High Country Tek HFS-3 - Manual (Page 5)

Hydraulic Fan System Controller – HFS-3-12v
ALL information contained herein is copyrighted to High Country Tek, Inc - © 2009.
Important Notes :
5
High Country Tek, Inc ( HCT ) recognizes that fan drive systems are an important part of the protection
needed for the engine and associated peripheral components to ensure maximum reliability, productivity
and long term operation. The fan drive system controller, HFS-3-12v offered by HCT will save fuel, reduce
emissions ( particle and noise ) and increase application productivity by only operating the fan when
required and matching the fan speed to the heat load that requires dissipation.
For fail- safe operation, HCT strongly recommends that the hydraulic valves used are of the ‘Negative logic’
variety. This means that the valve gives less pressure for an increasing drive current. This choice results in
full pressure and therefore defaults to full fan speed in the event of the electronic controller or the fan
speed requirement signal being dis-connected or disabled.
There are situations where full fan speed with no drive current may not be optimal so the controller in this
manual allows the user the choice of either ‘negative logic’ or positive logic ( Increasing pressure with
increasing current ) valves by a simple link setting, found under the units lid.
Because the controller is designed to connect directly to the engine ECU, all the decisions on ramp rates,
proportionality, slope angle e.t.c. are already calculated to suit the application. This means that adjustment
of the controller is simple with only five potentiometers –
 Dither frequency ( which is needed to ensure correct, repeatable and smooth valve operation ).
 I Min ( which sets the Max fan speed on Negative logic valves or Min fan speed in positive logic circuits ).
 I Max (which sets the Min fan speed on Negative logic valves or Max fan speed in positive logic circuits).
To maintain operational integrity and prevent unauthorized adjustments once set, the assembly of the
driver is such that the enclosure containing the electronics ( electronic printed circuit board and
components are fully isolated from the casing ) must be assembled as described in this manual and
mounted to the valve coil with the correct length screw.
The controller electronics are fully encapsulated in black flame proof resin to allow continuous operation in
adverse conditions while protecting them from vibration and external environmental influences.
This unit has been designed to meet all the current EMC requirements and is a well proven control circuit
with many years of field and time proven operation.
Important Note:-
Please be aware that fan blades can start rotating without warning and may cause
personal injury if precautions are not taken and safe working practices observed.