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9. Fan Control
EC Fan System Fan Control
All EC fan motors are controlled simultaneously by a single 4-20mA analog signal where 4mA is 0% speed and 20mA is 100%
speed. Control signals outside of this range will cause the unit to operate in emergency mode (approx. 40% fan speed).
Sequence of Operation
Fan Ramp Sequence
Before start-up, ensure that the unit is energized and a control signal between 4 and 20mA is provided to terminals AIN and
AGND. The fans will respond to an increasing speed signal, per Figure 19:
1.
If the control signal is less than or equal to 3.2mA for more than 60 seconds:
a.
The alarm light on the control panel will turn ON and an alarm signal will be enabled.
b.
All fans will rotate at the emergency speed.
2.
When the control signal reaches 4.6mA, the fans will initiate rotation.
3.
Between 4.6mA and 20mA, the fans ramp up linearly and proportionally to the input speed signal.
Vertex™ Evaporative Condenser Operation & Maintenance Manual – Fan Control
Figure 19. Ramp-up Sequence
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