*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 of the ALFA(NET) 51 e.g. 2°C to
much, the according Sensor Offset has to be decreased by 2°C.
*Error messages.
In the display of the ALFA(NET) 51 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 (1000Ωat 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 data.
Type : ALFA 51 Thermostat or
ALFANET 51 Thermostat
Range : -50/+150,0°C, above -10°C readout per 0,1°C
Supply : 230Vac 50/60Hz (-5/+10%)
Display : 3-digit 7-segments display
Relays : Ry1 = SPST(NO)250V/8A (cos φ=1) or 250V/5A (cos φ=0.4)
Ry2 = SPST(NO)250V/8A (cos φ=1) or 250V/5A (cos φ=0.4)
Ry3 = SPDT(NO/NC)250V/8A (cos φ=1) or 250V/5A (cos φ=0.4)
Relays have one common (C)
Control : By pushbuttons on front.
Front : Polycarbonate IP65
Sensors : 2x SM 811/2m (PTC 1KOhm @ 25°C).
Communication : RS485 Network, 2xTwisted-pair shielded min. 0,5mm2(A,B,Gnd(0V))
Dimensions : 90 x 71 x 58mm (HWD)
Panel cutout : 46 x 71mm (HW) for front mounting
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 are on request available.
*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 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 to change the value of this parameter.
If after 20 seconds no key is pushed, the ALFA(NET) 51 changes to the normal operation mode.
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