Changzhou Yingda New Material Co., Ltd , https://www.yingdaspc.com
Talking about the Characteristics of Single Phase Earth Fault
Power grid short circuits generally fall into four main types, with the three-phase short circuit being the most severe. Meanwhile, single-phase ground faults represent the most frequent type of short circuit issue. In the operational context of a 10kV distribution line, single-phase ground faults are particularly prevalent, especially during adverse weather conditions like heavy rain, strong winds, or snowstorms. For instance, in 2005, out of 24 anomalies recorded by the Longsha Power Supply Bureau in Heilongjiang Province, seven were single-phase ground faults. The following year, in 2006, among 31 anomalies, eight were attributed to single-phase ground faults. Upon occurrence, the faulted phase experiences a drop in voltage, while the voltages of the unaffected phases increase—though the line voltage remains balanced, allowing for continued power delivery to users for up to 1-2 hours. This characteristic is a key benefit of the small current grounding system. However, prolonged operation post-ground fault can severely impact the safety and efficiency of substation equipment and the distribution network.
To prevent such issues, sufficient clearance must be maintained around power lines, creating what’s known as "transmission corridors." These problems often stem from load imbalances. Common causes of single-phase ground faults include broken wires, insulator failures, and tree-related shorts.
When a ground fault occurs, several indicators come into play. Central signals typically include an alarm bell ringing, a lit panel indicating "a certain kV bus ground," along with an illuminated "arc suppression coil operation" light card. An insulation monitoring voltmeter shows that the faulted phase voltage drops (in partial grounding) or becomes zero (in complete grounding), while the other two phases show elevated voltages—either higher than the phase voltage (partial grounding) or equal to the line voltage (complete grounding). If the voltmeter pointer doesn’t oscillate, it indicates a steady fault; continuous swinging suggests intermittent grounding.
In systems using an arc suppression coil grounding setup, a neutral point displacement voltmeter displays either some indication (partial grounding) or the phase voltage value (complete grounding), accompanied by an arc suppression coil grounding alarm light. During arcing ground faults, overvoltages arise, causing the non-faulted phases to experience heightened voltage levels. This can lead to the blowing of high-voltage fuses on voltage transformers and, in extreme cases, damage to the transformers themselves.
Expanding on this topic further, understanding the nuances of single-phase ground faults is crucial for maintaining grid stability. Operators must remain vigilant about potential warning signs and take proactive measures to mitigate risks. Additionally, regular maintenance and inspections of critical components like insulators and transformers are essential to minimize the likelihood of such faults occurring.