How should the contact resistance of relay be measured?
Yes, in general, as long as the contacts are not exposed to sulfur, silicon and other substances, the surface if there is oxide film, as long as the current is repeated several times can be restored. This is mainly to use the energy of the arc to clean the contacts, and if this is not clean, then the relay can be judged to be invalid.
Arc is absolutely harmful, so there will be a vacuum relay and a high temperature metal with tungsten and molybdenum as contact. It is used to reduce arc and resist arc damage. If you use a large current to drive a contact that causes arcing, the result is that the contact creates an arc. The high temperature fusion will cause you to fail to separate the contact after power failure and cause an accident.
Arc can not clean electric shocks, who taught you? Isn't it harmful? The high temperature of arc will lead to contact surface pits, reduce contact area, high temperature shock accelerated oxidation, causing poor contact, effect of control equipment, if the arc can clean the contacts, why to relay with arc suppression circuit?Relay contact resistance is minimal when the normal head, almost with the conductive wire resistance, micro ohm meter measurement and not only as a reference, if long time high current, high temperature resistance caused by electric shock, increase the ultimate state of insulation was closed, this time is to use megohmmeter to measure, but this time has contact no, only the replacement of the emergency, the open water sandpaper potholes oxidation two contacts, glow after temporary use or use in small current equipment.
Can be judged by the sample of the manufacturer. Normally, this value is less than 100m. But if the relay is switched on for too long, the resistance will increase, but this increase will be fine as long as the current is loaded with a 1~3A. Can not be invalid.
