VDH ALFANET 71, ALFA 72 User Manual

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User manual
ALFANET 71
Thermostat

VDH doc. 030504 Version: v1.1 Datum: 22-03-2004

Software: ALFA(NET)71 File: Do030504.WP8 Range: -50/+50,0°C

* Installation.

On the top side of the ALFANET 71 is shown how the sensors, power supply and relays are to be
connected.
After connecting the ALFANET 71 to the power supply, a self test function is started. As this test is
finished the measured temperature appears in the display. Normally this is the temperature of
sensor-1, unless sensor-2 is active as control sensor (P05=1) in that case the average
temperature of both sensors is displayed and used for control. And the ALFANET 71 is by use of
the ALFANET PC-INTERFACE controllable on the PC.

* Control.

The ALFANET 71 thermostat can be controlled by four pushbuttons on the front. These keys are:

SET - view / change the setpoint.
UP - increase the setpoint.
DOWN - decrease the setpoint.
°C - hidden push button above the SET key and behind °C symbol.

* Viewing setpoint.

By pushing the SET key the setpoint appears in the display. The decimal point of the last display
starts blinking. A few seconds after releasing the SET key the setpoint disappears and the
measured temperature is shown again 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 together with the UP or DOWN keys to change the setpoint. A few seconds after

releasing the keys the measured temperature shows again in the display.

* Viewing the individual sensors.

By pressing the UP and DOWN key together, the individual sensors can be show in the display.
After releasing the keys, the measured temperature of sensor-1 can be shown by pushing the UP
key or the measured temperature of sensor-2 can be shown by pushing the DOWN key. A few
seconds after releasing the keys the (average) temperature shows again in the display.

* Status of the Relays.

By pushing the hidden °C key the display shows the status of the relays. Each display segment
shows the status of the relay output, showing 0=off and 1=on. The code 110 means relay 1 and 2
are on and relay 3 is off.

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* Setting internal parameters.

Next to the adjustment of the setpoint, internal settings can be made like differential, sensor offset,
setpoint range and the functions of the thermostat.
Push the DOWN key more than 10 seconds, to 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 key to change the value of this parameter.
If after 20 seconds no key is pushed, the ALFANET 71 changes to the normal operation mode.

* Adjustment sensors.

Sensor-1 can be adjusted by using the Sensor Offset parameter 06 and Sensor-2 can be adjusted
by using the Sensor Offset parameter 07. Indicates a Sensor e.g. 2°C to much, the according
Sensor Offset has to be decreased with 2°C.

* Error messages.

In the display of the ALFANET 71 the following error messages can appear:

LO - Minimum alarm. Solution E1,E2:
HI - Maximum alarm. - Check if the sensor is connected correctly.
E1 - Sensor-1 failure. - Check sensor (1000Ω at 25°C).
E2 - Sensor-2 failure. - Replace sensor.
EEE - Settings are lost. Solution EEE

:

- Reprogram the settings.

-L- - In case of sensor short-circuit the display alternates between error-code E..
and -L-, as indication for a short-circuit sensor.

-H- - In case of open-circuit sensor the display alternates between error-code E..
and -H-, as indication for a open circuit sensor.

Reset Alarm.When a error-messages appears it can be resetted by pushing the SET key. The

function of this key depends on parameter P37.

* Technical details.

Type : ALFANET 71 Thermostat
Range : -50/+50,0°C, above -10°C display per 0,1°C
Supply : 12Vac 50/60Hz (-5/+10%)
Display : 3-digit 7-segment display
Relays : Ry1= SPST(NO) 250V/8A (cos φ=1) of 250V/5A (cos φ=0.4)

Ry2= SPST(NO) 250V/8A (cos φ=1) of 250V/5A (cos φ=0.4)
Ry3= SPDT(NO/NC) 250V/8A (cos φ=1) of 250V/5A (cos φ=0.4)

Relays have one common (C).
Control : By push buttons on front.
Front : Polycarbonate IP65
Sensors : 2x SM 811/2m (PTC 1000Ω/25°C).
Communication : RS485-Network (2-wire shielded cable min. 0,75mm

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Dimensions : 35 x 77 x 71,5mm (HWD)
Panel cutout : 28 x 70mm (HW)
Accuracy : ± 0,5% of the range.

- Provided with memory protection during power failure.

- Connections with screw terminals on the back side.

- Equipped with sensor failure detection.

- Special versions on request available.