Electrical Power Measurements Research Articles

Estimation of Optical Power and Heat-Dissipation Coefficient for the Photo-Electro-Thermal Theory for LED Systems

With the use of wall-plug efficiency, estimation techniques for the optical power and heat-dissipation coefficient of LEDs are introduced in this paper to enrich the photo-electro-thermal theory, which has provided a framework for analyzing LED systems. The estimation methods consist of simple procedures for optical and electrical power measurements, which are easy for LED device manufacturers and system designers to follow. The extended theory has been tested with several types of LED devices, with reasonably good agreements between theoretical and practical results.

Luminous efficacy measurement of solid-state lamps

We present a system for luminous efficacy measurements of solid-state lamps (SSLs). It is based on a 1.65 m integrating sphere, originally designed for luminous flux measurements of dc-operated incandescent standard lamps. The sphere was slightly modified, and equipped with a programmable ac-power supply, as well as equipment for electrical power measurement of the lamps. The waveforms of both the electrical power and the luminous flux can be measured for analysing the quality of the electronics and the light produced by the SSLs. A goniospectrometer is used for angular characterization of the lamp intensity. Luminous efficacy test measurements were conducted for a group of 25 SSLs of different types. Special attention was paid to the spectral, spatial and self-absorption corrections to obtain low measurement uncertainty. The luminous efficacies were between 25 lm W−1 and 64 lm W−1, and the total harmonic distortions of the current waveforms were in the range of 30% to 280%. Depending on the lamp, the maximum deviation of the flux from its mean value was 0.06% to 105%. The relative expanded uncertainty obtainable for the luminous efficacy of a typical SSL with stable built-in electronics is 1.2% (k = 2).

The study of carbon nanotubes as coating films for electrically calibrated detectors

A UV electrically calibrated pyroelectric detector is developed in this paper which was used to establish an electrically calibrated system for high-accuracy UV radiometric calibration. A single crystal of (1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-PT), as one of the best pyroelectric materials, was selected as the detector material. Research on the coating film on the surface of the sensitive area was carried out. A carbon nanotube (CNT) film was selected as the coating material. The UV reflectivity of samples with the sheet resistance from 100 to 150 Ω is in the range of 1.6–4.2%, and the highest reflectivity is in the vicinity of 265 nm. Both the UV radiant heating and the electrical heating in the CNT film can result in a temperature change. Accordingly, the film can work both as an optical absorber and as an electric heater. By means of this, the measurement of UV radiation power can be converted to the measurement of electrical power. The uniformity of the detector was studied; the typical nonuniformity is less than 2% in the active region of the ϕ8 mm optical absorption. The responsivity of the detector is about 18.3 V W−1 at 14 Hz, 365 nm.

Meeting the challenges of precision testing of automotive electric vehicle machines

Intertek Transportation Technologies (ITT) has pioneered automotive high-voltage electric machine testing in the UK since 2011. This article describes the many challenges encountered in testing high-voltage, high-speed pulse width modulated inverter-driven electric machines and in delivering accurate and trustworthy data. The article describes how ITT has pioneered new developments in test rig design, overcome the significant challenges of gathering accurate data in an inherently electrically noisy environment and provided fully traceable high bandwidth instrumentation to deliver trustworthy measurement of speed, mechanical power, electrical power and temperatures. The article also looks to the future of testing in this fast moving landscape.

Development of Electric Power Measurement for Energy Harvesting using Unimorph-type Piezoceramics

In this study, a new electric power measurement system for energy harvesting using unimorph-type piezoceramics was developed. It shows Fig. 1(a). Relationships between electric power and material constants such as d33, d31, g31, k31, ε33T/ε0, s11E, Qe and Qm were investigated using various Lead zirconium titanate (Pb(Zr,Ti)O3, PZT) ceramics with different material constants. Using the equipment, stress with pulse-shape was applied to unimorph-type piezoceramics. Then, optimum measurement conditions were studied and determined. Under these conditions, the electric power for energy harvesting was measured as a function of the material constants. The result showed figure of merit for piezoelectric energy harvesting in case of using a unimorph-type device is combination of the 3 kinds of material constants such as large figure of d31, small figure of ε33T/ε0, and large figure of s11E.

