SPX Cooling Technologies Marley MC Humidifier User Manual


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Specifications
Specification Value
Marley
/
MC Fluid Cooler
/
Specifications: Options
24
intheoffpositionforsafety.TheVFD
system shall receive a speed reference
signal from the Building Management
System monitoring the tower fluid tem-
perature. As an option to receiving the
speed reference signal from a building
management system, the drive must
have the capability to receive a 4-20 ma
temperaturesignalfromanRTDtrans-
mitter.TheVFDshallhaveaninternalPI
regulator to modulate fan speed main-
taining set point temperature. The drive's
panel display shall be able to display
the set-point temperature and cold-fluid
temperature on two separate lines. The
bypass shall include a complete mag-
netic bypass circuit and with capability
toisolatetheVFDwheninthebypass
mode. Transfer to the bypass mode shall
bemanualintheeventofVFDfailure.
Once the motor is transferred to the by-
pass circuit the fan motor will run at con-
stant full speed. The bypass circuit will
not modulate ON and OFF based on fluid
temperature. The application must be
able to handle very cold fluid tempera-
tureswhiletheVFDisinaby-passmode.
Operator controls shall be mounted on
the front of the enclosure and shall con-
sistofstartandstopcontrol,bypass/VFD
selection,Auto/Manualselections,manu-
al speed control. To prevent heating prob-
lems in the fluid cooloer fan motor and
to assure proper gear reducer lubrication
theVFDsystemshalldeenergizethe
motoronce25%motorspeedisreached
and cooling is no longer required. The
fluid cooler manufacturer shall supply
VFDstart-upassistance.Towervibration
testing throughout the speed range is
required to identify and lockout any natu-
ral frequency vibration levels which may
exceed CTI guidelines.
Marley Premium VFD System
6.4 Add the following paragraph in the
Mechanical Equipment section when
VFD is used as a stand alone system:
AcompleteULlistedVariableSpeed
DrivesysteminaIP52indoororIP14
outdoor enclosure shall be provided. The
VFDshallusePWMtechnologywith
IGBT switching and integrated bypass
design.VFDoutputswitchingshallnot
cause mechanical issues with gearbox
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