indigoer
18-02-2020, 10:30 AM
Greetings!
This is our first install where we'd like to utilise an electronic TX valve, variable speed drive and water cooled compressor.
We bought the lot as a package from a local wholesaler (https://famaga.ch) and were assured it was compatible, but now their technical guy has disappeared on holidays and we're stuck trying to work out how things go together - and in my opinion it simply won't work as advertised.
The components are a Carel EVD Evolution (electronic TX valve), a Vacon VSD and a Bitzer compressor. The control is a Carel Mastercella.
In my mind, the electronic TX valve is stand alone, and is based purely on superheat. It doesn't connect to anything and will react purely on suction pressure (via a transducer) and temperature (via a sensor) to open and close the valve, regardless of room temperature or compressor operation.
The compressor is simply connected to the VSD output. No problem.
The MasterCella needs to turn the compressor on and off based on room temperature and defrost requirement. But the trick is... how do I make the VSD "work"?
I can easily connect the MasterCella to purely act as a "start" command to the VSD, but that will just make it a very expensive soft starter as without any speed instruction it will just go to maximum RPM. What I need is to send ramp up / ramp down commands based on load.
Should the electronic TX valve provide the ramp up/down commands to the VSD? There's a set of RX/TX/GND terminals that provide serial (RS485) connectivity, but what is it actually outputting? The manual shows it being connected to a Carel pCO control but we have a MasterCella. Can this go directly to the VSD and be programmed using some kind of standard, or is it Carel proprietory stuff?
The VSD has RS485 settings that allows protocols of "Modbus/RTU", "N2" and "BACnet MS/TP". What does Carel use?
Should there be another transducer in the suction side that controls the speed of the compressor / VSD output? The VSD seems to be able to accept input from 0..20mA or 0..10V as an analog input.
The MasterCella has a serial (RS485) connection, but it just says "To Supervisor" which I assume is a mimic panel of some kind for reading output, not accepting input.
I'd appreciate any help on this as I'm kind of lost here.
This is our first install where we'd like to utilise an electronic TX valve, variable speed drive and water cooled compressor.
We bought the lot as a package from a local wholesaler (https://famaga.ch) and were assured it was compatible, but now their technical guy has disappeared on holidays and we're stuck trying to work out how things go together - and in my opinion it simply won't work as advertised.
The components are a Carel EVD Evolution (electronic TX valve), a Vacon VSD and a Bitzer compressor. The control is a Carel Mastercella.
In my mind, the electronic TX valve is stand alone, and is based purely on superheat. It doesn't connect to anything and will react purely on suction pressure (via a transducer) and temperature (via a sensor) to open and close the valve, regardless of room temperature or compressor operation.
The compressor is simply connected to the VSD output. No problem.
The MasterCella needs to turn the compressor on and off based on room temperature and defrost requirement. But the trick is... how do I make the VSD "work"?
I can easily connect the MasterCella to purely act as a "start" command to the VSD, but that will just make it a very expensive soft starter as without any speed instruction it will just go to maximum RPM. What I need is to send ramp up / ramp down commands based on load.
Should the electronic TX valve provide the ramp up/down commands to the VSD? There's a set of RX/TX/GND terminals that provide serial (RS485) connectivity, but what is it actually outputting? The manual shows it being connected to a Carel pCO control but we have a MasterCella. Can this go directly to the VSD and be programmed using some kind of standard, or is it Carel proprietory stuff?
The VSD has RS485 settings that allows protocols of "Modbus/RTU", "N2" and "BACnet MS/TP". What does Carel use?
Should there be another transducer in the suction side that controls the speed of the compressor / VSD output? The VSD seems to be able to accept input from 0..20mA or 0..10V as an analog input.
The MasterCella has a serial (RS485) connection, but it just says "To Supervisor" which I assume is a mimic panel of some kind for reading output, not accepting input.
I'd appreciate any help on this as I'm kind of lost here.