Operation
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IOM 1281-2 • CENTRIFUGAL WATER CHILLERS
Enabling
To enable the chiller and its compressors when the “Control
Source” is “Switches” or “BAS,” all rocker switches (three
rocker switches for single compressor units, four rocker
switches for dual compressor units) and the Remote Switch, if
included, need to be closed (in the ON position).
If the “Control Source” is set to “Local” and a Remote Switch is
being used, the position of the Remote Switch will be ignored.
In that case, only the rocker switches need to be closed. Once
these rocker switches are closed, press the AUTO button on
the HMI to enable the chiller in “User” mode.
Disabling
Each of the four switches located on the unit have a different
functionality in terms of disabling. The descriptions below apply
if the “Control Source” on the HMI MODES Setpoint Screen is
set to “Switches” or “BAS.”
1. Unit Switch- When placed in the OFF position while
the chiller is running, the Unit Switch will shutdown the
chiller in a normal controlled sequence and will stop each
compressor that is running. This switch will leave the
entire chiller disabled until it is set in the ON position.
2. External Switch - This switch will disable the chiller in a
similar manner as the Unit Switch.
3. Remote Switch - This switch will disable the chiller in a
similar manner as the Unit Switch.
If the “Control Source” on the HMI MODES Setpoint Screen is
set to “Local,” press the STOP button on the HMI to disable the
chiller. This method of disabling will cause the chiller to act in a
similar manner as when it is disabled using the Unit Switch in
the “Switches” or “BAS” mode.
Human Machine Interface (HMI)
The HMI is turned on/off with a switch located at the lower
right-hand edge of the display panel. Screen control buttons
are located to either side of it and elicit on-screen prompts
when pressed. The HMI is equipped with a screen saver (a
blank, black screen). If the screen is black, touch it first to be
sure it is on before using the ON/OFF button.
Chiller Operation Without the HMI
The Human Machine Interface (HMI) communicates with the
unit control processor, displaying data and transmitting touch
screen inputs to the controllers. 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. All normal inputs and outputs
will remain functional. A PC monitor and USB mouse can
be connected to the unit control processor via its VGA and
USB ports and can be used to view operational data, to clear
alarms, and to change setpoints, if necessary. See
“Controller
Inputs and Outputs”
section starting on
page 61
for more
information.
Navigation Summary
The Home View Screen, see
Figure 34
, is the main information
page for the chiller. This screen contains the AUTO and STOP
buttons in the upper right hand corner, which are used to start
and stop the unit when in “User” control mode. Other groups
of screens can be accessed from the Home View Screen by
pressing one of the icons on the bottom of the screen.
An initial startup step may be to select the Operator icon on the
bottom right of the HMI to access the Operator screen (
Figure
33)
to set display language and unit of measure preferences as
well as input the appropriate level of password for making unit
adjustments going forward. Should the touch screen cursor
not respond to where the screen is being pressed, use the
Calibrate button to recalibrate the screen. The bar was made
longer to make it easier for the non-calibrated cursor to select.
Figure 33: Operator View Screen
