Calibration of electric current

Purpose

RISE's calibration at the National Laboratory for electrical quantities is available to customers who require the best possible accuracy in their calibration or have requirements which involves development of new calibration methods. Our customers are found among industry, research institutes, and calibration companies. The national reference standards at the National Laboratory have the highest level of accuracy in Sweden. The traceability to the realisation of the unit is always ensured.

Calibration at a National Laboratory meets all the typical requirements for traceability and accreditation commonly found in industry and society at large.

Method

RISE offers calibration of direct current in the range 10 fA – 6000 A. For calibration of calibrators in the interval 10 µA - 20 A, the current is determined by measuring the voltage across a resistance standard (current shunt). The calibrator is thereafter used as a stable current generator for calibration of current measuring instruments, for example multimeters. The calibrator can, however, be sensitive to different loads. If instead the current measuring instrument is connected in series with a current shunt, the current in the circuit can be determined by Ohm’s law and the measurement will not be load-dependent.

For calibration of currents smaller than 10 µA other instruments are used. For example a source meter to generate small currents, or an electrometer to measure small currents. Source meters and electrometers are calibrated either with a resistance standard (≥100 pA) or with voltage ramps across a capacitance standard (≤100 pA).

For calibration of currents higher than 100 A other methods are used. Those calibrations are carried out by the National Laboratory for high voltage and high current.

Deliveries

Delivery upon agreement with customer. The results of the calibration are reported in a calibration certificate.