Edward,
Exactly right. This was discussed in this thread
https://www.electrical-contractor.net/ubb/Forum1/HTML/006650.html The open air links that you see moving slowly are _not_ supposed to interrupt the load, and are not suitable as a switch for these high voltages and currents. The actual switches are in what appear to be insulators on the right hand side of the assembly. One of these failed to open, leaving the visible moving bits to open the circuit...which by demonstration they cannot do.
-Jon
