An indoor 13.8kV Vacuum Circuit Breaker switchgear has an arc flash incident this week. Investigation results showed that the wet weather increased the humidity inside the switchroom, incomplete covering of bus bar joints (as-built condition), 20 year old equipment and aggravated by the failure of exhaust blowers and defective substation doors.
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- Melted Bolts at Main Bus Joint
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- Exploded Main Bus Cover
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- Arc Flash Mark
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- Damaged Main Bus Joint Cover
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- Burnt Divider at Load Side Cable Termination
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- Main Incomer Protection Relay Instantaneous Trip on Phase A & C
It was fortunate that there were no casualties nor damages on other equipment during the incident.
As there were no available spares of bus bar cover, the alternative was to wrap the joints with high voltage tape to ensure that there are no bare bus bars or bolts. The cleaning, testing and restoration of the 13.8KV switchgear took about 48 hours prior to power up.
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