PT104 är en 4-kanals, högupplösande temperatur till PC omvandlare för användning med Pt100 och Pt1000 givare. Den kan också användas för att mäta resistans och spänning. Onoggrannhet 0,01 grd. C, upplösning 0,001 grd. C.
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Platinum resistance thermometers (RTDs) offer excellent accuracy over a wide temperature range (from -200 to 850 C). Sensors are interchangeable between different manufacturers, and are available in various accuracy ratings in packages to suit most applications. Unlike thermocouples, it is not necessary to use special cables to connect to the sensor. (See our application note on choosing and using PT100 sensors for more information).
Sensor manufacturers offer a wide range of sensors that comply with BS1904 class B (DIN 43760): these sensors offer an accuracy of ±0.3 C at 0 C. For increased accuracy, BS1904 class A (±0.15 C) or tenth-DIN sensors (±0.03 C). Companies like Isotech can provide standards with 0.001 C accuracy. Please note that these accuracy specifications relate to the SENSOR ONLY: it is necessary to add on any error in the measuring system as well.
In Pt100/Pt1000/resistance mode, the unit uses a four-wire circuit and applies a continuous sense current of 250uA. For Pt100 and 0..500 ohms, the signal passes through an amplifier with a gain of 21: for Pt1000 and 0..10k, it feeds directly into the ADC. The sense current passes through the input resistor and through and internal, 3ppm reference. The value of this resistor is stored in EEPROM inside the unit. Yearly calibration is recommended.
In voltage mode, the input connector can be treated as a differential input with ground, or two single ended inputs. Both inputs must be zero volts or above, though it does not matter which input has the higher voltage. The accuracy on the 2.5V range depends on the accuracy of the internal voltage reference. For the 113mV range, it also depends on the accuracy of the x21 amplifier. This may vary by 2%, and has a tempco of 100ppm/degC.
The PT104 is supplied with PicoLog software for advanced data logging. PicoLog will automatically detect which sensor is connected and will display readings in the correct units. For users who wish to write their own custom software, drivers and examples are supplied.
The pt104 is normally connected directly to a PC, but it is also possible to access the pt104 via a modem using the Windows driver. This enables the unit to be controlled or data to be accessed from a remote site.
| Temperature | Resistance | Voltage | |
|---|---|---|---|
| Sensor | Pt100*, Pt100 | ||
| Range | -200..800C | 0..500 ohms* 0..10k ohms |
0..113mV 0..2.5V |
| Linearity | 10ppm | 10ppm | 10ppm |
| Accuracy @25C | 0.005C | 20ppm | 0.2% |
| Temperature coefficient | 3ppm/degC | 3ppm/degC | 50ppm/degC |
| Noise (95% confidence limit) | 0.015C | 50ppm | 50ppm |
| Resolution | 0.001C | 1uohm | 0.156uV |
| Number of inputs | 4 | ||
| Connectors | 4-pin miniDIN | ||
| Input impedence | >>1MOhm | ||
| Overvoltage protection | +/-100V | ||
| Output | RS232, D9 female | ||
| Environmental | 20-30C for stated accuracy 0-70C overall 20-90% RH | ||
| Software | PicoLog data logging software Drivers for Windows 3.1/95/98/NT/2000/ME/Linux Examples for C, Delphi, Excel, Labview, Labwindows, HP-VEE |
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| Quoted accuracy is for options marked * | |||