User manual ALFA(NET) 77 BAR
Contents
1. RS485 Network Optional 2xTwisted pair shielded Attention If 12Vdc is not high enough use externa supply unit GND Common 0V V Supply Su or 24Vac 15 30Vdc PX75 PX77 Pressure Pressure sensor sensor ov Network connections _ H Shield only at Shield only at only at one point in the S Pair 1 pi one side of one side of Network May be provided in 2 FE 3 ti A Lj f the cable T thecable the controller with jumpers Paina LO to B LO to Earth to Earth Oruse ALFA 1 TERMINATOR O Connect GND 0V to GND 0V Shield Connect Shield to clean Earth only on one side of cable Adresse VDH Products BV Tel 31 0 50 30 28 900 Produktieweg 1 Fax 31 0 50 30 28 980 9301 ZS Roden Email info vdhproducts nl The Netherlands Internet www vdhproducts nl2. 1 Communication RS 485 2x Twisted pair shielded cable min 0 5mm Control Thru push buttons on the front Front Polycarbonate IP65 Pressure sensor PX25 PX75 PX77 Supply 12Vdc Signal input 4 20mA Only relative pressure sensors Not for absolute pressure sensors Pressure sensor who need a higher voltage supply than 12Vdc use external supply Dimensions 35 x 77 x 71 5mm hwd Panel cutout 29 x 70mm hw Accuracy 0 5 of the range Provided with memory protection during power failure Connection with screw terminals at the back side Special versions on request available Setting internal parameters Next to the adjustment of the setpoint internal settings can be made like differential sensor offset setpoint range refrigerants read out settings alarm settings and the functions of the thermostat Push the DOWN key for 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 the 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 NET 77 changes to the normal operation mode Parameters ALFA NET 77 Ee a Description Parameter So Range Default Function relay 1 Function relay 2 p
3. Function relay 3 a 3 with 1 Pressure temp increase 2 Pressure temp decrease 3 Alarm Offset pressure sensor 15 0 15 0 Bar Value pressure sensor at 4mA in 1 0 99 9 Bar Value pressure sensor at 20mA in 1 0 99 9 Bar Refrigerants 0 10 0 none 6 R407A BP 1 R22 7 R407C DP 2 R134A 8 R407C BP 3 R404A DP 9 R717 NHS3 4 R404A BP 10 R507 5 R407A DP DP Dewpoint BP Bubblepoint Display and control O Pressure Per 0 1 Bar 1 Temp Per 0 1 C 2 Temp Per 1 C Switching differential relay 1 1 15 Bar C Switching offset relay 1 15 Bar C Switching differential relay 2 1 15 Bar C Switching offset relay 2 15 Bar C Switching differential relay 3 1 15 Bar C Switching offset relay 3 15 Bar C Alarm mode 0 None 1 Absolute 2 Relative Minimum alarm setpoint 99 4 99 9 Bar C Maximum alarm setpoint 99 99 9 Bar C Time delay minimum alarm 0 99 Minutes Time delay maximum alarm 0 99 Minutes Function alarm relay 0 Watch alarm 0 1 1 Control alarm Reset alarm relay at recovering alarm O No 1 Yes Reset alarm relay by manual reset O No 1 Yes Network number Software version Production year Production week serial number x1000 Serial number units Changes when switched from Bar C of switching to another refrigerant Value changes when switching from display read out Control on pressure or temperature Check thes
4. User manual ALF A N ET T7 B AR 0 0 a OUT 2 me ALARM 4 20mA BAR Pressostat with temperature SET oS Read out and control based on several refrigerants ALFA 77 VDH doc 053105 Version v1 1 Date 24 03 2010 Software ALFA NET 57 67 77 4 20 File Do053105 wpd Range 1 0 99 9 BAR per 0 1 BAR Description The ALFA NET 77 is a Pressostat with three relay functions and the possibility to control on pressure or on temperature from the several refrigerants The ALFANET 77 has a RS 485 network connection so it can be read out control and adjusted on the PC when you connect it to our ALFANET PC INTERFACE Installation On the connection diagram is shown how to connect the pressure sensor power supply and relays As soon as you connect the ALFA NET 77 to the power supply the self test will be started automatically After this test the measured pressure or temperature will appear in the display Control The ALFA NET 77 Pressostat can be controlled by four push buttons on the front SET view change the setpoints UP increase a setpoint DOWN decrease a setpoint BAR hidden button under the BAR text Display and control on temperature The ALFA NET 77 Pressostat normally controls on atmospherical pressure not absolute pressure If you have selected a refrigerant parameter P08 the pressostat can also display and control on temperature see settings of parameter P09 Where it s possible to select r
