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FAN COMPATABILITY The off-the-shelf Cirrus is compatible with the common
open collector PWM controllable fan. Most other control
schemes can be accommodated with minor hardware
modifications. To confirm fan compatibility, send CRI
your speed controllable fan for analysis.
SETTING CONTROL MODES (switches #1,2) Unless otherwise specified, the Cirrus is factory set to
control fans in the voltage control mode. To control via a
current or thermistor source, set switches 1 and 2 as
shown below. If an on board pressure transducer or on
board thermistor is required, contact customer service.
SETTING NUMBER OF FANS (switch #3) The Cirrus can control one or two fans. When
controlling 2 fans, set switch 3 to the OFF position. For
one fan, set switch 3 to the ON position.
 SIGNAL LOSS OVERIDE FEATURE (Switch #4) If the control signal drops below 2% of the maximum
control signal (for voltage or current control) or is lost do
to a severed cable or loose wire (current or temp. control
only), fans can automatically switch to full speed and an
alarm will be triggered by placing switch 4 in the ON
position. To keep fans from switching to full speed (Y2)
in this event, place switch 4 in the OFF position. (see
figure 6)
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