3
installation
Sequence of Operation
In normal operation the switch is in a N.C. (normally closed) position with
or without power applied. Once powered, the switch will remain in a closed
state allowing mechanical equipment to operate. If the switch is subjected to a
continuous high vibration level for 3 seconds or more the switch will open and
remain open in a latched state until reset back to a closed position. The three
second delay allows the tower fan to accelerate through critical frequencies
avoiding nuisance tripping.
When the switch trips, the cooling tower has been subjected to a higher than
normal vibration and should be inspected before being put back into service.
Lockout the VFD or motor starter equipment and inspect the tower's mechanical
equipment for possible vibration issues . An unbalanced driveshaft or coupling
may cause enough vibration to trip the switch.
After the vibration issue is resolved and corrected, reset the vibration switch.
To reset, power must be discharged then reapplied to the switch. When the
switch is used in a VFD or motor starter safety circuit resetting may be ac-
complished by cycling power at the VFD or motor starter line side disconnect.
Refer to the starter equipment wiring diagram or manual before attempting this
operation. When cycling power off at a VFD, keep power off for 30 seconds
allowing the VFD capacitors to totally discharge.
Cooling tower controls are typically two wire circuits so once the switch is
reset the fan motor may start automatically without warning. Make sure
personnel are in a safe location.
Torque vibration switch 2-5 ft·lb
ƒ
(3-7 N·m) when installing or reinstalling
.
Warning
Caution
Vibration Switch
