Silver contacts are separated at constant speed and break arcs are generated in a 300V-450V DC and 10A resistive circuit. The transverse magnetic field of a permanent magnet is applied to the break arcs. Motion of the break arcs, arc duration and the number of reignitions are investigated when side surfaces of the contacts are covered with insulator pipes. Following results are shown. The motion of the break arcs and the arc duration when the anode is covered with the pipe are the same as those without pipes. When the cathode is covered with the pipe, the motion of break arcs change from that without the pipes and reignitions occur more frequently. The arc duration becomes longer than that without the pipes because of the occurrence of reignitions. The number of reignition increases with increasing the supply voltage in 300V-400V. The period of occurrence of the reignition with pipes is shorter than that when the cathode is covered with the pipe.

In this paper, a contactless measurement technique of passive intermodulation (PIM) using a coaxial tube excited with standing waves is proposed. The principle of the proposed method is described using a two-port network model with the lumped resistances representing the losses of a specimen and test equipment. To show its validity, a test using nickel wires producing high PIM is carried out, and its PIM-dependency on DUT-position in the coaxial tube is simulated using the FDTD method. The simulated result shows a good agreement to the experiment. Through the examination, it is found that the power consumption by the PIM source in a specimen is essential in PIM production, and sensitive PIM detection does not require good matching condition. Finally, the relation between PIM-source size and generated PIM level is also examined. The result shows that at least 18 dB-PIM reduction is obtained by PIM source size in a half-wavelength conductive wire.

VI time responses of a conventional electromagnetic relay during breaking contact operations were measured. In a conventional switching circuit, unstable contact resistance, irregular bouncing, and poor reproducibility were confirmed. Using a transient current switch circuit and two sharpened contact electrodes, bouncing during a breaking operation was suppressed, and unstable contact resistance changes and reproducibility of breaking operation were also improved.

We propose a new electric contact device that greatly improves arc discharge characteristics. Electric contact functions are divided into an energizing operation and a switching operation. A capacitor is connected in series to a contact for switching contact. Using two conventional relay contacts, no arc operation is confirmed for a 42 V/3 A break operation. Contact resistances are measured over many operations, and the surfaces of electrodes are observed. A chip capacitor is arranged at one side of the contact electrodes of a twin relay, confirming the possibility of miniaturization.