Electrical Metrology
The NMS Electromagnetic Metrology Programme covers the realisation, maintenance and development of measurement standards for electrical, magnetic and electromagnetic quantities used in the frequency range DC to near optical frequencies. These quantities include DC voltage, AC voltage and AC/DC transfer, AC voltage ratio, AC and DC resistance, capacitance, inductance, AC power, AC conductivity and magnetic standards at frequencies below about 10 MHz. RF and microwave quantities, which are typically but not exclusively above this frequency, include power, attenuation, impedance, noise, electric field strength, power flux density and antenna parameters. The programme also encompasses the development of standardised methods of measurement for the above quantities to meet UK needs.
The objectives of the programme are:
- to maintain and develop national measurement standards for DC and Low Frequency electrical and electromagnetic quantities, including the derived SI units of the volt and the ohm, and RF and Microwave electromagnetic quantities at a level consistent with the current and future needs of UK industry, national and local government, and research, and make them accessible to customers in as practical and economic form possible;
- to ensure that the UK measurement standards for electromagnetic quantities are harmonised with those of the UK’s trading partners, through intercomparisons and collaborative research leading to mutual recognition;
- to develop new and improved methods of measurement for electromagnetic quantities to meet identified UK needs, and promote international standardisation of these methods to ensure consistency in practical measurements, especially where these are used for regulatory and trading purposes;
- to promote knowledge transfer from the programme and the adoption of good measurement practice, and to provide technical support and advice to UK organisations and individuals undertaking measurement of electromagnetic quantities
The ability to measure electrical quantities in a consistent and repeatable manner is vital for maintaining and extending the economic and technical success of electrical and electronic technologies, from power generation and distribution to the development and exploitation of the most advanced communication systems.
The industrial needs for electromagnetic measurements are very diverse, and this is reflected in the range of capabilities required at the national standard level. Applications supported by the programme range from the relatively mature to the most novel and fast moving, in many of which the UK has a leading edge either as a manufacturer or in exploiting the wider benefits of use. The main factors in setting the objectives and deliverables for the programmes are:
Effects on key sectors
The sectors primarily affected such as electronics, telecommunications, information processing, defence, broadcasting, energy, transport and various aspects of health are widely recognised (for example in ‘Foresight’ studies) as those that will shape our changing technical and social environment. They are also the sectors that will dominate the economic well-being and competitiveness of the UK.
Leading edge requirements
For many industrial activities, availability of the best measurement capability is paramount for competitiveness. Most obvious here is the instrumentation sector, but for example, mobile telecoms, satellite communications and high data-rate processing all demand leading-edge metrological capabilities. The UK has a proven culture of innovation and has a firm presence in the supply of leading-edge equipment and systems based on electronic, and RF and microwave technologies.
Regulatory drivers
Regulatory requirements, such as for electromagnetic compatibility, the quality of electrical supply parameters, electricity metering, and health and safety are all strong drivers for measurement traceability. A key element in reducing the burden of conforming to Directives is the provision of reliable and cost effective measurement techniques.
International standardisation
The globalisation of markets puts particular emphasis on international specification standards and the need for ensuring the integrity of metrology and accreditation world-wide. It is important that specification standards are supported by reproducible test methods and underpinned by robust measurement standards. Therefore, the NMS Electromagnetic Programme must take into account the needs of international standardisation and support the deliberations of the standardisation committees either directly or through the established network of national delegates.
It is also essential that the UK’s primary measurement standards are harmonised with those of the UK’s trading partners. An important element of the programme is the international activities aimed at demonstrating the international equivalence of UK electrical and electromagnetic standards through EUROMET and CIPM intercomparisons.
Traceability to support accreditation
The network of UKAS accredited laboratories for electromagnetic measurements is well established, particularly in the DC and LF and guided wave fields. It is estimated that these laboratories issue over 100,000+ UKAS certificates each year. These laboratories depend on traceability to national measurement standards.
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