bypass position. The auxiliary contacts shall be used to activate
the damper control to provide fan load control in the bypass
position.
2.14.5.3
Controller Environmental Protection
a.
Ventilation: Design controllers enclosed and ventilated for
installation in a moderately dusty area. Provide forced filtered
ventilation including fans, filters, controls and accessories
required for operation. Enclosures shall be operated under
positive pressure at all times. Provide filtered ventilating
openings and gasketed doors to prevent infiltration of dust.
b.
Heating: Provide electric heaters to prevent condensation in the
enclosure and to prevent low in going air temperatures that exceed
the equipment rating. Provide a low temperature alarm to sound
when enclosure temperature falls below required minimum
temperature. Provide contacts for remote annunciation of alarm
condition.
2.14.5.4
Method of Control
Supply each controller from an electrically operated air circuit breaker or
motor starter. Controller ventilation and heating shall be from another
circuit.
a.
Start signal: Closes the electrically operated air circuit
breaker or motor starter to energize the controller. Controller
shall accelerate fan to operating speed. Fan speed shall be
controlled from the load control signal.
b.
Stop signal: Opens the electrically operated air circuit breaker
or motor starter to de-energize the controller. Upon
deenergization, the controller control system shall revert to the
stop condition.
c.
Boiler feedwater pump speed control system: Matches pump
discharge to system demand and maintains a system header pressure
controlled to the set point values. Provide Manual/Automatic
control stations for master pressure and for each boiler feed
pump. Provide indicators for feedwater header pressure and
individual boiler feedwater pump flow. See VAMS Section 15901N
CONTROLS AND INSTRUMENTATION BOILER PLANT.
2.14.6
Valve Actuators
[Electrically] [or] [pneumatically] operated designed so that valve may be
manually operated by removing the drive pins. Actuators shall be operated
by push button control. Locate one push button at a position adjacent to
the valve. Locate a second push button within the boiler control room.
Provide a valve position indicator utilizing indicating lights. A green
light shall indicate the valve is fully open and an amber light shall
indicate the valve is fully closed. Both lights on shall indicate when the
valve is partially open. [Provide torque limit controls to protect the
valve during opening and closing for electrically operated valves.]
Actuator electric motor shall be totally enclosed, [_____] volts, [_____]
phase, 60 Hz as specified under paragraph entitled "Motors and Drives" in
this section. Provide NEMA 4 control enclosures.
SECTION 15502N
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