Gert Rietveld | University of Twente (original) (raw)

Papers by Gert Rietveld

CPEM 2010, 2010

We present the dc properties of a set of recently developed ac-dc transfer current shunts in the ... more We present the dc properties of a set of recently developed ac-dc transfer current shunts in the range of 30 mA to 10 A. The measurements include the long-term drift, temperature coefficient and power coefficient, which all appear to have effects on the level of 1 to 10 parts in 106. These results prove the suitability of the shunts for wideband power applications where both small ac-dc transfer differences as well as stable dc characteristics are required.

CPEM 2010, 2010

We present the dc properties of a set of recently developed ac-dc transfer current shunts in the ... more We present the dc properties of a set of recently developed ac-dc transfer current shunts in the range of 30 mA to 10 A. The measurements include the long-term drift, temperature coefficient and power coefficient, which all appear to have effects on the level of 1 to 10 parts in 106. These results prove the suitability of the shunts for wideband power applications where both small ac-dc transfer differences as well as stable dc characteristics are required.

Sensor Technology in the Netherlands: State of the Art, 1998

For the realization of the electrical quantum metrology triangle (V-A-Ω) a device to amplify very... more For the realization of the electrical quantum metrology triangle (V-A-Ω) a device to amplify very small currents with high precision is needed. The cryogenic current comparator (CCC) is by far the best instrument to do this. In order to make a very current sensitive CCC for calibration of electrical standards, we have developed optimum dc Superconducting QUantum Interference Devices (SQUIDs). The design, fabrication and characterisation of these devices is presented. The measurements concern the flux-to-voltage transfer and the noise properties, especially the input current noise. The optimisation of the flux transformer circuit that links the CCC with the SQUID will be treated. In addition, typical fabrication aspects of the CCC as the wires and tube assembly, the shields and the support system will be addressed.

2020 Conference on Precision Electromagnetic Measurements (CPEM), 2020

A transformer loss measurement (TLM) system calibration setup consists of three main components, ... more A transformer loss measurement (TLM) system calibration setup consists of three main components, a voltage divider (VD), current transformer and a power meter. The phase errors of the individual components of the reference setup for TLM system calibration should not be more than 10mutextrad10\ \mu\text{rad}10mutextrad to achieve an overall system uncertainty of better than 20mumathrmW/textVA20\ \mu\mathrm{W}/\text{VA}20mumathrmW/textVA. We have verified the uncertainty level of the developed VD both from the component level and as a whole. Different practical conditions relevant for on-site measurements are considered, e.g. measurement cable lengths, cable types and grounding. The results shows that uncertainties of less than 10mumathrmV/mathrmV10\ \mu \mathrm{V}/\mathrm{V}10mumathrmV/mathrmV in ratio error and 10mutextrad10\ \mu\text{rad}10mutextrad in phase displacement are achievable.

2018 Conference on Precision Electromagnetic Measurements (CPEM 2018), 2018

A comparison has been performed of the VSL and PTB reference setups for the calibration of indust... more A comparison has been performed of the VSL and PTB reference setups for the calibration of industrial power transformer loss measurement systems (TLMS). Both setups are developed within the “ELPOW” European joint research project, with the aim to calibrate industrial TLMS as a complete system, rather than just via its individual components, with an overall uncertainty of better than pmb50mumathbfW/mathbfVA\pmb{50\ \mu} \mathbf{W}/\mathbf{V}Apmb50mumathbfW/mathbfVA, for voltages up to 100 kV, currents up to 2 kA, and power factors down to zero. The initial comparison results show excellent agreement of the PTB and VSL reference setups, with typical differences less than pmb15mumathbfW/mathbfVA\pmb{15\ \mu} \mathbf{W}/\mathbf{VA}pmb15mumathbfW/mathbfVA, well within the uncertainty of the setups.

