The following customary controls are provided:

(1) Synchronizing equipment for the generators and future lines (synchronizing lamps, synchroscope, synchronizing switches, automatic synchronizer, speed matcher, automatic synchronizing sequence relays, and voltmeters for incoming and running potentials).

(2) Control switches and indicating lamps for all generator and station-service breakers.
11
"Local-Automatic, or "Remote-Automatic" operation.

(3) Selector switch for "Local-Manual," "

(4) "Start-Stop" control switch for local-automatic control, and control switch for starting and stopping unit auxiliaries on local-manual control.

(5) Voltage regulator transfer switch, exciter field rheostat "Raise-Lower" control switch, voltage adjusting rheostat control switch, and field breaker tripping control switch.

(6) Speed droop control selsyn, wicket gate limit and speed changer control switches. These controls are duplicates of similar controls at the actuator which permit starting the unit at the actuator.

(7) Turbine normal shutdown solenoid control switch, compensating dashpot bypass control switch, and water depressing control switch.

(8) Generator brake control switch. With the airbrake control switch in the "Automatic" position, the brakes are set automatically when the unit speed decreases to 40 revolutions per minute. The brakes can then be released or reset by turning the generator brake control switch to "Off" to release the brakes or to "On" to reset the brakes.

(c) Local-Automatic Control. --With the selector switch on "Local-Automatic" control, the only operation necessary to start or stop a unit from the control room is to turn the local-automatic start-stop switch momentarily to "Start" or "Stop". Before starting a unit, the voltage regulator control switch should be in the "Regulate" position and the automatic synchronizer and speed matcher should be in operation. If the automatic synchronizing equipment is out of operation, a unit may be synchronized normally provided this is done before the incomplete sequence starting relay times out. Before stopping a unit, the speed changer control switch should be turned to the "Lower" position until the power output of the generator is reduced to zero, and the voltage adjusting control switch should be adjusted until the reactive power output of the generator is zero.

(d) Remote-Automatic Control. --With the selector switch on "Remote-Automatic" control, operations corresponding to those on "Local-Automatic" control are performed by means of keys on the supervisory control panel at Keswick Powerplant. The following remote control functions and telemetered quantities have been provided for each unit:

(1) Remote control and indication functions:

Start and stop unit with indication of breaker position.

Raise and lower governor gate limit setting.

Raise and lower governor speed changer setting.

Raise and lower generator voltage level setting.

Depress and indicate level of draft tube water for condenser operation.

Indication of position of control selector switch and alarm on change of switch position.

Emergency shutdown and lockout with indication.

Emergency closure of butterfly valve with indication of valve position.

Alarm and indicate unit shutdown and lockout by protective relays.

Alarm and indicate unit tripped by line relays.

(2) Selective telemetering:

Generator kilowatt-hours.

Generator megawatts.

Generator megavars.

Generator current (phase A).

Generator field amperes.

Generator volts.

Governor gate limit position.

The above control and telemetering functions are performed over a voice-grade leased telephone line by means of multiplexed audio tone channels. The circuits are designed so that any telemeter reading may be retained during a corresponding raise-lower operation, and so that a telemetered reading may be received simultaneously from each unit.

(e) Emergency Shutdown Controls. --The following controls are provided on the main control board for emergency shutdown regardless of the position of the selector switch:

(1) Unit emergency shutdown control switch. Operation of this switch actuates the governor emergency shutdown solenoid, and after the wicket gates have closed, trips the generator breaker and

Master relay for automatic stopping of unit and aux. timing reset relay.
Master relay for local stopping of unit auxiliaries, and aux timing reset relay
Battery undervoltage relays and timing, and auxiliary relays.
Time delay relay for station service transfer.
Main overspeed switch and auxiliary overspeed Switch.

IZAX,T,TX GSA-HIA¬ Auxiliary and timing relays for Device 12A

Overvoltage relay, time delay, instantaneous and frequency compensated
Balance relay for voltage regulator.

Generator air circuit breaker (UIA)

Amplidyne motor starter

Figure 107. --Trinity Powerplant electrical installation--Main single-line diagram. (Sheet 2 of 2.) From

drawing No. 416-D-952.

field circuit breaker. Operation of this switch also closes the unit butterfly valve, and starts a timing relay which closes the penstock gate if the butterfly valve fails to close within a predetermined time.

(2) Unit butterfly valve close-open control switch. This switch duplicates a similar function at the butterfly valve control cabinet. Normal control of the butterfly valve will be from the butterfly valve control cabinet.

(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 gate structure.

130. Protective Relaying. (a) General.--The protective relays for the line, transformer, and each generator are semiflush mounted on the rear panels of the main control board. The relaying scheme is shown on the single-line diagram, figure 107.

(b) Clear Creek 230-Kilovolt Line. --The following standard line distance relaying has been provided: Device 121--3-phase, single-zone directional distance relay.

Device 167G--Directionally controlled overcurrent ground relay.

In the event of a line fault, these relays trip the generator breakers and transfer the station-service supply to the emergency source.

(c) Main Power Transformer Bank. --Main transformer bank KRA is protected by a set of harmonicrestrained, percentage differential relays. The protected zone includes the transformer and the 13.8kilovolt circuits to the generator side of breakers 122 and 222. In the event of a fault in this zone, these relays will shut down the units, trip the generator breakers, the field circuit breakers, and the line grounding switch, and send a transfer trip signal to trip the Trinity line breaker at Keswick Switchyard.

