Unit installation

12 OMRCPMICRO
Field Wiring
Interconnecting wiring for the reciprocating control panel consists of:
Ø 115 VAC power wiring
Ø Analog input signals
Ø Digital input signals
Ø Digital output signals
Ø Condenser pump
Ø Fan starter
Ø Communications to a personal computer
Ø Telephone line for remote modem access
See Figure 5 and unit field wiring diagrams at the end of this manual for more details.
Power wiring
Separate disconnects for the cooler heating tape and control circuit transformer are available as options on
ALR units. The installing contractor provides the 115 VAC power source, disconnect, 10 amp fuse, and
necessary wiring for these circuits. All wiring must conform to the National Electrical Code and applicable
local building code. If the separate power option is used, then the installing contractor must remove wires 540
and 545 from terminals #13 and #16 on TB2 before running the unit. See the ALR Field Wiring Diagram for
more detail.
Power supplies
There are several internal power supplies used by the controller and related circuitry. The regulated 5 VDC
power on terminal #214 is used to support the analog inputs on the ADI board. Do not use this power supply
to operate external devices. An unregulated 12 VDC power supply is available on field wiring terminal #146
and an unregulated 24 VAC power supply is available on field wiring terminal #25.
Analog input signals
All sensors and transducers required for normal chiller operation are installed and wired at the factory. All
optional analog signal wiring provided by the installing contractor must be twisted, shielded pair (Belden
#8760 or equal). Figure 5 and unit field wiring diagrams at the end of this manual for more detail. The optional
demand limit and leaving water reset signals are 4 to 20 milliamp DC signals. The resistive load that conditions
the milliamp signal is a 249 ohm resistor mounted on the ADI board at the factory.
Remote demand limit
To use the demand limit function, the installer will connect the wiring to terminals #131 and #132 on TB7.
Demand Limit can only be used on WHR and ALR units. See the MicroTech schematic and Field Wiring
diagrams at the end of this manual for more detail. More information on how Demand Limit works is available
in the Remote Demand Limit section on page 12 of this manual.
Leaving water reset*
Leaving water reset on ALRs, WHRs and THRs may be achieved by using the "4-20mA Reset" option on
Menu 14. The installer must connect wiring to terminals #134 and #135 on TB7. See the Reset Options section
of this manual for more detail.