News

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NML enhances its calibration capability of the primary voltage standard by replacing its conventional Josephson voltage standard (CJVS) system to a programmable Josephson voltage standard (PJVS) system. The 10 V PJVS system, introduced from NIST/USA, was successfully set up and the evaluation on measurement uncertainty of this system has been completed in 2012. It supports NML to be the first National Measurement Institute which is able to provide the service of DC voltage calibration by using PJVS system in 2013.

In 2014, we conducted with NMIJ/Japan and KRISS/Korea a comparison of DC voltage at 1.018 V and 10 V between our own PJVS system to make a link to the key comparison reference value (KCRV). KRISS/Korea has participated in the related BIPM KCs and coordinated the previous APMP KC (APMP.EM.BIPM-K11.3). The comparison was approved by APMP TCEM and declared as APMP.EM.BIPM-K11.5. Same Zener standards (Three Fluke 732B) in APMP KC K11.3 were taken as traveling standards provided by NMIJ/Japan. The comparison had been completed in July 2014, and the report is expected to be issued by the end of 2015.

For this year, continuous efforts are putting on developing the measurement capability for AC voltage at low frequency (below 500 Hz). With the cooperation with NIST again, we have upgraded the cryoprobe and the bias source of our PJVS with relay PCB and trigger clock, respectively, to provide additional automated features when using for differential sampling measurements of AC voltage. It aims to establish the precision differential sampling measurements of synthesized sinusoidal waveform using 10 V AC PJVS system toward the low-frequency AC voltage standard.

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