Development of Electric Power Measurement for Energy Harvesting Using Unimorph-Type Piezoceramics

In this study, a new electric power generation measurement system was developed for piezoelectric energy harvesting using unimorph-type piezoceramics. Relationships between electric power and material constants such as d33, d31, g31, k31, e33T/e0, s11E, Qe and Qm were investigated using various lead zirconium titanate (Pb(Zr,Ti)O3, PZT) ceramics with different material constants. Using the equipment, pulse-type stress was applied to unimorph-type piezoceramics. Then, optimum measurement conditions were determined. Under these conditions, the electric power for piezoelectric energy harvesting was measured as a function of the material constants. Finally, it was clarified that for piezoelectric energy harvesting using a unimorph-type device, the figure of merit was combination of the 3 kinds of material constants such as large d31, small e33T/e0, and large s11E.

Study of a TE (thermoelectric) generator incorporated in a multifunction wood stove

Replacing traditional open fire stoves, characterized by low efficiency, with improved ones is an important challenge for developing countries. Adding TE (thermoelectric) generators can provide electricity that permits not only the use of an electric fan increasing the ratio air to fuel to achieve a complete combustion in the stoves but also the satisfaction of basic needs: light, phones and other electronic devices. A review of existing TE generators for stoves is presented. To test the TE modules, an experimental device has been carried out in our laboratory where a gas heater simulates the stove. The generator set-up is described including the switching electric regulator that stabilizes the fluctuating voltage from the modules and stores the energy in a battery. The performance of the generator mostly depends on the heat transfer through the modules and especially on the thermal contact resistances. First experiments show the influence of the pressure on these resistances. Then a study of temperatures and electrical power measurements is compared to a theoretical analysis using TE and heat transfer equations. The very reasonable value of the obtained contact resistances shows that the mechanical design of the generator is almost optimized. The TE generator has produced up to 9.5 W.

Instantaneous input electrical power measurements of HITU transducer

HITU (High Intensity Theraupetic Ultrasound) transducers are widely used in therapeutic ultrasound in medicine. The output ultrasonic power of HITU transducer can be measured in number of methods described in IEC 61161 standard [1]. New IEC standards specifically for measurement of HITU equipment are under development. The ultrasound power radiated from a transducer is dependent on applied input electrical voltage and current and consequently power. But, up to now, no standardised method has been developed and adopted for the input electrical power measurements. Hence, a workpackage was carried out for the establishment of such method in the frequency range of 1 to 3 MHz as a part of EURAMET EMRP Era-net plus "External Beam Cancer Therapy" project. Several current shunts were developed and evaluated. Current measurements were also realized with Philips current probe and preamplifier at NPL and Agilent current probe at UME. In this paper, a method for the measurement of instantaneous electrical power delivered to a reactive ultrasound transducer in the required frequency range is explored.

Measurement of Instantaneous Shaft Speed by Advanced Vibration Signal Processing - Application to Wind Turbine Gearbox

Condition monitoring of machines working under non-stationary operations is one of the most challenging problems in maintenance. A wind turbine is an example of such class of machines. One of effective approaches may be to identify operating conditions and investigate their influence on used diagnostic features. Commonly used methods based on measurement of electric current, rotational speed, power and other process variables require additional equipment (sensors, acquisition cards) and software. It is proposed to use advanced signal processing techniques for instantaneous shaft speed recovery from a vibration signal. It may be used instead of extra channels or in parallel as signal verification.

Efficiency Evaluation of Phosphor-white High-power Light-emitting Diodes

High-power light-emitting diode (LED) efficiencies are strongly dependent on device type and operating conditions. Electrical and optical power measurements are performed on five commercially available phosphor-white LED types for a number of independently enforced forward currents and junction temperatures. The experimental results allow for a comparative evaluation of dominant loss mechanisms and their current and temperature dependences.

Characterization and Transport Properties of Indium Sesquitelluride Monocrystals

In the present study, single crystals of defect semiconductor In2Te3 were grown by the Bridgman technique. An investigation was made on the Hall effect, electrical conductivity and thermoelectric power of In2Te3 monocrystal in wide temperature range. The investigated samples were p-type conducting. The Hall coefficient yields a room-temperature carrier concentration of 7.8 x10 9 cm -3 . The band gap was found to be Δ Eg = 0.99 eV. Hence a combination of the electrical conductivity and Hall effect measurements enable us to study the influence of temperature on the Hall mobility and to discuss the scattering mechanism of the charge carriers. Also the present investigation involves thermo -electric power measurements of In2Te3 single crystals, These measurements enable us to determine many physical parameters such as carriers mobilities, effective masses of free charge carriers, diffusion coefficients, diffusion length, as well as relaxation time. Also the figure of merit was determined.

