Reading RTD''s
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Posts: 46,084
With either RTD or TC's you will need to shield the cable.
If you are running a significant length of wire I would recommend
shielded twisted pair, That will help the noise levels.
With an RTD you will HAVE to run a 4 to 20 converter or your
temperature will be way off due to the resistance of the wire (
unless you are running 4 wire!)
We use 3-wire RTD's. But in my opinion, it is a peace of a cake to
re-calibrate the sensor taken into account the resistance of the wire (which
will be always the same value once installed)
We never used shielded cable for the RTD's, sometimes with lengths of +/-
500 ft.
To avoid the problem with the wire resistance, we more and more use PT1000
sensors.
If you only need one measuring point, then you don't have to look for a
cheap sensor, especially because you are dealing with an industrial process.
But really for just 100c arn't there semicondutor sensors?
Either that, put the stamp close to the oven and send the signal
digitally, via rs-422 to your computer or whatever (RS232, or
straight serial will get noisy too remember, and a lot harder to
troubleshoot)
If you are running a significant length of wire I would recommend
shielded twisted pair, That will help the noise levels.
With an RTD you will HAVE to run a 4 to 20 converter or your
temperature will be way off due to the resistance of the wire (
unless you are running 4 wire!)
We use 3-wire RTD's. But in my opinion, it is a peace of a cake to
re-calibrate the sensor taken into account the resistance of the wire (which
will be always the same value once installed)
We never used shielded cable for the RTD's, sometimes with lengths of +/-
500 ft.
To avoid the problem with the wire resistance, we more and more use PT1000
sensors.
If you only need one measuring point, then you don't have to look for a
cheap sensor, especially because you are dealing with an industrial process.
But really for just 100c arn't there semicondutor sensors?
Either that, put the stamp close to the oven and send the signal
digitally, via rs-422 to your computer or whatever (RS232, or
straight serial will get noisy too remember, and a lot harder to
troubleshoot)