2
* Operation of the alarm functions.
This alarm thermostat has two adjustable alarms namely, a minimum and a maximum alarm. Whereby
can be chosen from watch or control alarms (Parameter 27):
- Watch Alarm:
The relay is normally activated and LED ‘set high’ is off. At alarm the relay is
deactivated and the LED ‘set high’ is lit. This is also the case at power failure.
- Control Alarm:
The relay is normally deactivated and the LED ‘set high’ is off. At alarm the relay
is activated and the LED ‘set high’ is lit.
Furthermore, an alarm can be hold or reset automatically (parameter 28).
- If alarms are hold (default), the alarms must be confirmed by pressing the
SET
button. Only when
the alarm cause is solved and the alarm is confirmed, the relay is set to its normal position.
- If alarms are not hold and the alarm cause is solved, the alarm will automatically reset and the relay
is set to its normal position.
Also, an offset (zone) and the differential for each alarm can be set. See the function diagram.
Furthermore, a delay time (Parameter 23 and 24) for each alarm can be set, during the delay time the
led ‘set high’ flashes. If after ending the delay-time the alarm is still present, an alarm is given and the
relay is set into the alarm position. If the temperature is recovered within the delay time, than there will
be no alarm.
In the display is continuously shown
H
at maximum alarm and
L
at minimum alarm. Once the
alarms are confirmed, the measured temperature is shown again alternating with any outstanding
actual alarm indications.
With parameter 29 set to 1 (Yes), the relay of the controller can be set to its normal position by
confirming the alarm, although the alarm is not being solved. Then the led ‘set high’ is switched off, the
relay is set to its normal position and the display starts showing the measured temperature again,
alternated with the outstanding alarm indications.
* Sensor Fault Detection.
If a sensor fault is detected, there is error message
Er
in the display and the relay works according to
the setting of parameter 11.
The error remains in the display until it is manually confirmed by pressing the
SET
key. Once the
sensor fault is confirmed by the measured temperature is displayed alternating with any outstanding
actual error.
After the sensor fault is solved, the relay works again according to setting of parameter 27 as:
- the sensor fault is/shall be confirmed by hand, or
- an alarm is detected.
In most situations it will be logical to set Parameter 11 and 27 to the same value.
* Sensor adjustment.
The sensor can be adjusted by using the Sensor Offset (parameter 04). Indicates the
ALFA(NET) 33
DP
e.g. 0.2
/
C too much, the Sensor Offset has to de decreased by 0.2
/
C.
* Error messages.
In the display of the
ALFA(NET) 33 DP
the following error messages can appear:
Er
- Sensor broken.
Solution: - Check if the sensor is connected correctly.
- Check the sensor (1000
S
at 25
/
C).
- Replace the sensor.
EE
- Settings are lost.
Solution: - Settings must be reprogrammed.
* Setting internal parameters.
Next to the adjustment of the setpoint, some internal settings are possible like differential, sensor-
offset, setpoint range and alarm settings.
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. 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
keys, allows you to change the
value of this parameter. If no key is pushed for 20 seconds, the
ALFA(NET) 33 DP
changes to it's
normal operation mode.
