Rittal Liquid Cooling Package
47
9 Operation
EN
– Retrieve all measurements via the CAN bus from the
fan modules and the water module (temperature,
speed, flow, etc.).
– Evaluate all measurements and generate alarm and
warning signals.
– Calculate the thermal output of the inlet and return
temperature as well as determine the water flow vol-
ume.
– Control air temperature in the server enclosure by
regulating the fan speed and the water volume
through the heat exchanger.
– Set the setpoint temperature for the incoming cold
air (factory setting 20 °C).
– Activate an optional display with touch function via
an RS-232 interface.
– Display the measurements and settings of parame-
ters and setpoints via the Web interface.
– Retrieve the sensor and setting values via SNMP.
The measurements supplied by the individual mod-
ules are evaluated by the control unit, and warning
and alarm signals are generated where applicable. If
a new warning or alarm occurs, the internal beeper
communicates this. At the same time, the alarm relay
is switched. This acoustic alarm may be cleared by
pressing down the clear button "C" briefly. The exact
cause of the malfunction can be displayed in plain text
as an alarm or warning message on the connected
optional graphical display with touch function. The fol-
lowing messages can be displayed:
Warning messages
– Speed of fan 1 faulty
– Speed of fan 2 faulty
– Speed of fan 3 faulty
– Speed of fan 4 faulty
– Speed of fan 5 faulty (not LCP Inline flush)
– Speed of fan 6 faulty (not LCP Inline flush)
– Flow faulty
– Control valve faulty
Alarm messages
– Temperature sensor 1 (server-in/server-out temper-
ature) faulty
– Temperature sensor 2 (server-in/server-out temper-
ature) faulty
– Temperature sensor 3 (server-in/server-out temper-
ature) faulty
– Inlet temperature sensor faulty
– Return temperature sensor faulty
– Water module not present
– Leak message
– No fan module detected
Design of the temperature control circuit
The actual temperature values of the cold air on the air
input side (server-in temperature) supplied by the
three temperature sensors on the heat exchanger are
used to control the air which is blown into the server
enclosure. The mean is calculated from the actual
temperature values. The control unit constantly com-
pares this (average) actual temperature with the set-
point temperature. If the setpoint temperature is ex-
ceeded, the control unit attempts to maintain a con-
stant temperature by opening and closing the control
valve. The control valve is only kept closed (or set to
the value stored in the parameter "MinValvePosition")
if the actual temperature falls below the "setpoint tem-
perature" value, i.e. cold water no longer flows through
the heat exchanger. Additionally, the temperature dif-
ference between the set temperature and the air ex-
pelled on the server outlet side (server-out) is used to
determine and control the fan speed. The temperature
values of the sensors on the server outlet side may ei-
ther be averaged, or the maximum temperature is
used (see section 8.2.4 "LCP configuration"). The set-
point speed for the fans and the control valve setting
are sent to the connected control units via the CAN
bus.
Up to four additional standard sensors may be con-
nected to the control unit (CMC III PU) to monitor ad-
ditional physical parameters of the Liquid Cooling
Package. To this end, the sensors are connected to
the first CAN bus connection on the rear of the control
unit (fig. 52, item 11) and configured via the Web in-
terface.
Information about a wide range of additional sensors
may be found in section 15 "Accessories".
9.2.2
Acknowledging messages
Generally speaking, there are three different ways of
acknowledging messages:
Note:
Further details of operation and the diverse
setting options and features of the CMC III
PU may be found in the assembly and oper-
ating instructions of the CMC III PU.
Note:
After connecting for the first time or follow-
ing repair work, it is possible that the Liquid
Cooling Package will operate in emergency
operation mode.
In order to switch the device to normal op-
eration (control operation), briefly press the
"C" button (fig. 51, item 1) once.
Note:
In emergency operation, device cooling is
ensured even if there are malfunctions in-
side the unit. All fans will then operate at
100% output, and the control valve will
open completely.
