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

Gas accumulation: Free gas is present in the transformer oil. Response: The gas in the liquid rises and accumulates in the Buchholz relay, compressing the transformer oil. As the liquid level drops, the float also descends. The movement of the float drives a switch element (magnetic contact), thereby triggering an alarm signal. However, the float is not affected, because a certain amount of gas can flow through the pipe into the storage chamber.Fault: Due to leakage causing loss of transformer o

(1) Generator Protection:Generator protection covers: phase-to-phase short circuits in stator windings, stator ground faults, inter-turn short circuits in stator windings, external short circuits, symmetrical overload, stator overvoltage, single- and double-point grounding in the excitation circuit, and loss of excitation. Tripping actions include shutdown, islanding, limiting fault impact, and alarm signaling.(2) Transformer Protection:Power transformer protection includes: phase-to-phase short

I. CLAIMS A sealing structure for lead wires of contacts in an oil-filled SF6 gas density relay, characterized by comprising a relay housing (1) and a terminal base (2); the terminal base (2) comprising a terminal base housing (3), a terminal base seat (4), and conductive pins (5); the terminal base seat (4) being disposed inside the terminal base housing (3), the terminal base housing (3) being welded onto the surface of the relay housing (1); a central through-hole (6) being provided at the ce

1. Introduction SF6 electrical equipment, renowned for its excellent arc-quenching and insulating properties, has been widely applied in power systems. To ensure safe operation, real-time monitoring of SF6 gas density is essential. Currently, mechanical pointer-type density relays are commonly used, providing functions such as alarm, lockout, and on-site display. To enhance vibration resistance, most of these relays are filled internally with silicone oil.However, oil leakage from density relays

The 110kV substation at our plant was constructed and put into operation in February 2005. The 110kV system employs ZF4-126\1250-31.5 type SF6 GIS (Gas-Insulated Switchgear) from Beijing Switchgear Factory, comprising seven bays and 29 SF6 gas compartments, including five circuit breaker compartments. Each circuit breaker compartment is equipped with an SF6 gas density relay. Our plant uses the MTK-1 model oil-filled density relays manufactured by Shanghai Xinyuan Instrument Factory. These relay

IntroductionSF6 gas is widely used as an insulating and arc-quenching medium in high-voltage and extra-high-voltage electrical equipment due to its excellent insulation, arc-extinguishing properties, and chemical stability. The insulation strength and arc-quenching capability of electrical equipment depend on the density of SF6 gas. A decrease in SF6 gas density can lead to two main hazards: Reduced dielectric strength of the equipment; Decreased interrupting capacity of circuit breakers.Additio

1. BackgroundSF6 electrical equipment has been widely applied in power utilities and industrial enterprises, significantly advancing the development of the power industry. Ensuring the reliable and safe operation of SF6 equipment has become a critical task for power departments.The arc-quenching and insulating medium in SF6 equipment is SF6 gas, which must remain sealed—any leakage compromises the reliability and safety of the equipment. Therefore, monitoring the SF6 gas density is essential.Cur

Thermal Relays for Motor Overload Protection: Principles, Selection, and ApplicationIn motor control systems, fuses are primarily used for short-circuit protection. However, they cannot protect against overheating caused by prolonged overloading, frequent forward-reverse operation, or undervoltage operation. Currently, thermal relays are widely used for motor overload protection. A thermal relay is a protective device that operates based on the thermal effect of electric current, and is essentia

1.SF6 Electrical Equipment and the Common Problem of Oil Leakage in SF6 Density RelaysSF6 electrical equipment is now widely used in power utilities and industrial enterprises, significantly advancing the development of the power industry. The arc-quenching and insulating medium in such equipment is sulfur hexafluoride (SF6) gas, which must not leak. Any leakage compromises the reliable and safe operation of the equipment, making it essential to monitor the SF6 gas density. Currently, mechanical

Role and Selection of Microcomputer Integrated Protection Devices in High-Voltage SwitchgearIn recent years, the application of microcomputer integrated protection devices in medium- and high-voltage power distribution system projects has increased significantly. These devices are user-friendly and overcome the drawbacks of traditional relay protection, such as complex wiring, low reliability, and cumbersome setting and debugging procedures. Microcomputer integrated protection devices feature co