A current transformer test set (CTTS) calibrator consisting of capacitors and resistors was fabricated. The calibrator was utilized for the calibration of several commercial CTTSs and covered a ratio error and phase error range up to ±10% and ±10 crad, respectively. From the calculated and measured values of the corresponding readings, the errors in the ratio and phase readings are derived. The calibration results for several commercial CTTSs are presented with the measurement uncertainty and are compared with the specifications provided by the manufacturer. The absolute uncertainty of a CTTS for both the ratio and the phase for the entire investigated range was obtained. The absolute uncertainty for the ratio error range of –0.1% to +0.05% was found to be less than 10 × 10−6 and the absolute uncertainty of the phase error range of –0.1 to +0.1 crad was not more than 6 µrad.

A portable error simulator for evaluating voltage transformer test set(VTTS) using a voltage divider consisting the serial combination of the resistor and capacitor was developed. The error simulator was applied to the calibration of several type commercial current-comparator-based VTTS and covered the ratio error and phase error range up to 10 % and 15 crad, respectively. From the calculated and measured values of corresponding readings, the errors in the ratio error and phase displacement readings are derived and compared with the accuracy provided by manufacturer.Index Terms -Voltage divider, current comparator, voltage transformer test set, ratio error, phase displacement, calibration.

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: Methicillin-resistant Staphylococcus aureus (MRSA) is a substantial contributor to morbidity and mortality. In search of a natural products capable of inhibiting this multidrug resistant bacteria, we have investigated the antimicrobial activity of brazilein (BRZ) isolated from Caesalpinia sappan L. (Leguminosae) against 8 different strains of Staphylococcus aureus (S. aureus). New antimicrobial activity was found using the minimum inhibitory concentrations (MICs), broth dilution as well as checkerboard method. Against the 8 strains, the minimum inhibitory concentrations of BRZ were in the range of 62.5-500 ㎍/mL. From those results we performed the checkerboard test to determine the synergism of BRZ in combination with Hygromycin-b (HgB) against 4 strains. The combined activity of BRZ and HgB against 4 strains resulted in a fractional inhibitory concentrations index (FICI) ranging from 0.18-0.5. The effect of BRZ with HgB was found to be synergistic. We found that BRZ reduced the MICs of HgB. BRZ and HgB could lead to the development of new combination antibiotics against MRSA infection.