hello friends ,

please help me that , Can I connect parallelly to the analog out( 0 to 10 volt ) A0 of delta plc Dvp10sx to three

Delta EL- W series VFDs

 

There is nothing in the VFD manual that suggests the analogue i/p or more important the common can be connected together. Like wise for the PLC A/O common. One suspects if you asked the manuafacturer's distributor you wouldn't get a straight answer either.
Clearly the VFD is designed RS485 comms. and invites 'daisy chaining' of drives together.
https://inverterdrive.com/file/DELTA-VFD-EL-W-User-Manual

RS485 comms is an alternative, but staying with analogue i/p, rather than say 'Yes', I would be recommending the safer use of 3 isolators; there are many on the market such as:
https://www.foxtamcontrols.co.uk/products/isolating-signal-conditoners-coverters

 

I generally am not in factor of paralleling voltage outputs or series stringing 4-20mA current outputs because of common mode issues, directly related to 'using a common ground'. Multiple drives have a high likelihood of their analog inputs NOT having the same ground potential with the result being common mode problems at either the PLC analog output or the drive analog input.

You can try it and see. It might work, or it might not. A low level of common mode might be tolerated by either or both ends. A medium level of common mode could saturate at either end and pull other signals up or down depending on the polarity of the saturation. A high level of common mode can drive enough current through either end to burn out the input or output. No, I cannot put numbers on low, medium or high level of common mode, it is device dependent.

I am unaware of a PLC that does not have a multiple output analog output card/module. If you drive individual analog outputs, one for each drive, but with a single ended AO you still have a potential common mode issue but you can isolate each analog output from each of the analog inputs with signal isolator modules.

A set of voltage isolator modules, 0-10V input to 0-10V output, will isolate each analog output from its analog input and provide a viable control signals.