Effect of modified multipliers resistors on measurement of AC voltages above 50 V

The effect of the modified multiplier resistor on the measurement accuracy of ac voltages higher than 50 V is studied and evaluated in this paper. Modification in construction is made in the multiplier design which used for higher voltages. Ten resistors are radially connected in series and mounted on a high insulation PCB board instead of using one resistor which has higher power rating and thickness. The introduced multipliers values which are established at the National Institute of Standards (NIS), Egypt are 10 k Omega, 20 k Omega and 40 k Omega for voltages 50 V, 100 V, and 200 V respectively. The high voltage modified multipliers are joined with single junction thermo-elements to produce the modified thermal voltage converters (TVCs). The modified TVCs are calibrated against other standard TVCs at different frequencies 20 Hz, 55 Hz, 1 kHz, 10 kHz, and 100 kHz. The ac-dc transfer differences of the modified TVCs are compared with the traditional TVCs to evaluate its performance. They introduce lower ac-dc differences than the traditional ones specifically at higher voltages and frequencies. The modified TVCs performance is also evaluated by comparing their measurement accuracy and precision at range 100 V with the traditional TVCs.