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VLT
®
6000 HVAC
MG.60.B1.02 - VLT is a registered Danfoss trademark
20
Water Inlet
Water Outlet
CHILLER
Temperature
Sensor
BASIN
Conderser
Water pump
Supply
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Cooling Tower Fan
Cooling Tower Fans are used to cool condenser
water in water cooled chiller systems. Water cooled
chillers provide the most efficient means of creating
chilled water. They are as much as 20% more efficient
than air cooled chillers. Depending on climate,
Cooling towers are often the most energy efficient
method of cooling the condenser water from chillers.
They cool the condenser water by evaporation.
The condenser water is sprayed into the cooling
tower onto the cooling towers “fill” to increase its
surface area. The tower fan blows air through the fill
and sprayed water to aid in the evaporation.
Evaporation removes energy from the water dropping
its temperature. The cooled water collects in the
cooling towers basin where it is pumped back into
the chillers condenser and the cycle is repeated.
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The new standard
With a VLT frequency converter, the cooling towers
fans can be controlled to the required speed to
maintain the condenser water temperature. VLT
frequency converters can also be used to turn the fan
on and off as needed.
Several features of Danfoss HVAC dedicated drive, the
VLT 6000 HVAC can be utilized to improve the
performance of your cooling tower fans application.
As the cooling tower fans drop below a certain speed,
the effect the fan has on cooling the water becomes
small. Also, when utilizing a gear-box to VLT
frequency converter the tower fan, a minimum speed
of 40-50% may be required.
The customer programmable minimum frequency
setting of the VLT is available to maintain this
minimum frequency even as the feedback or speed
reference calls for lower speeds.
Also as a standard feature, you can program the VLT
frequency converter to enter a “sleep” mode and stop
the fan until a higher speed is required. Additionally,
some cooling tower fans have undesireable
frequencies that may cause vibrations. These
frequencies can easily be avoided by programming the
bypass frequency ranges in the VLT frequency
converter.