Data creazione 10/09/03 DS03I009GB--00 Pagina 52 di 59
STEP ACTIVATION – SCAN TIMES
The temperature controller can activate one and one only step at a time, and only at the expiry of the
activation scan time. At all other times no steps may be activated. The activation scan time is not fixed, but
rather varies according to the temperature difference between the water outlet temperature and the current
set point. The higher the difference (both positive and negative), the shorter the interval between the scan
points.
STEP DEACTIVATION
The active capacity-control steps can be deactivated, one step at a time (except where protected by the
safety devices), at the expiry of the time defined for the parameter TSRelease.
COMPENSATION
1) LOAD COMPENSATION
The load compensation function acts by modifying the capacity-control step activation point as the
difference between the exchanger water inlet and outlet temperature changes.
It is assumed that the temperature difference is a direct consequence of the extent of the load applied.
The compensation value will be higher (capacity-control step activation point further away from the set
point) the lower the temperature difference.
The compensation value will be null (capacity-control step activation point nearer to the set point) at the
maximum temperature difference.
The value of the difference between the water inlet and outlet temperature is the average measured over
the last (MediaDelta) seconds.
2) DUTY-CYCLE COMPENSATION
The control algorithm estimates the more critical load conditions for the unit, based on the operating
times and the frequency of compressor starts. In the event of critical operation, the controller increases
the offset in reference to the activation threshold.
3) RUNNING TIME COMPENSATION
The number of compressor starts is counted over a certain interval of time. If the compressor running
time is critical (too short), the controller increases the offset in reference to the activation threshold.
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