Search

BACKGROUND: Epilepsy is a neurological disorder and its treatment is carried out with anti–epileptic drugs. Carbamazepine has been in use since 1965, as a safe and effective anti–epileptic agent. In this paper, a poly(vinyl chloride) (PVC) membrane carbamazepine selective potentiometric sensor was developed for the determination of carbamazepine in pharmaceutical formulations. Carbamazepine–tetraphenylborate (CBZ–TPB) ion−pair was synthesized as an electroactive component and PVC membrane sensors were prepared with different CBZ–TPB ratios. The membrane with the best analytical properties was determined as the one with 2.0% CBZ–TPB ion–pair, 33.0% PVC and 65.0% o–nitrophenyl octyl ether (o–NPOE). RESULTS: The proposed sensor exhibited linear responses over the concentration range 1.0 × 10−5 – 1.0 × 10−2 mol L−1 (R2 = 0.999). The limit of detection was 9.60 × 10−6 mol L−1. The developed sensor showed high selectivity against carbamazepine over some ionic species investigated and also over other anti–epileptic drugs. The potentiometric response of the sensor was not affected by pH in the wide pH range of 4.0–9.0 and the response was fast, at ≈10s. CONCLUSION: The fabricated carbamazepine–selective sensor was applied for the determination of carbamazepine contents of some pharmaceutical formulations. The potentiometric measurement results for the pharmaceutical formulations gave results with good agreement with data obtained using UV–visible spectroscopy. As a result, the developed carbamazepine selective potentiometric sensor can be considered as an alternative to other analytical methods for the determination of carbamazepine in pharmaceutical samples. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

This paper describes the design, implementation, and performance of a medium-size distribution-type static synchronous compensator (D-STATCOM) with the simplest two-level three-leg voltage-source converter (VSC) topology. Reactive-power control is achieved by phase-shift-angle control, and VSC harmonics are eliminated by selective harmonic elimination method (SHEM). VSC has been designed at the highest low-voltage level of 1 kV and connected to a medium-voltage (MV) bus through a low-pass input filter and [DELTA]/Y-connected MV/1-kV coupling transformer. At the MV side of D-STATCOM, line-current harmonics are minimized to comply with the IEEE Std. 519-1992 for the weakest supply conditions by applying 8-angle TLN2 elimination technique. This necessitates switching the water-cooled high-voltage insulated-gate bipolar transistor (HV-IGBT) modules at 850 Hz, thus eliminating 5th, 7th, 11th, 13th, 17th, 19th, 23rd, and 25th voltage harmonics at the input of VSC. By carefully designing the laminated bus system and selecting minimum stray-inductance dc-link capacitors directly mountable on the laminated bus, stray inductance of the commutation path is brought to a nearly absolute minimum of 60 nH, thus maximizing the utilization of wire-bond single-side cooled HV IGBTs and eliminating the need for RCD clamping snubbers. The performance of SHEM, together with the phase-shift-angle control, has been tested in the field on a 0-1780-kVAr capacitive 6.3-kV VSC-based D-STATCOM (-750/+ 900 kVAr VSC) prototype. Field-test results show that SHEM, together with phase-shift-angle control, leads to optimum switching frequency and device utilization for HV IGBTs and high system performance at the expense of slower response as compared to the other known control techniques. Index Terms--Power quality, selective harmonic elimination, static VAR compensator, voltage-source converter (VSC).

This paper deals with the development and implementation of a current-source-converter-based static synchronous compensator (CSC-STATCOM) applied to the volt-amperereactive (VAR) compensation problem of coal mining excavators. It is composed of a [+ or -] 750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a [DELTA]/Y-connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyristor (IGCT) connected in series with a reverse-blocking diode and switched at 500 Hz to eliminate 5th, 7th, 11th, and 13th current harmonics produced by the CSC. Operating principles, power stage, design of dc link, and input filter are also described in this paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAR consumption of electric excavators, resulting in nearly unity power factor on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with the IEEE Std. 519-1992. Index Terms--Current-source converter (CSC), harmonic elimination, power quality, static VAR compensator (SVC).

Design and implementation of a unified, relocatable static var compensator (SVC) meeting the reactive power compensation needs of various coal enterprises of Turkey for open-cast lignite mining are presented. Design and sizing of SVCs are based on mains data for all possible connection points, load bus data recorded in the field, monthly electric bills, and simulations carried out on PSCAD/EMTDC, SPICE, and MATLAB. In addition to standard ac/dc converter and motor tools used in the modeling of electric excavators, actual load characteristics obtained from data collected in the field by means of a data acquisition system have been processed in PSCAD/EMTDC to find out reactive power demand of each load bus, and to optimize sizing of the SVC within the power-factor penalty limits imposed by electricity authorities. The SVC component ratings have been based upon the suitability to all possible loads under worst operating conditions, thus making sure that they can be operated for different loading conditions, minimizing stock requirements, and inspection and maintenance costs. The implemented systems are flexible and extendable in order to meet the future needs of coal enterprises. Index Terms--Reactive power control, real-time data simulation, relocatable, thyristor applications.

In this paper, the combination of a thyristor-switched shunt reactor and a current source converter-based active power filter has been proposed for mitigation of power quality (PQ) problems of Light Rail public Transportation Systems (LRTSs) fed by long medium-voltage underground cables. A case study has been carried out on a typical LRTS to assess the performance of the proposed solution for both capacitive reactive power compensation of underground cables and harmonic filtering of 12-pulse catenary rectifiers. It has been shown by extensive field tests carried out that this solution meets the requirements satisfactorily, thus constituting a complete solution to the PQ problems of LRTS. Conventional PQ solutions have been also assessed, and the corresponding theoretical results are given in comparison with the proposed system. [ABSTRACT FROM PUBLISHER]