High Country Tek HFS-2Q - Manual (Page 12)

Hydraulic Fan System Controller : HFS - 2
Proportional Output :
A variable current output is used for driving a proportional valve to control the
fan speed.
The value of the valve drive current is derived from a closed loop calculation
relative to the temperature set-points that the user has entered in the set-up.
BOTH wires from the valve coil must be connected to the controller where BOTH wires from the valve coil must be connected to the controller where
indicated by ‘+Prop Vlv O/P’ and ‘-Prop Vlv O/P’. At NO time should any coil
wires be connected to 0V or application chassis e.t.c. as this will effect the
operation of the controller and could have damaging effects.
The output is internally fully protected against shorted or mis-wired coils with
errors being both indicated locally on the associated LED and annunciated on
the controller software if the program is running on a PC connected to the unit.
Shorted coils or connection wires are detected only when the controller tries to
drive the coil and is indicated with a RED FLASHING output LED.
Open circuit coils or connection wires are detected only when the controller
tries to drive the coil and is indicated with a GREEN FLASHING output LED.
In either of the above cases, the ‘Alarm output’ comes ‘ON Steady’ to indicate
an error and if connected, the PC program will show annunciators.
The proportional valve coil selected must be capable of withstanding the power
supply's maximum voltage or the user must set the maximum output current
( I Max ) to a safe value.
User adjustable minimum current ( I Min ) and selectable PWM frequency ( 31
to 250 Hz ) allows tuning for smoothly starting the fan from a stop.
The proportional output is rated for a 3.3A coil current maximum at the
connected supply voltage
connected supply voltage.
The software allows user selection of driving normally open and normally
closed proportional valves, this sets the system default fan speed in the event
of an electrical power loss to the controller module.
The proportional output is turned off if the units internal temperature sensor
temperature exceeds 80 C.
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