4-20 switch


Thread Starter


Does anyone make a switch that auto transfers a 4-20 ma signal from a second signal 4-20 ma if the main source fails ?
Perahaps a simple relay with a couple of change-over contacts should suffice. If you can give more details, it will be helpful.
Kamath RL

Gerald Moore

I would just monitor both and make sure the readings never drift outside a calculated tolerance. If they do then one of them must have failed. But, how do you know which one? Which brings the question:

How are you determining what qualifies as a failure? Please, give more info!