1
User manual
ALFA 72 VS 0-20
O
C
Differential Thermostat.
VDH doc. 080333
Version: v1.2
Date: 22-04-2010
Software;
File: Do080333.wpd
Static range (see sticker);
992903 ALFA 52/72 VS 20 -50..+50
Typenr. 904.000702
-50/+50,0
C
100320 ALFA 52/72 VS 20 -20..+80
Typenr. 904.000925
-20/+80,0
C
992901 ALFA 52/72 VS 20 0..+100
Typenr. 904.000678
0/+100,0
C
* Installation.
On the connection diagram of the
ALFA 72-VS
is shown how the sensors, power supply and relays
has to be connected. After connecting the
ALFA 72-VS
to the power supply, a self test function is
started. As this test is finished, the measured differential temperature of sensor-1 minus sensor-2
appears in the display.
* Control.
The
ALFA 72-VS
thermostat can be controlled by four pushbuttons on the front These keys are:
SET
- view / change set point and reset the alarm
(UP)
- increase the set point.
(DOWN)
- decrease the set point.
C
- hidden key under unit symbol
* Viewing the temperature from sensor-1 and sensor-2.
By pressing the
UP
and
DOWN
keys simultaneously and after that the
UP
key, the measured value
from sensor-1 can be read-out. If the down key is pressed, the measured value from sensor-2 is
shown. If no key is pressed for a few seconds, the differential temperature is shown again.
* Viewing the delta-setpoint.
Viewing set point delta thermostat:
By pushing the
SET
key, the set point of delta thermostat appears in the display.
A few seconds after releasing the keys the set point disappears and the differential temperature is
shown again in the display.
* Changing the delta-setpoint.
Push the
SET
key. The delta-setpoint appears in the display. Release the
SET
key. Now push the
SET
key again together with the
UP
or
DOWN
keys to change the set point. A few seconds after releasing
the keys, the measured differential temperature is shown again in the display.
* Status of the Relays.
By pushing the hidden
C
key the display shows the status of the relays. Each digit shows the status
of one relay output, showing 0=off and 1=on. The code 110 means relay 1 and 2 are on and relay 3
is off.
Relays 1 and 2 are used for the differential thermostat (see function diagram).
Relay 3 is used as an alarm relay.
