McQuay AGR 070AS, Руководство по эксплуатации

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IOMM AGR-1 AGR 070A through 100A 43
UNT Controller Operation
This section provides setup and troubleshooting information for the Global UNT controller.
All operational descriptions are based on the Global UNT software SURE4-2A. Operational
characteristics may vary with other versions of software.
General Description
The Global UNT is a microprocessor based leaving water controller designed for multiple stage
operation.
The Global UNT’s operation is based on an adjustable setpoint and control band. Controller software
is available for different reset options, refrigerants and metric units. Optional equipment includes a
Zone Terminal that can be installed in the unit or remotely. The Zone Terminal provides a user
interface to all reset options and adjusts specific setpoints. Downloading of software or changing
selected operating parameters requires the Global UNT Interface Kit.
Optional Sensors
•
Return water temperature sensor
•
Zone temperature sensor
Sensors and Transducers
Sensors and transducers are mounted and connected to the Global UNT controller with sensor cable.
The evaporator pressure transducers depress the Schrader fittings and can be replaced without
pumping the unit down. The pressure transducers are connected to the Global UNT controller analog
inputs with IDC connectors (Insulation Displacement Connectors). The low pressure transducers
have a blue dot. The leaving water sensor is in a thermal well for easy replacement without draining
the water system. As standard, an outside air sensor is provided on the back of the control box.
When other reset options are selected, the outside air sensor is not provided as only one (1) type of
reset is available.
Control Wiring
Low voltage control wiring is installed, labeled and tested by the factory before shipment.
External Voltage Inputs
The signal for remote reset option (2 to 10 Vdc) or demand limit (0 to 10 Vdc) is provided by the
installing contractor. Connect to TB -7 terminals #134 (+) and #135 (-) as indicated by the unit
wiring diagram. A 4 to 20mA signal conditioned by a 500 ohm resistor can provide the 2 to 10 Vdc
input for the remote reset option. Polarity of the external DC signal must match the controller
polarity.
Interlock Wiring
All interlock wiring to field devices (such as a flow switch or time clock) is provided by the installing
contractor. All interlocking wiring must be connected to the Global UNT 24Vac power supply.
External power supplies connected to the Global UNT controller can damage the controller. See unit
wiring diagram.
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.