5. e buzzer as mounted will make noise The ALFA NET 77 remembers it s error message although it is already solved as parameter P36 is default value 0 The error message is resettable with the SET key only when parameter P37 is set on 1 If after pressing the SET key Alarm reset and the alarm is still not solved the ALFA NET 77 displays the pressure temperature and the error code alternated Is the alarm solved the error message disappears and the actual pressure temperature is displayed again Through parameter 35 the alarm relay function can be changed from default on watch alarm to control alarm At control alarm the relay will be activated when an alarm occurs at watch alarm the relay is normally active and in case of alarm the relay falls off also in case of power failure Through parameter P30 you can select the type of alarm none absolute or relative alarm At the function relative alarm the minimum and maximum alarm settings will be taken relative from the control setpoint Technical details Type ALFA NET 77 Pressostat Range 1 0 99 9 BAR readout per 0 1 BAR As a refrigerant is chosen the temperature can also be displayed Within a range of 60 0 until 60 0 C Supply 12 Vac 16 5Vdc 5 10 Readout 3 digit 7 segments display Relays The three relays have one common Ry 1 Out 1 SPST NO 250V 8A cos 1 Ry 2 Out 2 SPST NO 250V 8A cos 1 Ry 3 Out 3 Alarm SPDT NO NC 250V 8A cos
6. e parameters after switching over Dimensions Connections REMARK Connect a 250 Ohm Resistor between Line A and Line B at both CABLE ENDS of RS485 Networkcable Shield to ground only at one side of the networkcable ALFA NET 77 4 20mA 2 Trafo 3VA 230 12Vac Common c VDH art nr 350 010073 Alarm 12 24Vdc Relay 2 Out 2 Relay 3 Out 3 Relay 1 Out 1 230Vac PX25 2 DP Pressure sensor RS 485 NETWORK CONNECTIONS 2 twisted pair shielded cable Place Terminator resistor One of the can be the _____ ends ofthe RS485 cable ___ PC Interface between line A and line B May be provided in the controller with a jumper For signal conditioning Place Pullup down resistors Repeater is also a contr lt lt gt lt SC gt o gt a WSS POS SS SCP O MERE KS KC lt S lt SC oo eo S lt SCXIK SSCS OHI XIX S a lt gt lt SC gt Cxoxox gt lt gt lt SC Poo XIX gt Endpoint Endpoint Network cable Connection Network cable Network 2 twised pair shielded point 2 twised pair shielded Network i min 0 5mm Network min 0 5mm j Pair 1 A B Pair 2 Gnd Pair 1 A B Pair 2 Gnd Max Cable length depends on speed Note 1 AVOID LONG STUB CABLES No longer than 0 5M otherwise use a Repeater o Hee
7. eading per 0 1 C or per 1 C To indicate temperature reading in stead of the pressure reading the most right decimal point is on C When switching from pressure to temperature some parameters will be transferred in the other value It is advisable to check all these parameters Viewing and changing the setpoint By pressing the SET button the setpoint appears in the display At the same time the most right decimal point will blink indicating the setpoint is being displayed Release the SET button 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 Relays By pushing the hidden BAR key the display shows the status of the relays Each display segment shows the status of the relay output showing O off and 1 on The code 110 means relay 1 out 1 and 2 out 2 are on and relay 3 out 3 is off Pressure sensor adjustment The pressure sensor can be adjusted by using the Offset pressure parameter 05 Indicates the Sensor e g 0 2 BAR to much than the Sensor Offset has to be decreased with 0 2 BAR Error messages In the display of the ALFANET 77 the following errors can appear LO Minimum alarm HI Maximum alarm EE Settings are lost solution EE Reprogramm the settings Alarm function As a failure or alarm occurs an error message is shown in the display and th
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