Development of Platinum Resistance Temperature Measurement System with 30mK Precision

Platinum resistance thermometer is a carrier for metrological transferring by international temperature scale. This paper introduced a temperature measurement system that is designed base the data of metrological transferring, the operation of its upper computer include three user interface, the interlace of "temperature measurement" can display real time temperature and track record its curve, the interface of "parameter setting" can make the calibration points table according to the data of metrological transferring, the interface of "system calibrate" makes digital calibrate of the zero and full scale value. In apparatus of the system, the thermocouple effect of contact resistance is eliminated by countercurrent method; the infection of noise wave of the reference source is restrained by the current source on rule of three. The thermostatic chest within the apparatus take on advanced control policy, it guarantees the reference resistance can work in invariableness temperature environment. The software skill contains that translating the measure value to temperature by bisearch linear interpolation, filtering de-noises with sampling value, and digital calibration technology etc. Experiments show that the precision and 3 month stability are all not exceeded 30 mK.