Startup sequence

Microprocessor control generally results in less operator attention required, higher levels of reliability, and ease of changing groups of set points. Other advantages are automatically programmed startup sequences, over temperature alarm, thermocouple loss alarm, heater failure alarms, and closer temperature control accuracy (Chapter 3). 

The construction schedule must support the required startup sequence. 

Piping design leaders must get familiar with startup sequences to incorporate into the piping systems sufficient connections to facilitate... 

Startup driven by a static frequency converter up to the moment when turbine torque becomes positive This startup sequence is very close to GEC/Alsthom practice on large gas turbine applications. 

The primary function allocated to the machine side of this interface involves prevention of adverse pressure differentials. This function is performed by the ventilation system fan sequencing interlock, which establishes a hierarchy of fan operation to ensure that hot exhaust ducting does not get pressurized in the event of exhaust fan failures or mis-operation. An interlock automatically starts the backup fan upon loss of an operating fan. in addition, the interlock automatically shuts down all upstream fans if both of the Zone 1, Zone 2A, or stack exhaust fans fail. The interlock also allows only a sequenced startup of ventilation system fans to prevent pressurization of the hot exhaust ducting because of operator failure to adhere to the required fan startup sequence. 

The above compressor rules are only valid when the gas turbine is at a steady state condition. This can be reached when the following conditions are met end of startup sequence is reached (signal from the Mark V controller) and the temperature derivative with respect to time is below a certain X °C/s. 

Relay K3 may next be energized in the startup sequence, provided upper limit switches on all three safety rods are closed. A manually operated key switch completes the interlock circuit for Relay K3, allowing the dump valve to be closed by operation of the control switch. The "dump valve" key switch is bypassed by a contact of Relay K3 and may then be removed. 

Mission Control will not be in direct control of each step of the startup sequence. Time delays in the communication path between Mission Control and the spacecraft preclude real time monitoring and control of plant functions. Also, continuous communication with the spacecraft is not assured during the deployment and startup phases (Level 2 Requirements are 92%). It is therefore assumed that the control architecture for the Reactor Module would be designed such that an entire series of steps or phase of the startup would be initiated by a command from Mission Control and controlled autonomously from the spacecraft. Mission Control would wait for satisfactory indications that the sequence steps had been completed before proceeding with the next phase of the sequence. How the steps in the following startup sequence would be accomplished within the respective spacecraft controllers (Reactor Module and PCAD) has not been determined. 

These programmed sequences for the reactor startup will be initiated from Mission Control and will be executed autonomously by the Reactor l C segment. Continuous downlinks from the spacecraft will provide status information to Mission Control on the progress of the startup. Mission Control would be able to stop the startup sequence at any point. 

Adding reactivity to owly heat the plant from a crdd condition while motoring a Brayton unit to maintain a constant reactor coolant how rate is potentially the most challenging part of the startup sequence. As the turbine inlet temperature slowly increases from reactor heat, the turbine will begin to produce work and ttte power drawn from the start inverter will decrease. 

Shutdown would cause a reduction in the turbine inlet temperature of the Brayton unit energy converters. This would reduce their power output, and require that power be supplied from the test facility to motor their alternators for decay heat removal (similar to the beginning of the reactor startup sequence). The Brayton units could be continuously motored to provide decay heat removal, or a separate circulator could be added to the prototype support facility to provide the function and allow the Brayton units to be secured. The prototype support facility would also need to provide a continuous source of power to the 28 Vdc bus for uninterrupted power to the reactor controllers to completely withdraw the sliders and allow for continuous reactor monitoring after the shutdown. 

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