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FEATURES:
Input Power: The Multi-SD can accept one or two power
sources in the range of 10-75 VDC. If two power supplies
are used, they are logically OR’d on the Multi-SD so that
the operating voltage is equal to the higher of the two
supplies. The Multi-SD can supply up to 4.0 Amps to the
fan load with natural convection or 5.0 Amps to the fan
load with 200 LFPM of forced convection, at 12, 24 VDC
or 48 VDC.
Input Power Fuse: A 7.0 Amp input power fuse is
provided to protect the Multi-SD from over-current
conditions.
Inrush Current: The input power supply connected to
the Multi-SD will see 100 microfarads of capacitance
through 0 Ohms.
Fan Soft Start: At the application of power, the Multi-SD
output voltage starts at 0 VDC. Then, over a period of
approximately 5 seconds the fan voltage is modulated from
0 VDC to full voltage and then temperature (or PWM)
based control begins.
Fan Speed Control: The speed of all fans is varied by
adjusting the voltage applied to the fan(s). Voltage
adjustment is accomplished with a current mode, buck
type control circuit. The fan voltage range is 6.6-13 VDC
for 12 VDC fans, 13-25 for 24 VDC fans and 26-50 VDC
for 48 VDC fans.
Fan Current Limiting: The load regulating circuitry is
configured with a 5 Amp active current limit.
Multiple Control Temperature Settings: Three control
temperatures (35°, 40°C or 45°C) are selectabe by jumper.
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Temperature based fan control: The voltage applied to
the fan(s) is determined by the temperature sensor(s)
connected to header J8. Single point or multiple point
sensing can be accomplished by connecting one to three
thermistor sensors to positions T1, T2 and T3. The sensor
reading the hottest temperature is used for fan voltage
control when more than one sensor is used.
PWM based fan control: The voltage applied to the fans
can be controlled based on an isolated PWM signal applied
to position T3 on header J8.
Fan Speed Up Command Input: A non-isolated input at
header J5 allows the user to apply a signal that commands
the fans to go to full speed. This command over-rides the
temperature sensor or PWM input signals at header J8.
Temperature Alarm: An isolated alarm output provides
indication of a high temperature condition or a shorted or
open sensor. Temperature alarm output is from an open
collector output or MOS relay.
Specialized Configurations of the Multi-SD
The following parameters can be specialized by CRI
through software and/or component values changes:
- Relationship between sensed temperatures and fan
voltage
- Relationship between PWM control signal and fan
voltage
- Temperature alarm trigger point
- Fan turn off below a certain sensed temperature
Customized Configuration of the Multi-SD
Contact Control Resources’ Sales Department for details
on custom products.
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