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The DC Low Frequency and Radio Frequency section is responsible for maintenance of National Measurement Standards for Voltage, Resistance, Impedance, AC-DC Transfer, AC Power and energy, RF Power, RF Attenuation and RF Impedance, and dissemination of measurement traceability to the industry through calibration of measurement equipment. 

Key Facts 

The services provided by the DC Low Frequency and Radio Frequency laboratories are in line with Claimed measurement capabilities listed in the International Bureau of Weights and Measures (BIPM) Key Comparison Database (KCDB). 

DC Voltage

NMISA maintains a Josephson Voltage Standard as a national measurement standard. DC voltage measurements are traceable to the national measurement standard for Time and Frequency. The service provided includes calibration of DC reference standards at 1 V, 1,018 V and 10 V reference and DC voltage sources and meters from 100 mV to 1 kV.

Resistance 

NMISA maintains the national DC resistance measurement standard using the two 1Ω and  
1 kΩ standard resistors. Resistance bridges are used to maintain the resistance measurement scale from 10 µΩ to 1 TΩ. Competence is maintained through participation in inter-comparison programs and results published in the BIPM KCDB. 
The Services provided include calibration of dc resistance standards source and meter from 10 µΩ to 1 TΩ, and inter-laboratory comparison schemes.

Capacitance 

NMISA maintains the national capacitance measurement standard using 3 terminal standard capacitors from 1 pF to 100 pF, and four terminal standard capacitors from 1 pF to 10 µF at nominal test frequency from 1 kHz to 1 MHz. Capacitance bridges are used to maintain the capacitance measurement scale from 1 pF to 10 µF at 1 kHz to 1 MHz. Competence is maintained through participation in inter-comparison programs and results published in the BIPM KCDB. 

The Services provided include calibration of capacitance standards source and meter from 1 pF to 10 µF, and inter-laboratory comparison schemes.

Inductance

NMISA maintains the national inductance measurement standard using six inductance standards from 100 µH to 10 H, at nominal test frequency from 100 Hz to 1 kHz. Inductance bridges are used to maintain the inductance measurement scale from 100 µH to 10 H at 100 Hz to 1 kHz. Competence is maintained through participation in inter-comparison programs and results published in the BIPM KCDB. 

The services provided include calibration of inductance standards sources and meters from 100 µH to 10 H and inter-laboratory comparison schemes. 

AC-DC Transfer, AC Voltage and AC Current

The AC-DC transfer standards constitute a primary element in traceable linking of the ac voltage, current, power and energy quantities to their DC counterparts. NMISA maintains scales of the national standards for precision AC-DC difference measurements in voltage and current.  
The AC-DC voltage transfer scale is constituted by the thermal voltage converter standards with the nominal ratings in the range from 300 mV to 1 kV and the active thermal transfer standard in the range from 2 mV to 200 mV. The AC-DC voltage transfer standards are calibrated in the frequency band from 10 Hz to 1 MHz.

The AC-DC voltage transfer standards serve as references in the calibration of the working AC-DC difference standards, AC voltage sources and meters in the corresponding nominal and frequency ranges (2 mV to 1 kV, 10 Hz to 1 MHz). 

The AC-DC current transfer scale is constituted by the thermal current converter standards with the nominal ratings in the range from 2 mA to 100 A that represent a combination of a shunt with non-inductive/non-capacitive design and a thermal voltage converter. The AC-DC current transfer standards are calibrated in the frequency band from 10 Hz to 100 kHz.

The AC-DC current transfer standards serve as references in the calibration of the working AC-DC difference standards, AC current sources and meters in the corresponding nominal and frequency ranges (2 mA to 100 A, 10 Hz to 100 kHz).

AC Power and energy

NMISA maintains a three-phase power comparator as the national measurement standard. Competence is maintained through an inter-comparison program using a second power standard which is calibrated from time to time by other National Metrology institutes.  
The Services provided include calibration of active, reactive and apparent power and energy in the ranges of 30V to 480V, 10mA to 160A and for power factors -1 to +1.

Radio Frequency Power

NMISA maintains a 7 mm coaxial dual-line calorimeter and various national measurement standards for RF power in the form of power sensors. The standards cover the frequency range from 100 kHz to 50 GHz and are traceable to international RF power standards. Competence is maintained through participation in inter-comparisons.

The services provided include the characterisation of calibration factors for coaxial RF power sensors and absolute power for coaxial RF power meters and sources.

Radio Frequency Impedance

NMISA provides services including calibration of Voltage Reflection Coefficient (VRC) or Return Loss for single-port and multi-port devices for different coaxial connector sizes such as Type-N, PC-7, PC-3.5, PC-2.92, PC-2.4, BNC and balanced lines (CF).

The NMISA reflection standards are traceable to international RF impedance standards. Competence is maintained through inter-comparisons and calibrations support the NMISA CMCs in the KCDB.

Radio Frequency Attenuation

NMISA maintains an IVD attenuation measurement system as a national RF attenuation standard. The IVD is traceable to the SI units and/or units of measurements realised in recognised national metrology institutes. Metrology grade vector network analysers, a measuring receiver, and other reflectometer systems are then used to calibrate RF attenuation for related devices.

Calibration for RF attenuation is performed for various attenuators with different connector types including Type N, PC-7, PC-3.5, PC-2.92, PC-2.4, BNC and balanced lines (CF).

The team

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