Unit installation

The following figure represents schematically the front panel of the controller:

USER SEQUENCE OF OPERATION

Machine starting:

• If OFF the machine is started pushing the ON/OFF key.

• The on LED will be lit.

• After 15 seconds of delay the system will be running.

Machine shut-down:

• If ON the machine is halted pushing again the ON/OFF key.

• The on LED will be off.

Set point change:

• Press <SET>, the LCD will ask the password input.

• Using the <UP> <DOWN> keys input the right password.

• Press <SET>, the ‘MODIFY’ word will appear allowing the parameter to be changed; the LCD will show the

set point actual value.

• Using the <UP> <DOWN> keys modify the set point value.

• Press <SET> to store it or <ESC> to exit without memorising.

CONFIGURATION

The mother board, provided with the relevant user interface, can control up to two compressors. In a 4+

compressors chiller the mother board will be serially connected with the slave compressor boards (one per two

compressors). All the interactions with the machine are made through the master board (M.B.) user interface

(U.I.).

The two water temperatures probes (Tin RWT Return Water Temperature and Tout Leaving Water temperature)

are connected to the MB.

SOFTWARE CONTROL CONCEPT

This procedure runs on the master board, switching all the compressors on and off according to the plant

requirements:

• According to all parameters the software will control the System using a PID like control algorithm to maintain

Tc to the desired Set Point. The algorithm also takes care of the running hours of any compressor, the

minimum interval between two insertions of the same compressor, the minimum time between any

compressor startup and the alarm status.

• Every 4 hours the more used compressor is halted and is replaced by the less used one. (Not applicable to

the leader compressor).

• Each time a compressor is normally stopped (not for alarms) the pump down procedure is executed according

to the set up parameters.

COOLINE

AIR CONDITIONERS

TOUT = 10°C TIN = 15°C

COOLING 75%

SET

Esc

On/Off