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Click
on drawing to view large scale version
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| SmartFan
TachScan-9 is a digital fan speed alarm that monitors the
tach pulses from up to nine DC or AC fans or blowers and provides
both individual and OR’d pass/fail signals. TachScan-9 is compatible
with any fan that provides open collector or voltage source
tach pulses. Three trigger speeds are selectable by jumper.
If the speed of any air mover falls below the trigger speed,
alarm signals are generated. Alarm signals can drive LEDs, logic,
optical isolators or MOS Relays. |
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|
Features
- Accepts any
supply voltage from 6 to 60 VDC and distributes power to
DC fans through the same header used to sense tach pulses.
It can also be used to power the DC tach circuits built
into AC fans
- Nine inputs
monitor fans with any open collector or voltage source tach
pulses
- Provides individual
outputs for each fan, which can drive logic, LEDs or remote
optical isolators.
- Provides OR’d
outputs to drive two single LEDs or one bi-colored LED
- Provides simultaneous
NO and NC isolated outputs from a Dual-Pole MOS Relay which
can sink up to 100 mA to drive heavy loads
- Jumper sets
trigger speed to 1,000, 2,000 or 4,000 PPM.
- Compatible with
any SmartFan speed controller
- Small size of
5” X 1.5” permits mounting in small spaces within fan trays,
etc.
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| SPECIFICATIONS |
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Part
Number
|
Supply
Voltage Range
|
Maximum
Input Current
|
Maximum
Output Current to Any Fan
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030M920
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6
to 60 VDC
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8.0
Amps
|
2.50
Amps
|
|
H116
|
Hardware
Pack
|
|
| Note:
Maximum operating temperature is 65°C |
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| INSTALLATION |
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|
Power-In Connection
(J11)
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| Refer
to Figure 2 for supply power wiring. Connect supply power in
the range of 6 to 60 VDC at header J11. Header J11 is rated
at 4.0 Amps per pin. For applications requiring less than 4.0
Amps, a single pair of power and return wires should be connected
to a single pair of + and – pins, respectively. For applications
requiring between 4.0 and 8.0 Amps, connect two pairs of supply
power and return leads to both pairs of + and – pins on J11
to handle the higher current. |
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| Fan
Connections |
| For
three wire DC fans operating at supply voltages between 6.0
and 60.0 VDC, TachScan-9 distributes power to the fans in addition
to accepting tachometer pulses from the fans. Connect the fan
wires to headers J1 through J9. Fan wires are usually color
coded with red for +, black for – and white or yellow for A
(alarm). Fan current at each header must not exceed 2.5 Amps.
Total fan current through J11 must not exceed 8.0 Amps. |
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| AC
Fan Alarm Monitoring |
| TachScan-9
cannot distribute AC power to AC fans. AC fans usually have
5 wires, 2 for power and 3 for the tachometer pulse circuit.
Connect the AC fan power leads to the rated source of power.
Connect the tachometer pulse leads (+, -, tach pulse) to J1
through J9. TachScan-9 distributes power to run the tachometer
pulse circuits within the fans. Apply a DC voltage as specified
by the fan manufacturer for the tachometer pulse circuits at
J11. |
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| When
Fewer Than 9 Fans Are Installed |
| If
tachometer pulses are not connected to all of the A inputs at
J1 through J9, TachScan-9 will indicate a fan failure at the
OR’d outputs on J13 and at the isolated OR’d output on J12.
(See Operation sections for details of the OR alarms.) Connecting
each fan’s tachometer output to more than one A input will avoid
this problem (See figure 1). Example: When monitoring 5 fans,
a seven position plug can be used with four of the fans and
a 3 position plug can be used with the 5th. Each 7 position
plug mates with adjacent headers J1 and J2, J3 and J4, etc.
applying a single fan tachometer signal to two A inputs. The
single 3 pin connector would plug into J9. |
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Figure
1
Connection of single fan tachometer output to two fan
headers when less than nine fans are used.
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| CONNECTIONS
/ JUMPERS |
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Figure
1 Wiring Diagram
Click
on drawing to view large scale version
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| Using
TachScan-9 with a SmartFan Speed Controller |
| Because
of the wide range of power supply voltages that may be connected
to J11, TachScan-9 may be used with any DC SmartFan speed controller.
The power output of the speed controller that would otherwise
be connected directly to the fan load is instead connected to
J11 (See figure 3). TachScan-9 in turn distributes this power
to the fans. |
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Figure
3
Multi-board configuration for variable fan speed control
and tachometer alarm monitoring.
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| OPERATION
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| Settings
(J10) |
| Trigger
Speed (WA ): Use this jumper to set the trigger speed. |
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| Position
L = 1000 PPM |
| Position
M = 2000 PPM (Factory Setting) |
| Position
H = 4000 PPM |
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| Since
fan tachometer circuits are designed with one, two, or even
more pulse outputs per revolution, settings are listed in pulses
per minute (PPM) rather than revolutions per minute (RPM). Given
the fan’s rated speed (W) and number of pulses per revolution
(N), use the following formula to select the trigger speed (WA
): |
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| WA
= W x N x 0.4 |
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| (Note:
When used with a SmartFan speed controller the factor in the
above equation should be changed from 0.4 to 0.3). |
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| For
example, a 3300 RPM fan with two pulses per revolution would
have a trigger speed (WA ) of: |
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| WA
= 3300 RPM x 2PPR x 0.4 = 2640 RPM |
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| Since
the 2000 PPM trigger is closest, set jumper J5 to the “M” position.
