PTB's new standard impulse voltage divider for traceable calibrations up to 1 mv

Summary

Due to the growing energy demand, not only in Europe, the energy grid capacitance is needed to be enlarged significantly. Such an evolution of energy distribution, especially of transmission grids is characterized by enlargement of the voltage levels up to e.g. 800 kV, 1000 kV or even 1200 kV. This continuously increasing voltage levels on power transmission lines require enhanced testing equipment for higher voltages. Unless a direct calibration is possible, the high voltage dividers are calibrated at 20 % of the measurement range and extrapolated to the rated voltage with a linearity test using varied techniques. However, this extrapolation is time consuming and adds an assigned measurement uncertainty to the high voltage calibration. The need for precise calibration of ultra-high voltage (UHV) dividers requires particular facilities and reference measuring systems for high voltages up to 1 MV to reach 20 % of the expected UHV range of 4 MV to 5 MV. The design, setup and calibration of PTB’s new modular 1 MV damped-capacitive voltage divider, commonly known as a Zaengl divider, for HV impulse measurements are presented. The divider consists of two high voltage arms including non-inductive carbon resistors, frequency independent ceramic capacitors as well as ceramic resistors in the low voltage arm. The matching of the divider, the measuring cable and the transient recorder has been carried out carefully. A complete calibration with lightning, switching, and chopped lightning impulses in the range of 200 kV to 1 MV was undertaken at the Physikalisch-Technische Bundesanstalt (PTB) in cooperation with the TU Braunschweig. An entire evaluation of the calibration uncertainty was carried out in order to confirm this new divider as a part of the reference system. The determined peak-voltage and time deviations of the new divider compared to the existing reference divider are below the measurement uncertainties of the PTB for peak voltages and time parameters.

Additional informations

Authors

FIGUEROA, AHTIAINEN, HILBERT, KURRAT

Keywords

lightning impulse, metrology, siwtching impulse, damped capacitive divider