Neutral Grounding Resistor is protective equipment developed for practical operational pain points of medium‑voltage low‑current grounding systems. It resolves the most frequent and influential on‑site issues in distribution networks and industrial power‑supply systems, covering equipment damage, power‑grid abnormalities, fault handling, and power‑supply safety. It makes up for operational defects of systems without grounding protection and applies to critical power‑consumption sites such as factories, commercial parks, municipal power‑distribution facilities, mines, and hospitals. First of all, it thoroughly mitigates equipment damage and safety accidents originating from single‑phase‑to‑ground faults. Line aging, external mechanical damage, insulation dampening, and tree‑to‑line contact frequently trigger single‑phase‑to‑ground faults on‑site.
In systems without Neutral Grounding Resistor, unrestricted capacitive grounding current produces high‑magnitude fault current that burns cable cores, switchgear contacts, and instrument transformers. Consequences include cable rupture, equipment burnout, and insulation scrapping. In severe cases, electrical fires may break out. After the Neutral Grounding Resistor is installed, fault current is limited within safe thresholds. Destructive effects of fault current are substantially reduced, and on‑site safety hazards such as equipment damage, fire risks, and electric leakage stemming from single‑phase‑to‑ground faults are fundamentally controlled. Expenses for equipment repair and replacement are greatly lowered.
Secondly, it tackles frequently‑occurring on‑site overvoltage failures, which represent persistent yet easily‑overlooked hazards. When single‑phase‑to‑ground faults take place in low‑current grounding systems, electric arcs extinguish and reignite intermittently and generate arc‑grounding overvoltage up to three‑to‑four times the rated voltage. Long‑term exposure gradually damages line insulators, cable insulation, and switchgear insulating components, creates hidden insulation defects, and triggers secondary failures such as multi‑point grounding and phase‑to‑phase short‑circuits. Meanwhile, ferromagnetic resonance may arise between voltage transformers and line capacitances under light‑load or no‑load grid conditions, producing resonant overvoltage, abnormal voltage surges, and transformer burnout. The Neutral Grounding Resistor rapidly dissipates overvoltage energy and dampens voltage oscillation to eliminate arc‑related and resonant overvoltage and resolve stubborn on‑site troubles including insulation aging, equipment breakdown, and abnormal voltage fluctuation.
Thirdly, it overcomes difficulties in fault identification, protection refusal, and large‑scale power outages. Traditional low‑current grounding systems generate extremely faint grounding‑fault signals, which conventional relay‑protection devices cannot identify accurately. Protection refusal or delayed response often occurs, allowing faults to persist and hazards to expand. Besides, fault‑line identification is difficult. Maintenance staff have to conduct section‑by‑section line inspection, which consumes substantial manpower and time and causes long‑lasting wide‑range power outages. The Neutral Grounding Resistor creates stable and controllable fault current and amplifies fault signals. Zero‑sequence protection and fault‑line‑selection devices respond instantly to isolate faulty circuits and pinpoint fault locations. Problems of hard‑to‑diagnose faults, prolonged power cuts, and full‑grid blackouts are solved, and power supply for non‑faulty sections remains normal.
Finally, it resolves three‑phase voltage imbalance and neutral‑point potential shift. Uneven on‑site load distribution, asymmetric line layout, and equipment‑parameter deviations result in neutral‑point offset and uneven three‑phase voltages. Some phases show excessive voltage while others deliver insufficient voltage. This impairs operating precision of sophisticated power‑consuming devices and accelerates insulation aging. The Neutral Grounding Resistor stabilizes neutral‑point‑to‑ground potential and balances three‑phase system voltages. Voltage offset and potential‑drift problems are eliminated to improve power‑supply quality, prevent equipment malfunctions triggered by abnormal voltage, and enhance overall stability and safety of on‑site power‑supply systems.