Specifications
Specification Value
MH Fluid Cooler —
Specifications: Options
21
Water Level Control System:
11.2 Add the following paragraph in the Cold
Water Basin section: Provide a water
level control system including a NEMA
4X control panel, water level probes and
probe stilling chamber. The control system
shall monitor the water level in the cold-
water basin to determine level events
used for cold-water make-up, high and
low alarms and/or pump shut down. The
control panel shall use electromechanical
relays providing power for the make-up
solenoid and electrical contacts for alarm
and pump shutdown control circuits.
Probes shall be contained in a vertical
stilling chamber to stabilize the water in
the cold-water basin. Probes shall have
replaceable stainless steel tips and level
height shall be field-adjustable.
Fan Motor Variable Speed Drive:
ACH550 VFD System
6.4 Add the following paragraph in the
Mechanical Equipment section when
VFD is used with customers Building
Management System: For fan control a
complete UL listed variable speed drive
system in a NEMA 1 indoor, NEMA 12
indoor or NEMA 3R outdoor enclosure
shall be provided. The VFD shall use
PWM technology with IGBT switching.
VFD output switching signal shall be
programmed to not cause mechanical
vibration issues with backlash in gear-
box teeth or vibration issues associated
with long driveshafts. The VFD shall be
programmed for variable torque applica-
tions and shall catch a fan spinning in
the forward or reverse direction without
tripping. VFD panel construction shall
include a main disconnect with short cir-
cuit and thermal overload protection with
external operating handle, lockable in the
off position for lock-out tag-out safety
procedures. A service switch directly
ahead of the VFD shall be provided for
voltage isolation during VFD maintenance.
An integrated full voltage non-reversing
bypass starter shall be furnished allowing
fan motor operation if VFD has failed. The
VFD system shall receive a speed refer-
ence signal from the building manage-
ment system monitoring the fluid cooler
■ Solid-state liquid level controls provide you with state of the art systems to
control and monitor the water level in your fluid cooler collection basin. Relays
operating in conjunction with suspended stainless steel electrode probes moni-
tor basin water levels, providing simple solenoid-valve water makeup or discrete
on/off signals to more sophisticated automation controls. Optional configura-
tions might include water makeup along with high and low water level alarm and
cutoff, or pump cutoff. Packaged systems including any of these variations are
available. Consult your Marley sales representative or download a copy of
ACC-NC-9 from spxcooling.com for additional information.
■ Marley VFD drive systems are designed to combine absolute temperature con-
trol with ideal energy management. The fluid cooler user selects a cold water
temperature and the drive system will vary the fan speed to maintain that tem-
perature. Precise temperature control is accomplished with far less stress to the
mechanical equipment components. The improved energy management provides
fast payback.
Motors operated on a VFD shall carry a service factor of 1.0. When operating on
a VFD, the drive parameters should be programmed to limit the current to motor
nameplate hp. Adjust the Motor specification accordingly.
(44 Seiten)
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