Iwao Miyachi

Estimation of High Temperature in Air Arc by Integrated Measurement of Emission Coefficients in Concentrated Band Spectrum Radiated from N2+ Molecules

A new spectroscopic method is proposed for measuring high temperature in air arc discharges. The remarkable feature of this method is to measure the integrated emission coefficients of the selected nineteen rotational lines concentrated around the band head of 391.5 nm, which are radiated due to B2¿u+-X2¿g+(0, 0) transition in N2+ molecules. Since the band spectrum is not resolved into an individual line in this method, it is permissible in experiments to use a conventional mono-chromater with a low resolving power. The observed intensity is strong enough to be detected. The temperature dependence of the integrated emission coefficients has a maximum of 8900 K in air at 1 atm, and, therefore, the temperature can be easily estimated from the relative intensity measurement by means of Larenz method. The obtained temperature distributions in the wall-stabilized air arc columns are in good agreements with the theoretically obtained ones.

Characteristics of lightning surges observed at 77 kV substations

In order to improve power supply reliability, it is necessary to prevent lightning faults in transmission lines and substation apparatus. However, faults are caused occasionally in lower-voltage power systems, particularly at the 77 kV level. The governing factor for insulation strength of substation apparatus is the lightning impulse voltage, and it is necessary to know the voltage level and distribution in a substation caused by lightning surges in order to investigate rational insulation coordination. For this purpose, the authors measured lightning surges at two 77 kV conventional substations from 1990 to 1993. In this paper, the characteristics of induced lightning surges and back flashover lightning surges are described. Comparisons of related surge voltages at two substations, the power line phases in grounding faults, and the equivalent capacitance of the substations are also discussed.