Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Main Transformer Backup ProtectionThe purpose of main transformer backup protection is to prevent overcurrent in transformer windings caused by external faults, serve as backup protection for adjacent components (busbars or lines), and, where possible, act as backup for the transformer's primary protection in the event of internal faults. Backup protection is used to isolate faults when primary protection or circuit breakers fail.Main transformer zero-sequence protection is a backup protection f

Insulator Pollution Flashover and Its HazardsPollution flashover refers to a phenomenon where contaminants on the surface of electrical equipment insulators (external insulation) dissolve in moisture, forming a conductive layer that significantly reduces the insulator's insulation level. Under the influence of an electric field, this leads to severe discharge. During pollution flashover incidents, the success rate of automatic reclosing is very low, often resulting in widespread power outages. T

Contradiction PointsIn automatic tracking arc suppression coils, the adjustment precision is high, the residual current is small, and the operation is close to the resonance point.In an automatic tracking arc suppression coil grounding system, two factors must be considered: Under normal operating conditions, the long-term voltage displacement of the neutral point should not exceed 15% of the system's nominal phase voltage; In the case of a ground fault, the grounding residual current should b

Definition of Voltage StabilityVoltage stability in a power system is defined as the ability to maintain acceptable voltages at all buses under both normal operating conditions and after being subjected to a disturbance. In normal operation, the system’s voltages remain stable; however, when a fault or disturbance occurs, voltage instability may arise, leading to a progressive and uncontrollable voltage decline. Voltage stability is sometimes referred to as "load stability."Voltage instability c

Substance of Second - harmonic Restraint in Overcurrent ProtectionThe substance of second - harmonic restraint in overcurrent protection is to use the second - harmonic component to judge whether the current is a fault current or an excitation inrush current. When the percentage of the second - harmonic component to the fundamental - wave component is greater than a certain value, it is judged to be caused by the excitation inrush current, and the overcurrent protection is blocked.Therefore, the

Key Differences Between Glass and Porcelain InsulatorsBoth porcelain and glass insulators are widely applied in power transmission and distribution to insulate overhead line conductors from supporting towers and poles. With extended service lives and suitability for high voltage ratings, their unique characteristics and properties define their distinct application scenarios.Porcelain InsulatorsPorcelain, a ceramic material, is valued for its absence of internal defects such as voids, cracks, or

Current Limiting ReactorA current limiting reactor is an inductive coil characterized by a significantly higher inductive reactance compared to its resistance, designed to restrict short-circuit currents during fault conditions. These reactors also mitigate voltage disturbances in the remainder of the power system. They are installed in feeders, tie lines, generator leads, and between bus sections to reduce the magnitude of short-circuit currents and alleviate associated voltage fluctuations.Und

A fuse is a device employed in electrical circuits to protect electrical equipment against overloads and short circuits. It is the simplest and most cost-effective component for interrupting an electrical circuit when exposed to short-circuit currents or excessive overloads.Fuses are used for overload or short-circuit protection in high-voltage systems of up to 66 kV and low-voltage systems of up to 400 V. In certain applications, their use is limited to scenarios where their performance charact

A fuse is a current-interrupting device that breaks or opens a circuit by melting its element when the current in the circuit surpasses a specific value. Fuses are predominantly categorized into two types: high-voltage fuses and low-voltage fuses. Low-voltage fuses can be further divided into two subtypes: semi-enclosed or rewirable fuses, and fully enclosed cartridge fuses.Rewirable FusesRewirable fuses, commonly referred to as kit-kat fuses, are widely utilized in residential wiring and small-

What is a High Rupturing Capacity (HRC) Fuse?A High Rupturing Capacity (HRC) fuse is a type of protective device used in electrical systems to safeguard against overcurrent and short-circuit faults. It is engineered to safely interrupt high-magnitude fault currents without causing damage to surrounding equipment or itself. HRC fuses can reliably handle and clear large fault currents, typically up to 80 kA or higher, while eliminating risks of explosion or fire.An HRC fuse contains a fuse element