Grand Coulee Dam Photo Gallery
Here are photos of various pieces of dam equipment such as pumps, generators, turbines, and transformers. All photos are stored in JPEG format to provide good color and image quality in a minimum amount of space. Photos are 1024 pixels in length measured on the long axis and take up approximately 100kB of storage.
All photos were taken by the author unless otherwise noted.
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Third Powerhouse Intake Service Crane:
This crane, located on the dam roadway above the third powerhouse, is used to service the penstock inlets. A section from one of the inlet trashracks can be seen suspended from the crane. The left and right powerhouses and the pumping plant have similar cranes.
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Right Powerhouse Generators:
This is a view of the right powerhouse generator bay. The powerhouse contains nine 125,000 kW turbine generators numbered G-10 through G-18 (nearest). In the photo you will notice that generator G-12 appears to be missing. It has been torn down for maintenance. The rotor for G-12 is shown below.
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G-12 Generator Rotor:
This is the rotor out of the right powerhouse's G-12 generator. It is 31 feet in diameter, 18 feet tall and weighs 600 tons. It consists of many vertical bundles of copper conductor wound around iron cores. During operation the copper conductors are energized with DC current turning the rotor into a giant spinning electromagnet. The rotor spins inside the 'stator' -- a ring of vertically oriented coils of copper wire -- at 120 turns per minute. As the magnetic field lines of the spinning rotor sweep through the stator coils they induce an electric current thereby generating electricity. For a more detailed description of hydroelectric generators and their theory of operation visit Doug Filer's "Hydroelectric Generators" page.
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G-18 Turbine Shaft:
This shaft couples the rotor (shown above) to the turbine. This shot was taken below unit G-18 in the right powerhouse.
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Right Powerhouse Turbine Control Bay
This is a picture of the turbine controls for the right powerhouse. From these controls an operator can open or close the wicket gates which control the water flowing through the turbine. A governor automatically makes minute adjustments to the gates so that the speed of the turbines is maintained at exactly 120 revolutions a minute. Although operators can manually control the turbines from this location the turbines are usually started, stopped, and monitored from a remote computer control center.
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Third Powerhouse Stator Shell
This is a picture of the stator ring from one of the Canadian General Electric (700 megawatt) generators in the third powerhouse. It is approximately 65 feet in diameter. The stator has been removed from the generator, placed at one end of the generator bay and stripped down. Here you can see the slots in the laminated iron core into which the copper stator windings are placed. This stator and two others (on the remaining CGE units) are in the process of being rebuilt. The yellow pillars are mount points for the 2000 ton capacity hydraulic crane which services the generator bay.
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Third Powerhouse Generator
This picture was taken from the top of the stator ring of one of the Canadian General Electric generators in the third powerhouse. The ring of fiberglass boxes which can be seen streching around the perimeter of the stator are coil connection points. They represent the top end of the loops of conductor which form the stator. The white surface inside the ring is the top of the generator's rotor. The stator on this unit has just undergone a complete rebiuld by Siemens Power Corporation. The original stators suffered from binding under thermal expansion (the generators operate at over 100 degrees F above ambient) which caused their laminated steel cores to buckle. Siemens has incorporated a number of advancements into this stator which will bring its generating capacity up to 825 megawatts (from its previous rated capacity of 700). That makes this the largest hydroelectric generator in the world. With further improvements to the unit's rotor and transformer it might be possible to boost its output capacity to 1000 megawatts!
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Current Transformer on Third Powerhouse Stator
The new stators are divided into 18 independent circuits -- six for each for each of the generator's three phases. The output of each circuit is ringed by a "current transformer" like the one shown here. This device monitors the magnitude and direction of the electric current traveling through the circuit. At any given instant the net output of all the current transformers combined should be ZERO. This combined output provides and important indicator of proper generator operation.
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Scroll Case / Wicket Gates for Third Powerhouse Turbine
This photo was taken from inside the scroll case of one of the third powerhouse generators. The lighting was serendipitiously provided by workmen who were repairing cavitation damage to the turbine. A generator scroll case is a large snail-shell shaped spiral which winds once around the turbine inlet. The diameter of the scroll case gradually decreases from the diameter of the penstock (about 35 feet in this case) as it winds around. This geometry provides even water flow into the turbine from all sides. As can be seen in the picture, the inlet to the turbine is ringed by a series of louvers called wicket gates. These can be opened and closed as necessary to maintain constant generator speed.
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Third Powerhouse Turbine
This picture was taken from the draft tube just below a third powerhouse turbine. The individual turbine blades can be seen curving down from the top. When in operation, water falling through the blades causes the turbine to spin in a counter-clockwise direction (as seen from below looking up). The yellow blur running from center left to lower center is a fluttering "caution" streamer.
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Third Powerhouse Generator Bay
This is the third powerhouse generator bay. Unlike the right and left powerhouses, generators in the third powerhouse are all below floor level. One of the generator pits can be seen near the center of the picture. In the background is the 2000 ton capacity hydraulic service crane.
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Third Powerhouse 2000 Ton Cap. Service Crane
This, the largest crane in the world, was designed to move the heavy rotors and turbines which make up the generators in the third powerhouse. It is powered by four large hydraulic rams which can be seen protruding from the top. The crane can travel the length of the generator bay on railroad tracks which are recessed into the floor on either side. One of the generator pits can be seen in the foreground. The actual generator lies 12 feet below the surface of the pit cover.
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Preparing to Move Third Powerhouse Stator Shell
Here workmen can be seen moving the third powerhouse service crane into position over an old stator core. The stator core will be moved to the other end of the generator bay where it will be rebuilt and eventually installed in another generator. A complete stator rebuild takes nearly a full year to complete. By building the stator "on deck" the generator which will eventually receive it can remain in operation using its old stator until the new one is ready. This reduces generator down time from a year to several weeks.
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Third Powerhouse Cable Switchyard:
This is the third powerhouse cable switchyard located up above the gorge a couple miles west of the dam. Electricity from the third powerhouse is routed via oil-filled conduits through galleries in the main dam. From there they travel up a tunnel to the 525kV cable spreading yard and then overhead to this switchyard.
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Pump/Generating Plant Pump Bay:
This is a view into the pump bay of the pump/generating plant. The four pumps in the foreground are 65,000 horsepower pump-only units which derive their power from dedicated generators in the left powerhouse (two pumps per generator). Two other pumps of this type are out of the field of view to the left. The six pumps in the background are newer pump/generator units (notice that they have a slightly different appearance). These units provide 67,500 horsepower of pumping power and can be reversed during times of high power demand and made to act as generators. In the generator mode these units can provide 50 megawatts of electrical power.
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Pump Unit P-2 Stator:
This view is looking down into the partially dismantled P-2 pump unit. The rotor has been removed and the stator ring can be clearly seen.
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Pump Unit P-1 Control Pannel:
This view shows the control and status indicators for the P-1 pump unit. The other 11 pumps have similar stations.
This page is maintained by Charles Hubbard as a private effort. Mr. Hubbard is in no way associated with the U.S. Bureau of Reclamation or the Columbia Basin Project.
||September 19, 1995
||April 20, 1996