Liebert XDK-W user manual Control, PDU Box

CoolTherm

Manual / Bedienungsanleitung

3.5Control

The server cabinet temperature is controlled by the fan control board VR 2.2. A air temperature sensor continuously measures the temperature of the server cabinet (server feed air). The air circulation flow rate is controlled by the fan speed according to the current thermal load.

At temperatures lower than 20°C / 68°F fans rotate at 75% of maximum speed.

Between 20°C / 68°F and 23°C / 73,4°F speed increases proportional to the temperature up to 96% of maximum speed.

The failure of the temperature sensor set the fans to maximum speed.

Air temperature sensor

PDU – Box*)

*) by 12 kW rack under the roof

Status LED:

Green

System OK

Yellow

fault controller cooling/fans or rear door open

Red

fault controller cooling/fans and rear door open

Fuses for each fan and switching power supply

Space for optional equipment

Service socket and fuse

CoolTherm front view

The water flow rate is controlled by a three-wayvalve depending on thermal load. (distribution flow control) Before all a undertemperature at part load operation can be avoided.

By using a blind sieve in the bypass a hydraulic volume control could be achieved (two way valve function).

In case of failure the valve opens and the all the chilled water flows through the heat exchanger. From 16°C / 60,8°F to 19°C / 66,2°F the three-way valve controls the water flow rate from 0% to 100% of the nominal flow rate.

CoolTherm 01_998_330_0_k page / Seite 15/83