Assuring the Quality of Impulse Voltage Calibration Results Issued by a Calibration Laboratory
This paper describes high-voltage impulse measurements made under the controlled conditions of a calibration or national measurement laboratory to establish the best agreement that could be achieved in comparison measurements on small reference dividers. This comparison to establish mutual international traceability between NRC and National Grid has shown that the peak voltage of a smooth lightning impulse was measured by both laboratories to within 0.2% with an estimated uncertainty of ±0.2% at a level of confidence not less than 95%. The authors make recommendations on how calibrations of reference measuring systems should be performed.
Uncertainty Evaluation of the Waveform Parameters of 1-kV Low-Impedance Impulse Voltage Calibrator
The low-impedance impulse voltage calibrator of high accuracy and stability can be used as a primary reference of impulse voltage. It is recommended to be utilized in the calibration of the reference measuring system composed of impulse resistor divider and digital recorder in IEC 61083. The impulse voltage calibrator is made up of resistors and capacitors of given values. The parameters of its output waveform, Up, T1, and T2, can be calculated based on the parameters of the circuit elements and circuit principle of the calibrator. The uncertainties of the waveform parameters are always evaluated by Guide to the Expression of Uncertainty in Measurement (GUM) in previous publications. However, GUM exhibits some limitations when it is applied. In this paper, a 1-kV low-impedance impulse voltage calibrator (1.56 μs/60 μs) is developed. The values and uncertainties of Up, T1, and T2 are evaluated with another two new approaches, Monte Carlo method and random fuzzy variable (RFV). Particularly, the combination of several RFVs with both random and nonrandom effects is also discussed when RFV method is applied. The detailed process of each approach is presented and the results are compared.
Natural history and long‐term evolution in families with autosomal dominant cortical tremor, myoclonus, and epilepsy
Purpose:  To investigate for the first time the natural history and long‐term evolution of “familial cortical tremor, myoclonus, and epilepsy.”