Erratic Readings on Sensatronics E4/E16 units

Why do the values on some of my probes jump around?

Sometimes probes report temperatures that vary wildly over a period of a minute or two, sometimes jumping to 255, sometimes reporting minus numbers?

Causes

Electrical interference is the usual cause of this behavior. In many cases the probes will be running close to lighting ballast units (as used for fluorescent lights) or near to electric motors. This is particularly likely in industrial applications where space in cabling ducts is at a premium.

Usually this will only happen on one or two of the probes.

Solution

First of all disconnect the probes one at a time until the problem disappears. You should be able to make the problem appear and disappear by connecting and disconnecting the probe. This identifies the probe(s) that are being affected.

Try rerouting the probe cables to see if the problem goes away, avoiding lights, mains cables etc. if possible.

If there are any heavy duty electric motors or other electrical devices near by check that they are properly earthed.

In many cases rerouting the probe cables will resolve the problem.

If rerouting doesn’t help, try using a heavy duty temperature probe. The HD probes have a shielded cable which in many cases is sufficient to resolve the issue. If necessary you can also earth the cable shield for additional protection.

If none of the above remedies solve the problem please contact our Support department for help.