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

1.Neutral Point Establishment and System StabilityIn photovoltaic power stations, grounding transformers effectively establish a system neutral point. According to relevant power regulations, this neutral point ensures the system maintains certain stability during asymmetric faults, functioning like a "stabilizer" for the entire power system.2.Overvoltage Limitation CapabilityFor photovoltaic power stations, grounding transformers can effectively limit overvoltages. Generally, they can control o

1. Zero-Sequence Overcurrent ProtectionThe operating current for zero-sequence overcurrent protection of grounding transformers is typically determined based on the transformer's rated current and the maximum allowable zero-sequence current during system ground faults. The general setting range is approximately 0.1 to 0.3 times the rated current, with operating time usually set between 0.5 to 1 second to quickly clear ground faults.2.Overvoltage ProtectionOvervoltage protection is a critical com

1. High-Resistance Grounding SystemHigh-resistance grounding can limit ground fault current and appropriately reduce ground overvoltage. However, there is no need to connect a large high-value resistor directly between the generator neutral point and ground. Instead, a small resistor can be used together with a grounding transformer. The primary winding of the grounding transformer is connected between the neutral point and ground, while the secondary winding is connected to a small resistor. Ac

According to the "Eighteen Major Anti-Accident Measures for Power Grid of State Grid Corporation of China (Revised Edition)" promulgated in 2018, operation and maintenance units should improve the on-site operation regulations for intelligent substations, refine the usage instructions and abnormal handling methods for various messages, signals, hard pressure plates, and soft pressure plates of intelligent equipment, standardize the operation sequence of pressure plates, strictly follow the seque

In daily operations, various equipment defects are inevitably encountered. Whether maintenance personnel, operation and maintenance staff, or specialized management personnel, all must understand the defect classification system and adopt appropriate measures according to different situations.According to Q/GDW 11024-2013 "Operation and Management Guide for Relay Protection and Safety Automatic Devices in Smart Substations," equipment defects are classified into three levels based on severity an

The line circuit breaker auto-reclosing signal will be locked out if any of the following conditions occur:(1) Low SF6 gas pressure in circuit breaker chamber at 0.5MPa(2) Insufficient energy storage in circuit breaker operating mechanism or low oil pressure at 30MPa(3) Busbar protection operation(4) Circuit breaker failure protection operation(5) Line distance protection zone II or zone III operation(6) Short lead protection operation of circuit breaker(7) Presence of remote tripping signal(8)

1. Power Interruption Problems Caused by RCD False Tripping During Lightning StrikesA typical communication power supply circuit is shown in Figure 1. A residual current device (RCD) is installed at the power supply input terminal. The RCD primarily provides protection against electrical equipment leakage currents to ensure personal safety, while surge protective devices (SPDs) are installed on power supply branches to protect against lightning intrusions. When lightning strikes occur, the senso

1. Function and Significance of Reclosing ChargingReclosing is a protective measure in power systems. After faults such as short circuits or circuit overloads occur, the system isolates the faulty circuit and then restores normal operation through reclosing. The function of reclosing is to ensure continuous operation of the power system, improving its reliability and safety.Before performing reclosing, the circuit breaker must be charged. For high-voltage circuit breakers, the charging time is g

1. Introduction Transmission line faults can be classified into two types based on their nature: transient faults and permanent faults. Statistical data shows that most transmission line faults are transient (caused by lightning strikes, bird-related incidents, etc.), accounting for approximately 90% of all faults. Therefore, after a line is disconnected due to a fault, attempting reclosure once can significantly improve power supply reliability. The function of automatically reclosing a circuit

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-