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Sequence Of Operation For Closed Control Unit CCU

Closed Control Unit (CCU) Sequence Of Operation

The server rooms shall be provided with DX type Close Control Units. The system shall be constant volume package Close Control Unit (CCU).

Electrical Rooms, IDF, MDF Rooms etc


The unit shall consist of:

  1. Panel (Pleated) Filter
  2. Water Steam Humidifier
  3. Direct Expansion (DX) Cooling Coil & Condenser
  4. Supply Fan
  5. Electric Heater Battery
  6. Sensors and controls (refer to BMS Schematic Diagram)

The below sequence will be managed by the Micro Processor based internal controller of the CCU.

The Close Control Unit (CCU) shall provide a full temperature/humidity control system. Each CCU shall consist of an indoor evaporator module and a condensing module. The evaporator shall be installed against a wall inside the computer room.

The system is also to include a humidifier which operates with a normal domestic water supply. A re-heater shall also be provided. A safety thermostat shall be provided for manual re setting to cut off power supply in the event of overheating. The CCU system shall include one stage of cooling for temperature control as well as a single stage electric reheat. The

humidity control shall use one stage to dehumidify and one stage to humidify. The system controller shall automatically switch over to the required functions (cool/heat, dehumidify/humidify) based on programmed set points and room conditions.

The room is to be maintained at room condition of 22°C (+/- 2 °C) room temperature and 55% (+/- 5 %) relative humidity.

These units shall supply cooled air to the raised access floor of the Server room and air shall be returned at high level to the units. The air suction shall be provided on the top of the unit and the fans shall be provided at the bottom of the unit. Necessary differential pressure switches shall be provided to enable monitoring of the filter clog conditions.

The microprocessor control shall control the complete unit management and shall have necessary arrangements to interact with the other units to enable environmental conditions are met. In case of any failure of one of the system, the Building Management system shall monitor and control the status of the CCU units.

The unit management systems shall have the ability to interface with the BMS thru volt free contact (VFC) in the control panel to DDC. Moreover the CCU units shall have water leak detection system and smoke sensors. Upon detection of water leaks on floor level, the unit shall shut down and an alarm shall be generated.


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