OM Centrif Micro ΙΙ-5 5
General Description
General Description
The centrifugal MicroTech ΙΙ control system consists of microprocessor-based controllers that
provide all monitoring and control functions required for the controlled, efficient operation of the
chiller. The system consists of the following components:
• Operator Interface Touch Screen (OITS), one per unit-provides unit information and is the
primary setpoint input instrument. It has no control function.
• Unit Controller, one per chiller-controls unit functions and communicates with all other
controllers. It is the secondary location for setpoint input if the Interface Screen is inoperative.
It is located in a panel adjacent to the OITS.
• Compressor Controller for each compressor on a chiller-controls compressor functions and can
operate a compressor without the unit controller or Operator Interface Panel. The controller is
located in a panel adjacent to the compressor.
The operator can monitor all operating conditions by using the unit-mounted OITS. In addition to
providing all normal operating controls, the MicroTech II control system monitors equipment
protection devices on the unit and will take corrective action if the chiller is operating outside of
it’s normal design conditions. If a fault condition develops, the controller will shut the compressor
or entire unit down and activate an alarm output. Important operating conditions at the time an
alarm condition occurs are retained in the controller’s history log to aid in troubleshooting and
fault analysis.
The system is protected by a password scheme that only allows access by authorized personnel.
The operator must enter the password into the touch screen (or one of the controller's keypad)
before any setpoints can be altered.
NOTE: It is important to understand that the OITS is the operator interface device under normal
conditions. If, and only if, it is unavailable, the unit controller can be used to operate the chiller.
Furthermore, if the unit controller is unavailable, the compressor controller(s) will still operate the
compressors and try to maintain chilled water temperature. Certain data and operability will not
be available under either of these operating modes. If the MicroTech II controller controls the
tower and system pumps, they will have to run manually during this emergency situation.
Control Architecture
Figure 1, Major Control Components
OPERATOR
INTERFACE
TOUCH-SCREEN
UNIT
CONTROLLER
COMPRESSOR
CONTROLLER
SECOND
COMPRESSOR
CONTROLLER
Color Graphics
Touch-Screen Interface
View Data, Input Setpoints
Stores History
UNIT
Analog Inputs
Analog Outputs
Digital Inputs
COMPRESSOR
Analog Inputs
Analog Outputs
Digital Inputs
Digital Outputs
BAS
pLAN
D3 Starter
D3 Starter
Universal
Comm. Module
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