A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratori...A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.展开更多
An automated multi-range multipliers（range resistors）system is established for the AC voltage measurements by using a thermal voltage converter.It is performed automatically by selecting the appropriate multiplier w...An automated multi-range multipliers（range resistors）system is established for the AC voltage measurements by using a thermal voltage converter.It is performed automatically by selecting the appropriate multiplier whose voltage range contains the voltage to be measured without changing it manually through a new designed system.It consists of control part through a micro-controller controlled by specified prepared Lab-VIEW program and switching part through electronic relays in one circuit as clearly described in this work.It is used for measuring the ac voltage in the range from 1 V to 200 V.Also,it can be used for the voltage ranges up to 1 000 V by putting some factors into consideration.The AC-DC transfer differences for these multipliers combined with thermal voltage converter are determined automatically against another standard thermal voltage converter by using another Lab-VIEW program.展开更多
文摘A new system for measuring low-ohmic standard resistors through a dual current sources bridge is introduced.It is used for low resistance measurements from 1 mΩto 1Ωat 1∶1 ratio,which is suitable for the laboratories without cryogenic current comparators(CCC)or direct current comparators(DCC)bridges.Behavior of this bridge is evaluated by comparing its measured values with the unknown resistor values obtained by another method.The accuracy of the introduced bridge is in the level of 10-5 for the 1 mΩresistor,and in the level of 10-4 for the 10 mΩ,100 mΩand 1Ωresistors.Moreover,a dual voltage sources system for the measurement of DC standard resistors from 1 kΩto 100 MΩis also presented.In this system,a modification is made on the modified Wheatstone bridge to evaluate its performance by adding another digital multimeter to measure the ratio between the unknown and the standard resistors simultaneously.This bridge is verified by comparing the measured values of 10 kΩresistor obtained by the two methods with its actual value.The bridge accuracy is in the level of 10-6 except for the 1 kΩresistor,and the bridge asymmetry is also evaluated.It is found the asymmetry is in the level of 10-6 for the resistors from 10 kΩto 100 MΩand in the level of 10-5 for 1 kΩresistors.The introduced bridges operations are controlled by LabVIEW programs designed specially for this purpose,and the expanded uncertainty is also evaluated for all measurement results.
文摘An automated multi-range multipliers（range resistors）system is established for the AC voltage measurements by using a thermal voltage converter.It is performed automatically by selecting the appropriate multiplier whose voltage range contains the voltage to be measured without changing it manually through a new designed system.It consists of control part through a micro-controller controlled by specified prepared Lab-VIEW program and switching part through electronic relays in one circuit as clearly described in this work.It is used for measuring the ac voltage in the range from 1 V to 200 V.Also,it can be used for the voltage ranges up to 1 000 V by putting some factors into consideration.The AC-DC transfer differences for these multipliers combined with thermal voltage converter are determined automatically against another standard thermal voltage converter by using another Lab-VIEW program.
