High Country Tek HFS - Manual (Page 9)

Hydraulic Fan System Controller: HFS
The controller uses "PI" to regulate the temperatures to be no more than the Set points entered by the user.
The „P‟ and I terms act on temperature difference between set point and actual temperatures, with the P term used to
change the amount of response at the control valve and should be adjusted to respond smoothly to smaller
temperature changes. The larger the number set, the more aggressive the change will be for a small difference.
The „I‟ term tracks the temperature difference and automatically adjusts the control valve to increase or de-crease fan
speed while attempting to get as close as possible to the set point. The larger the number set, the bigger corrective
step to the control valve will be seen.
General operation default values for the P & I terms are embedded in the software but may be altered by users with
the proper password level of authorization to fine tune a system.
Temperature error is the difference between the actual measured temperature and the „temperature set point‟,
scaled by the difference between the „temperature set point‟ and the „'Overtemp' alarm set point.
The scaling is required to allow comparison of all the thermistor inputs on an equal basis.
The active thermistor input with the largest scaled error above its set point will be used by the PI process.
If all temperatures are below their user set points, the thermistor closest to it‟s set point will be used to give control.
In a properly tuned system, this process will result in the fan turning just fast enough to keep one temperature
regulated to its set point and all other temperatures less than their Set points.
If a thermistor input is shorted or open, the unit will ramp to full fan speed. This error behavior will continue until
power is turned off if the user programmable „Retry All Faults‟ is NOT selected, otherwise, it will resume normal
operation when the fault is cleared.
A thermistor reaching „Overtemp‟ is an error that results in ramping to full fan speed. The „Overtemp‟ error condition is
automatically cleared if the thermistor drops below „Overtemp‟, ramping to the PWM% value demanded by the PI loop.
Password protection has been provided to ensure that damage cannot be caused once commissioning is completed.
There are three levels of security, all of which may only be accessed via the Opto 3000 and PC software and with the
proper password level of authorization:
Level 1:- ( NO Password ) Monitor controller operation only, no change in parameters allowed, can data
log for system diagnosis if required.
Level 2:- ( OEM Password ) Authorized user has access to the functions that are needed for programming and
set-up.
Level 3:- ( Professional Password ) HCT Engineering level which allows access to ALL base controller settings
and some RESET functions.
Contact High Country Tek , Inc. on the e-mail address ( [email protected] ) for password .
Fan Control Logic:
Password Protection:
9