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

1. Induced Lightning OvervoltageInduced lightning overvoltage refers to the transient overvoltage generated on overhead distribution lines due to nearby lightning discharges, even when the line is not directly struck. When a lightning flash occurs in the vicinity, it induces a large amount of charge on the conductors—opposite in polarity to the charge in the thundercloud.Statistical data shows that lightning-related faults caused by induced overvoltages account for approximately 90% of total fau

Error Tolerance of Total Harmonic Distortion (THD): A Comprehensive Analysis Based on Application Scenarios, Equipment Accuracy, and Industry StandardsThe acceptable error range for Total Harmonic Distortion (THD) must be evaluated based on specific application contexts, measurement equipment accuracy, and applicable industry standards. Below is a detailed analysis of key performance indicators in power systems, industrial equipment, and general measurement applications.1. Harmonic Error Standar

The solid-state transformer (SST), also known as a power electronic transformer (PET), uses voltage level as a key indicator of its technological maturity and application scenarios. Currently, SSTs have reached voltage levels of 10 kV and 35 kV on the medium-voltage distribution side, while on the high-voltage transmission side, they remain in the stage of laboratory research and prototype validation. The table below clearly illustrates the current status of voltage levels across different appli

Air-insulated ring main units (RMUs) are defined in contrast to compact gas-insulated RMUs. Early air-insulated RMUs used vacuum or puffer-type load switches from VEI, as well as gas-generating load switches. Later, with the widespread adoption of the SM6 series, it became the mainstream solution for air-insulated RMUs. Similar to other air-insulated RMUs, the key difference lies in replacing the load switch with an SF6-encapsulated type—where the three-position switch for load and grounding is

1 IntroductionAccording to the provisions of the national standard GB/T 1094.3-2017, the primary purpose of the line terminal AC withstand voltage test (LTAC) for power transformers is to evaluate the AC dielectric strength from the high-voltage winding terminals to ground. It does not serve to assess inter-turn insulation or phase-to-phase insulation.Compared with other insulation tests (such as full lightning impulse LI or switching impulse SI), the LTAC test imposes a relatively more stringen

Expected service life of 30–40 years, front access, compact design equivalent to SF6-GIS, no SF6 gas handling – climate-friendly, 100% dry air insulation. The Nu1 switchgear is metal-enclosed, gas-insulated, featuring a withdrawable circuit breaker design, and has been type-tested according to relevant standards, approved by the internationally recognized STL laboratory.Compliance Standards Switchgear: IEC 62271-1 High-voltage switchgear and controlgear – Part 1: Common specifications for altern

Solid insulation assistance combined with dry air insulation is a development direction for 24 kV ring main units. By balancing insulation performance and compactness, the use of solid auxiliary insulation allows passing insulation tests without significantly increasing phase-to-phase or phase-to-ground dimensions. Encapsulation of the pole can address the insulation of the vacuum interrupter and its connected conductors.For the 24 kV outgoing busbar, with the phase spacing maintained at 110 mm,

Ring main units (RMUs) are used in secondary power distribution, directly connecting to end-users such as residential communities, construction sites, commercial buildings, highways, etc.In a residential substation, the RMU introduces 12 kV medium voltage, which is then stepped down to 380 V low voltage through transformers. The low-voltage switchgear distributes electrical energy to various user units. For a 1250 kVA distribution transformer in a residential community, the medium-voltage ring m

What Are the Handling Procedures After Transformer Gas (Buchholz) Protection Activation?When the transformer gas (Buchholz) protection device operates, a thorough inspection, careful analysis, and accurate judgment must be carried out immediately, followed by appropriate corrective actions.1. When the Gas Protection Alarm Signal is ActivatedUpon activation of the gas protection alarm, the transformer should be inspected immediately to determine the cause of operation. Check whether it was caused

In the field of electrical engineering, the stability and reliability of power systems are of paramount importance. With the advancement of power electronics technology, the widespread use of nonlinear loads has led to an increasingly serious problem of harmonic distortion in power systems.Definition of THDTotal Harmonic Distortion (THD) is defined as the ratio of the root mean square (RMS) value of all harmonic components to the RMS value of the fundamental component in a periodic signal. It is