LG RCWW Operation & Maintenance Manual page 47

(7) Controlling cooling tower fan inverter
This control method is applied when an inverter is used to control the cooling tower fan motor to stabilize the
cooling water inlet temperature.
In the control unit, the selection for Main menu/System Menu/safety control setting/Cooling tower control se-
lect should be done by inverter.
- Operation is possible only when the inverter is mounted on the user's MCC(MOTOR CONTROL CENTER)
panel. This function is optional. Please contact LG Electronics for details before using.
- The output of the cooling tower fan control is 4~20 mA at the micom.
<Cooling water temperature P value>
When using inverter to control the cooling water inlet temperature, the proportional zone P of PID control
should be set.
<Cooling water temperature I value>
When using inverter to control the cooling water inlet temperature, the integral zone I of PID control should be
set.
<Cooling water temperature D value>
When using inverter to control the cooling water inlet temperature, the differential zone D of PID control
should be set.
<Cooling water inlet temperature>
Cooling water inlet temperature is set, which will be the standard to control the cooling tower fan inverter.
(8) Limiting motor current
This menu is to set the motor current control to protect the motor from overheating.
When the motor current is limited, the temperature control is not implemented.
However, in case the PID calculation value is smaller than the value of the valve opening when the current is
limited, the closing operation is executed pursuant to the PID calculation value.
Current limit setting
Current control operation
Rated current
Valve opening
518A
80% (518×0.8 A 414)
100% 105%
Valve closing
(414A) (414×1.05 A 435)
4. CONTROL SYSTEM
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