Calibration of capacitance

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

The calibration resources for capacitance at low voltages (≤ 100 V) covers the interval 100 fF – 1 mF. The most commonly used method for calibration of capacitance standards in the interval 1 nF – 10 μF is substitution measurements where the object is compared to a known standard with the same nominal value. Such capacitance calibrations are carried out with an LCR-meter or a capacitance bridge. Calibrations can be performed at frequencies up to 10 kHz (in special cases higher). The measurement uncertainty is at best 10 μF/F at 1 kHz.

In cases where a reduced measurement uncertainty is required, or when the substitution method is not applicable, calibration of capacitance standards can instead be carried out with a manual capacitance bridge. The most common frequency at which the calibration is carried out is 1 kHz, but calibrations can also be performed at other frequencies, up to 10 kHz (sometimes higher). The measurement uncertainty at 1 kHz is at best 3 μF/F with a dissipation factor of 3∙10^-6.

Measurement bridges and LCR-meters are calibrated by measurements against secondary capacitance standards.

Calibrations of high voltage capacitors can be performed up to 300 kV (for more information see the National Laboratory for high voltage and high currents)

Other types of measurements can also be performed, for example, measurements of temperature coefficients.

The measurement uncertainty given for a calibration depends, in addition to the calibration equipment’s performance, also on the calibration object’s performance (stability, temperature coefficient, voltage dependence and so on). In most cases, a preliminary estimate of the measurement uncertainty can be given from experience before the calibration.

Deliveries

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

When becoming a client you will also get access to our customer website for calibration, where you may also place orders. 

Customer website for calibration