VDH ALFA 25 DP User manual

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User Manual
ALFA 25 DP and
ALFANET 25 DP
Cool/Defrost
Thermostat
VDH doc: 072254 Versie: v1.1 Datum: 07-11-2007
Software: 043377_ALFA 15/25/35DP File: Do072254.wpd Range: -10/+40C per 0,1C
*Function.
The ALFA(NET) 25 DP is a digital thermostat for panel mounting. The thermostat
controls the cooling and defrost. Defrost will be done by temporarily switching off the
cooling (natural defrost). The defrost starts on intervals or on compressor runtime.
The defrost stops on time. The ALFANET 25 DP has a RS 485 network connection
so it can be read out and adjusted on the Alfanet.
*Installation.
On the topside of the ALFA(NET) 25 DP is shown how the sensor, power supply and
relay have to be connected.
After connecting the ALFA(NET) 25 DP 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(NET) 25 DP Thermostat can be controlled by three push buttons on the
front. These keys are:
SET - view / change the set point.
UP - increase the set point.
DOWN - decrease the set point.
*Viewing set point.
By pushing the SET key the set point appears in the display. The led 'set' starts
blinking. A few seconds after releasing the SET key the set point disappears and the
measured temperature is shown in the display.

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*Changing set point.
Push the SET key and the set point appears in the display. Release the at SET key.
Now push the SET key again and together with the UP or DOWN keys the set point
can be changed. A few seconds after releasing the keys the measured temperature
shows again in the display.
*Starting/stopping defrost.
The defrost cycle is automatically started and stopped. Programming by the internal
parameters. During defrost the led 'defrost' will light-up.
If there is a defrost cycle, the defrost can be stopped by hand, pushing the UP key
and then the SET key, while the UP key is held.
If there is no defrost cycle, the defrost can be started by hand, pushing the UP key
and then the SET key, while the UP key is held.
*Setting internal parameters.
Next to the adjustment of the set point, some internal settings are possible like
differential, sensor-offset, set point range and the function cooling or defrost.
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(NET) 25 DP changes to it's normal
operation mode.
*Adjustment sensor.
The sensor can be adjusted by using the Sensor Offset (parameter 04).
Indicates the ALFA(NET) 25 DP e.g. 2C too much, the Sensor Offset has to de
decreased with 2C.
*Error messages.
In the display of the ALFA(NET) 25 DP the following error messages can appear:
Er - Sensor broken. Solution:
- Check if the sensor is connected correctly.
- Check the sensor (1000at 25C).
- Replace the sensor.
EE - Settings are lost. Solution:
- Reprogram the settings.
*Function Diagam.

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*Parameters ALFA(NET) 25 DP.
Para-
meter
Description Parameter Range Standard
Value
01
02
03
04
Switching differential
Minimum set point
Maximum set point
Offset temperature sensor
1..30C
-10..+40C
-10..+40C
-15..+15C
3
-10
+40
0
05
06
Compressor start-up protection
0 = start-up delay in seconds
1 = start-up delay in minutes
2 = delay between switch off and switch on minutes
3 = delay between switch on and switch on minutes
Compressor start-up time
belonging to parameter 05
0..3
0..99
0
10
07
08
09
10
11
12
13
14
15
Defrost cycle time
Defrost time
Defrost delay after power failure (if Parm. 14 = 1)
Startup delay after power failure
Relay on at sensor failure
Defrost cycle time based on compressor on time
Temperature display locked during defrost cycle
After power failure starting with defrost cycle
Maximum time display locked after defrost
(if parameter 13 = 1)
1..99 hours
0..99 minutes
0..99 minutes
0..99 minutes
0 = no, 1 = yes
0 = no, 1 = yes
0 = no, 1 = yes
0 = no, 1 = yes
0..60 minutes
12
15
0
0
0
0
0
0
5
90
95
96
97
98
99
Network number
Software version
Production year
Production week
Serial number (x1000)
Serial number (units)
1..250
0..255
00..99
1..52
0..255
0..999
1
-
-
-
-
-
1) During delay time the LED ‘on’ is flashing.
*Technical details.
Model : ALFA 25 DP Cool/Defrost Thermostat
ALFANET 25 DP Cool/Defrost thermostat with Network
Range : -10/+40C, readout per 0,1C
Supply : 230 Vac 50/60Hz
Relay : SPDT 250V/16A(C-NO), 8A(C-NC) (cos phi=1)
Control : by push buttons on the front.
Communication : RS485-Network (2x twisted-pair shielded, min. 0,5mm2)
Front : Polycarbonate
Sensor : SM 811/2m (1000at 25C)
Dimensions : 144 x 72 x 50mm (hwd)
Panel hole : 139 x 67mm (hb)
- 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 on request available.

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*Dimensions. *Connections.
*Adresse.
VDH Products BV Tel: +31 (0)50 - 30 28 900
Produktieweg 1 Fax: +31 (0)50 - 30 28 980
9301 ZS Roden Email: [e-mail]
The Netherlands Internet: www.vdhproducts.nl