76
OMM 1008-1
Remote SWITCH
Selecting SWITCH in SP3 will put the unit under the control of a remote switch that must be wired into the
control panel (see
Figure 8
on page 29).
BAS
BAS input is field-wired into a card that is factory-installed on the unit controller.
Control Panel Switches
The unit control panel, located adjacent to the Interface Panel has switches inside the panel for stopping the
unit and compressors. When the UNIT switch is placed in the OFF position the chiller will shut down
through the normal shutdown sequence whether one or two compressors.
The COMPRESSOR switch(s) (two on dual compressor units) will immediately shut down the compressor
without going through the shutdown sequence when placed in the OFF position. It is equivalent to an
emergency stop switch.
Change Setpoints
Set points are easily changed on the Operator Interface Touch Screen (OITS). A complete description of the
procedure begins on page 38. Set points can also be changed in the unit controller but this is not
recommended except in an emergency when the OITS is unavailable.
Alarms
A red ALARM light in the lower middle of any screen is illuminated if there is an alarm. If the optional
remote alarm is wired in, it too will be energized.
There are three types of alarms:
•
FAULT, equipment protection alarms that shut a unit or compressor off.
•
Problem, limit alarms that limit compressor loading in response to an out-of-normal condition. If the
condition that caused a limit alarm is corrected, the alarm light will be cleared automatically.
•
Warning, notification only, no action taken by controller.
Any type will light the ALARM light. Procedures for dealing with alarms are shown below:
6.
Press the alarm light button. This will go directly to the ACTIVE ALARMS screen.
7.
The alarm description (with date stamp) will be shown.
8.
Press the ACKNOWLEDGE button to recognize the alarm.
9.
Correct the condition causing the alarm.
10.
Press the CLEAR button to clear the alarm from the controller. If the fault condition is not fixed, the
alarm will continue to be on and the unit will not be able to be restarted.
Interface Panel Failure
Chiller Operation without the Operator Interface Panel
The Interface Panel communicates with the unit controllers and the OITS PC, displaying data and
transmitting touch screen inputs to the controller. It does no actual controlling and the chiller can operate
without it. Should the Touch Screen become inoperable, no commands are necessary for continuing unit
operation. The unit controller can be used to view operational data and to change setpoints if necessary.
