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

Transformer grounding protection measures are divided into two types: The first is transformer neutral point grounding. This protection measure prevents neutral point voltage drift caused by three-phase load imbalance during transformer operation, enabling protection devices to trip quickly and reducing short-circuit currents. This is considered functional grounding for the transformer. The second measure is grounding of the transformer core and clamps.This protection prevents induced voltages f

Reclosing can be categorized into single-phase reclosing, three-phase reclosing, and comprehensive reclosing.Single-phase reclosing: After a single-phase fault occurs on the line, single-phase reclosing is performed. If reclosing occurs onto a permanent fault, all three phases are tripped and no further reclosing attempts are made. For interphase faults, all three phases are tripped without reclosing.Three-phase reclosing: Regardless of fault type, all three phases are tripped followed by three-

On May 7, China's first large-scale integrated wind-solar-thermal-storage comprehensive energy base UHV transmission project—the Longdong~Shandong ±800kV UHV DC transmission project—was officially energized and put into operation. The project has an annual transmission capacity exceeding 36 billion kilowatt-hours, with new energy sources accounting for more than 50% of the total. After commissioning, it will reduce carbon dioxide emissions by approximately 14.9 million tons annually, contributin

Currently, China has achieved certain accomplishments in this field. Relevant literature has designed typical configuration schemes for grounding fault protection in nuclear power plant low-voltage distribution systems. Based on the analysis of domestic and international cases where grounding faults in nuclear power plant low-voltage distribution systems have caused maloperation of transformer zero-sequence protection, the underlying causes have been identified. Furthermore, improvement suggesti

35 kV Distribution Transformers: Core Grounding Fault Analysis and Diagnostic Methods35 kV distribution transformers are common critical equipment in power systems, carrying important electrical energy transmission tasks. However, during long-term operation, core grounding faults have become a major issue affecting the stable operation of transformers. Core grounding faults not only impact transformer energy efficiency and increase system maintenance costs, but may also trigger more serious elec

Recently, a Chinese transformer manufacturer independently designed and manufactured six 750kV ultra-high voltage transformers for a 750kV boosting substation project in Xinjiang. All products passed factory acceptance tests and type tests on the first attempt, obtaining KEMA type test reports. Testing confirmed that all performance indicators exceed national standards and technical agreement requirements. Notably, the high-voltage partial discharge is only 8pC and the medium-voltage partial dis

Single-Phase ReclosingAdvantage:When a single-phase-to-ground fault occurs on a line and three-phase auto-reclosing is applied, it results in higher switching overvoltages compared to single-phase reclosing. This is because three-phase tripping interrupts the current at zero-crossing, leaving residual charge voltages on the unfaulted phases—approximately equal to the peak phase voltage. Since the de-energized interval during reclosing is relatively short, the voltage on these unfaulted phases do

The rural power grid transformation plays an important role in reducing rural electricity tariffs and accelerating rural economic development. Recently, the author participated in the design of several small-scale rural power grid transformation projects or conventional substations. In rural power grid substations, conventional 10kV systems mostly adopt 10kV outdoor auto circuit vacuum reclosers.To save investment, we adopted a scheme in the transformation that removes the control unit of the 10

An Automatic Circuit Recloser is a high-voltage switching device with built-in control (it inherently possesses fault current detection, operation sequence control, and execution functions without requiring additional relay protection or operating devices) and protective capabilities. It can automatically detect the current and voltage in its circuit, automatically interrupt fault currents according to inverse-time protection characteristics during faults, and perform multiple reclosures accordi

Lightning strikes, fallen tree branches, and even Mylar balloons are enough to interrupt current flow on power lines. That’s why utility companies prevent outages by equipping their overhead distribution systems with reliable recloser controllers.In any smart grid environment, recloser controllers play a critical role in detecting and interrupting transient faults. Although many short circuits on overhead lines can resolve themselves, reclosers help improve service continuity by automatically re