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

I. Introduction to Cable Grounding Loop CurrentCables rated 110 kV and above use a single-core structure. The alternating magnetic field generated by the operating current induces a voltage on the metallic sheath. If the sheath forms a closed circuit through the earth, a grounding loop current will flow on the metallic sheath. Excessive grounding loop current (loop current exceeding 50 A, more than 20% of the load current, or a ratio of maximum-to-minimum phase current greater than 3) not only a

I. Functions of Metallic Sheaths and Necessity of RepairThe metallic sheath of high-voltage cables is a metal shielding structure laid outside the insulation layer, including types such as lead sheaths, aluminum sheaths, and steel wire armor. Its core functions include mechanical protection (resisting external impact and compression), electrochemical corrosion protection (isolating moisture and soil pollutants), electromagnetic shielding (reducing electromagnetic interference to the environment)

The arc extinguishing system of a DC circuit breaker is crucial for the safe operation of equipment, as the arc generated during current interruption can damage contacts and compromise insulation.In AC systems, the current naturally passes through zero twice per cycle, and AC circuit breakers take full advantage of these zero-crossing points to extinguish the arc.However, DC systems lack natural current zero crossings, making arc extinction significantly more difficult for DC circuit breakers. T

With the continuous development of smart grids, smart electricity meters are being increasingly widely applied, and various types of operational faults in smart meters are frequently encountered in energy measurement work. This paper analyzes the causes of smart meter failures and proposes corresponding solutions, using several actual operational fault cases as examples.1. Black ScreenA black screen refers to a powered meter with no display, which is the most commonly occurring fault in field-op

1 Analysis of Smart Meter Faults and Their Impact on the Power Grid1.1 Introduction to Smart Meter Functions and Their Critical Role in Modern Power GridsSmart meters exchange data in real time with power companies through two-way communication, enabling functions such as remote meter reading and dynamic tariff adjustment. This capability allows users to adjust their consumption based on real-time pricing, achieving energy savings and cost reduction. Meanwhile, smart meters support grid automati

Transformer testing, inspection, and maintenance are essential tasks to ensure normal operation and extend the service life of transformers. Below are some recommended steps: Visual Inspection: Regularly inspect the transformer's exterior, including the enclosure, cooling system, and oil tank. Ensure the enclosure is intact, free from corrosion, damage, or leakage. Insulation Resistance Testing: Use an insulation resistance tester to check the transformer's insulation system. Verify that the ins

Common operational faults of indoor load switches primarily concentrate on three core aspects: mechanical operation, electrical performance, insulation, and arc extinguishing. These issues can be broadly categorized as follows and are often related to component aging, environmental influences, or improper operation.1.Mechanical Faults The most typical issue is abnormal operation during opening and closing. This includes excessive resistance, jamming, or even refusal to operate when manually turn

If the fuse element on the high-voltage side of the transformer blows or the circuit trips, the first step is to determine whether one phase, two phases, or all three phases are interrupted. This can be determined according to the fault symptoms as shown in the following table:When a fuse element blows, first check whether the high-voltage side fuse or the lightning arrester gap has short-circuited to ground. If no abnormalities are found during external inspection, it can be concluded that an i

Use and MaintenanceIn low-voltage power distribution systems, fuses are protective electrical devices. Widely used for power grid and electrical equipment protection, fuses automatically cut off circuits when short circuits or overloads occur in the grid or equipment, preventing damage to electrical devices and preventing accidents from spreading.A fuse consists of an insulating base (or support), contacts, and a fuse element. The fuse element is the primary working component, acting like a spec

Simplicity means fewer components. According to the principle that system reliability equals the product of individual component reliabilities, fewer parts lead to higher reliability.For PT trolleys in air-insulated switchgear, a simplified drawer-type design is adopted. On the cable compartment side, the PT trolley eliminates the need for a 200mm chassis to rack in and dispenses with blossom contacts. Instead, it uses the PT’s built-in fuse and striker mechanism, making direct contact