Control; The "Chiller Control" System - SystemAir AQWL 1404 STD-LN Manuel D'installation

General information
Introduction
This document contains the information and the operating
instructions for the units.
This information is for the after-sales service and the production
operators, for the end-of-line testing.
Main characteristics
– Microprocessor control
– User-friendly keyboard
– Proportional and integral control of the return
water temperature (RWT)
– Hysteresis control of the leaving water
temperature (LWT)
– Access code to enter the Manufacturer's Level
– Access code to enter the Assistance Level
– Alarm and LED
– Backlighted LCD
– Closed-loop condensing pressure control
– Pump-Down logic (start-stop)
– Rotation of the compressor operation
– Oil return function
– Night mode (or Low Noise) control
– Counting of the pump/compressors' hours of
operation
– Display and control of superheating by EEV
– Display of discharge and suction pressure values
– History of stored alarms (option)
– Programming of different setpoints with 4 ranges
of time/setpoint.
The following accessories can be also connected:
– Real Time Clock Memory Card: alarm history and programming of
different setpoints with ranges of time
– serial communication RS485 card; to connect the "Chiller
Control" to a BMS network
– remote display terminal
– wire remote control.

6 - Control

6.1 The "CHILLER CONTROL" system

Units are provided with a microprocessor card which is fully
programmed in factory for the control of a chiller with 2 circuits,
2/3 compressors per circuit, a high-pressure transducer and an
electronic expansion valve per circuit.
Keyboard & Display Terminal
General information
The figure shows the terminal with the front door open.
It is provided with a LCD 4 lines x 20 columns, keyboard and
microprocessor-controlled LED's, so as to allow the programming of
the control parameters (setpoint, differential bands, alarm thresholds)
and themain operations to be carried out by the user.
Terminal & Key Board description
The terminal makes it possible to carry out the following operations:
– the initial configuration of the machine
– the change of all the main operating parameters
– the display of the detected alarms
– the display of all the measured quantities
The terminal and the card are connected by a 6-way phone cable.
The connection of the terminal to the basic card is not essential for
the normal operation of the controller.
21