High Country Tek HFS-2Q - Manual (Page 10)

Hydraulic Fan System Controller : HFS - 2
PI ( Proportional/Integral) Logic :
The controller uses "PI" to regulate the temperatures to be no more than the Setpoints entered by the user.
The P and I terms act on temperature error, with the P term used to instantaneously respond to temperature
errors and should be adjusted to respond quickly to large temperature changes, but have little impact
otherwise.
The I term is used to track the average fan current required to keep the hottest temperature measured closest
to its setpoint and should be set-up for slow and smooth response while giving accurate control round the
setpoint
setpoint.
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 setpoint’,
scaled by the difference between the ‘temperature setpoint’ and the ‘'Overtemp' alarm setpoint.
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 setpoint will be used by the PI process.
If all temperatures are below their user setpoints, 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 setpoint and all other temperatures less than their Setpoints.
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
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 2000 and PC
Password Protection :
completed. There are three levels of security, all of which may only be accessed via the Opto 2000 and PC
software and with the proper password level of authorization:
Level 1:- ( NO Password ) Monitor controller operation only, no change in parameters allowed.
Level 2:- ( OEM Password ) Authorized user has access to the functions that are needed for
programming and set-up.
Level 3:- ( Factory Password ) HCT Engineering level which allows access to ALL base controller
settings and some RESET functions.
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Contact HCT on the e-mail address ( [email protected] ) for password .