possible to maintain gage b. Adjust sequence volve to give a minimum goge reading of 100 4 The oil pressure switch is set to open contacts and stop motor pumps a. Set relief valve slightly above its minimum setting of 500 psi b if butterfly valve is open press OPEN push button, if closed. c. Do not open valve R when gage reads less then unloading valve d Slowly close Valve R and build up goge pressure until pressure e Close Valve v and almost close Valve Q Restart motor-pumps as F MAINTENANCE. The service and maintenance procedures prescribed by the 2 The oil tanks and lower cylinder heads of operating units shall be 3. The oil filters should be removed and cleaned immediately after 4. Check oil level in grease pump crankcoses periodically, and grease ,5 Butterfly valve mounting bedplates should be greased periodically 6. When butterfly valves are not operated for prolonged periods, grease 7. Check operation of entire control system including both hydraulic 8 Every two years, check gages for accuracy and adjust pressure 9 Method of making operational test with butterfly valve open and a. With operators stationed at the local control center in the valve b. As soon as the green light turns on at the local control center, indicating CAUTION: Valve closure must be stopped before it interferes with c. Reopen the butterfly valve from the main control board using the appropriate OPEN switch BVICS or 2CS 10. Unbalanced closure tests d Test procedure: (1) Install test pressure goge at valve C. (2)Set turbine wicket gates to produce desired flow thru unit to be tested, (3) Initiate butterfly valve closure using BVICS or BV2CS at power plant control I For seal and operating unit adjustment instructions see The electrical control equipment for bath butterfly valves is housed 8. OPENING VALVE NOI BY REMOTE CONTROL: C. CLOSING VALVE NO.1 BY REMOTE CONTROL: TRACES ... ECOMMENDED. спесикоза. APPROVED. DENVER, COLORADO, NOV 30, 1962 416-0-2676 Figure 158. --Clear Creek Powerplant--Controls and operating diagrams for 156-inch butterfly valve. (Sheet 2 of 2.) B. Clear Creek Powerplant 1. Powerhouse Structure 196. General Structural Design. As stated in section 99, the general and structural layouts of Clear Creek and Trinity Powerplants were very nearly identical, but opposite hand. The structural design was therefore intimately related. It was decided that where the structures were comparable from a design standpoint, one design analysis would be made and the results used for both structures. The analysis used was based on composite critical design conditions from both structures. This decision was made as an economy move in the design office and to speed up the design which was tightly scheduled for the number of personnel available. The final structures were somewhat overdesigned in a few areas, but separate analyses were made where possible savings were indicated. Figures 159 through 163 show the general arrangement of Clear Creek Powerplant, and figure 164 shows a view of the powerplant. 197. Loading Conditions. Principal data pertaining to the structural design of Clear Creek Powerplant are shown on figure 165. Among the more important items shown are live loads on floors and decks throughout the plant including trailer loads, weights of generators, cranes, turbines, oil tanks, and transformers; and loading conditions for analysis including assumed loads for water, temperature, wind, earthquake, backfill, and uplift pressures. Working stresses and allowable increases in unit stresses for various loading combinations are also shown. The original design was based on estimated weights and dimensions of equipment. When final manufacturer's data indicated that the equipment weight and size were in excess of estimated values, the design was reviewed and revised accordingly. 198. Basic Data and Codes. See section 101 for a listing of data and codes used in designing both the Trinity and Clear Creek Powerplant structures. 199. Stability Analysis. Loading conditions tending to cause instability and flotation of the structure were investigated for construction and normal operation of the powerplant as shown on figure 165. Allowable values of cohesion, friction, and bearing as determined from laboratory tests are also indicated. Full uplift pressures were assumed effective over the entire base area as outlined in present Bureau policy. Loads of primary importance considered include dead load, equipment loads, hydraulic thrust, water and backfill loads, and earthquake. It was determined from stability studies that the powerplant would be stable for any forseeable construction and operation conditions with the exception of failure by sliding. The primary question was the amount of cohesion which would develop between the concrete and rock foundation. A key placed at the downstream toe of the powerplant was added to insure necessary stability against sliding. 200. Foundation Preparation. (a) General. --The location of Clear Creek Powerplant was changed several times to avoid major faults. Excavation, however, revealed the final site to be badly faulted. These faults crisscrossed and dipped in different directions and in a random manner. It was generally agreed that faults could not be avoided by minor shifting of the powerplant location. Necessary adjustments in the foundation preparation were therefore undertaken as the most feasible solution at the late date. (b) Gas Collection System. --It was further determined during preliminary exploration and later during excavation that methene gas was seeping out of these faults under low pressure. This is a light, odorless, and flammable gas. It was feared that the gas would seep into the plant over a period of time and cause a serious fire hazard and might even be exploded by a mere spark. A method of venting this gas into the atmosphere and above the powerplant roof was therefore deemed necessary. Since the gas was coming primarily from the faults, it was desirable to collect it in or at the faults before it spread under all areas of the plant. Accordingly, loose material in faults greater than 1 foot in width was gouged out to a depth of twice the width of the fault plus 6 inches. Coarse gravel covered with building paper was placed in the bottom few inches to provide a makeshift channel to collect the gas. top of this channel was maintained at near constant elevation but with slight slope to prevent pockets of gas collecting. Concrete backfill was then placed on top of this in the gouged-out area. The Where the faults were too narrow for the above treatment and where drill holes had been made during exploration, steel channels were provided in place of the gravel and building paper channels. These steel channels were placed on a gravel bed for leveling purposes. All channels for the flow of gas terminated in a perforated clay pipe header embedded in gravel at the edge and base of the structure. Gas was then piped from this header to a point above the powerplant roof and vented to the atmosphere. The location of all channels was determined in the field at points where escaping gas could be detected. A maximum spacing of 25 feet was recommended, however. The gas collection system is shown as details on figures 166 and 167. At first glance, the collection channels may not appear to form a positive collection system. It should be realized, however, that the gas will flow along the path of least resistance. Also, the channel barrier formed by the building paper needed to be little better than the surrounding foundation material, which was badly deteriorated. These criteria, coupled with the low pressure which the escaping gas was under and the submergence of the whole system, precluded more refined treatment. |