Voltage vs Current sensors

[gleblanc 1]

In the past, I've always used current loop sensors (4-20mA). I've found that they're a lot less susceptible to noise than voltage signals. However, I happen to have some sensors that have been here for ages, which include a voltage (1-5V) output. Anybody had issues using this type of analog signal on the factor floor, or have any advice about using them? Thanks, Greg

[BobB 58]

3 problems may occur - noise, injected voltage and voltage drop. injected voltage is the biggest pain - readings go all over the place.

[Duffanator 1]

We use a lot of 0-10 volt control (mostly for controlling inverter speeds and such) around our plant. We don't usually have any problems with it, as long as you follow some guidelines you probably won't have many problems at all. You need to keep the 0-5 volt wires as far away from higher voltage, higher current lines as possible. The more current a wire is carrying the more inductive influence it will have over your low voltage signal wires. If you do have to bring low voltage signal and higher voltage control wires close try and do it at right angles where ever possible. NEVER run them parallel to each other (for example, in conduit). Make sure your low voltage signal wires are shielded and ground the shield only at one end. If you ground it at both ends you'll turn it into a long antenna and it'll be even worse than if you didn't ground it at all. Those are the "big three" for running low voltage control, I'm sure other people will be able to chime in with some additional things that they have run into but if you follow those it should be pretty reliable.