the supply circuit and the load.
b.
Bypass Position: Bypass shall be closed and the controller shall
be electronically isolated from the supply and the load.
Isolating contacts shall be located so that it is possible to
verify by visual inspection that the contacts are open and the
controller is electrically isolated. In the bypass position the
motor shall be operated at constant speed and controlled from the
air circuit breaker. Provide auxiliary contacts that close in the
bypass position. Auxiliary contacts shall be used to activate the
damper control to provide fan load control in the bypass position.
2.9.5.12
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 ingoing 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.
2.9.5.13
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. The
controller shall accelerate the 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 deenergize 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 INSTRUMENTATIONS BOILER PLANT.
2.9.6
Valve Actuators
[Electrically] [or] [pneumatically] operated and 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
SECTION 15511N
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