sleeves. During the final press, the rim studs were tightened with an impact wrench and all the rim stud nuts were lock welded.

Field poles were delivered as required for each unit and were checked for dielectric insulation resistance prior to installation. Those pole pieces that were low in value were internally heated, using electric welders or high-current rectifiers, until the proper dielectric value was obtained. The individual pole pieces were placed on the rotor with the powerplant overhead crane. They were held in place by vertical keys driven tight; the surplus key stock was cut off and stop plates were installed on both ends of the keys. Series field connections between the poles were silver-soldered and final connections were made to the slip rings by a bus system. The rotor was spray-painted with insulating varnishes before being installed in the stator bore. Figure 290 shows a closeup of the rotor for unit 8.

(c) Stator Assembly.-Each stator was shipped in three sections on flatcars to Flagstaff, Ariz., then transported to Glen Canyon by special truck. Stator erection began by placing the foundation pedestals to proper elevation. The three sections were placed in approximate position, bolted together, rounded to proper diameter, and then bolted and horizontally doweled to the foundation pedestals.

Each stator section was shipped with the armature coils in place. At each location where the stator sections bolted together, eight makeup coils were installed by armature winders. The 14 coils originally installed at the factory were lifted and replaced after the eight makeup coils were added at each junction. All makeup and lift coils were heated to 85° C. surface temperature for 1 hour, which rendered the insulation flexible. Series coil connection phase jumpers and the bus sections in the splits were silver-soldered. The completed coil assembly with buses and jumper was given two coats of insulating varnish. The completed stator assembly was centered in the pit with reference to the center of the turbine shaft and was set to a grade elevation 0.035 inch high to allow for settlement of the assembled machine.

(d) Assembly of Major Parts.-The major assembly work began after the rotor, stator, lower bearing bracket, and upper bearing bracket assemblies were completed. The lower bearing bracket and upper bearing bracket were assembled in the field and all connections were hot-bolted together. The lower bearing bracket, with the lower cover plates in place, was placed on the foundation plates, centered, leveled, and bolted into place. This was used as a working platform for the stator erection. After the stator was

rounded out, centered, and winding completed, the brake jacks were placed and leveled to the proper elevation, which prepared the unit for placing of the rotor assembly.

The completed rotor (fig. 288) was connected to the 580-ton-capacity lifting beam, which was supported by the four 150-ton hooks on the two 300-ton overhead cranes. The assembled rotor was lifted off the pedestal and suspended in the erection bay where workmen cleaned the coupling face. The rotor was then moved to the stator bore and carefully lowered into position, resting on the brake jacks. In placing the rotor, masonite guide slats were used to keep the rotor from contacting the stator bore.

and pullers from 3 to 10 tons, one engineers transit, two engineers precision levels, three sets small tools consisting of electric and pneumatic portable drills, grinders, sounders, nibblers and impact wrenches, sockets, wrenches 3 inches down to one-fourth inch, end wrenches, machinist levels, micrometers, gauges, scales, etc., and one power-driven wood saw, one power-driven hacksaw, and a sufficient supply of special tools and instruments as required by the electrical, machinist, and millwright crafts.

The contractor made available, for a fee, one alternating-current high-potential testing transformer with control and power supply for the Government to perform the required alternating-current high-potential proving tests.

(g) Work Procedures and Practices.-The completion contract provided under specifications No. DC-5750 that the generator contractor would furnish the lower bearing bracket anchor bolt, lower bearing bracket foundation plates, stator foundation pedestal anchor bolts, stator foundation pedestal, which would be installed and to proper level by the completion contractor. The lower bearing brackets were shipped partially assembled. Two arms were hot-bolted to the center hub in the field. The physical dimensions of an overall width of 22 feet 11 inches made it impractical to preassemble this subassembly at the factory. The lower cover plates were assembled on the bearing bracket before placing it on the lower bearing bracket foundation plates. The bracket assembly was placed on the foundation, brought to elevation by checking from the turbine crown plate, and centered by using a tightwire from a tripod above the generator foundation to the turbine shaft true center. After the alinements were completed, the bearing bracket was doweled to the foundation plates, which were then grouted in place. The brake jacks and brake jack piping were placed into position on the lower bearing bracket, taking advantage of the clear working space.

The stator foundation pedestals were installed under specifications No. DC-5750. Care was taken to give the final grade on these pedestals with the reference to the top of the stator section. By doing this research on the stator section, shims were eliminated between the stator and the foundation pedestals.

