VDH ALFA 71 User manual
1
User manual
ALFA 71 0/+150OF 24Vac
Thermostat
VDH doc. 032181 Version: v1.0 Datum: 06-10-2003
Software: ALFA71NR File: Do032131.WP8 Range: 0/+150,0°F(1)
* Functions.
The ALFA 71 spec is a thermostat with one temperature sensor, one relay with function heating
on/off and one 0-10Vdc PI-output with function cooling. The power supply is 24Vac.
*Installation.
On the top side of the ALFA 71 spec is shown how the sensor, power supply, PI-output and relay
are to be connected.
After connecting the ALFA 71 spec to the power supply, a self test function is started. As this test
is finished the measured temperature appears in the display.
*Control.
The ALFA 71 spec 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.
°F - hidden push button above the SET key and behind °F symbol.
*Viewing setpoint.
By pushing the SET key the setpoint appears in the display.
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.
*Status of the Outputs.
By pushing the hidden °F key the display shows the status of the outputs. The first segment
indicates the status of relay heating (1 = on, 0 = off)
The last two segments indicate the actual percentage of the PI-cooling output from 00 until 99%.
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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 ALFA 71 spec changes to the normal operation mode.
*Adjustment sensors.
The Temperature-sensor can be adjusted by using the Sensor Offset parameter 03. Indicates the
Sensor e.g. 2°F to much, the according Sensor Offset has to be decreased with 2°F.
*Error messages.
In the display of the ALFA 71 spec the following error messages can appear:
E1 - Sensor-1 failure. Solution E1:
- Check if the sensor is connected correctly.
- Check sensor (1000Ωat 25°C).
- Replace sensor.
EEE - Settings are lost. Solution EEE:
- Reprogram the settings.
* Technical details.
Type : ALFA 71 spec Thermostat
Range : 0/+150°F, display per 1°F
Supply : 24Vac 50/60Hz (-5/+10%)
Display : 3-digit 7-segment display
Relay : Heating SPDT(C/NO/NC) 250V/8A (cos φ=1) or 250V/5A (cos φ=0.4)
Analog-out : 0..10Vdc P(I) Cooling output
Control : By push buttons on front.
Front : Polycarbonate IP65
Sensors : 2x SM 811/2m (PTC 1000Ω/25°C).
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.
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*Parameters ALFA 71 spec
Para-
Meter Description Parameters Range Default
01
02
03
Minimum setpoint setting
Maximum setpoint setting
Offset temperature sensor
0..+150°F
0..+150°F
-15..+15°F
0
+150
0
10
11 Switching differential relay heating
Switching offset relay heating 1..15 °F
-15..+15°F 1
0
20
21
22
PI offset cooling
Proportional-band cooling
Integration-time (0 gives only P-action)
-15..+15°F
1..30°F
0..99 Minutes
0
10
0
30 Control delay after power failure 0..99 Minutes 0
95
96
97
98
99
Software version
Production year
Production week
Serial number (x1000)
Serial number (units)
0..255
00..99
1..52
0..255
0..999
0
0
1
0
0
*Address.
VDH Products BV Tel: +31 (0)50 30 28 900
Produktieweg 1 Fax: +31 (0)50 30 28 980
The Netherlands Internet www.vdhproducts.nl
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*Connections.
*Dimensions.
Table of contents
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