In a D.C.42 V-10A resistive circuit, break arcs are generated between electrical contact pairs. The materials of the contact pairs are Ag, Ag/C 2wt%, Ag/SnO2 12wt%, and Ag/ZnO 12wt%. The arc spectral intensities are measured by a time-resolved spectroscopic temperature measurement system. The arc temperature is calculated from the spectral intensities by using the method of relative intensities of two spectra. The experimental results are as follows. The arc temperature gradually decreases with increase of the gap of electrical contacts. The ranges of arc temperature for Ag, Ag/C 2wt%, Ag/SnO2 12wt%, and Ag/ZnO 12wt% contacts pairs are 4500-11000 K, 4000-6000 K, 4000-7000 K, and 4000-11000 K, respectively.

Breaking arcs are generated between a pair of Cu electrical contacts in a DC 42 V/10.5 A circuit, and the arc voltage, the arc current and the time-resolved arc spectral intensities near contact surfaces are simultaneously measured. The arc temperature is calculated from some spectral intensities emitted from Cu neutral atoms using the Boltzmann plot method. The arc temperatures near the cathode and anode surfaces are measured, and the following experimental results were obtained. (1) Time evolutions of the spectral intensities and the calculated arc temperature have similar characteristics. (2) The arc temperature near the anode surface is higher than that near the cathode surface, and the temperature fluctuation near the anode surface is larger than that near the cathode. (3) Just before arc extinction, the arc temperature near the cathode surface is almost constant for many breaking operations but the arc temperature near the anode surface varies.