High Tc Superconductor Thin Films, 1992

29th Conference on Precision Electromagnetic Measurements (CPEM 2014), 2014

In order to perform traceable measurements of the electrical parameters of solid-state lightning ... more In order to perform traceable measurements of the electrical parameters of solid-state lightning (SSL) products, it is essential to technically adequately define the measurement procedure and to identify the relevant uncertainty sources. This paper fills the related gaps in the present written standard for testing SSL products. New uncertainty sources with respect to conventional lighting sources are determined and their effects quantified. For power measurements on SSL products the main uncertainty sources are temperature dependence, power supply THD, and stabilization of the SSL product. For current rms measurements the influence of bandwidth, shunt resistor, power supply source impedance, and ac flatness error are significant as well.

2018 Conference on Precision Electromagnetic Measurements (CPEM 2018), 2018

Recent studies involving large errors in static electricity meters when exposed to step changes i... more Recent studies involving large errors in static electricity meters when exposed to step changes in the current waveform are reviewed. Triggered by these findings, a joint European research project has recently started to further evaluate these effects. A description is given of this pre-normative research programme which aims to provide evidence and techniques to resolve this unsatisfactory meter error situation. The need or otherwise for a regulatory and standardisation response to these large meter errors is discussed.

IEEE Transactions on Instrumentation and Measurement, 2018

Prototype distributed digitizers have been developed with the metrological precision of the indiv... more Prototype distributed digitizers have been developed with the metrological precision of the individual measurement nodes. A master controller aggregates the data of the nodes and performs all computational tasks. A crucial part of the system is the synchronization of the individual nodes at the nanosecond level using white-rabbit technology. Fiber-optic communication is used to reduce interference and to obtain high isolation. When operated on battery power, this allows for special applications such as the measurement of currents in high-voltage lines. First, results show that a phase difference between nodes of a few microradians can be achieved with a resolution of better than 0.1 µrad.

MRS Proceedings, 1992

ABSTRACTSeveral attempts have been made by different groups to grow (110) YBa2Cu3O7−δ thin films ... more ABSTRACTSeveral attempts have been made by different groups to grow (110) YBa2Cu3O7−δ thin films on (110) substrates. In most of the cases, both (103) and (110) orientations of YBa2Cu3O7−δ have been found in the film. The substrate temperature during deposition is one of the major factors that determines the crystal orientation of the YBa2Cu3O7−δ. In our experiment, effort is made to examine the influence of the initial substrate temperature from 595 °C to 660 °C on the relative amount of (110) and (103) oriented grains. The orientations are determined by x-ray analysis with a Weissenberg camera. The amount of (103) oriented YBa2Cu3O7−δ is reduced systematically with decreasing substrate temperature. At the lowest deposition temperatures we find only (110) oriented growth.

2016 Conference on Precision Electromagnetic Measurements (CPEM 2016), 2016

A reference system is developed for the on-site calibration of power transformer loss measurement... more A reference system is developed for the on-site calibration of power transformer loss measurement systems (TLMs). A crucial element in such calibrations is the availability of voltage and current signals with adjustable phase close to 90, that is power factor near to zero, in order to apply a known and stable loss or reference power to the TLM. In the new VSL reference system, digital signal processing is used to maintain the phase relation between the voltage (up to 100 kV) and the generated current (up to 2000 A) applied to the TLM. Initial results indicate that phase uncertainties of better than 20 rad can be obtained.

The propagation of Power Quality (PQ) phenomena through distribution networks is dependent on a n... more The propagation of Power Quality (PQ) phenomena through distribution networks is dependent on a number of parameters, including the characteristics of the disturbance source, impedances and configuration of the network and behaviour of loads and generators in the analysed area. Due to the large numbers of network users, estimation of disturbance levels in the network includes a large number of uncertainties. This paper proposes a method for analysing the propagation of PQ phenomena through the distribution network based on wide-area field measurements. In the future, the method will be used to analyse the data obtained from Live-Lab-the permanent field experiment of the Dutch DSO Alliander. The analysis takes into account the state of the network, loading of substations and measurement uncertainty.

