Teamwork Mode 3 (Optimized Aisle); Figure 48 Teamwork Mode 3-Fixed Speed Vs. Variable Speed - Emerson Liebert iCOM Manual

4.2.4

Teamwork Mode 3 (Optimized Aisle)

Teamwork Mode 3 can be selected when the units are set to operate in Optimized Aisle Control mode
and have been connected in a unit-to-unit network. Teamwork provides coordination between the
units that will prevent "fighting" by not allowing units to operate in conflicting modes of operation at
the same time by selecting which mode to operate within based on the average of the collective unit
sensors (Cooling vs. Heating and Humidifying vs. Dehumidifying).
Teamwork Mode 3 allows the cooling capacity (Supply Sensor) to operate as a local control by
removing only the amount of load required to maintain the discharge air temperature at each unit.
This allows for an unbalanced room load while maintaining a consistent discharge air temperature.
The fan speed is controlled by the remote rack sensors of all units, providing a controlled delivery
method of the air to the cold aisle. In raised floor applications, Liebert iCOM units will share sensor
information to achieve even under-floor air distribution. This distribution is achieved by operating all
fans in parallel, which will also yield the greatest energy efficiency.
Figure 48 shows the difference in both under-floor air distribution and energy consumption when
Variable Fan speed and Teamwork Mode 3 are applied to the Liebert cooling units. The example on
the left is using the standard standby configuration; the example on the right is utilizing Teamwork
Mode 3. The units below are assuming that the fan power consumed at each unit is 8.1kW when
operating at 100%.
Figure 48 Teamwork Mode 3—Fixed speed vs. variable speed
C
R
A
C
C
R
A
C
Three Units On—One Unit in Standby
Fans must operate at 100% to meet demand
3 Units x 8.1kWh = 24.3kW per hour
Cascade
When data center environments require the cooling equipment to modulate from very low loads to the
full design load, iCOM can coordinate unit capacity and unit activation in accordance with the
Teamwork Mode 3 operation described above. The iCOM optimized aisle controlled units that are
placed into Standby mode will activate as the room environment demands more cooling capacity.
iCOM will monitor the rack sensors and current operating state of each unit to determine when to
activate a standby unit.
To provide the most efficient operation from a system perspective, the Liebert iCOM will first ramp
the operating units fans and chilled water valve to compensate for the increased heat load. Once the
operating units have reached a set fan speed, the supply compensation (see Figure 83) may be
activated to determine if a lower supply temperature can compensate for the load increase. Once the
supply compensation routine has reached its threshold then the Liebert iCOM will activate a standby
unit within the group.
® ®
Liebert iCOM for Liebert DSE
Fixed Speed
Area within dotted lines is
being cooled by CRAC units
controlled by Liebert iCOM
™
C C
R R
A A
C C
C C
R R
A A
C C
Variable Speed
Four Units Operating Together
Fans can operate at 75% to meet demand
4 Units x 3.43kWh = 13.72kW per hour
72
Teamwork
C
R
A
C
C
R
A
C