Contactor control dual inputs


This question might be a little simple for here but, here it goes...

A little intro to what we are trying to accomplish...Basically, we are trying to control a motor from two sources (24v). Its a three phase 0.75kW motor that needs to work whenever it recieves a signal from either source. However, both sources might be on at the same time as well, then it needs to still keep working until none of the sources are on. We thought about using a contactor but, we dont exactly know what type of a contactor is required. We cant use a regular contactor with a single coil as we cant have the 24v travelling between sources. I guess we can place diodes at each source but, we believe there are probably better ways of doing this. So, it would be great if we can get help on solving this in the simplest form. Btw, we usually use Siemens in our machines so, if anyone has part numbers as to which devices we should look at, that would be greatly appreciated as well. Thank you.
You'll have a motor starter contactor + overload relay (or similar arrangement) or a drive to power the motor. Your two "run" commands will each power the coil of a small relay (something like this would be fine). The contacts of the relays would be wired in parallel and would provide power to the coil of the motor starter (or the "run" terminal of the VFD, or whatever).
Thanks for the reply. Is this a special relay? What prevents voltage from one source crossing over to the other source when wired in parallel?
Oh, I thought you meant a single relay, I read it wrong. What you meant was two relays, one for each source, sorry. Got it.
That should work...but...
If source 2 turns on, then source 1 turns on and off repeatedly, your motor starter will "blink" every time the DPDT relay changes state. That's going to be hard on the relay, the motor starter contactor, and the motor.

It would be smoother (and I think easier to troubleshoot) to use 2 single-pole relays.