pt1000 rtd error
Thank you!
Yes, I'm planning to use schematic on fig.5 / page 4 in AN687 of microchip.
2 OpAmps are used for current generator, which requires Voltage Reference of 2,5V,
for example LM336Z2.5 or other.
1 OpAmp is used to make cable resistance compensation, when using 3 wire sensors
1 OpAmp is used as voltage preamplifier with 2 pole low-pass filter.
I'll upgrade the circuit to add support for stopping the current. For example with
simple stopping the Voltage Reference.
I should start the current generator minimum 1 second before sampling and should
stop it after measurement. I'll calculate the time to be sure that all transitional
processes should pass and when everithing becomes stable I should start sampling.
Starting and stopping current generator is a good idea.
But my problem is that I burned one RTD Pt1000 (bought from China, unknown
manufacturer) last week with 2.5mA current.
So this is my fears, not to burn more RTDs
))
My hesitation is what is the best set of constant current for Pt1000, gain of the
amplifier to be safe for the sensor?
Even in extreme conditions - defective OpAmps and etc (ocoz I'm not paranoic to
plan to protect the sensor in high radiation or lightning or etc...)?
Is it safe to use 1mA current with Pt1000, if the sensor is applied with the current
for 2-3 seconds per / each minute?