VDH ALFA 79 ST-PID User manual
1
User manual
ALFA 79 ST-PID
Hygrostat.
VDH doc: 080657 Version: v1.1 Date: 13-04-2010
Software: ALFA79-ST-PID File: Do080657.wpd Range: 0/+100%RH
* Installation.
On the upper side from the ALFA 79 ST-PID is shown how the sensor, supply and
relays should be connected. After power up a self test is started. If the self test is
completed the measured humidity will be shown on the display.
*Control.
The ALFA 79 ST-PID hygrostat can be controlled by four push buttons on the
front:
SET - viewing / changing the adjusted value and reset alarm.
UP - raise the adjusted value.
DOWN - lower the adjusted value.
%RH - hidden key above the SET key.
*Viewing the set points.
By pushing the SET key the adjusted set point can be read out. The led ‘set’ also
starts flashing. A few seconds after releasing the SET key, the set point
disappears and the measured value will be visible again.
*Changing set point.
Push the SET key and the set point appears in the display. Release the SET key.
Push the SET key again together with the UP or DOWN keys to change the set
point. A few seconds after releasing the SET key the set point disappears and the
measured humidity is shown again.
*Status of the Relays.
By pushing the hidden %RH key the display shows the status of the relays. The
three digits are indicating the status from the relays, hereby 0=off and 1=on. The
code 110 means that relay 1 and relay 2 are on and relay 3 is off.
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*Setting internal parameters.
Next to the adjustment of the set point, some internal settings can be made like
differentials, sensor-adjustments, set point-range and alarm-settings.
By pushing the DOWN key for more than 10 seconds, you enter the 'internal
programming menu'. On the left display the upper and the lower segments are
flashing. 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 and DOWN keys allows you
to change the value of this parameter.
If no key is pushed for 20 seconds, the ALFA 79 ST-PID changes to it’s normal
operation mode.
*Sensor adjustments.
The sensor can be adjusted by using the offset sensor (parameter 05).
Indicates a sensor e.g. 2%RH too much, the according Sensor-offset parameter has
to be decreased with 2%RH.
*Error codes.
On the display from the ALFA 79 ST-PID can appear the following error codes:
E1 -RH sensor defect. Solution E1:
-Check if the sensor is connected well.
-Check RH-signal (0/+100%RH = 0/+10Vdc)
-Replace the sensor.
EE -Adjustments are lost. Solution EE:
-Reprogram the adjustments.
*Technical details.
Type : ALFA 79 ST-PID Hygrostat.
Range : 0/+100%RH read out per 1%RH
Read out : 3-digit 7-segments display
Status LED’s : LED 'SET' en LED 'RH'
Supply : 12 Vac 50/60Hz (-5/+10%).
Solid-state : Ry1 solid state output 12Vdc (pulse modulating)
Relays : Ry2 spdt (C/NO/NC) 250V/8A(cos=1) or 250V/5A(cos=0.4)
Control : Through push buttons on the front.
Front : Polycarbonate.
Input voltage : 0/+10Vdc (0/+100%RH) (Ri = 10KOhm)
Input contact : C/NO contact(= 100% output) (Potential free input contact)
Dimensions : 35 x 77 x 71,5mm (hwd).
Panel cut out : 29 x 71mm (hw).
Accuracy : ± 0,5% from the range.
- Provided with memory protection during power failure.
- Equipped with self-test function and sensor-failure detection.
- Connection with screw-terminals.
- Special version on request available.
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*Parameters ALFA 79 ST-PID
Para-
Meter Description Parameter Range Default
value
01
02
03
04
Proportional band
Integration time
Differential action percentage
Cycle time
1..15 %RH
0..99 Seconds
0..100 %
0..999 Seconds
5
0 (=off)
0 (=off)
20
05 Offset humidity sensor -15..+15%RH 0
10
11 Switching offset relay 2
Switching differential relay 2 0..+20%RH
1..5%RH 10
1
20
21 Minimum adjustable set point
Maximum adjustable set point 0..100%RH
0..100%RH 0
100
40
41
42
Control delay after power failure
Forced solid-state output at sensor failure
Forced relay-2 output at sensor failure
0..99 min.
0=No, 1=100% out
0=No, 1=Yes
0
0
0
95
96
97
98
99
Software version
Produktion year
Produktion week
Serial number (x1000)
Serial number (units)
0..255
00..99
1..52
0..255
0..999
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-
-
-
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(c) VDH Products BV
*Function Diagram.
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