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

1. Methods for Detecting Busbar Discharge1.1 Insulation Resistance TestThe insulation resistance test is a simple and commonly used method in electrical insulation testing. It is highly sensitive to through-type insulation defects, overall moisture absorption, and surface contamination—conditions that typically result in significantly reduced resistance values. However, it is less effective in detecting localized aging or partial discharge faults.Depending on the equipment’s insulation class and

1. Purpose of Handling Total Substation BlackoutA total blackout at a 220 kV or higher substation may lead to widespread power outages, significant economic losses, and instability in the power grid, potentially causing system separation. This procedure aims to prevent voltage loss in main grid substations rated 220 kV and above.2. General Principles for Handling Total Substation Blackout Establish contact with dispatch as soon as possible. Restore station service power promptly. Quickly restore

0 Introduction Dissolved gas analysis (DGA) in insulating oil is a crucial test for large oil-immersed power transformers. By employing gas chromatography, it is possible to timely detect the aging or changes in internal insulation oil of oil-filled electrical equipment, identify potential faults such as overheating or electrical discharges at an early stage, and accurately assess the severity, type, and development trend of the fault. Gas chromatography has become an essential method for monito

1. IntroductionRing main units (RMUs) are primary power distribution equipment that house load switches and circuit breakers within a metal or non-metal enclosure. Due to their compact size, simple structure, excellent insulation performance, low cost, easy installation, and fully sealed design [1], RMUs are widely used in medium- and low-voltage power systems across China’s grid network [2], especially in 10 kV distribution systems. With economic growth and increasing electricity demand, requir

1. Insufficient Creepage Distance or Air ClearanceInadequate creepage distance and air gaps are the main causes of insulation failure and accidents in solid-insulated ring main units (RMUs). Especially in drawer-type cabinets, manufacturers reduce cabinet size by minimizing space for circuit breakers, significantly decreasing isolation distances between plug contacts and ground. Without adequate reinforcement of insulation structure, such designs increase the risk of flashover under overvoltage

I. IntroductionThe Guanting–Lanzhou East 750kV transmission and substation demonstration project in China was officially put into operation on September 26, 2005. This project includes two substations—Lanzhou East and Guanting (each equipped with four 750kV transformers, three of which form a three-phase transformer bank in operation, with one on standby)—and one transmission line. The 750kV transformers used in the project were independently developed and manufactured in China. During the on-si

Core Standards for Calibration of Online Power Quality Monitoring DevicesThe calibration of online power quality monitoring devices follows a comprehensive standard system, encompassing mandatory national standards, industry technical specifications, international guidelines, and requirements for calibration methods and equipment. The following provides a structured overview with practical recommendations for real-world applications.I. Core Domestic Standards1. DL/T 1228-2023 – Technical Require

There is extensive literature on the analysis of overvoltage at transformer neutral points under lightning surge conditions. However, due to the complexity and randomness of lightning waves, an accurate theoretical description remains elusive. In engineering practice, protective measures are typically determined based on power system codes by selecting appropriate lightning protection devices, with abundant supporting documentation available.Transmission lines or substations are susceptible to l

Discharge Load for Energy Absorption: A Key Technology for Power System ControlDischarge load for energy absorption is a power system operation and control technology primarily used to address surplus electrical energy caused by load fluctuations, power source faults, or other disturbances in the grid. Its implementation involves the following key steps:1. Detection and ForecastingFirst, real-time monitoring of the power system is conducted to collect operational data, including load levels and

The Critical Role of Monitoring Accuracy in Power Quality Online DevicesThe measurement accuracy of online power quality monitoring devices is the core of the power system’s “perception capability,” directly determining the safety, economy, stability, and reliability of power supply to users. Inadequate accuracy leads to misjudgment, incorrect control, and flawed decision-making—potentially causing equipment damage, economic losses, or even grid failures. Conversely, high accuracy enables precis