the IFT. This indication shall be extinguished only when the IFT
relay is reset.
d.
Main Oil Burner Control: Starting and stopping of each main oil
burner may be accomplished either locally or from the insert
panel. Proven igniter groups shall be one of the permissives
required for starting. Fuel oil trip first out indications and a
main fuel oil trip (FOT) relay shall be provided.
e.
Fuel Safety Subsystem: The fuel safety subsystem comprises the
MFT system, main FOT system, and IFT system. Each fuel safety
system shall provide the protection for its respective fuel and
shall include a dedicated hardwired relay which may be directly
operated from operator insert panel. The MFT system shall provide
overall HTW Generator protection, shall also include a dedicated
hardwired relay, and shall directly trip all other fuel safety
system relays. The system shall be designed to de-energize to
trip.
f.
Flame Monitoring: Individual self-checking flame scanners are
required for each burner. Igniter flame safety devices shall
discriminate individually from any flame that may exist at other
burner locations. Burner flame shall be discriminated
individually from the associated igniter flame and any other flame
that may exist in the furnace. Igniter and burner flame
discrimination shall cover the range from startup to full load
operation. Blocking interlocks from closed valves in flame
discrimination circuits to avoid false flame indication are not
acceptable. If required to obtain satisfactory flame
discrimination, extended tube scanners shall be included.
Individual flame detector output level indicators are required.
Provisions for cooling and cleaning shall be provided, if required.
g.
Enclosures: The system logic cabinets shall contain all control
devices, power supplies, circuit protective devices, cable plugs,
and terminal blocks. Spare space shall be provided to accommodate
a minimum of 20 percent additional devices. The cabinets shall be
accessible from both front and back, and each shall have gasketed
hinged doors with latches. Each door shall not exceed 610 mm 24
inches in width. Natural draft cooling of the control system
cabinets is preferred. If cabinet cooling fans are furnished, the
loss of any fan shall be alarmed.
h.
Local Termination Boxes: The system shall include local junction
boxes, one at each burner level. Burner level junction boxes
shall contain separate pushbuttons and indicating lights for local
control of each igniter group. In addition, the terminal boxes
shall contain terminals for field wiring, internal wiring, cable
connectors for intersystem wiring, circuit breakers, and if
required by the system, relays and reversing starters. Terminal
boards for field wiring shall include 20 percent spare connections.
i.
Interconnecting Cable Requirements: Interconnecting cables
between the logic cabinet, insert panel, and local burner junction
boxes shall be via prefabricated plug-in cables, including
connectors. Flame scanner cables shall also be furnished.
j.
Buffered Output Signals: Output signals required for tripping,
control, and monitoring shall be fully isolated from each other.
SECTION 15555A
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