General

The data hall cooling utilises an indirect air cooling (IAC) system with DX cooling. Air is supplied to the data hall via a supply air plenum and returned from a ceiling void. Hot aisle containment is therefore required to be installed during the Customer IT Rack Fit-Out Works.

There is no raised floor in the data hall. Allowance for N+1 and N+2 IAC units at maximum data hall fit-out of 1.5MW of IT load has been made.

Data Halls S210 and S220 are provided with 8 number IAC Units each (N+2 configuration)

Data Halls S230 and S240 are provided with 7 number IAC Units each (N+1 configuration)

The IACs are located on a gantry at first floor level and support each data hall (S210, S220, S230, S240) from one side.

Refer to the As-Built layout drawings and schematics for system configuration.

 

Indirect Air Cooling (IAC) Units Overview

The Indirect Air-Cooling (IAC) Unit’s cool the data hall hot return air by passing it through the internal air path of a plate heat exchanger, the other side of which is passed outside air. If the outside air temperature is low enough, the correct supply air temperature can be maintained in the internal air path. In this case the outside air volume is modulated to maintain the correct internal supply air temperature.

In the event that the outside air temperature is too high for the above operation to attain the correct internal supply air temperature, the integral DX refrigerant system cools it. The DX cooling coil is installed in the supply air path so that the supply air temperature can always be met. This is provided integral to the unit with the condensers in the external air path exhaust.

A controls system is provided so that all IACs ramp up and down together. Each IAC is provided with an ATS and energy meter.

 

IAC Unit Power Supply

Each IAC Unit is provided with an A and B power source. An Automatic Transfer Switch (ATS) is provided with the IAC so that if one power source goes down, the unit will automatically transfer load to the other power source.

The IAC units are provided with on-board controls battery to enable a fast restart in the event of temporary power loss.

IAC Unit Control

The IAC units can operate standalone modulating the fans and DX to maintain the design supply air temperature and supply-to-return air temperature difference across the data hall.

The IACs units are also provided with pressure sensors to modulate internal air supply on hot-to- cold aisle pressure.

The IACs units are networked together such that they can ramp internal fans up and down together under normal operating conditions.

In normal operations, multiple Excool units are controlled under a common system demand ensuring uniform control across the entire data hall.

In order for the Excool equipment to operate as a system rather than individual standalone control units they employ a master/master control method. All Excool units transmit their individual return air temperature readings and aisle differential pressure sensor readings to each other. The sensors are then averaged, and a demand is then calculated to achieve the set point.

Each unit individually controls all cooling processes respectively based on supply air set point.

If an Excool unit has failed and/or is isolated and network communications to this unit is compromised, the remaining healthy units will not use the compromised Excool unit’s sensors in their calculations. Once the unit has been re-instated and is deemed to be back online the Excool units will then use the sensors from this unit to calculate in their averages.

If the entire Excool network is lost or compromised then each Excool unit will operate in a standalone condition, so that each Excool unit individually controls space conditions irrespectively of the other Excool unit’s operational conditions.

Excool units have different modes of operation, these modes can be manually switched between or set to automatic mode selection which will change the operation of the unit dependent on different conditions.

Excool units use Carel logic controllers. These controllers use falling edge, low inputs to register a digital signal. These logical values are inverted during the first stage of the strategy software in order to simplify the subsequent logic.

 

Site Specific Set Points

• Aisle pressure set point [-20] Pa

• Supply air temperature set point [23] °C

• Return air temperature set point [36] °C

• Minimum indoor fan speed [30] %

• Minimum outdoor fan speed [20] %

 

Associated Information:

Refer to the Data Hall IAC Units “Technical Data” Section for further information.

Refer to the Data Hall IAC Units “Manufacturers Operating & Maintenance Instruction Literature” Section for further information.

Associated Equipment:

Data Hall S210:

• 8 No. IAC Units

  • S210-IAC-01

  • S210-IAC-02

  • S210-IAC-03

  • S210-IAC-04

  • S210-IAC-05

  • S210-IAC-06

  • S210-IAC-07

  • S210-IAC-08

Data Hall S220:

• 8 No. IAC Units

  • S220-IAC-01

  • S220-IAC-02

  • S220-IAC-03

  • S220-IAC-04

  • S220-IAC-05

  • S220-IAC-06

  • S220-IAC-07

  • S220-IAC-08

Data Hall S230:

• 7 No. IAC Units

  • S230-IAC-01

  • S230-IAC-02

  • S230-IAC-03

  • S230-IAC-04

  • S230-IAC-05

  • S230-IAC-06

  • S230-IAC-07

Data Hall S240:

• 7 No. IAC Units

  • S240-IAC-01

  • S240-IAC-02

  • S240-IAC-03

  • S240-IAC-04

  • S240-IAC-05

  • S240-IAC-06

  • S240-IAC-07