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CPU-unit
Cool/Defrost thermostat
with Fan control and
Watch Alarm.
VDH doc. 011524
Software: ALFA 45A
* Installation.
The ALFA-45A consist of two parts, a Supply-unit for rail-mounting and a CPU-unit for front-mounting
(with operation buttons, display and alarm relay). These two units are connected with each other by an
cable with 8-pole data-connector.
On the front of the ALFA-45A Modulbox supply-unit is shown how sensors, power supply and relay
are to be connected. The watch alarm relay with C/NC contact is to be connected on the CPU-unit.
After connecting the ALFA-45A to the power supply, a self test is started. As this test is finished the
measured temperature of the product-sensor appears in the display.
The Supply-unit has three relay outputs, one for the compressor, one for the fan and one for defrost.
The compressor-relay and the defrost-relay got there own led-indication in the display.
* Control.
The ALFA-45A thermostat can be controlled by three pushbuttons on the front. These keys are:
SET
- view / change of settings.
UP
- increase of settings.
DOWN
- decrease of settings.
User manual ALFA-45A
Version: v1.2
Doc: Do011524.wpd
1
SUPPLY-unit
Range: -50/+50C, per 1C
Datum: 27-10-2005
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Summary of Contents for VDH ALFA-45A
- Page 1 The watch alarm relay with C/NC contact is to be connected on the CPU-unit. After connecting the ALFA-45A to the power supply, a self test is started. As this test is finished the measured temperature of the product-sensor appears in the display.
- Page 2 * Viewing setpoint. By pushing the SET key the setpoint appears in the display. The led ‘set’ starts blinking. A few seconds after releasing the SET key the setpoint disappears and the measured product temperature is shown in the display. * Changing setpoint.
- Page 3 * Parameters ALFA(NET)-45A. PARA- DESCRIPTION PARAMETER RANGE STANDARD METER VALUE Switching differential 1..15 C Minimum temperature alarm -50..+50 C Maximum temperature alarm -50..+50 C Offset product sensor -15..+15 C Compressor start-up protection 0..3 0 = start-up delay in sec. 1 = start-up delay in min.
- Page 4 * Compressor control. The compressor relay activates when the product sensor measures a higher temperature than the setpoint + switching differential (parameter 1), and deactivates when the temperature descents below setpoint. There are 4 different modes off delay on the compressor possible with parameter 05 as shown below; Parameter 05 = 0 : The compressor relay has a start-up delay of "parameter 6"...
- Page 5 * Defrost control. The automatic defrost is started by the defrost cycle time (P07) and stopped by the maximum defrost time (P08) or sooner by reaching the maximum defrost temperature (P09). Further has the ALFA(NET)-45A additional parameters to control defrost; Parameter 25 = 0: Function defrost with a fixed defrost cycle time.
- Page 6 * Alarms. In the display of the ALFA(NET)-45A the following error messages can appear: - Product sensor error Fatal error, display shows 'E1' and all relays are deactivated, accept when parameter 24 is 1, then the compressor and fan are activated as needed. - Defrost sensor error Non fatal error, the ALFA(NET)-45A go’s on regulating and the display shows 'E2'.
- Page 7 * Technical details. Types : ALFA-45A Cool/Defrost Thermostat with fan control ALFANET-45A Cool/Defrost Thermostat with fan control and RS485-network connection CPU-unit of the ALFA(NET)-45A Range : -50/+50C, readout per 1C Display : 3-digit 7-segment display Control : pushbuttons on the front.
- Page 8 * Dimensions CPU-unit. * Dimensions SUPPLY-unit. * Connections drawing 010061w1.
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