Interface for Speed Controllable Fans
Introducing

SmartFan
�

Cirrus
, Programmable

Interface for Speed Controllable Fans

Rev: 2

CONTROL
RESOURCES

INCORPORATED

TEL: (978) 486-4160
FAX: (978) 486-4772
Email: sales@controlres.com
www.controlres.com
Page 1 of 8

2006 (11)







Fig. 1: CRI #036BCT00 with DIN350 DIN
rail mount kit (sold separately).

Fig. 2: CRI #036BCT00

Fig. 3: CRI #036BJW00 with 4x4 Job Box
(not supplied).

SmartFan
�
Cirrus

is a compact, microprocessor based PWM fan interface designed for the electronics, industrial and
HVAC control markets. The Cirrus can automatically control most speed controllable (4 wire) 24 and 48 VDC fans used
in applications such as: equipment cooling, humidity control, clean room pressurization, exhaust ventilators, duct fans &
blowers. The Cirrus regulates fan speed from a 0-20mA-control signal, 0-10VDC-control signal, remote transducer or
thermistor. On board programming, three mounting and connection configurations, including DIN rail mount and 4x4 job
box mount, make this design extremely flexible and economical.
Benefits of using SmartFan include acoustical
noise reduction, environmental (humidity, temperature, pressure or flow) regulation, greater system reliability,
increased fan life, improved safety and energy savings.



FEATURES & OPTIONS
Features (off the shelf)
Controls one or two (sometimes more) 24 or 48 VDC open
collector PWM controllable fans.
Power source: 20 60VDC (passed through to fan).
Settable PWM frequencies between 1000Hz and 10,000Hz.
Controls fans from a:
0-20mA control signal or
0-10VDC control signal or
Remote transducer (temperature, humidity, pressure, flow)
Remote thermistor (sold separately)
Isolated
control
inputs.
Temperature & loss of signal alarm
Tach alarm with 3 selectable speed settings
Remaining fan switches to full speed upon fan failure
Potentiometer settable Max and Min fan speeds
Potentiometer settable Max and Min control signal
Potentiometer settable 0-18VDC supply voltage to drive
external transducer or alarm
Mounting Options: PCB mount, DIN Rail mount, 4x4 electrical
job box mount
Customizing Options
Can be readily modified to control most any
speed controllable fan
PWM frequencies below 1000Hz and above
10,000Hz.
Fused fan inputs.
Hard coded control curve
Hard coded alarm trigger points
Hard coded transducer supply voltage.
Dual thermistor and transducer inputs.
On board thermistor
On board pressure transducer.
NEMA 4X case
Connections: Terminal Block, 18 AWG
wires.




Cirrus Datasheet




CONTROL
RESOURCES

INCORPORATED

TEL: (978) 486-4160
FAX: (978) 486-4772
Email: sales@controlres.com
www.controlres.com
Page 2 of 8

2006 (11)







Electrical job box mount style CRI# 036xJWxx
Figure
4 Figure
5











*
When used in the thermistor control mode, a sensor (sold
separately) is required. Choose an air, surface or liquid temperature
sensor from the CRI catalog or website at
www.controlres.com
.

** When a transducer is required one can select a humidity transducer
from the CRI catalog or website at
www.controlres.com
or use the
remote transducer of your choose.


Stock Product:
036BCT00 (fig. 2)
036BJW00 (fig. 3)

DIN Rail Option (Fig 1)
:

Units supplied in the circuit board only configuration (036xCxxx) can be mounted on a DIN rail using
DIN rail kit CRI
#DIN350
.
Table 1: Part Numbering System

Nominal
voltage

Control Mode

Configuration

Connector
Customized
options
036
B = Current, Voltage, Thermistor* or
remote Transducer**
C = Circuit Board only
J = Job Box Mount
T = Terminal Block
W = 18awg wires
00 = standard
-F = RoHS Cirrus Datasheet




CONTROL
RESOURCES

INCORPORATED

TEL: (978) 486-4160
FAX: (978) 486-4772
Email: sales@controlres.com
www.controlres.com
Page 3 of 8

2006 (11)



FAN COMPATABILTIY

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.

Table 2: Setting Control Modes
DIP switch

Control Via
1 2
Voltage Source
OFF
OFF
Current Source
ON
OFF
Thermistor Source
OFF
ON


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)


CUSTOMIZING YOUR CONTROL CURVE (figure 7)

The off-the-shelf Cirrus is designed to give the user
optimum flexibility in experimenting with control
parameters. Once the desired control parameters are
chosen, the user may order their own customized
version of the Cirrus preprogrammed with the desired
control curve and other custom features avoiding switch
and potentiometer settings. Refer to figure 7 when
setting switches 5,6 and 7.

Until this point, all settings can be made without power,
control signal or fans

connected. From here on, the
Cirrus must be powered, fans connected and an
adjustable control signal (decade box or other resistance
substitute to simulate a thermistor, an adjustable voltage
source for voltage control or adjustable current source
for current control or to simulate a transducer) must be
connected to the board. (see
CONNECTIONS
section
for details).

For steps A H, switch 8 will activate and deactivate
POT1 for programming, to avoid accidental
programming errors be sure to deactivate POT1 by
turning switch 8 OFF before changing switches 5,6 or 7.

A) Transducer or Alarm Power

When controlling from a remote transducer or powering
an alarm, the Cirrus can be used as a power source up
to 18VDC (see figure 9). If not powering a transducer or
alarm, skip this step. To set the supply voltage, set
switches 5-OFF, 6-OFF, 7-OFF (see table 3), then set
switch 8 to the ON position. Place a multimeter across
OUT and GND and adjust POT1 until the desired voltage
is set. When finished, set switch 8 to the OFF position.

Table 3: Potentiometer (POT1) Adjustment Settings
DIP switch
Settable Parameter
5 6 7
A) Trans. or Alarm Power (0-18VDC)
OFF OFF OFF
B) PWM Frequency
ON
OFF
OFF
C) Full Speed Duty Cycle (Y2)
ON
ON
OFF
D) Idle Speed (Y1)
OFF
OFF
ON
E) Minimum Control Point (X1)
ON
OFF
ON
F) Maximum Control Point (X2)
OFF
ON
ON
G) Fan ON/Fan OFF setting (X3)
ON
ON
ON
H) Tach alarm threshold
OFF
ON
OFF


B) Setting PWM Frequency

The standard Cirrus can control PWM controllable fans
between 1000Hz and 10,000Hz. Check your fan for the
specified PWM signal. To program for this signal, set
switches 5-ON, 6-OFF, 7-OFF (see table 3), then set
switch 8 to the ON position. Adjust POT1 for the closest
setting to the PWM signal specified for your fan (see
figure 6). When finished, set switch 8 to the OFF
position.
Note:
POT1 settings are not graduated, knob
alignment need not be exact.

Figure 6 Cirrus Datasheet




CONTROL
RESOURCES

INCORPORATED

TEL: (978) 486-4160
FAX: (978) 486-4772
Email: sales@controlres.com
www.controlres.com
Page 4 of 8

2006 (11)




Y2
2
4
0
X3
4
8
20