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

Overheating of Busbar Isolating Switches: Causes and Handling ProceduresOverheating of busbar isolating switches is a common electrical equipment defect. If not addressed promptly, the situation can severely deteriorate during a system short circuit—when high short-circuit current flows through the overheated point, potentially causing contact melting or even destruction of the switch.When overheating of a busbar isolating switch is detected, follow these steps for safe handling: Report the defe

Isolating Switch: Definition and OverviewAn isolating switch (or disconnector) is a switching device primarily used for isolating power sources, switching operations (bus transfer), and making or breaking small-current circuits. It has no arc-quenching capability.When in the open position, there is a specified insulation distance between contacts and a clearly visible disconnection indicator. When in the closed position, it can carry the normal operating current and, for a specified duration, th

Application of Isolating Switches in Generator Neutral Grounding Resistor CabinetsIsolating switches are commonly installed in NS-FZ generator neutral grounding resistor cabinets. They provide a clearly visible disconnection point, ensuring the safety of maintenance and testing personnel. However, as high-voltage devices without arc-quenching capability, isolating switches must only be operated when the circuit is de-energized—i.e., under no-load conditions.The primary function of an isolating s

The selection principles and precautions for fuse-switch disconnectors are crucial to ensuring the safe and stable operation of power systems.Selection Principles for Fuse-Switch Disconnectors Rated Voltage:The rated voltage of the fuse-switch disconnector shall be equal to or greater than the rated voltage of the electrical system to ensure the equipment operates normally without damage. Rated Current:The selection of rated current should be based on the load conditions of the electrical system

Causes of Fire and Explosion in Oil Circuit Breakers When the oil level in an oil circuit breaker is too low, the oil layer covering the contacts becomes too thin. Under the effect of the electric arc, the oil decomposes and releases flammable gases. These gases accumulate in the space beneath the top cover, mixing with air to form an explosive mixture, which can ignite or explode under high temperature. If the oil level inside the tank is too high, the released gases have limited space to expan

The basic meaning of a high-voltage circuit breaker is, simply put, that under normal conditions, it is used to open (interrupt, trip) and close (make, reclose) circuits, feeders, or specific loads—such as those connected to transformers or capacitor banks. When a fault occurs in the power system, protective relays activate the circuit breaker to interrupt either load current or short-circuit current, thereby ensuring the safe operation of the power system.A high-voltage circuit breaker is a typ

Based on years of field statistics on switchgear accidents, combined with analysis focusing on the circuit breaker itself, the main causes have been identified as: failure of operation mechanism; insulation faults; poor breaking and closing performance; and poor conductivity.1.Failure of Operation MechanismFailure of operation mechanism manifests as delayed operation or unintended operation. Since the most basic and important function of a high-voltage circuit breaker is to operate correctly and

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

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,