(d) Generators. --Each generator is provided with the following protective relays:

(1) A set of percentage differential relays.

(2) A set of split-phase differential relays for differential protection of each half of the generator winding.

(3) A ground relay of the overvoltage induction disc, inverse-time type, set to protect 90 to 95 percent of the generator winding.

(4) A set of voltage-restrained overcurrent relays for backup protection of the generator.

(5) An overvoltage relay with instantaneous unit set to trip at 150 percent rated voltage, and time delay unit set to trip at 140 percent rated voltage in 20 seconds.

(6) A negative-sequence type, phase balance relay.

(e) Station-Service Transformers. --The normal source station-service supply transformer is protected by a set of overcurrent relays set to coordinate with the 460-volt main supply breaker. This transformer is not included in the main power transformer or generator differential relaying circuits. The emergency source station-service supply transformer is protected by a fused disconnect switch.

131. Metering and Indication. (a) General.--Indicating instruments are mounted on the front of the main control board. Instruments for the line, the station-service equipment, and the generators are provided on their respective panels. A mimic bus for the powerplant station-service system and line is painted on the front of the board. Recording and metering equipment for the generators is provided on the unit graphic board.

(b) 230-Kilovolt Line. --The line to Clear Creek Powerplant is provided with instruments mounted on the main control board to indicate amperes, watts, and vars. Relay potential indicating lamps are provided for each phase. Lamps are also provided to indicate receipt of transfer trip signals from Keswick.

(c) Station Service. --A voltmeter with switch, two ammeters with switches, and a normal-supply watthour demand meter are provided on the main control board for the 440-volt powerplant station-service system. Normal and emergency supply breaker positions are indicated by red and green lamps directly over each breaker control switch.

(d) Generating Units. --Each generating unit is provided with instruments on the main control board to indicate generator amperes, volts, watts, vars, field amperes, voltage regulator output volts, percent speed, speed level, turbine gate limit and gate position, and speed droop. Percent speed, gate limit and gate position, speed level and speed droop indicators are also provided at the governor actuator, but are duplicated on the main control board so that the operator can perform all control functions from the control room. An operating time meter is provided on the unit gage board for each generator. A temperature recorder, a recording wattmeter, and "În" and "Out" watthour meters are provided for each generator on the unit graphic board.

The following lamp indication has been provided on the main control board:

(1) Generator "Start-Stop" lamp.

(2) Annunciator group lamp.

(3) Auxiliaries "Running" lamp.

(4) Normal "Shutdown-Reset" lamps.

(5) Brake "On-Auto-Off" lamps.

(6) Generator breaker position lamps.

(7) Generator illuminated symbol.

(8) Exciter field rheostat lamps.

(9) Turbine emergency shutdown lamps.

(10) Penstock gate position lamps.

(11) Butterfly valve position lamps.

(12) Exciter field breaker position lamps.

Lamp indication of tailwater depressing control position is provided on the governor actuator.

(e) Tailwater Level. --The tailwater level indicator and recorder is located on the line graphic board. 132. Annunciators and Sequential Operations Recorder. (a) Annunciators. --Annunciators have been provided as follows:

(1) A 32-drop annunciator for each generating unit.

(2) A 24-drop annunciator for transformer and station-service trouble contacts.

These annunciators are located on the front of the main control board.

Closing of a trouble contact will light the yellow group lamp, light an annunciator window, sound a common bell in the control room, and sound common alarm horns on the generator floor inside the building, and outside on the powerplant wall. The bell and horns can be silenced and the group lamp extinguished by pushing the horn reset pushbutton. Releasing the reset button will not cause the bell and horns to sound nor the group lamp to light; however, the bell and horns will sound and the group lamp will light when another trouble contact closes. The annunciator windows can be reset by pushing the lamp reset pushbutton; however, if a trouble contact remains closed, the associated annunciator window will remain lighted. Each annunciator group can be tested by pushing the test pushbutton. With this test, all annunciator windows in the group should light.

The generating unit annunciator systems are designed so that there will not be annunciation for normal startup or normal shutdown.

(b) Sequential Operations Recorder. --A sequential operations recorder is provided in a separate recording cabinet mounted on a console housing in the control room at a convenient location near the operator's desk. The recording cabinet is connected by a cable to the console housing so that the recording cabinet can be placed on the operator's desk or installed up to 50 feet away from the console housing.

The recorder makes a printed record on chart paper of the opening and closing of up to 100 contacts to which it may be connected. Events are recorded in the sequence of their occurrence, and the time of each event is printed so that it can be read to approximately the nearest millisecond. The recorder is connected to record indirectly the closing of trouble contacts connected to each of the three local annunciators, and also to record directly the closing and opening of auxiliary switches on the generator air circuit breakers and line grounding switch.

133. Grounding System. The grounding system consists of a ground mat under the powerhouse foundation and a ground mat anchored in the tailrace with ground rods. The two mats are tied together at two points at the downstream wall of the powerplant. Field tests after installation indicated a resistance to ground of approximately 6 ohms with the two mats connected together, which is considered satisfactory for a plant of this size.

Fourteen 500,000-circular-mil risers are provided from the ground mat to the powerplant and switchyard. Each riser is capable of withstanding 43, 000 amperes short-circuit current for approximately 3 seconds. The frames and exposed surfaces of all electrical equipment are grounded, as are cable tray supports, superstructure metallic elements, oil tanks and air receivers, hatch frames, and the rotor erection plate.