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overview
The IMI 686B vibration switch is designed and applied specifically for cooling
tower applications. The casing is stainless steel, hermetically sealed and the
cable set is molded to the casing to prevent water vapor and contaminants
from entering the switch or its connection points.
The switch is factory programmed by SPX specifically for cooling tower vibra-
tion protection and should not be reprogrammed unless directed by SPX.
Refer to wiring diagrams in this manual for interfacing with VFD and motor
starter equipment. Typically the switch is wired to the shutdown circuit of a
VFD or motor starter. The internal switch contact is rated at 20mA, do not
exceed this value. Most VFDs have a 24 VDC low current safety circuit which
is well under the 20mA value.
The IMI 686B vibration switch has a single contact. If two contacts are required
use a Marley IB1 interface box or one of the output fault contacts on the VFD
to indicate a VFD shutdown.
Applying this switch directly in line with a motor starter operating coil may
damage the switch due to high inrush current when energizing the coil.
When applying the switch to a motor starter consider using the Marley
IB1 interface box.
General Features
• Tested in cooling tower applications by SPX engineers who rated its perfor-
mance superior to mechanical vibration switches.
• Factory-programmed by SPX specifically for cooling tower vibration protection.
• Switch may be reset remotely without entering the cooling tower.
• Repeatable trip-point includes built-in delay for startup and momentary
vibration spikes.
• Monitors vibration velocity for consistent results.
• Able to sense low frequency vibrations better than a mechanical switch.
• Integral 30' (9m) cable with molded connection at the switch protects the
connection point wiring from humidity and chemical exposure.
• NEMA4X/IP68 hermetically-sealed stainless steel enclosure withstands
harsh internal environments in a cooling tower.
• Factory installed at location near primary source of vibration.
• 2-wire combination power and control circuit adaptable to most VFD circuits.
• Wide operation temperature range: -40 to 185°F.
Caution
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