Centrifugal blowers develop high pressure-to-volume performance at low rotational speeds for quiet cooling of tightly packaged electronic equipment under severe environmental conditions in airborne, ground based, and shipboard applications. Simplex blowers have 1 squirrel cage impeller wheel while Duplex blowers have 2 squirrel cage impeller wheels mounted on a common shaft - both are available for either clockwise or counterclockwise rotation. Duplex blowers simplify ductwork and allow greater volume performance in tight locations. As with all squirrel cage blowers, air enters axially and exits tangentially, making a 90 degree turn. All models are built to applicable military specifications.
Brushless DC Operation and Frequency Converters
Centrifugal Blowers are available for single or multiple operations from DC power sources. Rotron also provides Frequency Converters to allow higher or lower motor speeds, where required, than are possible with a 50/60 or 400 Hz sources. Converters are also available to operate single or multiple units.
Performance Sensors
All Models equipped with optional performance sensors send out a tachometer-type signal generated from a hall sensor activated by a small permanent magnet mounted on the rotor of the fan motor. The signal depends on the fan type:
|
Fan Type |
Signal |
Output V Nominal |
|
AC |
10% on 90% off sq. wave pulse |
10V |
|
E.C.D.C. |
50% on 50% off sq. wave pulse |
10V |
Low Speed Warning Detector (LSWD)
The Low Speed Warning Detector (LSWD) utilizes a programmable frequency switch capable of turning “on” or “off” a load such as an LED, audible alarm, back-up fan, etc, at a predetermined motor RPM. If fan speed falls below the present value, the back-up or warning device is activated. Once the fan speed exceeds the present value, it is deactivated. The RPM value is preset at the factory between 2,000 and 20,000 RPM (actual value is determined by the specific fan performance and customer requirements).
Inverted Blowers
Inverted Blowers have their driving motor located inside the squirrel cage wheel. This results in unusual compactness and excellent motor cooling. Such an arrangement is only feasible whenever the wheel diameter is large in proportion to the volume of air moved. This situation may be obtained in slow volume of air moved. This situation may be obtained in slow running blowers as well as in tight scroll squirrel cage blowers that have a high pressure-to-volume ration performance.
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