SmartFan TachStrip Fan Speed AlarmOperation/Installation Manual
Trigger Speed (WA): Use this jumper to set the trigger speed. Select a trigger that is 40 to 50% of rated speed.
Position L = 1000 PPM
Position M = 2000 PPM (Factory Setting)
Position H = 4000 PPM
Since fan tachometer circuits are designed with one, two, or even more pulse outputs per revolution, settings are listed in pulses per minute (PPM) rather than revolutions per minute (RPM). Given the fan’s rated speed (W) and number of pulses per revolution (N), use the following formula to select the trigger speed (WA):
WA = W x N x 0.4
For example, a 3300-RPM fan with two pulses per revolution would have a trigger speed (WA) of
WA = 3300 RPM x 2PPR x 0.4 = 2640 PPM
Since the 2000 PPM trigger is closest, set jumper J5 to the “M” position. The alarm trigger accuracy is +/- 20%.
Alarm Outputs (J2)
Three alarm circuits are located on header J2. All circuits are non-isolated, have the same electrical ratings, and are referenced to board ground found at J2:
Alarm Output Logic
|Alarm Output||Above Trigger Speed||Below Trigger Speed||Power Removed from Unit|
|NC||Short to Ground||Open Circuit||Open Circuit|
|NO||Open Circuit||Short to Ground||Open Circuit|
|OR||Open Circuit||Short to Ground||Open Circuit|
Power for an LED alarm indication is provided by Pin J2:L via an internal 12 mADC constant current source. Power for logic gate alarm circuitry must be provided externally. For logic circuit alarm indication, each alarm output can sink up to 4 mA at <= 0.4 VDC. When open, a maximum of 30 VDC can be applied to each output. Pin J2:P and J2:OR can be used for a piezo buzzer alarm output. Below the alarm speed trigger, the board supply voltage (Vs) will be applied to the piezo. Note: L and P are positive (+); NC, NO and OR are negative (-).
ADDITIONAL MANUAL PAGESOperation/Installation Manual
Use the links below for addtional manual pages or for a complete manual or click on the Operation/Installation Manual PDF link above.