Electrical Quantities in Terms of the International System of Units

--The electrical International System of Units (SI) are defined and realized as DC electrical quantities. National Institute for Standards (NIS), Egypt maintains the DC voltage unit by using the DC Josephson Voltage Standard (JVS) as a primary standard for DC voltage adding to eight zener diode reference standards as DC voltage secondary standards. The JVS is used to provide traceability of electrical measurements to the SI units. In order to disseminate the DC voltage traceability to the secondary standards, one of the NIS zener diode reference standards has been calibrated via the JVS in 1.018 V and 10 V ranges; then, this traceable zener diode has been used to automatically calibrate the other zener diode reference standards. Accordingly, an automatic system for controlling and calibrating the zener diode reference standards has been specially constructed using the Laboratory Virtual Instrument Engineering Workbench (LabVIEW) software. This automatic calibration system is a consistent construction from the national zener diode reference standards that can disseminate the traceability of all the electrical instruments under calibration. The standard development procedures have been followed in the building of the system software. The software requirement specifications as well as functional specifications are taken into consideration. Design, implementation and testing of the software have been performed. Furthermore, software validation for measurements' uncertainty as well as results' compatibility in both automatic and manual modes has been achieved.