Thermal Protection System for Underwater Use in Cold and Hot Water

Underwater workers, sport and military divers, are exposed to thermal stress since most of the waters of the world are below or above what is thermally neutral. Although divers wear insulation suits for passive thermal protection they are inadequate. Active heating is currently accomplished by resistive heating and open-flow tubes delivering hot water; however, these methods are problematic. The challenge of this project was to design, build and test an active diver thermal protection system (DTPS) to be used with wet suit insulation that is effective, user-friendly, reliable, and that could be used by a free-swimming diver. The DTPS has a minimum number of moving parts, is low maintenance, has no unsafe or toxic working fluid and uses no consumables except a safe, high density, modular electrical power source. A portable and swimmable, self-contained, electrically powered unit (DTPS) has been designed, built, and tested that produces and circulates thermally conditioned water in a closed-loop through a zoned tube suit worn by a diver under a wetsuit to maintain skin and body core temperatures within prescribed safe limits. The system has been validated by using physiological data taken on human subjects over a wide range of ambient water temperatures. Corresponding enthalpy and electrical power measurements were used as the basis of a thermodynamic analysis. The DTPS maintained skin and body core temperatures within safe and functional ranges by providing up to about 200 W of heating in cold water and up to about 330 W of cooling in hot water. The corresponding electrical power consumption was up to about 300 W in cold water and up to about 1500 W in hot water. The results of a complete audit of the power use and heat transfer are presented along with the efficiency of the thermoelectric heating/cooling modules and the duty cycle of the system for a range of water immersion temperatures from 10°C to 39°C. The DTPS proved to be an effective and reliable apparatus for diver thermal protection in water temperatures from 10°C to 39°C, which covers most of the range of the earth’s waters. The data presented here can be used to modify the design of the DTPS to meet specific needs of the diving community.

Total solar irradiance absolute level from DIARAD/SOVIM on the International Space Station

Current measurements from DIARAD/VIRGO, PMO6V/VIRGO and ACRIM3 radiometers are of the same order of magnitude, but differ from TIM/SORCE by about 4.5 W m −2. This difference is higher than the sum of the claimed individual absolute uncertainties of the instruments. In this context, the SOLAR payload on the International Space Station embarks the SOVIM package. We give the results of the differential absolute radiometer DIARAD/SOVIM and discuss its associated uncertainties. Compared to DIARAD/VIRGO, all possible efforts have been made to improve the absolute accuracy. Substantial progress has been made in the aperture area and electrical power measurements. The measured TSI value from the left channel of DIARAD/SOVIM during three days of June 2008 is 1364.50 ± 1.38 W m −2 (Total) or ±0.49 W m −2 (if we combine the individual contributions in quadrature). The right channel gives 1364.75 W m −2 with the same uncertainties. These values are about 1.2 W m −2 lower than DIARAD/VIRGO and about 4 W m −2 higher than TIM/SORCE. The difference between the left and right channels measurements is as low as 0.25 W m −2 which is within the improved uncertainty limits.

Mechanochemically induced amorphous/crystalline phase transition in the Bi 4Ti 3O 12 compound

Concurrent milling of Bi 4Ti 3O 12 was carried out in a planetary ball mill with hardened-steel 13 or 6 mm diameter balls with a goal to investigate how the system responds to the constrains imposed by milling. Milling intensity for various milling parameters was derived from the electrical power measurement. The reverse amorphous ↔ crystalline phase transition induced by milling is governed by impact energy and frequency. Below a certain threshold value of impact energy crystallization does not occur, whereas a higher impact frequency accelerates amorphization. Mechanochemical reactions are predominantly discrete processes, which occur at the moment of impact.

