Recloser Failure

[saladhawks]

Below is a picture from above of a failed medium-voltage solid-dielectric recloser with vacuum interrupters from an unnamed manufacturer. This recloser is designed with the control enclosure on top of the actual medium-voltage terminating components. The recloser was issued an open command immediately prior to failure and it appears the unit failed catastrophically during the actual attempt to open. Moisture within the top control enclosure was evident prior to this failure. I am curious as to the following:

- Is it feasible that moisture in the top control enclosure could have "seeped" downward along the drive assembly and into the actual medium voltage components (i.e. solid dielectric insulation and vacuum interrupter)?

 

[dpc]

Seems really unlikely that moisture would have gotten into an intact vacuum bottle.

Possible loss of vacuum event?

 

[apowerengr]

I agree with dpc, if moisture got into the bottle then by definition you had a loss of vacuum event. Could there have been a contamination problem internal to the unit and when the open command was issued the overvoltage condition following the contact opening caused a flashover? What did the upstream overcurrent device target for this fault and did the recloser control store any event information - phase to ground or otherwise? It's another example of why we design systems which remote the controls/operator interfaces from the interrupting devices.