29th Conference on Precision Electromagnetic Measurements (CPEM 2014), 2014

ABSTRACT A description is given of a new EU funded project on metrology in support of smart elect... more ABSTRACT A description is given of a new EU funded project on metrology in support of smart electrical grids. This project is a partnership of 14 EU NMIs and two universities. Research themes are described including: i) wide-area power quality (PQ) propagation, ii) Phasor measurement Units (PMU) for distribution networks, iii) network impedance measurements and iv) transducer metrology in support of PMU/PQ.

29th Conference on Precision Electromagnetic Measurements (CPEM 2014), 2014

ABSTRACT This paper describes the design and construction of an openable core current transformer... more ABSTRACT This paper describes the design and construction of an openable core current transformer (CT) to be used on high-voltage lines or busbars. The current sensor consists of a high current stage with a ratio of 400:1 and a low current stage with a ratio of 100:1. Both have a toroid core and are of the enhanced core type. The high current stage is cut in two halves to be able to connect without breaking the high voltage line. The overall accuracy is limited by the cut core of the high current stage. The accuracy is < 10 µA/A and < 5 µrad.

2012 IEEE Power and Energy Society General Meeting, 2012

ABSTRACT Instrument transformers are crucial elements in the metering infrastructure of high volt... more ABSTRACT Instrument transformers are crucial elements in the metering infrastructure of high voltage grids. With the evolvement of smart grids and the liberalization of the electricity market, new billing points can arise in the grids where electrical energy is transferred between different parties. When these new billing points are at existing places in the grid, it is strongly preferred to use the available instrument transformers for realization of a revenue metering system rather than installing new CTs and PTs. However, these available instrument transformers do not always meet the accuracy class requirements prescribed by legislation like electricity metering codes. In this paper, we present the results of an extensive performance evaluation of the ratio error of high voltage CTs under actual operating conditions. The aim of this evaluation was to find out to what extent CTs that do not meet the required accuracy class can nevertheless be used for revenue metering systems when their ratio errors are measured and corrected for. The study has a significant impact on the expansion of the metering infrastructure within smart grids, since it paves the way to a significant cost saving in the realization of new revenue metering setups.

2012 Conference on Precision electromagnetic Measurements, 2012

ABSTRACT This paper describes the selection and characterization of resistors for a 1000 kV HVDC ... more ABSTRACT This paper describes the selection and characterization of resistors for a 1000 kV HVDC divider. One thousand 10 MΩ resistors will be connected in series in the final design. Due to the large number of resistors only a randomly selected set has been characterized. The measured temperature and voltage coefficients of the resistors are around 1 μΩ/Ω/K and -10 μΩ/Ω/kV respectively, which make them very suitable for reaching the overall desired divider uncertainty of better than 100 μV/V.

Physical Review Letters, 1996

Film growth of a complex oxide is investigated during nucleation on a substrate surface. Using at... more Film growth of a complex oxide is investigated during nucleation on a substrate surface. Using atomic force microscopy we have imaged subunit cell coverage of SmBa 2 Cu 3 O 7 deposited by reactive molecular beam epitaxy on a (100) SrTiO 3 substrate. After a threshold deposition, c-axis islands are observed to nucleate predominantly along the surface steps. The heights of the nucleation islands are examined and a consistent layer stacking model is proposed. Cation stoichiometry of the nucleation islands is inferred to be dependent on the substrate surface and different from the bulk. [S0031-9007(96)00404-8]

Physica C: Superconductivity, 1993

Abstract We have fabricated Sm---Ba---Cu---O thin films at 550–850 C and at oxygen pressures of 1... more Abstract We have fabricated Sm---Ba---Cu---O thin films at 550–850 C and at oxygen pressures of 1.2–6.0× 10− 5 mbar in the presence of ozone. Various groups have reported on the existence of a solid solubility region in bulk Sm 1+ x Ba 2-x Cu 3 O y made at ...

