board for one operator to have adequate supervison over the entire plant including unit starting and stopping operations. For emergency conditions, it is expected that the operator will first ascertain the cause of difficulty and will then call appropriate personnel for correction of the trouble. Automatic load and frequency control of the three generating units from the Montrose Power Operations Center, and breaker position scanning equipment for map board indication at the Montrose Power Operations Center are features of this design. The major electrical equipment to be controlled is shown on the single-line diagram (fig. 147). 112. Main Control Room. The main control room is located in the control bay at the west end of the powerplant. It is at the same elevation as the generator room and not more than 150 feet from the farthest unit. The main control room was designed to accommodate the present main control board CCA with space for three future panels, the present unit graphic and miscellaneous control board CCB with space for one future panel, and the present line graphic board CCC with space for four future panels. Space has also been provided for one operator's desk facing the main control board, one sequential operations recorder, and future supervisory control consoles. The main control board is of the dead-front, walk-in, duplex switchboard type with fixed panels both front and rear and with the synchroscope mounted on a small hinged panel. The unit graphic and miscellaneous control board and the line graphic board are enclosed-type, walk-in switchboards with equipment mounted on the fronts only. These types of boards were selected to provide adequate instrument, meter, and relay space on compact boards of simple construction having ready access for maintenance. The boards are finished light green so as to provide a more pleasing atmosphere in the control room. All control switches are located at a convenient operating height on the fronts of the boards. The indicating instruments are also located on the fronts of the boards above the control switches for easy reading. All protective relays having targets or other requirements for operating accessibility are semiflush mounted. Auxiliary relays are located behind the panels. All major protective relays are drawout type for convenient testing and maintenance. A hinged patch-panel has been provided behind the oscillograph so that currents and potentials can be easily connected. Panels for similar circuits have been grouped together on the board (i.e., generator panels, plant general, and line panels). For operating convenience the panels have been arranged to conform with the physical arrangement of equipment in the powerplant and switchyard as far as possible. 113. Control Equipment. (a) General. --Controls duplicating those on the main control board are not provided. The auxiliaries can all be started from the main control board. They can also be started locally at each auxiliary for testing. No supervisory control is in use at the present time at this plant. (b) Local Manual Control. --The control equipment mounted on the front of the main control board CCA is for local manual control of the powerplant and switchyard. The following customary controls are provided: (1) Synchronizing facilities for units and lines--synchronizing lamps, synchroscope, synchronizing switches, automatic synchronizer, speed matcher, and voltmeters for incoming and running potentials. (2) Control switches and indicating lamps for all generator, line, and bus-tie breakers. (3) Voltage regulator transfer switch, exciter field rheostat "Raise-Lower" control switch, voltage adjusting rheostat control switch, and field breaker tripping control switch. (4) Governor "Shutdown-Reset" control switch, wicket gate limit control switch, speed changer control switch, compensating dashpot bypass control switch, water depressing control switch, and turbine emergency shutdown control switch. (c) Additional Controls. --The following controls have also been furnished: (1) Unit auxiliaries control switch. --This switch duplicates a similar switch located on the unit instrument panel. Operation of either switch will start or stop all auxiliaries provided that the hand-off-auto switch at each auxiliary is in the "Auto" position. (2) Generator brake control switch. --The brakes are set automatically on shutdown when the unit speed decreases to 48 revolutions per minute (provided that the air brake control switch 20ACS is in the "Automatic" position). The brakes can then be released or reset by turning the generator brake control switch 69GBCS to "Off" to release the brakes, or to "On" to reset the brakes. (3) Penstock gate emergency close control switch. --This control is for emergency use only. All normal functions will be performed at the penstock fixed-wheel gate control cabinet located at the intake structure. (4) Reclosing relay cutout switch for each line breaker. --Reclosing is provided when the switch is in the "On" position and is blocked when the switch is in the "Off" position. (5) Transfer trip switches are provided (on the rear of the main control board) to take their associated differential circuits out of operation and to transfer trip to other breakers when a breaker in the switchyard is taken out of service, is bypassed, or is used in place of another breaker. (d) Unit Graphic and Miscellaneous Controls. --The following recording, indicating, metering, and control equipment is located on the unit graphic and miscellaneous control board CCB: (1) Temperature recorder, wattmeter, and watt-hour meter for each generator. (2) System clock, total generation recording wattmeter, system frequency recorder, and switchyard bus voltage recorder with switch. (3) Indicating instruments and breaker control switches with indicating lamps for 24.9-kilovolt lines. (4) Indicating instruments, control and transfer switches with indicating lamps, annunciation, metering, and protective relaying equipment for station-service system. (e) Line Graphic Equipment. --The following metering and recording equipment is located on the line graphic board CCC: (1) One (watts out) digital demand recorder and one (out) watt-hour meter for each of the two 24.9-kilovolt Moon Lake lines. (2) One (watts out) and one (watts in) digital demand recorder and one (out) and one (in) watt-hour meter for the 69-kilovolt Bridger Valley line. line. (3) Equipment similar to that listed in (2) above for the 230-kilovolt PP and L (f) Load and Frequency Control Equipment. -- The load and frequency control equipment is used to provide remote control of the output of each generator from the Montrose Power Operations Center located south of Montrose, Colo. The desired megawatt output for each unit is held within the setting of the high and low limits as set by the Montrose dispatcher. The limit settings are compared with the actual unit generation. The difference between "desired" and "actual" unit generation develops the megawatt requirement for each unit, or the unit control error. This is then used by a computer located at the Montrose Power Operations Center to develop raise-lower impulses which will bring the "actual unit generation" into balance with the "desired unit generation." The impulses developed by the computer provide a mandatory raise-lower control signal to the unit governor. The raise-lower impulses are transmitted to the powerplant by Government microwave equipment. Unit load controllers, thermal converters, and auxiliary equipment are located on cabinet CCE in the cable spreading room, directly below the main control room. The unit controller turret is located on the operator's desk in the control room and provides manual "On-Off" load and frequency control of each unit. Remote control of the unit |