The photo above is the actual faulted starter. Take notice of the 3- tan fuses and how the white leads are jumpered. The tan fuses are the main fuses into the starter. The white leads jump voltage from the bottom of the fuse, to the top of the vacuum contactor.
Contactors are a set of contacts that are operated by a coil. While voltage is energizing the coil, the contactor remains closed. As soon as the coil voltage disappears, the contactor opens.
If you see in this photo, the fuses are slightly offset from the contactor. “A” Phase of the contactor is aligned with “B” Phase or the middle fuse. This potentially causes the issue of having to cross phasing in a close proximity.
Above you can see the discoloration between the “A” Phase conductor and the “B” Phase conductor. This is the result of the conductors being too close without the proper insulation. This was potentially going to be another fault.
This is where the “B” Phase and “C” Phase conductors cross. The cable was bent back to get a clear picture. Take note of the tracking. The arc point was actually in the corner which is not visible and tracked to the front of the starter.
As seen in the picture above, the contactor has been removed from the cubicle and set on the concrete pad outside the gear. This was the start of the repair. It is being replaced and put back in service.
This was the final result of the repair. The plastic that is around the leads is rated at 7500 volts.