Measurement of electric power using an optical fiber grating

AbstractThere is increasing motivation to develop sensors and actuators to manage domestic electric power consumption. This article demonstrates an optical fiber sensor using a superstructure fiber grating (SFG) to measure electric power consumption. The sensor head is based on SFG encapsulated in a polymer‐half‐field metal cylinder embedded a magnetic material at measure point. The operating mechanism is that the sensor can be attracted by the induced magnetic force created by the electric power in the solenoid along one radial direction only, and responds to an axial force on the magnetic rod attached to the round plate, creating an axial attraction on the SFG. Therefore, variations in attractive force cause center‐wavelength variations in SFB and long‐period grating acts as an edge filter converting strain‐induced wavelength variation into optical power measurement. Thus, the sensor can be used to measure electric power without the use of power meter. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2438–2441, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24660

Standard of Electrical Power at Frequencies Up to 200 kHz

This paper describes a standard for traceable measurements of electrical power of sinusoidal signals at voltages up to 1000 V, currents up to 20 A, and frequencies from 40 Hz to 200 kHz. The standard uses thermoelectric effects to relate the alternating power to that of known dc signals. It is comprised of a thermal power comparator, inductive and resistive voltage dividers, and a range of wideband current shunts. The performance of each of the components has been evaluated through traceable measurements in terms of fundamental standards. The paper presents the design of the system and its components, evaluation techniques, and measurement uncertainties.

Precision Differential Sampling Measurements of Low-Frequency Synthesized Sine Waves With an AC Programmable Josephson Voltage Standard

We have developed a precision technique to measure sine-wave sources with the use of a quantum-accurate AC programmable Josephson voltage standard. This paper describes a differential method that uses an integrating sampling voltmeter to precisely determine the amplitude and phase of high-purity and low-frequency (a few hundred hertz or less) sine-wave voltages. We have performed a variety of measurements to evaluate this differential technique. After averaging, the uncertainty obtained in the determination of the amplitude of a 1.2 V sine wave at 50 Hz is 0.3 muV/V (type A). Finally, we propose a dual-waveform approach for measuring two precision sine waves with the use of a single Josephson system. Currently, the National Institute of Standards and Technology (NIST) is developing a new calibration system for electrical power measurements based on this technique.

Electrical and thermoelectric power measurements of GaInSe2 single crystals

Abstract A single crystal of GaInSe 2 was prepared from melt using a vertical Bridgman technique. The crystal was characterized by X-ray diffraction and Energy dispersive X-ray fluorescence spectrometer (EDXRF). Electrical conductivity, hall effect, and thermoelectric power (TEP) measurements were performed in the temperature range from 120 to 570 K. Throughout these measurements, various physical parameters such as carrier mobilities, effective masses of charge carriers, diffusion coefficient, relaxation time, and the diffusion length for both majority and minority carriers were estimated. In conjunction with the electrical conductivity and the charge carrier concentration, the TEP is discussed. All crystals were found to be of p-type conductivity.

Changes in AC Power Standard in Japan

AbstractThe precise measurement of electric power will increase in importance because of the growth of power consumption and the deregulation of electric utilities. An electric power and energy calibration system was developed at the Japan Electric Meters Inspection Corporation (JEMIC) in 2004, and it was designated as the national electric power and energy standards in Japan in 2005 to replace the aging AC/DC watt comparator. The methods of establishing the electric power standard at foreign National Metrology Institutes (NMIs) can be classified roughly into a method by a sampling wattmeter, a method by the principle of the current comparator, and a method based on dual‐heater multijunction thermal converters. This article describes the transition of the electric power and energy standards in Japan and in foreign countries. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Electrical and thermoelectric properties of CuInS2 single crystals

Abstract Single crystals of CuInS2 were prepared by chemical vapor transport (CVT) technique. The crystals were characterized structurally by X-ray diffraction and compositionally by microprobe analysis. Measurements of the electrical conductivity and Hall effect were carried out in a wide temperature range (130–580 K). From these measurements the conductivity of the crystals was p-type. The electrical conductivity, Hall mobility and hole concentration at 300 K were found to be about 5 × 10−3 Ω−1 cm−1, 400 cm2 v−1 s−1 and 7.1 × 1012 cm−3, respectively. The energy gap was found to be 1.51 eV. Also, the present investigation involves the thermoelectric power measurements in temperature range (130–540 K). The combination of the electrical and thermoelectric power measurements in the present investigation makes it possible to find various physical parameters.