Emerson Liebert CRV User Manual page 39

Insert the rack temperature sensor connector in the temperature sensor port (CAN port like in
figure below) at the iCom interface. After cabling like shown in pictures to exit from the top or from
the bottom of the unit, connect to first probe, then from first to second one, from second to third one
and so on, like a chain. Secure the temperature sensor in front of the warmest heat source in the
enclosure. Do not secure in front of a blanking panel. For this operation use the support provided
for each probe (refer to picture n°1). The sensors must be installed where lack of sufficient cooling
air is most likely. The optimum position of the rack temperature sensors will vary from installation
to installation. A standard position is at 1.5m in height. Due to air flow behaviour (see Chap. 2.0),
sometimes it would be better to reconsider the layout, or particular attention must be taken posi-
tioning the sensors.
Liebert 2T Sensor Placement Guidelines
The Liebert 2T sensors come with the Liebert CRV unit to help avoid any problem spots in the row.
Using the rack sensors can help combat cooling problems users experience related to: recirculation
air, uneven rack loading, and air distribution. The Liebert 2T sensors are intended for cold aisle
use only.
Positioning of the Liebert 2T Sensors within a Cold Aisle Row:
Using the following guidelines to place the Liebert 2T sensors will help ensure proper cooling.
S Place the Liebert 2T sensors on racks adjacent to the Liebert CRV.
S Place the Liebert 2T sensors on the highest density racks.
S Place the Liebert 2T sensors on racks far away from the Liebert CRV.
Positioning of the Liebert 2T Sensor probes within an individual rack:
Using the following guidelines to place the Liebert 2T sensor probes will help ensure proper cool-
ing.
S Placing a probe on the top of the perforated rack door.
S Placing a probe in front of the highest mounted servers in the rack.
S Placing a probe in front of the highest density area of the rack.
S Place the probe in the airflow path entering the rack.
S Do not place the probe directly on metal of the perforated door.
Sensor chain – CAN termination:
The CAN Bus of sensor chain needs to be terminated. If a CAN device is the last component in the
CAN Bus (the last Liebert 2T sensor), the termination Jumper has to be set to 2-3. If a CAN device is
in the middle between other CAN devices, no termination has to be set, the jumper remains on 1-2.
To connect the temperature probes to use only cable with these characteristics:
S 6 wires, 3 couples, shielded twisted pair.
S Termination: RJ12.
S Coupling: according to 273702 (iCOM User Manual Hw page 19).
S 3 x 2 x 0.14 mmq (min), twisted pairs, shielded.
S Plenum rated
S 300V
S (-5/+70°C)
S Flexible
S Characteristic impedance of between
108 and 132 Ohm @50kHz
S Conductor resistance < 150 Ohm/km
S Flame retardant
S Black jacketing
Fig. m -
31
Electrical Connections