(2) Turbine Bearings Shaft: Ring oiled, anti-friction type.
Shaft shall be stainless steel or chrome plated under the packing
glands. Shaft seals shall be segmented carbon rings with springs
and stops.
(3) Speed Governor: Variable speed governor for speed limiting
and pneumatic operator to maintain an adjustable preset level in
[deaerator tank] [condensate receiver] by variation of turbine
speed. Input to the operator shall be a 20 to 103 kPa (gage) 3 to
15 psig pneumatic signal and vary the turbine speed from minimum
to full speed in a linear response. Maximum and minimum speed
shall be adjustable. Provide an electro-pneumatic transducer to
accept the 4 to 20 mA signal from the controller.
(4) Emergency Overspeed Governor: Completely independent of the
speed governor and shall operate a separate trip valve.
(5) Insulation: Turbine shall be insulated and lagged as
specified in Section 15080 THERMAL INSULATION FOR MECHANICAL
SYSTEMS.]
2.14.5
Variable Speed Motor Control
Remotely installed cabinet housed units with solid state rectification and
inverter equipment to vary frequency of electrical power to drive motors.
2.14.5.1
Housing
House controller in a [wall] [floor] mounted, NEMA [_____] enclosure
finished with manufacturers standard painted finish. Provide control panel
complete with fused disconnect switches, magnetic [across the line] [part
winding] starters with thermal overload protection, transformer,
hand-off-automatic selector switches, hand potentiometer for manual speed
control, fuses and running lights.
a.
Provide the manual switch within the control panel so that in the
event failure of a component, motor can be put across the line at
full voltage to maintain air or pump pressure. Provide a
mechanical door interlock that allows panel to open only when
fused disconnect is in the off position.
b.
Variable Frequency Controllers: Variable frequency controllers
shall use solid-state semiconductor power conversion equipment.
Provide controllers as integrated and assembled products.
Controllers shall be furnished by the same manufacturer.
(1) Each controller shall be rated for a supply of [_____] volts,
three phase, 60 Hz. Output shall be [_____] volts, three phase
with frequency variable between zero and 60 Hz. Controllers shall
be rated to operate motors continuously at their rated horsepower
and frequency. Speed regulation shall be three percent or better
without tachometer feedback. Electrical supply system has an
available short circuit rating of [_____] amperes symmetrical.
(2) Each controller shall be capable of driving motor
continuously at a lower speed no greater than 20 percent of full
rated motor speed with stable operation and without overheating
the motor under rated ambient conditions. Provide estimate of
minimum speed at which motor can be operated continuously without
SECTION 15501N
Page 130
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