PT1000 sensor requirments to be compatible?



  • I've searched high and low and can't find any official guidelines on how to pick some compatible sensors, so I hope this post can clear it up?

    I have seen a wealth of links to compatible sensors, but nothing to tell me why they are compatible, so it's not all that usefull to me.

    I'm asking as I'm talking to Keenovo where we can get PT1000 sensor embedded in it instead of a Thermistor, for better accuracy and response (is it better response than thermistor?) and Keenovo asks for specifications requirments to ensure compatiblitity?



  • A PT1000 is a specification, it is a platinum resistance probe with a resistance of 1000ohms at 0 deg C and a resistance of 138.4 ohms at 1000 deg C. Its response is broadly linear.

    So if you can find a PT1000 probe in the size you want to use, connect it to a spare thermistor channel and define it using:

    M305 P0 X500 R4700 ; heater 0 uses a PT1000 connected to thermistor channel 0 (500) which has a 4.7K series resistor

    We're shortly to begin stocking them in E3D sensor cartridge format.



  • @DjDemonD:

    A PT1000 is a specification, it is a platinum resistance probe with a resistance of 1000ohms at 0 deg C and a resistance of 138.4 ohms at 1000 deg C. Its response is broadly linear.

    So if you can find a PT1000 probe in the size you want to use, connect it to a spare thermistor channel and define it using:

    M305 P0 X500 R4700 ; heater 0 uses a PT1000 connected to thermistor channel 0 (500) which has a 4.7K series resistor

    We're shortly to begin stocking them in E3D sensor cartridge format.

    But there are multiple different kinds of PT1000 sensors with different specifications.

    Are you telling me that Duet can handle any and all kinds of PT1000 sensors? (this IS the question)

    I'm asking as Keenovo asked for specifications to be sure the PT1000 sensors they use in the Silicone heater is compatible and delivers correct readings.

    Edit:
    I see you list them in E3D cartridge format, but PT100 is the better option here where PT1000 is fine at lower temperatures.



  • PT1000 sensor all follow a std where the resistances at certain temps are followed and the different models are fo Temp max and accuracy range I have used these on my bed and they are pretty close https://docs-emea.rs-online.com/webdocs/1554/0900766b81554046.pdf If it was me I would ask Keenovo to do you a heater with a 10mm diam hole in the middle of it so you can attach the sensor directly to your bed (This what I have done) make more sense to me then you can select something to suit your own system (You can glue the sensor to the bed with some Arctic Silver ceramic Epoxy stuff and you can even drill a small blind hole if the bed is thick enough to get it closer to the surface) the PT1000 sensors I got are good to 600 degrees so can be used in the hotend



  • Difference between PT100 and 1000 is that 100 should be faster and more accurate. Especially at higher temperatures (over 100).. at least how I read it.
    Edit: I've reread some of my sources and I'm a bit confused to be honest 🙂

    Must admit I don't get the "they all follow the same" as they do have different specifications… I don't know what the different specs means, but even I can see that they aren't the same.

    About selecting something to suit my system... that is what I'm doing here... making sure Keenovo use a PT1000 that works perfectly with Duet.
    Edit: I don't want to glue anything etc.. I want it simple, which is a combined heater you slap on the underside and that's it. (+ temperature thermostat).



  • The basic differences are the base accuracies and the max operating temps be aware that I believe All of the Silicon heaters have the sensor embedded in the side away from the bed (I could be wrong here as Keenovo may well be able to place it Glue side). but for a bed anything 200 degrees or above operating temp and the wide tolerance should be fine for a bed as you will find the best setting anyway all you need is for it to be reliable. The ones with Lower max Temp also seem to be the better accuracy ones from the spec sheet I posted above but I am no expert on them.



  • I'd ask keenovo to measure the resistance of their pt1000 at two known temperatures, then we can see if it fits onto a standard curve (technically more likely to be a line). I have one printer currently using the samples we obtained of the pt1000s we ordered, which are annoyingly stuck at customs for now, running the hotend, bed and chamber temp and all function extremely well.

    The difference is just that the pt1000 will not offer such precision in temperature measurement, I am led to believe +/-2 deg C approximately, this is the limit of what the 10 bit DAC on the duet thermistor inputs can resolve, given the range of resistance change we are likely to see between room temp and 270 deg C. With PT100 and a precision circuit (daughterboard) to measure the resistance the resolution is better.

    As for mounting the bed sensor, I did this by drilling a hole into the side of the aluminium plate (you'll need minimum 4mm plate thickness, as the sensor is 3mm dia.) and inserting the cartridge covered in silicone thermal compound, then just secured it with a cable tie to the other wiring but you could drill and tap a hole for a grub screw.

    I then ran the bed up to 110 deg C and verified the surface temperature with a thermocouple, and an IR thermometer (paint a small section black with a sharpie marker) and both read 110 deg C.


  • administrators

    There are two common standards for PT100 and PT1000 sensors: the European one (DIN/IEC 60751 or simply IEC751) and the North American one (SAMA). The European one is also an international standard and is more commonly used, so RRF assumes that one. See https://www.omega.com/techref/pdf/What_are_RTD_Sensors.pdf for more.



  • We now have PT1000's in our store in E3D cartridge format.

    https://www.precisionpiezo.co.uk/product-page/pt1000-sensor



  • Simon

    Think there may be a typo on the page at the bottom it states the R at 20 degrees as being 110 have you done a Cut and paste from the PT100 description?


  • administrators

    Also the resistance rise of a PT1000 isn't quite linear, and it should be 1077.9 ohms at 20C. 1100 ohms is almost right at 25C.



  • Thanks guys I'll check with Idris he set up the product page. Also, I don't yet have one of the production units myself.

    EDIT so just checked against my sample units which are the same sensor but in a 10mm cartridge (production units are 20mmx3mm cartridge) a Precision Piezo PT1000 sensor thermally connected to a type K thermocouple probe at 20.0 degC has a resistance of 1071 Ohms. Product page updated. Good catch.


 

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