DC Current

SP provides calibration services for current shunts and various types of current measuring and generating instruments.
The current unit

At SP the unit of current, the ampere (A), is realised at dc with the use of Ohms law with traceability to the units of voltage and resistance. The measurement uncertainty is on the order of 25 nA/A for the realisation at the 100 µA level.

At levels below 100 pA an alternative realisation method is used. A well defined generated voltage ramp is applied to a capacitor. The lowest measurement uncertainty is on the order of 30 µA/A. Traceability is from the units of voltage, frequency and capacitance.

In order to further secure traceability, SP also participates regularly in international comparisons.

Calibration service

SP offers calibration of dc current in the range 10 fA - 6000 A. Other types of measurements are also performed, for example, determination of temperature coefficient. See also ac current.

The final uncertainty given at calibration depends not only on the uncertainty contribution from the calibration equipment but also from the device under test contribution (stability, temperature coefficient, voltage dependence, etc.). A preliminary measurement uncertainty can often be estimated from experience prior to calibration.

SI - The International System of Units

Read more...

The traceability chain - the link to basic quantities

A key concept of measurement technology is that of traceability, which means that all measurements made with a calibrated instrument or device must have a directly traceable link back to the defined quantity. Read more...

Related Information

Contact Persons

Techical issues
Tobias Bergsten

Phone: +46 10 516 51 16

Gunnar Eklund

Phone: +46 10 516 53 91

Booking
Kristina Holsner

Phone: +46 10 516 50 95

SP Technical Research Institute of Sweden, Box 857, SE-501 15 Borås Phone +46 10-516 50 00, E-mail info@sp.se