LG RCAW Operation & Maintenance Manual page 15

I/O Display
I/O Display
User Setting
Alarm Display
Content
Remote Control
System Oil
Main Contactor
Contactor
Low Temp Switch
Pressure Switch
Phase Protect
Chilled Flow
Dif-pressure
Comp Overload
Fan 1A1B
Fan 2A3A
The I/O display is composed of 9 screen cuts. Through the I/O Display, switch status of signal inputs to the PLC can be
identified. In the I/O display, ON means close status of a contact and OFF means open status of contact.
The remote control means remote start input to the PLC. When the contact is closed and the control mode is remote,
the chiller starts from stop. When the control mode is local, the switch input is disregarded.
The oil system means the serially connected input of oil flow switch and oil level switch. When both of the oil flow and
the oil level are normal during running compressor, both are closed, and consequently the oil system is also closed.
When anyone of them is abnormally opened, the switch input to the PLC is also changed into open. The PLC considers
the open status of the switch to be oil system alarm.
The compressor contactor switches indicate the status of compressor run. When only the main contactor is closed, the
compressor is in the Star-start phase, and when the both of them are closed, the compressor is in the Delta-start phase.
Because the contactor switches are contactor status input to the PLC, the contactor inputs must be differentiated from
output to the contactors. When there is any problem with a contactor, the input from the contactor and the output the
contactor can be different. Consequently, the PLC evaluates the normality of the contactors by checking inputs after
making outputs to the contactors be on.
The antifreeze S/W indicated the contact status from the anti-freezing switch. The switch is normally closed, and opens
when temperature is under setting value. The PLC considers the openness of the switch to be anti-freezing switch
alarm.
The pressure means the serially connected input of high pressure cutout switch and low pressure cutout switch. Both
switches are packaged in a dual pressure switch. Both switches are normally open. But if compressor discharge pres-
sure is over the setting value of the high pressure cutout switch or if compressor suction pressure is under the setting
value of the low pressure cutout switch, the cutout switch opens. The PLC considers the openness of the switch to be
pressure alarm.
DISCRETE INPUTS1
Fan4A5A
Fan2B3B
Fan4B5B
Emergency Stop
DISCRETE INPUTS2
OFF
Alarm Output
OFF
M1 Contactor
OFF
M2 Contactor
OFF
M3 Contactor
DISCRETE INPUTS3
25% Magnet Valve
OFF
50% Magnet Valve
OFF
75% Magnet Valve
OFF
OFF
Pump
DISCRETE INPUTS4
Fan1A1B
OFF
Fan2A3A
OFF
Fan4A5A
OFF
Fan2B3B
OFF
DISCRETE INPUTS5
OFF
OFF
OFF
OFF
DISCRETE INPUTS6
OFF
OFF
OFF
OFF
DISCRETE OUTPUT1
OFF
OFF
OFF
OFF
DISCRETE OUTPUT2
OFF
OFF
OFF
OFF
Fig. 4
Operation & Maintenance Manual 15
General
DISCRETE OUTPUT3
Fan4B5B OFF
SV2 Magnet Valve OFF