MAPAN
Regular calibration of the Instrument Transformers (ITs) is very essential for the accurate measurement of power and energy at high voltages. ITs are also used in the measurement of high currents & high voltages at power frequencies. The nominal transformation of an IT depends only on the number of turns of its windings but due to various losses there are always errors in the Instrument Transformers’...
A portable system for on-site calibrations of isolating current transformers in stationary energy meter test systems is described. The uncertainties of the calibration system are in the order of 0.005 % for the ratio error and 0.01 crad for the phase displacement of the current transformer at power frequencies. The power comparator based measurements can be done at test currents from 50 mA to 120...
The present PTB primary standard allows power measurements with a measurement uncertainty of about 2.5 μW / VA (k = 2). It operates at voltages up to 240 V and currents up to 10 A in the frequency range from 16 Hz up to some kHz. This paper gives a short overview of the working principle of the standard and recent improvements.
The magnetic field of a single-layer solenoid (length L=1020 mm, average radius R=114.67 mm, pitch p=1.0001 mm and wire diameter d=0.799 mm) with a multi-current method was calculated to improve the uniformity and optimized by using Legendre polynomials. The optimum conditions obtained by the calculations for the uniform magnetic field lead to insensitive magnetic field with respect to the radius...
AC power & energy standard of National Physical Laboratory, India (NPLI) is responsible for maintenance of national measurement standard of ac power & energy and international traceability through intercomparisons. It serves as the basis for dissemination of traceability in measurement through high level calibration and measurement services to the various user organizations in the country...
Proficiency testing (PT) program in AC Power & Energy measurements was conducted for 12 National Accreditation Board for Testing and Calibration Laboratories (NABL) accredited laboratories of India. The program is conducted to determine the performance of individual laboratories for specific measurements and to monitor continuing performance by assuring the quality of results. National Physical...
The paper contains a full derivation of formulas that enable the conversion of current transformer errors measured at unity power factor burden to equivalent errors at 0.8 power factor lagging burden, required by IEC 60044-1, as well as errors at any other burden. The assumptions and limits of the formulas are discussed.
Measurement of volume ratio forms an essential part of the characterization of a static expansion system (SES) for the generation of pressures in the medium and high vacuum region. Because of the complexity of the vacuum chambers, it is not possible to determine the absolute volumes of the chambers involved. Hence an expansion process is resorted to, in which the gas enclosed in the small volume at...
The main factor to affect lower limit of static expansion vacuum standard is outgassing of the inner surface. A new method has been demonstrated to extend the lower limit by using a non-evaporable getter pump (NEGP) to eliminate the outgassing influence. Because NEGP has no pumping speed for inert gases, it can maintain the ultra-high vacuum background without changing gas quantity in the calibration...
Korea Research Institute of Standards and Science (KRISS) has assembled a new flow-control system (FCS-705) for the study of advanced applications and calibration of different types of vacuum gauges by comparison method. This report details the measurement of the outgassing rate of the main vacuum chamber by the pressure rate of rise method. Constant pressure was generated inside the vacuum chamber...
This paper reports the performance of the calibration results obtained by 21 laboratories using digital pressure calibrator as an artifact in the pressure range 7–70 MPa. National Physical Laboratory (NPLI), New Delhi has coordinated this programme and also acted as a reference laboratory. The program started in May, 2006 and completed during May, 2008. The comparison was carried out at 10 equally...
The Part 1 of this paper discussed the determination of the volume ratio of the Static Expansion Primary Vacuum Standard (SES). Part 2 of the paper discusses in detail the use of the SES thus characterized for generating primary pressures. This standard has been used to calibrate Spinning Rotor Gauges (SRGs) at a number of pressures in the range 0.1 Pa to 1 Pa in steps of 0.1 Pa. The Gauge Coefficient...
This paper discusses an extended usage of conventional pressure balances for measurements of pressure down to a few Pa. Generally pressure balances are widely used as pressure standards but they have a major disadvantage, that is, their inability to operate at pressures below a limit determined by the mass of floating elements. This limit is typically around 5 kPa. Several approaches have been tried...
Accurate calibrations of gauges to ever lower pressures (higher vacuum) are increasingly becoming necessary. The calibrations over the entire ultra high vacuum (UHV) range i.e. up to 10−10 Pa are already sometimes demanded by the users of vacuum measuring devices. Standards covering part of this range are available in some national metrological laboratories while primary standards covering the entire...
The online version of the original article can be found at http://dx.doi.org/10.1007/s12647-009-0016-8
Compact and cost-effective array spectroradiometers are increasingly used in photometric and radiometric measurements. In this report, results of the colorimetric characterisation of LEDs using both low-end and high-end array spectroradiometers are compared to those obtained with the help of a conventional scanning double-monochromator spectroradiometer. Problems related to the utilisation of the...
In detector output-signal measurements, where the measurement uncertainty critically impacts the total uncertainty of a detector-based radiometric scale realization, traceability of the photocurrent measurement to SI traceable electrical standards is needed. A reference photocurrent-to-voltage conversion scale has been developed and described here. The new standard has internal reference resistors...
Versatile applications in radiometry and photometry require uniform light source systems with a highly Lambertian radiance/luminance output. Examples for this kind of requirements include different applications such as calibration of photometers and radiometers, testing of electronic imaging devices like CCDs or similar array detectors or the use as a homogenous light source in, for instance, gonioreflectometric...