D-EOMWC00803-26_01EN - 5/39
2
GENERAL DESCRIPTION
2.1
Basic Information
MicroTech is a system for controlling single or dual-circuit air/water-cooled liquid chillers. MicroTech controls compressor
start-up necessary to maintain the desired heat exchanger leaving water temperature. In each unit mode it controls the
operation of the condensers to maintain the proper condensation process in each circuit.
Safety devices are constantly monitored by MicroTech to ensure their safe operation. MicroTech also gives access to a
Test routine covering all inputs and outputs. All MicroTech controls can work in accordance with three independent modes:
•
Local mode: the machine is controlled by commands from the user interface.
•
Remote mode: the machine is controlled by remote contacts (volt-free contacts).
•
Network mode: the machine is controlled by commands from a BAS system. In this case, a data communication
cable is used to connect the unit to the BAS.
When the MicroTech system operates autonomously (Local or Remote mode) it retains all of its own control capabilities
but does not offer any of the features of the Network mode. In this case monitoring of the unit operational data is still
allowed.
2.2
Abbreviations used
In this manual, the refrigeration circuits are called circuit #1 and circuit #2. The compressor in circuit #1 is labelled Cmp1.
The other in circuit #2 is labelled Cmp2. The following abbreviations are used:
CEWT
Condenser Entering Water Temperature
CLWT
Condenser Leaving Water Temperature
CP
Condensing Pressure
CSRT
Condensing Saturated Refrigerant Temperature
DSH
Discharge Superheat
DT
Discharge Temperature
E/M
Energy Meter Module
EEWT
Evaporator Entering Water Temperature
ELWT
Evaporator Leaving Water Temperature
EP
Evaporating Pressure
ESRT
Evaporating Saturated Refrigerant Temperature
EXV
Electronic Expansion Valve
HMI
Human Machine Interface
MOP
Maximum operating pressure
SSH
Suction SuperHeat
ST
Suction Temperature
UC
Unit controller (MicroTech)
W/C
Water Cooled
2.3
Controller Operating Limits
Operation (IEC 721-3-3):
•
Temperature -40...+70 °C
•
Restriction LCD -
20… +60 °C
•
Restriction Process-Bus -25
…+70 °C
•
Humidity < 90 % r.h (no condensation)
•
Air pressure min. 700 hPa, corresponding to max. 3,000 m above sea level
Transport (IEC 721-3-2):
•
Temperature -40...+70 °C
•
Humidity < 95 % r.h (no condensation)
•
Air pressure min. 260 hPa, corresponding to max. 10,000 m above sea level.
2.4
Controller Architecture
The overall controller architecture is the following:
•
One MicroTech main controller
•
I/O extensions as needed depending on the configuration of the unit
•
Communications interface(s) as selected
•
Peripheral Bus is used to connect I/O extensions to the main controller.