Physica B: Condensed Matter, 1990

Specific heat measurements between about 25 and 800 mK, and in magnetic fields of 0, 0.45 and 1.5... more Specific heat measurements between about 25 and 800 mK, and in magnetic fields of 0, 0.45 and 1.55 T are presented of the high-Tc superconductors RBa2Cu307-x with R = Y and Tm, and x~0.2. For both compounds, the zero field results can be described with C = aT-2 +bT a , where a = 0.31 and 0.70

CPEM 2010, 2010

We present the dc properties of a set of recently developed ac-dc transfer current shunts in the ... more We present the dc properties of a set of recently developed ac-dc transfer current shunts in the range of 30 mA to 10 A. The measurements include the long-term drift, temperature coefficient and power coefficient, which all appear to have effects on the level of 1 to 10 parts in 106. These results prove the suitability of the shunts for wideband power applications where both small ac-dc transfer differences as well as stable dc characteristics are required.

CPEM 2010, 2010

We present the dc properties of a set of recently developed ac-dc transfer current shunts in the ... more We present the dc properties of a set of recently developed ac-dc transfer current shunts in the range of 30 mA to 10 A. The measurements include the long-term drift, temperature coefficient and power coefficient, which all appear to have effects on the level of 1 to 10 parts in 106. These results prove the suitability of the shunts for wideband power applications where both small ac-dc transfer differences as well as stable dc characteristics are required.

Sensor Technology in the Netherlands: State of the Art, 1998

For the realization of the electrical quantum metrology triangle (V-A-Ω) a device to amplify very... more For the realization of the electrical quantum metrology triangle (V-A-Ω) a device to amplify very small currents with high precision is needed. The cryogenic current comparator (CCC) is by far the best instrument to do this. In order to make a very current sensitive CCC for calibration of electrical standards, we have developed optimum dc Superconducting QUantum Interference Devices (SQUIDs). The design, fabrication and characterisation of these devices is presented. The measurements concern the flux-to-voltage transfer and the noise properties, especially the input current noise. The optimisation of the flux transformer circuit that links the CCC with the SQUID will be treated. In addition, typical fabrication aspects of the CCC as the wires and tube assembly, the shields and the support system will be addressed.

2020 Conference on Precision Electromagnetic Measurements (CPEM), 2020

A transformer loss measurement (TLM) system calibration setup consists of three main components, ... more A transformer loss measurement (TLM) system calibration setup consists of three main components, a voltage divider (VD), current transformer and a power meter. The phase errors of the individual components of the reference setup for TLM system calibration should not be more than 10mutextrad10\ \mu\text{rad}10mutextrad to achieve an overall system uncertainty of better than 20mumathrmW/textVA20\ \mu\mathrm{W}/\text{VA}20mumathrmW/textVA. We have verified the uncertainty level of the developed VD both from the component level and as a whole. Different practical conditions relevant for on-site measurements are considered, e.g. measurement cable lengths, cable types and grounding. The results shows that uncertainties of less than 10mumathrmV/mathrmV10\ \mu \mathrm{V}/\mathrm{V}10mumathrmV/mathrmV in ratio error and 10mutextrad10\ \mu\text{rad}10mutextrad in phase displacement are achievable.

2018 Conference on Precision Electromagnetic Measurements (CPEM 2018), 2018

A comparison has been performed of the VSL and PTB reference setups for the calibration of indust... more A comparison has been performed of the VSL and PTB reference setups for the calibration of industrial power transformer loss measurement systems (TLMS). Both setups are developed within the “ELPOW” European joint research project, with the aim to calibrate industrial TLMS as a complete system, rather than just via its individual components, with an overall uncertainty of better than pmb50mumathbfW/mathbfVA\pmb{50\ \mu} \mathbf{W}/\mathbf{V}Apmb50mumathbfW/mathbfVA, for voltages up to 100 kV, currents up to 2 kA, and power factors down to zero. The initial comparison results show excellent agreement of the PTB and VSL reference setups, with typical differences less than pmb15mumathbfW/mathbfVA\pmb{15\ \mu} \mathbf{W}/\mathbf{VA}pmb15mumathbfW/mathbfVA, well within the uncertainty of the setups.

