| 摘要 |
PURPOSE:To easily detect the formation state of an insulating thin film formed on the surface of a contact to be measured by comparing the distortion of an applied voltage with that of a passing current when a low-voltage AC current is flowed to the contact to be measured. CONSTITUTION:The AC voltage is applied to the contact S to be measured in a made state from an AC power source E through a load resistance R. The voltage applied to the contact S to be measured is at several V, but it is difficult to measure directly the passing current of the contact because the current level is extremely low. For the purpose, the voltage developed across the load resistance R is amplified by a linear amplifier A and inputted to a distortion factor meter DM. A changeover switch SW is placed on the side of a standard resistance RS firstly to measure the distortion factor of the AC power source itself, and the switch SW is then switched to the size of the contact S to be measured to measure the distortion factor of the current passing through the contact to be measured. In this case, the relation between the film thickness and distortion factor is obtained previously, and consequently the thickness of a film of the same kind is estimated.
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