VDH ALFA 31 User manual

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User manual ALFA 31
Cool/Heat Thermostat.
VDH doc. 931224 Version: v1.3 Date: 22-08-1995
Software: ALFA31DP File: DO931224.WP8 Range: -50/+50°C per 1°C
*Installation.
On the topside op the ALFA 31 you can see how the sensor, power supply and relay have to be
connected.
Afterconnecting the ALFA 31 to the power supply, a self test function is started. As this test is finished
the measured temperature appears in the display.
When the relay is activated, the led 'on' will light-up in the display.
*Control.
The ALFA 31 thermostat can be controlled by three pushbuttons on the front. These keys are:
SET - view / change the setpoint.
UP - increase the setpoint.
DOWN - decrease the setpoint.
*Viewing setpoint.
By pushing the SET key the setpoint appears in the display. The led 'set' starts blinking. A few
secondsafter releasing the SET key the setpoint disappears and the measured temperature is shown
in the display.
*Changing setpoint.
Push the SET key and the setpoint appears in the display. Release the SET key. Now push the SET
key again and together with the UP or DOWN keys the setpoint can be changed. A few seconds after
releasing the keys the measured temperature shows again in the display.

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*Setting internal parameters.
Next to the adjustment of the setpoint, some internal settings are possible like differential, sensor-
offset, setpoint range and the function cooling or heating.
By pushing the DOWN key more than 10 seconds, you enter the 'internal programming menu'. In the
left display the upper and lower segment are blinking. Over the UP and DOWN keys the required
parameter can be selected (see table for the parameters).
If the required parameter is selected, the value can be read-out by pushing the SET key. Pushing the
UP or DOWN keys together with the SET key allows you to change the value of this parameter.
If after 20 seconds no key is pushed, the ALFA 31 changes to its normal operation mode.
*Adjustment sensor.
The sensor can be adjusted by using the Sensor Offset (parameter 04). Indicates the ALFA 31 e.g.
2°C too much, the Sensor Offset has to de decreased by 2°C.
*Error messages.
In the display of the ALFA 31 the following error messages can appear:
Er - Sensor broken. Solution:
- Check if the sensor is connected correctly.
- Check the sensor (1000Ωat 25°C).
- Replace the sensor.
EE - Settings are lost. Solution:
- Reprogramme the settings.
* Technical details.
Model : ALFA 31
Range : -50/+50°C, readout per 1°C
Supply : 230 Vac (or 24Vdc or 12Vdc)
Relay : SPDT 250V/16A(C-NO), 8A(C-NC) (cos phi=1)
Control : by pushbuttons on the front.
Front : Polycarbonate IP65
Sensor : SM 811/2m (1000Ωat 25°C)
Sizes : 35 x 77 x 71,5mm (hwd)
Panel hole : 28 x 70mm (hw)
- Provided with memory protection during power failure.
- Connection with screw terminals on the back side.
- Equipped with self test function and sensor failure detection.
- Special version are available upon request.

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*Parameters ALFA 31.
PARA-
METER DESCRIPTION PARAMETER RANGE STANDARD VALUE
01
02
03
04
10
11
15
16
17
18
19
20
Switching differential
Minimum setpoint
Maximum setpoint
Offset temperature sensor
Startup delay after power failure
Relays on at sensor failure
Function cooling or heating
Switch on delay relays 1)
Switch off delay relays 1)
Parameter 16/17 in sec. or min.
Minimum on-time relays
Minimum off-time relays
1..15°C
-50..+50°C
-50..+50°C
-15..+15°C
0..99 min.
0 = No
1 = Yes
0 = Cool
1 = Heat
0..99
0..99
0 = sec.
1 = min.
0..99 min.
0..99 min.
3
-50
+50
0
0
0
0
0
0
0
0
0
1) On active delay led 'on' blinks.
*Address.
VDH Products BV Tel: [phone]
Produktieweg 1 Fax: [phone]
9301 ZS Roden Email: [email protected]
The Netherlands Internet: www.vdhproducts.nl

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*Dimensions.
*Connection Diagram.
* Function Diagram.