installed. These data are correlated with data from the triangulation measurements for information to detect possible deformation of the foundation of the dam.

(i) Records and Reports.-Readings of the instruments embedded in the dam, deformation meters, Invar tapes, uplift pressure pipes, the drain flows, and measurements on the plumblines are made in accordance with the schedule shown by the designers' operating criteria. These data are recorded on appropriate data sheets and transmitted as a monthly report to the Engineering and Research Center, Denver.

Daily records of air and water temperature, reservoir and tailwater elevations, and any other data that may have an effect on the structural action of the dam, along with comments concerning the operation of the apparatus or the measurements are included with the report.

Measurements of the movement of the deflection targets on the face of the dam and measurements over the system of theodolite piers are made at a less frequent interval than the other measurements. The schedule for these triangulation measurements is also indicated by the designers' operating criteria. These data are transmitted to Denver as they become available.

Check measurements of embedded instrument cable resistances are made semiannually. As these data become available, they are transmitted to Denver with the monthly reports of instrument readings on appropriate data sheets. The Bourdon-tube pressure gages used for uplift pressure measurements are cleaned and recalibrated annually.

C. DAM ELECTRICAL SYSTEM

39. ELECTRICAL SYSTEM FOR DAM AND RELATED STRUCTURES. The extent of the electrical system serving Glen Canyon Dam and related structures generally appears on figures 98 and 99. The major portion of the system was installed under specifications No. DC5750, and the following materials were installed under specifications No. DC 4825 Empecced electrical materiais incitaing portions of electrical conduit and grounding systems, emcecced parts of lighting fixtures along the crest

roadway on the dam, on the right abutment service bridge, and at the river outlet valve structure; and the gantry crane power outlet receptacles along the crest roadway. The system serves electrically operated equipment and lighting systems located in and on the dam proper, the elevator towers, the spillway gate structures, and the river outlet valve structure. As shown on figures 98 and 99, the electrical system employed for the dam, elevator towers, and spillway gate structures is served by two transformer banks located in the dam. Each transformer bank is served by a primary service circuit originating at switchgear in Glen Canyon Powerplant. These primary service circuits are energized nominally at 4,160 volts, 3-phase, 60 cycles, and each circuit is connected to and served by a circuit breaker in the powerplant 4,160-volt switchgear. The transformer banks provide service at nominally 480 volts, 3-phase, 60 cycles to two main power distribution panelboards located in the dam. From these two main power distribution panelboards, power distribution circuits energized nominally at 480 volts, 3-phase, 60 cycles are extended to distribution panelboards in the dam and elevator towers. The two spillway gate structures are each served by a power circuit energized nominally at 480 volts, 3-phase, 60 cycles. The power circuits to the spillway structures are connected to and served by circuit breakers in power panelboards located in the dam. Electrical service to the river outlet valve structure is provided by a power service circuit energized nominally at 480 volts, 3-phase, 60 cycles and connected to and served by a circuit breaker in one of the powerplant's unit-sub switchgear. This power service circuit extends to and serves a distribution board at the river outlet valve structure.

The power and lighting circuits are generally contained within a rigid steel conduit system and within equipment enclosures. Conduit systems employed in the gallery system of the dam and areas not normally available to public view are for the most part exposed conduit systems; otherwise, the conduit systems are generally embedded in the concrete of structures or are otherwise concealed from view. Also, electrical distribution and control equipment employed in the electrical system is contained within exposed surface-mounted type metal enclosures, and the enclosures are generally located in galleries, rooms, and areas not normally accessible to the public.

The power distribution circuits and branch power circuits operating nominally at 480 volts and which originate and emanate from the main power distribution panelboards and branch power panelboards in the dam and related structures are afforded overcurrent protection by automatic-trip, molded-case-type circuit breakers contained in the panelboards. The breakers are also manually operable and provide a means of disconnecting the power distribution circuits and branch power circuits from their source of supply. At locations where tap circuits are connected to the branch power circuits, and also at locations where loads and equipment served by the branch circuits are not immediately adjacent to the branch power panelboards, individual circuit breakers are provided to afford overcurrent protection and to provide a means of locally disconnecting the tap circuits and equipment from the branch power circuits. The individual breakers are also automatic-trip, molded-case type.

Electrically operated equipment and loads served by the electrical power distribution system in the dam proper and the elevator towers include the gallery drainage system sump pump motors, ventilating and heating system equipment and components, penstock filling-line valve motors, penstock gate hoist oil pump motors, river outlet ring-follower gate oil pump motors, gantry crane power outlet receptacles, elevator machinery motors, and lighting system transformers. Equipment served at the spillway gate structures includes radial gate hoist motors and lighting system transformers. Equipment served at the river outlet valve structure includes hollow-jet valve oil pump motors and a lighting system transformer.

All motors of the various items of motor-operated equipment employed in the dam and related structures are afforded overload protection by thermal overload protective devices incorporated in the motor starting equipment serving the motors. The overload protective devices are a manual reset type. Motor starters are installed either adjacent to or in the control cabinets containing the motors which the starters serve and operate. Most of the motor starters are normally controlled by pushbutton stations located at or adjacent to motor starter locations. The gallery drainage system sump pump motor starters are automatically controlled by float switch equipment located in the sump pump chamber, but can also be controlled manually by selector switch units also located in the pump chamber. A selector switch is provided for each pump unit so that pump can be placed on automatic operation or started and stopped manually by means of the switch as desired. Pump

motors in penstock gate hoist control cabinets are provided with an automatic starting system controlled through pressure switches which becomes effective after a penstock gate is raised. This automatic starting system functions in conjunction with the gate position restoring system. Should a gate partially descend after being raised, the pump motor automatically starts and provides hydraulic system oil pressure necessary to automatically return or restore the gate to its fully raised position. Upon restoration of the gate to the proper raised position, the stopping of the motor is effected through action of pressure switches incorporated in the hydraulic system.

