FRIEDHELM LOH Rittal 1194.42 Series, Assembly And Operating Instructions Manual

Page: 7 / 28

8 Handling instructions
Page 7 of 28 Rittal cooling unit assembly and operating instructions
5.1.8 Compressor: On / Off
Switching the compressor ON: press UP for more
than 3 s (when pressing the button, the display
shows ON).
Switching the compressor OFF: press UP for more
than 3 s. The display shows the message “OFF”.
In OFF status, the following functions are disabled (if
featured by the model):
 compressor control
 duty setting
 continuous cycle
5.2 Alarm parameters
A0: Alarm temperature differential
This represents the differential used to activate the
high temperature alarm (“AH”) .In the event of an
alarm, as seen in the figure, the value of “A0” deter-
mines the actual activation of the temperature alarm.
The value of “A0” (negative or positive) defines the na-
ture of alarm “AH” (absolute or relative):
 A0 ≤ 0  AH expressed as absolutes
 A0 > 0  AH expressed relative to the set point
Figure 4: High temperature alarm
AH: High temperature alarm
AH setting: 10 degrees is the factory setting (-50 to 99
is the lower and upper limit ). Other Factory settings:
Setpoint (ST) = 35°C; A0 = 2°C.
For example: If the internal temperature of the cabinet
is Ti = 46°C, ST (35°C)+ AH (10°C) = 45°C ,
so 46°C > 45°C the display will show AH-alarm. As
long as Ti is more than 43°C the display will show AH-
alarm, because ST (35°C)+ AH (10°C) - A0 (2°C) =
43°C. If the temperature Ti will fall to 42°C the alarm
AH will no longer be shown in the display. As long as
the temperature inside of the cabinet will not rise over
45°C again there will be no AH-alarm displayed.
Temperature alarm output
 Logo and buzzer on display: The information
“AH” and logo will be shown on the display and
buzzer.
 The over temperature message may also be
polled via a contact on the connection clamp of
the cooling unit (system message relay with
changeover contact, see connection diagrams).
--Terminal “ 1 ” C (connection of the supply voltage
to the fault signal relay)
--Terminal
“
2
”
NO (normally open) .
Notice!
Delay for high temperature alarm when
power ON: When alarm condition is
achieved but power is ON, the timer
start to count for a specify value (Ad1).
Alarm relay becomes active when this
time is elapsed.
Notice!
The unit of parameter “Ad” is “Sec”.
The unit of parameter “Ad1” is “Min”.
Notice!
The contacts of the relays are normally
open (NO). If the alarm occurs the con-
tacts close (NC).
HP
：
High pressure alarm output
 Logo and buzzer on display: The information
“HP” and logo will be shown on the display and
buzzer.

The over temperature message may also be
polled via a contact on the connection clamp of
the cooling unit (system message relay with
changeover contact, see connection diagrams).
--Terminal “ 1 ” C (connection of the supply voltage
to the fault signal relay)
--Terminal
“ 2 ” NO (normally open) .
Notice!
Delay for high temperature alarm when
power ON: When alarm condition is
achieved but power is ON, the timer
start to count for a specify value (Ad1).
Alarm relay becomes active when this
time is elapsed.
Notice!
The unit of parameter “Ad” is “Sec”.
The unit of parameter “Ad1” is “Min”.
Notice!
The contacts of the relays are normally
open (NO). If the alarm occurs the con-
tacts close (NC).
5.3 Evaluating system messages
Display
screen Buzzer Alarm
relay System
message Measures