I. Core Cause of Damage: Electrodynamic Impact (Complying with GB/T 1094.5 / IEC 60076-5)The direct cause of high-voltage winding end collapse is the instantaneous electrodynamic impact induced by short-circuit current. When a single-phase grounding fault occurs in the system (such as lightning overvoltage, insulation breakdown, etc.), the grounding transformer, as the fault current path, withstands high-amplitude and steep-rise-rate short-circuit currents. According to Ampère's force law

1 Theoretical AnalysisIn distribution networks, grounding transformers serve two key roles: powering low - voltage loads and connecting arc - suppression coils at neutrals for grounding protection. Grounding faults, the most common distribution network fault, heavily impact transformers’ operating characteristics, causing sharp changes in electromagnetic parameters and status.To study transformers’ dynamic behaviors under single - phase grounding faults, build this model: Assume a tr

1 Classification of Neutral Grounding Methods for Solar Photovoltaic Power StationsInfluenced by differences in voltage levels and grid structures across regions, the neutral grounding methods of power systems are mainly categorized into non-effective grounding and effective grounding. Non-effective grounding includes neutral grounding via arc suppression coils and neutral ungrounded systems, while effective grounding comprises neutral solid grounding and neutral grounding via resistors. The sel

In a neutral-insulated three-phase power system, an earthing transformer provides an artificial neutral point, which can be solidly earthed or earthed via reactors/arc suppression coils. The ZNyn11 connection is typical, where zero-sequence magnetomotive forces in the inner/outer half-windings of the same core column cancel out, balancing fault currents in series windings and minimizing zero-sequence leakage flux/impedance.Zero-sequence impedance is critical: it determines fault current magnitud

The neutral grounding mode refers to the connection between the power system neutral point and ground. In China's 35 kV and below systems, common methods include ungrounded neutral, arc-suppression coil grounding, and small-resistance grounding. The ungrounded mode is widely used as it allows short-term operation during single-phase grounding faults, while small-resistance grounding has become mainstream for its fast fault removal and overvoltage limitation. Many substations install grounding tr

With the expansion of power system scale and the cableization process of urban power grids, the capacitive current in 6kV/10kV/35kV power grids has significantly increased (generally exceeding 10A). As power grids at this voltage level mostly adopt neutral ungrounded operation mode, and the distribution voltage side of main transformers is usually in delta connection, lacking a natural grounding point, the arc during ground faults cannot be reliably extinguished, necessitating the introduction o