ML17054A302
| ML17054A302 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/22/1983 |
| From: | GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML17054A301 | List: |
| References | |
| GEK-11366, NUDOCS 8312280479 | |
| Download: ML17054A302 (6) | |
Text
G 6 K.lI3 66 (y
PROTECTIVE SYSTENL ELECTROHYDRAULIC CONTROL BASIC FUNCTIONS GENERAL The purpose of the protection system is to detect undesirable or dangerous operating conditions of the turbine generator and to take appropriate trip action automaticaily while informingtheopera-tor on the detected condition and the followingaction.
The principal signal flow of this system is shown in Figure 1.
The two major groups of components of the protection system are:
- 1. The Mechanical Hydraulic Trip System. This portion of the system is described in detail in the Electrohydraulic,Control Section of the instruction book.
- 2. The Electrical Alarm and Trip System. This portion of the system is described in detail in the Electrohydraulic Control Section of the instruction book.
PRINCIPLES OF OPERATION During normal operation, the emergency trip fluid system (ETS) is pressurized from the high pressure (HP) hydraulic fluid supply. This makes it possible to open all turbine valves by the presence of opening signals or the absenceof closingsignals from the electrohydraulic control. (EHC)
Any trip action of the protection system will ultimately remove the fluid pressure from ETS which will trip the main and reheat stop valves directly, the control and intercept valves through the relay trip valve and the extraction check valves through the air relay dump valve.
The MECHANICAL TRIP VALVE normally ad-mits fluid pressure to the lockout valve. It can be tripped by the overspeed trip, the manual mechanical trip and the mechanical trip solenoid (when energized by the master trip relay or the trip button).
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This will remove the pressure to the lockout valve.
The LOCKOUT VALVE will bypass the action of the mechanical trip valve when its solenoid is energized during testing of the overspeed trip.
Actuation of either the manual mechanical trip, the mechanical trip solenoid or the backup over-speed trip willde-energize the lockout valve, thereby making the mechanical trip valve effective aga'tn.
The lockout valve admits its output pressure to the master trip solenoid valve.
The MASTER TltiP SOLENOID VALVE admits the lockout valve output pressure to the EMER-GENCY TRIP SYSTEM (ETS), if either one or both of its pilot solenoid valves are energized with 24 v d-c through a normally closed contact of the master trip relay. De-energizing both pilot solenoid valves simultaneously will remove the ETS pres-sure.
A test switch is provided to test one solenoid pilot valve at a time for proper operation.
The MASTER TRIP RELAY is de-energized duringnormal operation. Any number oftrip signals of the electrical trip system willenergize the master
- action, of which each one will remove the ETS pressure independently:
- 1. DE-ENERGIZE both pilot solenoids of the master trip solenoid valve,
- 2. ENERGIZE the mechanical trip solenoid and
- 3. LOCK the master trip relay in energized po-sition until all trip signals are cleared and the reset push button is depressed.
Loss of the ETS pressure will,through the EMER-GENCY TRIP PRESSURE
- SWITCHES, lock the master trip relay in energized position until the reset push button is pushed and the ETS pressure has been re-established (two pressure switches in series are used to prevent accidental trip on failure of one pressure switch). The same signal from these pressure switches willalso lock the speed reference in "VALVESCLOSED" position and limitall servo-amplifier outputs substantially to zero until the ETS pressure has been re-established.
Depressing the TRIP BUTTON on the turbine panel will energize the master trip relay and the mechanical trip solenoid directly.
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TRIP BUTTON 0
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OVERSPEEO TRIP TEST N LOOTR SHAFT POSITION THRUST BEARING WEAR DETECTOR TRIP (HYDRAUU RESET CIRCUIT
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To SPEED REFERENCE ANO VALVE POSITIONING CIRCUITS VACUUM OTHER TRIP CIRCUITS VACUUM TRIP CIRCUIT MASTER TRIP RELAY REMOTE TRIP CIRCUIT RESET CIRCUIT SPEED I
I BACKUP OVERSPEEO TRIP RSPEED TRIP TEST CIRCUIT IJECHANI TRIP SOLENOID SPEED I
I OIL TRIP OVER SPEED TRIP MANUAL M CH-Ah~L TRIP RESET ECHANISM
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EMERGENCY TRIP PRESSURE SWITCHES LOCK IN (ELECTRICAL)
TEST SWITCH LOW-VALUE GATE TRIP MECHANISM EMERGENCY TRIP SYSTEM PRESSURE (ETS1 MASTER TRIP SOLENOID VALVE LOCKOUT VALVE MECHANICAL TRIP VALVE HIGH PRESSURE HYDRAULICFLUID DISK DUMP VALVE ON STOP VALVES DISK DUMP VALVE ON REHEAT STOP VALVES RELAY TRIP VALVE AIR RELAY DUMP VALVE ELECYR ICALSICHAL IIYCRIIHLICSISHAL MECHANICALSICIIAL OTHER SIGNALS CONTROL VALVE ACTUATORSAND 0 ISK DUMP VALVES INTERCEPT VALVE ACTUATORS AND DISK DUMP VALVES TO POSITIVE CLOSED EXTRACTION CHECK VALVES Fig.
1.
Signal flow chart for emergency tripping system, EHC
Protective System GEK-ll366 Depressing the RESET BUTTON on the turbine panel will'.
- 1. break the lock-in circuits,
- 2. reset the VACUUM TRIP CIRCUIT (even if vacuum is below 20-in. Hg) and
- 3. reset the mechanical trip valve.
The reset button must be held down until the "RESET" light on the panel comes on to assure that the ETS pressure has been re-established before releasing the button.
The OVERSPEED TRIP TEST provisions are used to test the overspeed trip device and the me-chanical trip valve action while operating at about rated speed and at load if desired. The logic system is built to provide flexibility while keeping the possibility of misoperation to a minimum.
ALARM contacts for the purchasers alarm system and indicating lights on the turbine control panel are provided in the electrical system.