Recent content by Dave

Apart from calibration drifts of thermocouples and RTD's, temperature sensors fail as an open circuits either gradually or instantly. Open circuit thermocouples read low, open circuit RTD's read high. As WTF mentioned the vendor is not using effective logic when multiple sensors are involved...

Mineral insulated (MI) Alloy 825 heating cable PRODUCT SPECIFICATIONS Technical Details Cable sheath material Alloy 825 Conductor material Various alloys and copper Max. exposure temperature 550°C (brazed heating units) 600°C* (laser welded heating units) The original post might explain what...

You need to consult the electrical standards such as NEMA

what are the controller settings

Ahmed, Please explain what you think PID means.

PID designates the control action being taken. Suggest you read the manual for your controller function.

why are you using PID for your water flow control valve?

You'll have to read through the manufacturers detailed description, before you asume how you might think it work.

Your battery room must be continually evacuated (fresh air) with slight negative pressure, and H2 gas detectors.

If you are dealing with process control, as you summary of valve errors suggest you might be, it is far more complicated.

If it is only an example, there are countless references to address accurracy and the various subcategories involved. You'll be better off sorting out what works in your case. It won't be simple as there are eighteen categories for static error, and that's just the beginning. Good luck,

Fundamental to establishing "hysterisis" you need to clarify the deadband error in your measurments

You need to explain how the individual tests are performed, and what standard is used to guage calibration error, before attempting to address hysteresis.

As with all sensitive signals, local grounding leads to the problems you have describe. Contact the supplier of the alarm system, they can explain it in detail. The redundancy you describe is not redundancy in a real sense, as that requires independent installations.

Use two wire link with your transmitter, do not ground your wiring separately.