High Tc Superconductor Thin Films, 1992

29th Conference on Precision Electromagnetic Measurements (CPEM 2014), 2014

In order to perform traceable measurements of the electrical parameters of solid-state lightning ... more In order to perform traceable measurements of the electrical parameters of solid-state lightning (SSL) products, it is essential to technically adequately define the measurement procedure and to identify the relevant uncertainty sources. This paper fills the related gaps in the present written standard for testing SSL products. New uncertainty sources with respect to conventional lighting sources are determined and their effects quantified. For power measurements on SSL products the main uncertainty sources are temperature dependence, power supply THD, and stabilization of the SSL product. For current rms measurements the influence of bandwidth, shunt resistor, power supply source impedance, and ac flatness error are significant as well.

2018 Conference on Precision Electromagnetic Measurements (CPEM 2018), 2018

Recent studies involving large errors in static electricity meters when exposed to step changes i... more Recent studies involving large errors in static electricity meters when exposed to step changes in the current waveform are reviewed. Triggered by these findings, a joint European research project has recently started to further evaluate these effects. A description is given of this pre-normative research programme which aims to provide evidence and techniques to resolve this unsatisfactory meter error situation. The need or otherwise for a regulatory and standardisation response to these large meter errors is discussed.

IEEE Transactions on Instrumentation and Measurement, 2018

Prototype distributed digitizers have been developed with the metrological precision of the indiv... more Prototype distributed digitizers have been developed with the metrological precision of the individual measurement nodes. A master controller aggregates the data of the nodes and performs all computational tasks. A crucial part of the system is the synchronization of the individual nodes at the nanosecond level using white-rabbit technology. Fiber-optic communication is used to reduce interference and to obtain high isolation. When operated on battery power, this allows for special applications such as the measurement of currents in high-voltage lines. First, results show that a phase difference between nodes of a few microradians can be achieved with a resolution of better than 0.1 µrad.

MRS Proceedings, 1992

ABSTRACTSeveral attempts have been made by different groups to grow (110) YBa2Cu3O7−δ thin films ... more ABSTRACTSeveral attempts have been made by different groups to grow (110) YBa2Cu3O7−δ thin films on (110) substrates. In most of the cases, both (103) and (110) orientations of YBa2Cu3O7−δ have been found in the film. The substrate temperature during deposition is one of the major factors that determines the crystal orientation of the YBa2Cu3O7−δ. In our experiment, effort is made to examine the influence of the initial substrate temperature from 595 °C to 660 °C on the relative amount of (110) and (103) oriented grains. The orientations are determined by x-ray analysis with a Weissenberg camera. The amount of (103) oriented YBa2Cu3O7−δ is reduced systematically with decreasing substrate temperature. At the lowest deposition temperatures we find only (110) oriented growth.

2016 Conference on Precision Electromagnetic Measurements (CPEM 2016), 2016

A reference system is developed for the on-site calibration of power transformer loss measurement... more A reference system is developed for the on-site calibration of power transformer loss measurement systems (TLMs). A crucial element in such calibrations is the availability of voltage and current signals with adjustable phase close to 90, that is power factor near to zero, in order to apply a known and stable loss or reference power to the TLM. In the new VSL reference system, digital signal processing is used to maintain the phase relation between the voltage (up to 100 kV) and the generated current (up to 2000 A) applied to the TLM. Initial results indicate that phase uncertainties of better than 20 rad can be obtained.

The propagation of Power Quality (PQ) phenomena through distribution networks is dependent on a n... more The propagation of Power Quality (PQ) phenomena through distribution networks is dependent on a number of parameters, including the characteristics of the disturbance source, impedances and configuration of the network and behaviour of loads and generators in the analysed area. Due to the large numbers of network users, estimation of disturbance levels in the network includes a large number of uncertainties. This paper proposes a method for analysing the propagation of PQ phenomena through the distribution network based on wide-area field measurements. In the future, the method will be used to analyse the data obtained from Live-Lab-the permanent field experiment of the Dutch DSO Alliander. The analysis takes into account the state of the network, loading of substations and measurement uncertainty.

29th Conference on Precision Electromagnetic Measurements (CPEM 2014), 2014

ABSTRACT A description is given of a new EU funded project on metrology in support of smart elect... more ABSTRACT A description is given of a new EU funded project on metrology in support of smart electrical grids. This project is a partnership of 14 EU NMIs and two universities. Research themes are described including: i) wide-area power quality (PQ) propagation, ii) Phasor measurement Units (PMU) for distribution networks, iii) network impedance measurements and iv) transducer metrology in support of PMU/PQ.

