Unit installation

32 ACZ 010A through 039A IOMM ACZ1-2
Unit Mode
The overall operating mode of the chiller is set by the Available Mode Setpoint with
options of COOL and TEST.
Unit Test Mode
The unit test mode allows manual testing of controller outputs. Entering this mode requires
the following conditions.
• Unit Switch = OFF
• Manager password active.
• Available Unit Mode setpoint = TEST
A test menu can then be selected to allow activation of the outputs. It is possible to switch
each digital output ON or OFF and set the analog outputs to any value. In test mode, the
compressors can be started, but will automatically turn off after 10 seconds. Also, if any
outputs are left on in test mode, they will be automatically turned off and/or normal control
logic resumed when the unit is taken out of test mode.
Power Up Start Delay
After powering up the unit, the motor protectors may not seem to work properly for up to
150 seconds. After the control is powered up, no compressor can start for 150 seconds. In
addition, the motor protect inputs are ignored during this time so as to avoid tripping a false
alarm.
Unit State
The Unit is always in one of three states. These states are Off, Auto, and Pumpdown.
Transitions between these states are shown in the following diagram.
Figure 10, Unit State Diagram
Off
Pumpdown Auto
T1
T4
T3
T2
Power On
Unit State Diagram
T1: Transition from Off to Auto
Requires all of the following:
• Unit Enable = True
• No Alarm
• At least one compressor enabled via manual setpoint