Generator overcurrent trips main breaker at Hostway Bundang data centre
Apr 2025Published 13 Oct 2026Responsible editor: Chief Editor
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Companies named in this entry: Hostway
What happened
At about 3:26 a.m. on 7 April 2025, a power outage hit the Bundang internet data centre (IDC) operated by Hostway, disrupting services on the third and fourth floors. According to a failure report obtained by Digital Daily, overcurrent in some generator units in the UPS room caused the main breaker in the substation switchgear room to trip, cutting power to the facility. According to the outlet, the emergency power infrastructure appeared not to operate properly.
Hostway said it identified the cause within about an hour and restarted the generators, restoring power at about 4:30 a.m. Server recovery was still under way when the report was published. The Mail Nara business email service run by Samjeong Data Service and the iName domain registrar were among the affected services, and Mail Nara was reported to be about 80% restored. Hostway said installing abnormality detection and cut-off sensors on the generators would take one to two weeks.
Contributing factors
According to the failure report as described by the outlet, the first fault was in the generator units rather than the grid supply or the UPS. An industry expert quoted by the outlet said that a generator failing before the UPS would be highly unusual, because the normal sequence is grid, then UPS, then generators. The report has not been published and does not say what caused the overcurrent in the generator units.
Lessons learned
- Test how backup generators behave under fault and overcurrent conditions, and confirm that protection settings isolate a faulty unit without tripping the main switchgear breaker.
- Verify that the emergency power sequence works as designed, because a backup that fails to take over can turn a local fault into a facility-wide outage.
- Fit abnormality detection and automatic cut-off on generator units, and check the time needed to install such protection before relying on the generators in the interim.
More lessons on electrical protection and isolation, outages, backup supply and restoration, detection and monitoring, from every incident on the register.
Source
Published 2026-10-13. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
