12-5
CONTROL SYSTEM
SM CKDDCI 2-A.3 GB
12.2.3.5 EEV
Expansion valve operated by step motor which controls the size of the orifice.
12.2.3.6 HMI
Consists of Four “7-Segments” + four push buttons for display, monitoring and setup
features.
12.2.3.7 Dry
Contacts
Dry contacts are used to interface the system with an external building management system
(BMS).
12.2.3.7.1 ODU Dry Contacts
Night
input. Switches the system to night mode when closed. During night mode, the outdoor
unit speed will be reduced in order to reduce the system noise level.
SB
input. System will be turned to Stand-by when the contact is closed.
Power Shedding
input. Limits the maximum power consumption when closed.
Alarm
output indicates a failure in the system.
Alarm output will be activated when there in the following ODU Faults/Protections
1 to 11, 13 to 20, 22 to 26, 28 to 29.
Alarm output will be OFF when the Fault/Protection is cleared.
12.2.3.7.2 IDU Dry Contacts
Presence detector input.
12.2.3.8 Temperature
Sensors
CTT – Compressor Top Temperature
OAT – Outdoor Air Temperature
OCT – Outdoor Coil (heat exchanger inlet) Temperature
OMT - Outdoor Coil (heat exchanger) Temperature
HST – Heat Sink Temperature
ICT – Indoor Coil (heat exchanger) Temperature
RAT – Return Air Temperature (Indoor Unit)
12.2.3.9 Base
Heater
Heating element designed to melt any ice that is accumulated on the outdoor unit base
during low heating operation.
12.2.3.10 Cranckcase Heater
Heating element designed to heatup the compressor oil cranck case during low outdoor
ambient temeratures.
12.2.3.11 Internal Coil Heater
Exists in 6HP and 4HP DCR units. The compressor is equied with built-in heating coils
designed to heatup the compressor oil cranck case during low outdoor ambient temeratures.
