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INSTALLATION
Mounting
Mount Wisp in a moving air stream using the
cable clamp supplied. Avoid placing the sensor
(located at the tip) near a hot component as this
may result in heating by radiation. To minimize
heating of the sensor by the Wisp circuits, avoid
mounting the unit vertically with the
sensor at the top.
Location
Install a closed-loop unit at or near the equipment
exhaust where it can sense any upstream
event that could affect cabinet temperature.
Install an open-loop (P suffix) unit at or near
the equipment inlet.
Connections
Temperature Alarm Output
A temperature alarm signal is available through
the yellow and black wires. An alarm can be
indicated using an external LED (Figure 1) or
logic circuit (Figure 2).
| Alarm Type: |
Non-Isolated Open-Collector |
| Trigger: |
10°C Above Control Temperature |
| Alarm States: |
Conducting (Closed), Above Trigger
Cut-Off (Open), Below Trigger |
| Max. Voltage: |
30 VDC |
| Max. Current: |
4 mA DC at 0.4 VDC (Logic Circuit),
10 mA DC (LED Circuit) |
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OPERATION
Fan Speed vs. Sensor Temperature
The relationship between fan speed, as a percentage
of full speed, and sensed temperature
is shown in Figure 4. Full speed occurs at the
Control Temperature (Tc ). Minimum speed temperature
(approx. 50% of full speed) depends
on part number. For closed loop units, the “X”
in Figure 4 is equal to 4. For open loop units the
“X” in Figure 4 is equal to 12.
Voltage Regulator and Limiter
Part Nos. 048W0XXX are intended to cover
telecommunications applications using supply
voltages ranging from 38 to 75 VDC. Minimum
idle voltage is regulated at 26 VDC. Maximum
voltage applied to the fans is limited to 50 VDC.
For supply voltages above 50 VDC, power is linearly
derated based on the curve shown in Figure 5.
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