8
OMM 1008-1
General Description
Major Components
Figure 1, Major Component Location
General Description
The centrifugal MicroTech
ΙΙ
control system consists of a microprocessor-based controller in the control
panel, as well as on-board the compressors, providing 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, controls unit functions and communicates with other auxiliaries. It is the secondary
location for setpoint input if, and only if, the OITS is inoperative.
•
On-board compressor controller mounted on each compressor that monitors compressor operation and
controls bearing operation.
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 its normal design conditions. If a fault
condition develops, the controller will shut a compressor, or the entire unit, down and activate an alarm
output. Important operating conditions at the time an alarm condition occurs are retained in the controller’s
memory to aid in troubleshooting and fault analysis.
The system is password protected and 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.
Compressor #2
Compressor #1
Power Panel
(Front End Box)
Unit
Control
Panel
Operator
Interface
Panel (OITS)
Electronic Expansion Valv
e
Condenser
Relief Valves
Behind Panel
Evaporator Relief
Valve, Behind Panel
Control Panel
