IOMM AGR AGR 055A through 100A 47
Unit Set Points and Calibration
The control software is installed and tested by the factory before shipping. No periodic calibration
of the controller is necessary. All control and safety set points must be checked by the installing
contractor and adjusted as necessary before starting the unit.
The “setpoint” control knob adjusts the leaving water setpoint. The “Control Band” knob
adjusts the controller temperature control band. To set, divide the chilled water temperature range
by the number of capacity steps and add 0.5°F for the minimum setting.
Example:
Evaporator water temperature range = 10°F from 54°F to 44°F
Capacity steps = 6
Control band = 10÷6 = 1.66 +0.5 = 2.2°F minimum
Optional Sensors
Optional sensor kits, available from the factory, can be installed in the field. The optional sensor
kits have the same characteristics as the leaving water sensor.
Field Wiring
Interconnecting wiring for the control panel may consist of the following:
• 115 VAC power wiring
• Analog input signals
• Digital input signals
• Digital output signals
• Communications to a personal computer
Power Wiring
The installing contractor provides the unit voltage power source, disconnect, fuses and necessary
wiring for these circuits. All wiring must conform to the National Electrical Code and applicable
local building codes. If the evaporator heater power source (120 Vac) is supplied from a separate
external supply, remove wires 540 and 545 as indicated on the unit wiring diagram.
Power Supplies
There are several internal power supplies used by the controller and related circuitry. The regulated
5 Vdc power is supplied by RSP1 and provides power to pressure transducers. Do not use this
power supply to operate external devices. A 24 Vac power supply is available for the alarm bell
option. Wire according to the unit wiring diagram.
Analog input signals
All sensors and transducers required for normal chiller operation are installed and wired at the
factory. All optional analog input signal wiring is provided by the installing contractor must be
twisted, shielded pair (Belden #8760 or equal). The optional demand limit and remote reset signals
are 0 to 10 VDC signals. The controlling range of the remote reset signal is from 2 Vdc to 10 Vdc.
Digital input signals
Remote contacts for all digital inputs into the Global UNT controller must be dry contacts suitable
for the 24 Vac control signals from the control panel. Do not connect 120 Vac power to the digital
inputs or 24 Vac from an external power source.
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