12
OMM 1008-1
Operator Interface Touch Screen (OITS) Settings
Settings for any type of linked multiple compressor operation must be made to the MicroTech II controller.
Settings on a dual compressor unit are made in the factory prior to shipment, but must be verified in the field
before startup. Settings for multiple chiller installations are set in the field on the Operator Interface Touch
Screen as follows:
Maximum Compressors ON – SETPOINTS - MODES screen, Selection #10 = 2 for a WMC, 4 for 2 WMCs.
Sequence and Staging – SETPOINTS - MODES screen, Selection #11 & #13; #12 & #14. Sequence sets the
sequence in which compressors will start. Setting all to “1” evokes the automatic lead/lag feature and is the
preferred setting.
Nominal Capacity – SETPOINTS - MOTOR screen, Selection #10. The setting is the compressor design
tons. Compressors on dual units are always of equal capacity.
Communication Setup
1.
With no communication connections between chillers, disconnect control power and set the pLan
address as shown in Table 1.
2.
With all manual switches off, turn on control power to each chiller and set each OITS address (see
Note 2 above).
3.
Verify correct nodes on each OITS Service Screen.
4.
Connect chillers together (pLAN, RS485, between J6 connections on each unit’s isolation boards.
The boards are not furnished, separate RS485 isolators must be field supplied.
5.
Verify correct nodes on each OITS Service Screen. See Figure 26 on page 50.
Operating Limits:
Maximum standby ambient temperature, 130
°
F (55
°
C)
Minimum operating ambient temperature (standard), 35
°
F (2
°
C)
Leaving chilled water temperature, 36
°
F to 60
°
F (2.2
°
C to 15
°
C)
Maximum operating evaporator inlet fluid temperature, 66
°
F (19
°
C)
Maximum startup evaporator inlet fluid temperature, 90
°
F (32
°
C)
Maximum non-operating inlet fluid temperature, 100
°
F (38
°
C)
Minimum condenser water entering temperature, 55
°
F (12.8
°
C)
Maximum condenser entering temperature, 105F (40.6C)
Maximum condenser leaving temperature, 115F (46.1C)
