ALFA(NET) 75 RTDF -50/+50°C
Doc.no.: 150014 version 1.0
Page 4 of 8
12
Adjustment sensors
The temperature sensor (control) can be adjusted by using the Sensor Offset parameter 05.
The defrost sensor can be adjusted by using the Sensor Offset parameter 07.
Indicates a Sensor e.g. 2°C too much, then the according Sensor Offset has to be decreased with
2°C.
13
Technical data
Type
ALFA 75 RTDF or
ALFANET 75 RTDF
Range
-50,0/+50.0°C
Readout per 0,1°C
Supply
12 Vac / 16,5 Vdc
(-5/+10%)
Or else see sticker
Display
3-digit 7-segment
LED display
Status LED’s
COMPR., FAN and DEFR.
On display thru hidden °C key
Sensor
SM 811 2-Wire
PTC 1000
Ω
/25°C
Relays
Ry1 Cool= SPST (NO)
250V/8A cos
n
=1 or 250V/5A cos
n
=0.4
Ry2 Fan = SPST (NO)
250V/8A cos
n
=1 or 250V/5A cos
n
=0.4
Ry3 Defrost = SPDT (NO/NC) 250V/8A cos
n
=1 or 250V/5A cos
n
=0.4
Relays have one common (C)
Communication
RS-485 Network
Twisted-pair shielded, min. 0,5mm
2
only at ALFANET
A, B, 0V (Twist A and B)
Control
By four push buttons
On the front
Front
Polycarbonate
Dimensions
35 x 77 x 71,5 mm
(H x W x D)
Panel cut out
29 x 70 mm
(H x W)
Accuracy
+/- 0,5% of the range
- Provided with memory protection during power failure.
- Connection with screw terminals.
- Equipped with senor failure detection.
- Special versions are on request available.
14
Setting internal parameters
Next to the adjustment of the setpoint, internal settings can be made like differential, sensor
adjustments, setpoint-range, compressor-, fan-, defrost- and alarm-settings.
Push the DOWN key for more than 10 seconds, to enter the 'Internal Programming Menu'. In the
left display the upper- and lower-segment are blinking
. With the UP and DOWN keys the
required parameter can be selected (see the parameter table).
If the required parameter is selected, the value can be read-out by pushing the SET key. Pushing
the UP or DOWN key together with the SET key to change the value of this parameter.
If after 20 seconds no key is pushed, the ALFA(NET) 75 RTDF changes to the normal operation
mode.