We are replacing some old GE drives with new ABs. The GE drives get there speed reference signal from a potentiometer system that takes a 0-30VDC reference and adjusts a master speed signal and which can then be adjusted slightly for each drive. The drive that is originating the reference signal is going away in the first phase of the project. I need to take the new digital speed reference in the PLC and somehow turn it into a 0-30VDC speed signal to link to the old drives that are not being replaced until a later phase of the project. Does anyone have suggestions for "off the shelf" applications that can be easily trouble shot in the middle of the night by an electrician? Thanks for any ideas.

 

how about 3 0-10vdc signals in series? would need to be isolated signals...

 

You did not specify the current. There are many off the shelf products for these. In fact the laboratory or bench power supply are adjusteable from 0-30, the current is normally up to 3 amps. On units that can supply higher current the trade off will be the voltage will be lower (for the sam price). Look in catalogs such as Farnell or RS components.

 

This is the method I am going with. I did not realize these divices could be connected serially for adding the voltages. I can put it upstream of an internal amplifier in the master unit of the old drive so loading will not be an issue. Thanks for responding all.