Long-life contacts for unidirectional currents of 1¿20 amperes

After an introduction to vibrator-contact problems it is shown that platinum contacts exhibit reverse and zero migration in two sets of circumstances, namely at 1¿2 volts and at 10¿20 amp, a small arcquench inductance having a critical influence. A long, though not unlimited, vibrator-contact life was obtainable either from platinum contacts with appropriate circuit conditions or from contacts of dissimilar metals, but an adequate life on heavy duty was obtained only with tungsten contacts in an atmosphere free of oxygen to a high degree. The trend of methods for producing exceptionally long contact life is reviewed.