Precise calibration on DC voltage

DC voltage was traced to DC voltage reference (FLUKE 732A) by the calibrated divider (datron 4902S). The divider supplied 18 fixed ratios to calibrate DC voltage from 10 mV to 1000 V. DC voltage traceability mainly depends on the DC voltage reference and DC voltage divider. The DCV reference is traced to JJAVS twice a year, with the uncertainty of 1 times 10-7 (k=l). After calibration, the uncertainty of DCV ratios can reach 1 times 10-7(k=l). As for daily calibration, the uncertainty of DC voltage depends on the long term stability of DCV ratios and the voltage effect of the ratios.