The alarm trigger accuracy is +/- 20%. |
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| Non-isolated
Alarm Outputs (J13) |
| Refer
to Figure 2 for alarm wiring. Nine separate non-isolated alarm
outputs are provided for each of the nine fan headers plus an
OR’d fan failure signal at header J13. Pins labeled 1 through
9 correspond to fan headers labeled J1 through J9. |
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| The
following table summarizes the alarm logic for each pin on header
J13. |
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| ALARM
LOGIC ON J13 |
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Pin
|
Above
Trigger Speed
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Below
Trigger Speed
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+
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High
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High
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OR
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Low
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High
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-
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Low
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Low
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1
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Low
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High
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2
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Low
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High
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3
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Low
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High
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4
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Low
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High
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5
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Low
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High
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6
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Low
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High
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7
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Low
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High
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8
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Low
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High
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9
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Low
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High
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OR-
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High
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Low
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| When
a fan’s speed drops below the trigger speed, the voltage at
its corresponding pin number on J13 switches from low to high.
In addition the voltage at J13:OR switches from low to high
and the voltage at J13:OR- switches from high to low. All voltage
levels are referenced to J13:-, which is internally connected
to the J11:-. |
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| Connecting
LED’s to J13 |
| Choose
LEDs with rated forward voltage (Vf ) between 1.6 and 2.4 VDC
at forward current (If)of between 15 and 25 mA. Nominal current
applied to the LEDs is 8 mA. Refer to the wiring diagram in
Figure 2. Each of the pins labeled 1through 9 on J13 will supply
8 mA to an LED connected between that pin and pin J13:- or J13:+.
To turn on an LED in response to a fan failure (usually a red
LED) connect it between the appropriate pin and pin J13:-. The
cathode (negative lead) of the LED is connected to pin J13:-.
To turn on an LED indicating that there has not been a failure
(usually a green LED) connect it between the appropriate pin
and pin J13:+. The anode (positive lead) of the LED is connected
to pin J13:+. |
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| Connecting
Logic Circuits to J13 |
| A logic
circuit connected to pins J13:1 through J13:9, J13:OR or J13:OR-
must have a ground reference connected to the Tachscan-9 circuit
ground available at J13:-, J11:-, and J1 through J9:-. If the
logic ground and Tachscan-9 circuit ground are common, only
the appropriate pin on J13 need be connected to the logic circuit.
If not, connect pin J13:- to the ground or negative terminal
of the logic circuit. When not in alarm, pins J13:1 through
9 and OR are LOW and can sink at least 1.0 mA at =< 0.4 VDC.
When in alarm, pins J13:1 through 9 and OR switch HIGH to at
least 2 VDC. Pin J13:OR- is HIGH when no fan failure is present
and LOW when a fan failure is present. In case of a power failure
to the TachScan board, all J13 outputs are open. Connection
of an external “pull-up resistor” will ensure an alarm state
in case of power failure. |
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| Connecting
Optical Isolators or MOS Relays to J13 |
| A resistor
must be connected in series with the input to the optical isolator
or MOS relay but otherwise it is connected in the same manner
as an LED (see Connecting LED’s to J13). A 1/4 watt resistor
with a value of approximately 200 ohms is recommended to set
isolator input current to approximately 5 mA. |
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| Isolated
OR’d Alarm Outputs (J12) |
| These
optically isolated outputs provide both normally open (NO) and
normally closed (NC) alarms permitting connection to logic circuits
or other loads with no electrical connection to the |
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| The
outputs are from a Dual-Pole MOS Relay, which are intended to
drive heavy loads. These outputs have a maximum on-state resistance
of 50 ½, maximum sinking current is 100 mA, and a maximum of
230 VAC can be applied to the alarm terminals. The outputs also
trigger in the event of cooling system power failure. |
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| ALARM
LOGIC ON J12 |
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|
Circuit
|
Above
Trigger Speed
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Below
Trigger Speed
|
Power
Removed
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1A
– 1B
|
Closed
|
Open
|
Open
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2A
– 2B
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Open
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Closed
|
Closed
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| Note:
At power-up, all outputs are held in the normal state for 10
seconds permitting the fans to come up to speed. |
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| SUGGESTED
CONNECTING HARDWARE |
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|
Ref.
Desc.
|
Header
on Board (1)
|
H116
Hardware Pack
|
|
Quantity
|
Description
|
Manufacturer
(1)
|
Part
Number (1)
|
|
J1-J9
|
22-29-2031
|
|
Housing
Terminal (gold)
|
|
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|
J11
|
43045-0412
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|
Housing
Terminal (tin)
|
|
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J12
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22-29-2041
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|
Housing
Terminal (gold)
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J13
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22-29-2131
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Housing
Terminal (gold)
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4
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PCB
Support
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Richco
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CBS-4-19
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| (1)
or equivalent |
