Research and application of testing and analyzing system for sealed relay's time parameters

The contact's mechanical parameters of sealed relay (such as contact over travel and contact force etc.) cannot be measured after the relay has been assembled. However, the time parameters of contact can be measured and can qualitatively reflect the change of contact mechanical parameters, which directly influence the reliability of contact. Hence, the time parameters can be used to qualitatively describe the reliability of contact. The testing and analyzing equipment for time parameters of sealed relay's contact was designed which took industrial control computer as central processor. By using the A/D data acquisition card specially designed (including ten sample channels, 4 MHz sample rate, 64 K byte data per channel stored), the current of single coil or double coils and the voltage of eight sets of change-over contacts could be sampled at the same time. Time parameters which would influence the contacting reliability, such as the over travel time, change-over time, bounce time and arc duration could be tested synthetically by dealing with the digital signal of coil current and contact voltage. The arc duration and the breaking over travel time of some type relay were tested by this system and their rules were analyzed.