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Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Practical experience with optical currentsensor design
Alf-Peter Elg
19 April 2017
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Optical current sensor design
• Targets and strategy
• System designs• Interferometry / Network Independent Modulation
• Phase / Birefringence modulation
• Free space propagation
• All fibre version
• Fibre development – University of Southampton• New materials
• Reference measurements at LNE
• Programming of API
• Theoretical dissemination
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Targets and strategy
• Targets
• 1 – 10 kA dynamic range.
• 100 ppm measurement uncertainty
• Strategy
• Selection of system working principle
• Interferometric, birefringence and phase modulationin Sagnac and Reflective mode have been studied
• Use of 633 with 4 x higher response than @ 1300 nm
• Not available on the market – Development needed
• Investigate Tb doping of fibres for higher response
• HiBi Spun fibre – avoid effects of birefringence
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System designs – Interferometric detection• Interferometer – Renishaw
• Network independent modulation - Arteche
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System design – Interferometer• Built around system interferometer developed for length
measurements (Renishaw)
• Results
• 10 turns of undoped spun LoBi fibre
• High noise level
• Sensitive to acoustics and temperature
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System design – Phase modulation
• System overview – reflective mode
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System design - Phase modulation• Free space propagation
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System design - Phase modulation
• Free space propagation
• Parameter space and modulation techniques
• Lock-in amplifier core system
• Modulation frequency and phase
• Modulation amplitude
• Polarisation state of source and at fibre entrance
• PID regulator for closed loop phase detection (NIM)
• Zero-Flux reference system for calibration at 53 Hz
• Full system control programming with LabVIEW
• Parameter space optimization performed in thissystem and then implemented in an all fibre system
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System design - Phase modulation
• Insensitive to nearby currents
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
System design - Phase modulation
• All fibre version instead of free space propagation
• Components not available on the market
• Fibre welding needed
• SP purchased a Fujikura in 2016
• Components
• SLED Source at 650 nm, EOM
• 50/50 Splitters ordered (delivery May 5)
• Splicing – Fujikura FSM-100P
• Sensing fibre – HiBi spun undoped fibre
• Calibration and final results in May 2017.
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Fibre development - University of Southampton
• Tb doping of glasses
• Possible Tb-doping in Al2O3-P2O5-SiO2, Al2O3-SiO2 orP2O5-SiO2 – A preform shown
• Spinning of fibres – pitch 3 – 7 mm
• HiBi fibres for optimum performance to counterinherent birefringence and induced by bending.
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Fibre characterization - LNE
• Verdet constant
• Temperature coefficient
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Fibre characterization - LNE
MeasurementsType of optical
fiberV (22.5 °C,632.8 nm)
[rad/(T∙m)]
V (SDEV)[rad/(T∙m)]
Comments
Sept – Oct2015
Spun LoBiundoped 5 mm
spin pitch3.97 0.38
1= 1.2 10 (1 °⁄ )
Nov. 2015Spun LoBi
undoped 7 mmspin pitch
4.50 0.09
June 2016 Unspun, TbAldoped HiBi 2.0* -
Very thin fibres. Cut-offwavelength 430 nm
*Birefringence obscure theFaraday Effect
Nov – Dec2016
Spun TbAl doped5 mm spin pitch 4.10 0.08
.
Spun TbAl doped7 mm spin pitch 3.94 0.55
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Conclusions and outlook
• The interferometer design offer highly sensitive detection, but isaffected by perturbations as acoustics and temperature
• The phase modulation design has given a robust and sensitivesolution but need further development to be used for metrologyand possible future on-site calibration
• A concept has been developed for producing doped and/or HiBi PMspun fibre at University of Southampton
• Doping of fibre material gave no increase of the Verdet constant
• A theoretical model of the complete system has been developed – isadaptable to any configuration and allow for advanced perturbationmodelling
Future work• To further develop the all fibre system for on-site calibrations
Research Institutes of Sweden
Safety and TransportMeasurement Science and Technology – Electricity
Thank you for your attention!
The TeamFibre characterization LNE D. Istrate, et.al.System development SP - RISE G. Bideberg, S.C. Ebenhag, A.P. Elg,
A. Nilsson, M. Lindgren, P.O. HedekvistVTT J. Hällström
Theory Univ. of Chalmers P. JohannissonFibre development Univ. of Southampton Prof. J. Sahu
nLIGHT Corporation P. KiiveriSystem selection LNE, SP-RISE, VTT, Univ. of Chalmers
Univ. of Strathclyde G. Fusiek, P. Niewczas