Fuji Electric FRENIC-HVAC User Manual page 524

J198 Wet-bulb temperature presumption control
This function is to be used mainly for fan control of a cooling tower. On days when outside air
temperature (humidity) is especially high, the wet-bulb temperature becomes higher than the
set temperature, preventing water temperature from reaching the set temperature. As a result,
the fan continues operating at high speed, resulting in no energy-saving effect. With this
function activated, the wet-bulb temperature is automatically estimated, and the fan is
controlled so that cooling water is adjusted according to outside air temperature (humidity),
resulting in reduction of wasteful power consumption.
 Wet-bulb temperature presumption control (J198)
Set a frequency reduction value per minute in terms of wet-bulb temperature estimation.
- Data setting range: 0.01 to 120.00 (Hz/min), OFF
Temperature [°C]
Output frequency [Hz]
Upper limiter
Set temperature < outside air (wet-bulb) temperature
The cooling-water temperature decreases only to the outside air temperature (humidity).
Outside air (wet-bulb) temperature
Control OFF: high-speed fan operation
Control ON
Cooling water is controlled by
wet-bulb temperature
Wet-bulb temperature estimation/control
6-214
Cooling-water temperature
Set temperature
Time
1 min
Elimination of
wasteful power
Time
J198