Niagara Falls 100.000-Hp. Development

Niagara Falls 1 00,000 Hp. Development [11 of the substructure, and can be relied upon to trans- mit the loads imposed upon it without distortion. The resistance of cast iron to corrosion insures a long life for the casing, which is a matter of importance since the casing could never be replaced without dismantling all of the surrounding concrete substructure. The cas- ing can be depended upon to be tight throughout the life of the plant, and there is no likelihood of local points of weakness being developed as in the case of a riveted structure. The casings have been subjected to hydro- static pressure tests in the shops to a pressure of 120 lb. per square inch, which is well in excess of any pressure to which the castings can be subjected in opera- tion during a quick gate closure resulting in water hammer. Another advantage of a cast-iron casing is the ease and speed with which it can be erected in the field. The heaviest section of the casing weighs slightly less than 60,000 lb. The movable guide vanes are of cast steel, cast integrally with their stems. The guide-vane stems turn in bronze bushed bearings in the distributor plates and head cover. Operating and Lubricating Mechanism The operating mechanism is unusually rugged throughout, the guide-vane stems being of large diam- eter, the cast-steel operating ring extremely rigid; and the levers and other parts of the mechanism being made sufficiently strong to render the failure of any portion of the mechanism an unusual occurence even when trash becomes lodged between two guide vanes and the entire governor power is concentrated on two vanes. Renewable breaking links are provided to pro- tect the other parts of the mechanism in case undue load should occur. The operating ring is supported on a ball bearing. It is turned by two operating cylin- ders which are bolted to pads or brackets cast on the turbine casing, thus making the entire operating mech- anism self-contained with the turbine. The connecting rods between the operating ring and pistons are pro- vided with adjustable ends of similar design to the connecting-rod ends used in steam-engine practice so that any wear may be taken up and lost motion avoided in the operating mechanism. The piston rod is provided with a bronze sleeve where it passes through the stuffing box in the cylinder head, and the rod is guided by a bearing supported in a guide bracket bolted to the cylinder. For the lubrication of the operating gear, the Taylor system of lubrication is used, consisting of a central grease gun supplying a system of piping leading to each individual bearing, so that the admission of grease or oil can be controlled to each beai’ing individually by turning a separate cock at each bearing, the lubri- cant being forced into the bearing by air pressure admitted to the grease gun. A special design of runner seals have been used to reduce the leakage around the runner and to assist in making the thrust relief effective. The seals are of the multiple or labyrinth design in which a series of contractions are interposed in the path of the leakage water alternating with enlargements in which the veloc- ity of the leakage flow produced eddies and reduces the quantity escaping. This provision although effecting only a small percentage of the total energy when the turbine is new will be of material advantage in pre- venting a serious deterioration in efficiency after the unit has been some time in operation. The leakage FIG. 12—I. P. MORRIS TURBINE ERECTED IN SHOP above the runner passes through a cored space in the turbine head cover and is vented through the runner hub, discharging into the center of the draft tube. The seals are formed in renewable wearing plates. The distributor plates above and below the movable guide vanes are also renewable. At discharge from the runner the draft tube is lined with a renewable ring which may be replaced if corrosion should occur during the life of the unit. The main shaft of the turbine is supported by a lignum-vitæ guide bearing in the turbine-head cover, and the shaft is provided with a renewable bronze sleeve where it passes through the bearing, seal and stuffing box. The bearing shell is split both hori- zontally and vertically to facilitate its removal. The equipment furnished with the turbine includes a set of brakes arranged to act upon the lower face of the generator rotor. These brakes consist of a series of shoes actuated by plungers, operated by air pressure. The operation of a brake is controlled from a cock mounted on the hand-control stand located close to the governor. Governor Regulation The turbine is regulated by a governor of the I. P. Morris double floating-lever type, belt driven from the main shaft of the turbine. The governor proper or the actuator and the separate hand-control stand are located on the gallery at the elevation of the thrust bearings mounted on top of the generators. The unit can therefore be operated fi'om this point. In order to avoid running a number of lines of the large governor piping from the operating cylinders up to the gallery with a consequent increase in the length of fluid column between the governor and the cylin- ders, resulting in increased inertia of this fluid column, the main governor valves are separate from the gov- ernor and placed on the level of the generator-room floor so that they are immediately above the operating cylinders. The Taylor control system is used with these units. This involves the use of fluid-operated plunger valves of the Johnson type, by the operation of which the operating cylinders can be connected to either the gov-