Our People

Sciencelens DSF2031

Tom Stewart

Principal Research Scientist


Areas of expertise

• Power and Energy
• Impedance
• Programmable Josephson Voltage Systems (PJVS)
• Measurement automation


• MSc, Electronics and Computer Systems Engineering


Tom started at MSL in 2008 following his Bachelor of Science and Technology (Electronics and Instrumentation) and Master of Science (Electronics and Computer Systems Engineering) completed at Victoria University of Wellington.

Tom has been working extensively with MSL’s mains energy standard, including its maintenance, calibration, and use for calibration of industry reference energy meters. He has been actively involved with the metrology requirements needed to support New Zealand’s power industry, including those of the Class A and B Approved Test Houses (ATH), whilst liaising with the Electricity Authority (EA) where required. Tom has been a technical expert for the assessment of IANZ accredited laboratories in New Zealand. Tom has also been involved in supporting MSL’s impedance standards, including the calibration of capacitors, inductors and associated reference equipment. Recent research has included making accurate voltage measurements to support MSL’s novel Kibble balance (linking the kilogram to the Planck constant). The optional oscillating mode would require high-accuracy AC voltage measurements (that would also ultimately support accurate power measurement). This has involved a collaboration with the National Institute of Standards and Technology (NIST), USA, to integrate a programmable Josephson voltage system (PJVS) into the Kibble balance.


Professional activities

  • Member of the IEEE


• Implementation of a programmable Josephson voltage standard in a zero boil-off dewar, Stewart T. J.; Lawson T. B.; Christian L. A. Conference on Precision Electromagnetic Measurements (CPEM 2016), Ottawa, Canada, 10-15 July, 2016; p. 1 – 2.
• Maintaining Traceability of a National Standard – Mains Power Improvements, Stewart, T. J.; Jones, K.; Metrology Society of Australasia Conference, Queenstown, New Zealand, 14-16 October, 2015.
• Traceable Calibration: Improvements to NZ’s National Standard of Power, Stewart, T.J.; Jones, K. EEA Conference & Exhibition 2015, 24 - 26 June, Wellington.
• Improvements to the MSL mains-frequency power standard, Stewart T. J.; Jones K. Conference on Precision Electromagnetic Measurements (CPEM 2014), Rio de Janeiro, Brazil, 24-29 August, 2014; p. 724 – 725.
• Building measurement capability for tomorrow, Jones, K.; Stewart, T.J. EEA Conference & Exhibition 2014, 18-20 June, Auckland, NZ.
• Spectral Leakage Errors When Using an Agilent 3458A to Measure Phase at Mains Power Frequencies, Stewart T. J. Conference on Precision Electromagnetic Measurements (CPEM 2012) Washington D.C., USA, pp278-279.
• Investigation of ac voltage measurement requirements for an oscillatory dynamic mode version of the watt balance, Christian, L.A.; Stewart, T.J.; Sutton, C.M. Conference on Precision Electromagnetic Measurements, Daejeon, Korea, 13-18 June, 2010
• High Temperature Superconductor Magnet Assist for a One-Sided NMR Instrument, Stewart, T. J.; Callaghan, P.T.; Coy A.; Gouws, G.J. ENZCon, Christchurch, NZ, 2006.