14 AGZ 025D through 190D OMM 1087
Overview
The MicroTech® III controller’s state-of-the-art design not only permits the chiller to run more
efficiently, but also can simplify troubleshooting if a system failure occurs. Every MicroTech IIII
controller is programmed and tested prior to shipment to facilitate start-up.
Operator-friendly
The MicroTech III controller menu structure is separated into three distinct categories that provide the
operator or service technician with a full description of :
1. current unit status
2. control parameters
3. alarms. Security protection prevents unauthorized changing of the setpoints and control parameters.
MicroTech III control continuously performs self-diagnostic checks, monitoring system temperatures,
pressures and protection devices, and will automatically shut down a compressor or the entire unit
should a fault occur. The cause of the shutdown will be retained in memory and can be easily
displayed in plain English for operator review. The MicroTech III chiller controller will also retain and
display the date/time the fault occurred. In addition to displaying alarm diagnostics, the MicroTech III
chiller controller also provides the operator with a warning of limit (pre-alarm) conditions.
Controller Inputs and Outputs
Main Controller
Table 9, Analog Inputs
# Description Type Expected Range
AI1 Evaporator EWT NTC 10k 340 to 300k Ω
AI2 Evaporator LWT NTC 10k 340 to 300k Ω
AI3
Outside Ambient
Temperature
NTC 10k 340 to 300k Ω
X1 Demand Limit 4-20 mA 1 to 23 mA
X4 LWT Reset 4-20 mA 1 to 23 mA
Table 10, Analog Outputs
# Description Output Type Range
X5 Circuit 1 Fan VFD Speed Voltage 0 to 10 volts
X6 Circuit 2 Fan VFD Speed Voltage 0 to 10 volts
Table 11, Digital Inputs
Description Signal Off Signal On
DI1 External Alarm/Event External Fault No External Fault
DI2 Evaporator Flow Switch No Flow Flow
DI3
Double Set Point/ Mode
Switch
See sections on Unit Mode Selection and LWT
Target
DI4 Remote Switch Remote Disable Remote Enable
DI5 Unit Switch Unit Disable Unit Enable
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