Device enables ultra precise measurement of electrical current
UK firm Cryogenic has teamed up with the National Physical Laboratory (NPL) to develop what is claimed to be the world's most accurate instrument for comparative measurements of electric current.
The Cryogenic Current Comparator (CCC) allows different electrical measurements to be related back to the ampere (the SI unit of current) with very high accuracy, making it useful in applications such as undersea cabling and medical technology.
The digital device relies on superconducting materials and a quantum magnetic flux detector to measure current ratios. It sits in a liquid helium dewar – a Thermos flask that holds very cold liquids – which keeps it at four Kelvin and allows superconductivity.
According to Cryogenic, the CCC is accurate to better than 1 part in 109. The company says using the optically isolated current sources enables the resistance bridge to make comparisons between resistors with an accuracy and repeatability of 10-8.
