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Custom SmartFan® Examples
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Examples of Custom SmartFan® Designs |
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Benefits
of using SmartFan include acoustical noise reduction,
environmental (humidity, temperature or pressure) regulation,
greater product reliability, increased fan life, improved
safety and energy savings. Applications that demonstrate
these benefits are described below.
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A high
end server cooled by two backward curved impellers. The challenge of this application
was to maintain very stringent current limits
while providing adequate airflow to cool the server.
A control board was designed that included active current limiting.
Current limits were specified for normal operation, start up, hot plug and
fault conditions. The fans are constantly monitored and individually
adjusted. Under critical
conditions, a fan could be shut down by the board circuitry. The board
also provides PWM control signals to maintain predetermined individual
blower speeds ± 100 RPM. Tach pulses from each fan are monitored. LED and
logic status outputs are provided.
FEATURES:
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Supply Voltage:
24 VDC
- Logic Supply
Voltage: 5 VDC
- Fans: Two 24
VDC, 93 watt impellers
- Speed Control:
Individual PWM speed control for each impeller
- Fan Performance
Monitoring: Based on monitoring current draw and tach pulses from the
impellers
- Alarm Outputs:
LED and open collector logic
- Active Current Limiting: Limits are
maintained for normal operation, startup, hotplug and fault
conditions
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A large telecom
system cooled by four different fan trays. The customer requested a single board that
would work with any of the four trays. A micro-controller based product was
designed that would adapt its operating parameters to any of the
four
fan trays based on an input signal from the system backplane. The board monitors tach pulses
from the fans and provides LED and TTL status
signals.
The board was later revised after the customer had problems
with a UL flammability test. The fans caused the flames to burn longer
than UL allowed. The board was redesigned to incorporate a “crowbar”
circuit that provides LED and TTL alarm signals and/or permanently
disables power delivered to the fans based on inputs from two heat
detection sensors.
FEATURES:
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Supply
Voltage: 24 VDC
- Fans: Up to
six 15 watt fans
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Fan Monitoring: Based on
monitoring tach pulses from the fans
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Alarm Outputs: LED and
TTL
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Fusing: Individual fan
outputs
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Test Input: Accepts a
TTL/LVTTL logic input that causes all alarm outputs to go to the failed
state to verify the control interface
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An industrial computer cooled by five
fans. In addition to fan
performance monitoring, the customer requested that the board also serve
as a system voltage and temperature monitor. Five DC voltages are
monitored. Jumpers allow 5 or
10% acceptable range selection.
In addition the board monitors the system AC power source through a
TTL logic signal supplied to the board from the AC source. Temperature is sensed through a
remote P8 sensor. A jumper allows four maximum temperature
selections.
Fan, voltage and temperature status is reported through an
RS-232 port and 8 bicolored LEDs.
when any red LED is powered, audible and relay outputs are also
provided.
FEATURES:
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Supply Voltage:
12 VDC
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Fans: Five 12
VDC, 7 watt fans
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Fan Performance
Monitoring: Based on monitoring current draw
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System Voltage
Monitoring: Five DC and one AC voltage
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Temperature
Monitoring: Maximum temperature as selected by jumper
- Alarm Outputs:
RS-232, bi-colored LEDs, speaker, relay
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A telecom switch cooled by ten fans. This application required providing multiple functions and 50 Watts of output power on a verysmall board. The board accepts and diode ORs dual power feeds with a supply voltage range of –37 to –60 VDC. The supply voltage is clamped at –54 VDC to prevent over voltage to the fans and a boost circuit provides voltages greater than the supply voltage to be applied to the fans when the supply voltage drops below –48 VDC. An I2C bus transmits circuit board inventory and temperature information from a digital thermometer. The fans are turned off when the temperature is below 0°C.
FEATURES:
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Supply Voltage:
-37 to -60 VDC
- Fans: Ten 48
VDC, 4.8 watt fans
- Fan Speed
Control: 48 VDC for normal operation, 54 VDC in an alarm condition The
fans are turned off when the temperature is below 0°C
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Fan Performance
Monitoring: Based on monitoring Tach Pulses from the fans
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Temperature
Monitoring: On board digital thermometer
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Alarm Outputs:
Optically isolated logic outputs for single and multiple fan
failure
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Serial
Interface: I2C bus transmits circuit board inventory and temperature
information
- Fusing: Both
power feed and individual fans
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EMI
Suppression: All input and output lines
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Current
Limiting: In-rush current at start up and output power to fans
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Base Tray
Heater Tray
Blower Tray
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Burn-in Cabinet
Temperature Control System. The customer
requested assistance designing cabinets for production burn-in of several
types of circuit cards with varying power dissipation levels. The cabinets
were desired as an alternative to expensive dedicated burn-in rooms. In addition, the cabinets would be
portable. The designed system consists of two trays. The Base Tray
contains six 118 CFM DC fans controlled by a SmartFan Omni SD controller
(cat. pg. 32), four 220 VAC, 500 Watt axial heaters controlled by a
SmartFan AC-VX controller (cat. pg. 24), one SmartFan HotSpot-Z
temperature alarm (cat. pg. 50), a power supply and a relay. The Heater
Tray contains four 220 VAC, 500 Watt axial heaters controlled by a relay
and one SmartFan HotSpot-Z temperature alarm. The system also includes
three temperature sensors and cabling to connect the two trays.
The system controls
the internal temperature of the cabinet (± 2°C). Temperature is monitored
at three locations and controlled at two locations.
Temperature is
maintained by linear/proportional control of both heating and cooling
elements. The system is
designed to add sufficient heat to ensure fast heating to control
temperature under light load conditions. Alternatively, the system will
power auxiliary air movers to dissipate excessive heat under heavy load
conditions.
A second system was designed to handle circuit cards with higher power dissipation levels. The system required more cooling and less heating capacity, so the Heater Tray was replaced with a Blower Tray. The Blower Tray consists of three 365 CFM AC fans and a relay mounted on a steel panel. The Blower Tray accepts a signal from the Base Tray that turns the three fans on and off based on temperature.
In addition, for safety reasons, an interlock harness was designed to dissable the heaters when the front or rear doors of the cabinet are opened. |
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