Improving the world’s resistance measurement
12 April 2013
What is believed to be the most accurate instrument for comparative measurements of electric current is now commercially available for National Measurement Institutes.
The National Physical Laboratory (NPL) and Cryogenic Ltd have designed and developed the most accurate instrument for comparative measurements of electric current. The instrument can now be used by National Measurement Institutes (NMI) and laboratories around the world, providing a more accurate standard for current ratio, and ensuring current measurement is not a limiting factor in innovation.
The new Cryogenic Current Comparator (CCC) provides the world's most accurate ratio of current, which together with the Quantum Hall effect allows resistance to be measured to very high accuracy. It is the primary standard of resistance. If you measure in milliamps or ohms, the CCC can relate this back to primary standards more simply and more accurately than ever before.
Accurately measuring current is vitally important for a range of applications. It is essential for billing people for electricity use thereby ensuring a stable electricity market. The right current input is important for controlling doses of ionising radiation in cancer treatment.
Challenges arise when measuring current. Ionising radiation is measured in picoamps, whilst undersea cables carry hundreds of amps; some industries measure resistance or voltage, rather than current itself. These all need to be related back to the ampere, the SI unit of current.
NPL and Cryogenic have been involved in the development of CCC technology for over two decades, the system was originally built for NPL, and is used on a daily basis for its measurements. The CCC is now commercially available from Cryogenic for any laboratories which require very precise electrical measurements.
Cryogenic has already signed a contract to install one at Singapore's NMI, where it will underpin all their electrical measurements, including improving the accuracy of temperature measurements, analysis of the super-material graphene and fundamental physics research.
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