2.4.7
HTW Generator Limit Controls
Controls shall be provided to include low generator water flow and high
generator temperature. The limit controls shall be interlocked with the
combustion control system to provide for generator alarm and shutdown.
2.4.8
Burner Control/Fuel Safety System
2.4.8.1
a.
General: The control system shall be of the microprocessor-based
(distributed digital or programmable controller) or relay type. A
dedicated hardwired insert panel shall be furnished for monitoring
and operator interface with the burner control/fuel safety system.
This insert panel shall also provide the operator with direct
fuel tripping capability in emergency situations. The burner
control system shall be sufficiently subdivided to permit
inservice checkout and maintenance without impairing the
reliability of the overall control system. The logic cabinets
shall include status indicating lights for all logic inputs and
outputs and for monitoring availability of control power to all
subsystems as required to facilitate troubleshooting. Indication
of equipment status and system permissives shall be provided at
the operator interfaces. Where common power supplies internal to
the system are furnished, a full-capacity on-line backup supply
shall be included. Failure of either power supply shall be
alarmed.
b.
Maintenance and Reliability Requirements: In general, maintenance
shall be accomplished on-line and without imposing any special
restrictions on overall plant operation. Diagnostic routines,
interchangeable electronic cards or boards, and clear written
procedures shall be provided as a minimum requirement of this
specification. Reliability, both software and hardware, shall be
incorporated into the system design. This shall include
redundancy, loop distribution, component specifications and
testing, and quality control to assure the highest level of system
reliability.
c.
Adverse Electrical Conditions: All equipment shall be capable of
operating as specified and without damage within the electrical
environment of the plant. This environment includes, but is not
necessarily limited to, high-voltage, high-frequency surges caused
by electro-mechanical equipment, energy coupled between conductors
by capacitance and mutual inductance, and imperfect grounds.
Input and output isolation, shielding, separation of circuits,
surge suppression, or other measures which may be required to meet
these provisions shall be provided. Inputs, outputs, and other
connections shall meet the surge to withstand requirements of IEEE
C37.90.
2.4.8.2
System Design
The burner control system shall be compatible in all respects with the HTW
Generator and auxiliary equipment. The system design shall meet the
requirements specified in NFPA 8501. The burner control system shall
incorporate a continuous purge of the furnace to insure that the HTW
Generator is free of any accumulation of combustibles. The burner control
SECTION 15555A
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