29th Conference on Precision Electromagnetic Measurements (CPEM 2014), 2014

ABSTRACT This paper describes the design and construction of an openable core current transformer... more ABSTRACT This paper describes the design and construction of an openable core current transformer (CT) to be used on high-voltage lines or busbars. The current sensor consists of a high current stage with a ratio of 400:1 and a low current stage with a ratio of 100:1. Both have a toroid core and are of the enhanced core type. The high current stage is cut in two halves to be able to connect without breaking the high voltage line. The overall accuracy is limited by the cut core of the high current stage. The accuracy is < 10 µA/A and < 5 µrad.

2012 IEEE Power and Energy Society General Meeting, 2012

ABSTRACT Instrument transformers are crucial elements in the metering infrastructure of high volt... more ABSTRACT Instrument transformers are crucial elements in the metering infrastructure of high voltage grids. With the evolvement of smart grids and the liberalization of the electricity market, new billing points can arise in the grids where electrical energy is transferred between different parties. When these new billing points are at existing places in the grid, it is strongly preferred to use the available instrument transformers for realization of a revenue metering system rather than installing new CTs and PTs. However, these available instrument transformers do not always meet the accuracy class requirements prescribed by legislation like electricity metering codes. In this paper, we present the results of an extensive performance evaluation of the ratio error of high voltage CTs under actual operating conditions. The aim of this evaluation was to find out to what extent CTs that do not meet the required accuracy class can nevertheless be used for revenue metering systems when their ratio errors are measured and corrected for. The study has a significant impact on the expansion of the metering infrastructure within smart grids, since it paves the way to a significant cost saving in the realization of new revenue metering setups.

2012 Conference on Precision electromagnetic Measurements, 2012

ABSTRACT This paper describes the selection and characterization of resistors for a 1000 kV HVDC ... more ABSTRACT This paper describes the selection and characterization of resistors for a 1000 kV HVDC divider. One thousand 10 MΩ resistors will be connected in series in the final design. Due to the large number of resistors only a randomly selected set has been characterized. The measured temperature and voltage coefficients of the resistors are around 1 μΩ/Ω/K and -10 μΩ/Ω/kV respectively, which make them very suitable for reaching the overall desired divider uncertainty of better than 100 μV/V.

Physical Review Letters, 1996

Film growth of a complex oxide is investigated during nucleation on a substrate surface. Using at... more Film growth of a complex oxide is investigated during nucleation on a substrate surface. Using atomic force microscopy we have imaged subunit cell coverage of SmBa 2 Cu 3 O 7 deposited by reactive molecular beam epitaxy on a (100) SrTiO 3 substrate. After a threshold deposition, c-axis islands are observed to nucleate predominantly along the surface steps. The heights of the nucleation islands are examined and a consistent layer stacking model is proposed. Cation stoichiometry of the nucleation islands is inferred to be dependent on the substrate surface and different from the bulk. [S0031-9007(96)00404-8]

Physica C: Superconductivity, 1993

Abstract We have fabricated Sm---Ba---Cu---O thin films at 550–850 C and at oxygen pressures of 1... more Abstract We have fabricated Sm---Ba---Cu---O thin films at 550–850 C and at oxygen pressures of 1.2–6.0× 10− 5 mbar in the presence of ozone. Various groups have reported on the existence of a solid solubility region in bulk Sm 1+ x Ba 2-x Cu 3 O y made at ...

Physica B: Condensed Matter, 1990

Specific heat measurements between about 25 and 800 mK, and in magnetic fields of 0, 0.45 and 1.5... more Specific heat measurements between about 25 and 800 mK, and in magnetic fields of 0, 0.45 and 1.55 T are presented of the high-Tc superconductors RBa2Cu307-x with R = Y and Tm, and x~0.2. For both compounds, the zero field results can be described with C = aT-2 +bT a , where a = 0.31 and 0.70