As indicated on figures 98 and 99, the gallery drainage system sump pump motors, the elevator machinery motors, and branch power panelboards PDC, PDD, PDE, PDK, PDL, PDQ, and PDR in the dam and elevator towers are each served through transfer switches. The transfer switches are manually operable and provide a means of connecting the indicated motors and panelboards to one of two power distribution circuits-a normal circuit and an emergency circuit. The apparent important or critical loads include the sump pumps, elevator machinery penstock gate hoists, river outlet ring-follower gates, and elevator towers heating, ventilating, and lighting systems.

The operation and control of the major portion of electrically operated equipment in the dam and related structures is normally accomplished by operation of controls locally provided at the location or site of equipment being operated. In a few instances, however, control circuits extend between equipment in the dam to control boards in the powerplant. The forebay (reservoir) water surface elevation is made available at a receiving instrument in the powerplant through a control circuit extending from a float-actuated transmitting instrument located in the elevator tower in block 8 at the top of the dam.

From each of the eight penstock gate hoist control cabinets located in the gate hoist structures of the dam, control circuits partially controlling penstock gate operation extend to main control board CCA in the powerplant. For each penstock gate, gate position indicating lights, a manually operable emergency complete unit shutdown switch to effect emergency closure of the gate, and a penstock gate test switch to test emergency closure of the gate are provided at the control board. Also, at the control board, the control circuits are so connected that automatic closure of a penstock gate will be effected through operation of generator main overspeed switch, governor oil level

switch, or governor oil pressure switch. These gate control circuits operate at 125 volts direct current, and the direct current is supplied by the powerplant station battery. Additional control circuits operating at 110 volts, 60 cycles, also extend from the penstock gate hoist control cabinets to the penstock filling line valve locations in the filling line gallery of the dam.

Pressure switches connected to the perstock filling line piping are so connected in the penstock gate control circuits that a closed gate cannot be raised (opened) until the penstock associated with the gate has first been filled with water by means of the filling line valve. An alarm circuit is provided between the sump pump chamber in the dam and main control board CCA in the powerplant. Abnormally high water in the drainage sump in the dam will cause a contact of the sump pump control float switch to close and thereby initiate an alarm signal at the control board. Further, should a thermal overload device in one of the sump pump motor starters operate or the control circuit operating the pumps be transferred from the normal to the emergency source of supply, contacts on the thermal overload device or on the automatic transfer switch for the control circuit will close to initiate an alarm at the control board. The alarm control circuit operates at 125 volts direct current with the direct current being supplied by the powerplant station battery,

Lighting systems employed in the dam and related structures provide general utilitarian illumination in galleries, adits, and machinery spaces in the dam; in rooms of the elevator towers; on the crest roadway of the dam and service bridge; on the spillway gate structures; at the river outlet valve structure; for the left and right abutment covered walkways between the powerplant and dam; in the pipe chase and vaults for the outlet pipe expansion joints located in the left abutment mass concrete between the powerplant and dam; and for the slide gate access shaft and parking area at the left abutment downstream from the powerplant. The lighting systems for the covered walkways between the powerplant and dam, in the pipe chase and vaults for the outlet pipe expansion joints, and for the slide gate access shaft and parking area at the left abutment downstream from the powerplant are served from lighting distribution panelboards in the powerplant. Otherwise, the lighting systems for the dam and related structures are served from lighting panelboards located in the gallery system of the dam, in the elevator towers, and on the spillway gate and river outlet valve structures. The lighting panelboards are supplied through dry type, air cooled distribution transformers energized from the power

distribution system in the dam and related structures. The transformers are generally situated adjacent to the respective lighting panelboards served by the transformers. The lighting system service voltages are nominally 208Y/120 volts, 3-phase, 4-wire (grounded neutral), 60 cycles, and all lamps energized from lighting system circuits are rated at 115 volts.

Lighting outlets within the gallery system of the dam consist generally of lampholder devices employing bare lamps. Lighting fixtures employed elsewhere are industrial and commercial types. Convenience outlets are provided in the same general areas and locations as are lighting outlets and fixtures. The convenience outlets are 2-wire, 3-pole, (grounded pole) types providing energy at nominally 120 volts, single-phase, 60 cycles at the outlet receptacles.

All lighting system panelboards contain automatic-trip, molded-case-type circuit breakers which afford short circuit and overload protection to the branch circuits originating at and emanating from the panelboards. Most of the branch circuits serving lighting outlets and fixtures are controlled by conventional lighting control switches. Switches are located at gallery entrances and intersections, and near or adjacent to access doors of rooms and compartments. For some of the longer circuits employed in the gallery lighting system, mechanically held magnetic contactors (remote control switches) are utilized to energize the circuits. The contactors are generally located in the lighting panelboards or mounted near the entrances to the grouting adits and are controlled by conventional momentary-contact-type lighting circuit switches.

The operation of crest roadway lighting units on the dam and on the service bridge is controlled by a time switch located in the utility gallery of the dam. The time switch, through control relays, controls the operation of mechanically held magnetic contactors (remote control switches) which energize the circuits serving the crest roadway lighting units. The contactors are located in the utility gallery lighting panelboards and the control relays are located adjacent to the panelboards. The roadway lighting units are mounted in the roadway parapets of the dam and service bridge. The canopy lighting units and the floodlights on the elevator towers, and the lighting units on the bridges and abutments of the spillway structures are controlled directly through individual time switches located adjacent to the elevator tower lighting panelboards or contained in the spillway structure control boards. The time switches are all a synchronous-motor-driven type and have an astronomic-type dial. The on and off