The three stator sections were placed in the pit on the foundation pedestals. Premilled vertical shear horizontal keys were placed in the three splices to control the 17-mil penetration of the stator laminations when the sections are fastened together. (It was anticipated that these keys would be inspected for tightness after 3 or 4 years of operation. If not tight, the split through bolts should be retorqued as looseness

at this point will develop a soft lamination assembly in the stator, eventually resulting in coil damage from either coil or iron migration.)

The stator section split bolts were tightened until the 17-mil penetration of the lamination was obtained. The stator section was rounded by establishing the true center of the unit using a tripod extending above the stator with the lower bearing bracket as the base. A tightwire was installed from the tripod upper bearing to the center of the lower guide bearing chamber in the bearing bracket. Micrometer readings were taken from this tightwire to the predetermined points on the inner circumference of the stator. Five measuring points were prepared about 6 inches from and on each side of the split. Measuring points were then prepared about every 20° around the inner circumference. At each location one point was about 3 inches from the top of the laminations, one up about 3 inches from the bottom, and a third in the middle of the lamination assembly. At the splits other points were located between the middle point and the upper and lower points. Five dual lift jacks were placed around the outside circumference of each stator section. Near the baseplate line, each jack was brought up to a light compression again at the stator frame. After each set of micrometer readings were taken of the stator inner circumference, the jacks were readjusted to bring the stator into proper conformation at the bottom ring, midsection, and top where it was practical to obtain this condition. Where eccentricity existed between the top and bottom ring, adjustments were made by raising the stator and shimming the pedestal contact to plumb the lamination form. The maximum shim installation was 25 mils on one pedestal.

Before releasing the jack holding the stator in position, the horizontal dowels were drilled and placed in the pedestal-stator junction and all foundation and mounting bolts were torqued to proper tension. A working platform was constructed on the lower bearing bracket to facilitate the installation of the lap coils.

(h) Handrails.-As originally constructed, the handrails on the top of the generator air housing enclosed only about one-sixth of the deck, providing a guarded passage from the access stairway landing to the exciter platform stairway and to part of the collector ring brushes. As maintenance workers needed access to the remainder of the deck, during routine maintenance operations, it was necessary to provide additional handrails to encircle the entire deck. Specifications No. DC-6441 provided for furnishing and installing this additional aluminum handrailing and for removing a portion of the existing handrail. Larsen Rigging and Equipment Co. of Salt Lake City, Utah, began work

226. GENERAL DESCRIPTION. The turbo-generating units require a substantial amount of mechanical equipment in support of the plant operation. Two 300-ton cranes in the main generator room and a 75-ton crane in the machine shop are required to maintain the units. A complex oil storage and handling system is necessary to lubricate the mechanical equipment, as well as a separate system to service the insulating oil requirements of the electrical equipment. Large water pumps are also needed to dewater the various sumps, others to circulate the generator cooling water, and even larger booster pumps are required for domestic water supply purposes. A compressed air system was required for specific and general service use in operation and maintenance of the plant, and a carbon dioxide fire extinguishing system was necessary to protect the generators and the oil handling rooms.

227. 300-TON POWERPLANT CRANES. Overhead in the main generator room in the powerplant are two 300-ton traveling cranes (fig. 290) with a span of 71.5 feet. Each of the cab-operated cranes has two trolleys with 150-ton-capacity main hoists and 30-ton-capacity auxiliary hoists. The lifting capacity of the two main hoists on each crane may be combined with a lifting beam to produce a total capacity of 600 tons when the trolleys on each crane and the bridges of the two cranes have been locked together. These electric cranes are for use in installing and maintaining the turbines and generators and for handling materials in the service area. Each main hoist

Figure 290.-Two 300-ton cranes with lifting beam moving unit 8 rotor from assembly pad to final placement location. P557-420-11333, July 21, 1965.

has a lift of 80 feet and is equipped with 12 parts of 1-3/4-inch-diameter wire rope and a sister hook drilled for a horizontal lifting pin. The auxiliary hoists are standard single-hook with four parts of 1-inch-diameter wire rope and have a lift of 100 feet. The 300-ton cranes were purchased under invitation No. DS-5260 by Yuba Consolidated Industries, Inc., of Benicia, Calif., and were installed by the prime contractor.

Erection of the 300-ton crane began in December 1961, in the Merritt-Chapman and Scott Corp. fabrication yard at the site. This yard work consisted of the structural steel assembly of the main bridge girders and placement of the trucks. The assembled bridge girders were placed on the powerplant crane rails by high-line cableway before the roof of the powerplant was installed. Most of the installation of equipment could then be performed with the bridges in place on the rails.

