Abstract: The expanding scale and increasingly complex topology of power grids bring severe challenges to fault diagnosis of dispatching systems. To address these bottlenecks, this paper develops a diagnostic model based on a time-series constraint network that spans the entire chain from primary equipment fault through protection response to breaker execution. For timestamp processing, the inconsistency of multi-source timestamps is formulated as a set of linear inequalities containing error variables, and an elimination method is applied to determine the compatibility of the inequality set, thereby filtering out logically contradictory fault hypotheses and retaining diagnostic conclusions consistent with the observed alarm sequences. Additionally, transient waveform features captured by fault recorders and action briefs from automatic bus transfer devices are incorporated into the diagnostic workflow—the former to identify the faulted phase and estimate fault distance, and the latter to trace load transfer paths and detect equipment overload risks after transfer, jointly supporting refined fault analysis. On this basis, the subgraph structure of the time-series constraint network is utilized to reorganize scattered alarms, fault recordings, and action briefs into a traceable event chain. Repeated validation in practical engineering scenarios confirms that the proposed method meets operational dispatching requirements in both accuracy and completeness of section-level fault location, and the resulting structured event sequences also lay a practical foundation for future deep integration with data mining and intelligent reasoning technologies.