On April 11, 1962, the erection engineer representing Yuba Industries reported to perform acceptance testing of the cranes. The cranes were adjusted and run-in for the formal acceptance testing. Tests on the No. 1 crane started April 16. Because of a faulty hoist motor brush position, the test load dropped a sufficient distance to throw out the windings of the main hoist motor. The hoist motor was repaired and returned in July. The testing resumed and an auxiliary motor was damaged. The contactors were then found to be defective on both cranes and were replaced. The test on the No. 2 crane was started July

25 with a 187.5-ton load and this test was completed in August.

By order for changes No. 15, the 300-ton cranes were tested in accordance with paragraph C-4 of invitation No. DS-5260 instead of in accordance with the requirements of subparagraph 182(b) of the construction specifications.

(1) All main and auxiliary hoists were tested at no load, half load, and rated load to determine electrical characteristics and hoisting and lowering speeds.

(2) When conducting the bridge speed test under subparagraph (d)(4) of paragraph C-4, only one main hoist had a test load of 150 tons on the hook. The other hoist was unloaded.

(3) The cranes were tested consecutively so that final adjustment could be made to assure all four hoists operating as nearly alike as possible.

The auxiliary motor on the No. 1 crane was repaired and returned, and tests on both cranes were completed November 1962. Separate technical reports on the cranes were made.

228. 75-TON MACHINE SHOP CRANE. The 75-ton machine shop crane is a cab-operated, indoor traveling-type crane with a span of 67.5 feet. This electric, overhead crane travels on a runway extending the length of the machine shop and is used for handling materials and equipment in the shop. The trolley is equipped with a 75-ton-capacity main hoist and a 15-ton-capacity auxiliary hoist. With rated load the main hoist operates at speeds up to 6.6 feet per minute. The main hoist has a lift of 40 feet and is rigged with eight parts of 1-1/4-inch-diameter wire rope and a sister-type hook bored for a lifting pin. The auxiliary hook is a standard type with the total lift of 55 feet with four parts of 0.785-inch-diameter wire rope. The bridge speeds are variable up to 85 feet per minute.

This crane was supplied by the Legnano Electric Corp. of New York and Torino, Italy, under invitation No. DS-5252 and was installed by the prime contractor. The formal load testing of the 75-ton crane was started on February 21, and was completed on March 2, 1962. The load test pointed up motor defects on the bridge and trolley. The replacement of motors was extended in time until the prime contractor's forces were moving out, and the supplier had the repair work performed by the completion contractor.

The prime contractor had installed the 75-ton crane in the powerplant machine shop during the month of January 1962. As the connections were turned bolts in fitted holes, the assembly was not difficult and very little drifting and no reaming was required. The major mechanical problem encountered involved the operation of the hydraulic bridge brakes. After several unsuccessful attempts to adjust the bridge brakes, a close check revealed that the crane supplier had installed master cylinders at the cab-operated pedal and also at the brake shoe locations on the trucks of the bridge. This situation could not be corrected without extensive revisions of the entire brake system design. Although the brake system would stop the crane under full load at full speed, the mechanical advantage of a large master cylinder to smaller servo-cylinders was not in the system, and a large amount of pressure on the brake pedal was required to stop the crane. However, after further study, it was determined that the brake system would serve the purpose intended and basically met the specifications. The installation was therefore accepted.

229. 10-TON GANTRY CRANE. The 10-ton crane is an outdoor, traveling gantry type and was installed on the transfer deck on a track allowing travel along the length of the powerplant. This crane is for use in operation and maintenance of the turbine draft tube bulkhead gates. The gantry is equipped with a 10-ton base-mounted hoist. The hoist has a lifting speed of 14 feet per minute and a total lift of 80 feet and the gantry travels at a speed of 35 feet per minute. Both hoist and travel motions are controlled from a pushbutton station on the hoist platform of the gantry. The crane was fabricated by Crane Hoist Engineering Co. of Bell, Calif., under invitation No. DS-5398, and was installed by the prime contractor. The 10-ton gantry crane was placed on the rails of the transformer deck of the powerplant in March of 1962 and the counterweight was placed in April of 1962. During a trial run, when the crane was being used to install the draft tube bulkhead gates, the worm gear reducer drive unit was damaged and it was determined that this unit was not of sufficient capacity to meet the specification requirements. The worm gear reducer was replaced by one of greater capacity received on August 21, 1962.

230. OIL STORAGE AND HANDLING SYSTEMS. The lubricating and governor oil storage facilities consists of two vertical 4,000-gallon tanks. These tanks were furnished by American Steel and Iron Works of Denver, Colo., under invitation No. DS-5265 and were installed by Merritt-Chapman and Scott Corp. The tanks were installed, except for final cleanup and painting, during the spring of 1961 in the