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

Leakage in Hydraulic Operating MechanismsFor hydraulic mechanisms, leakage can cause short-term frequent pump starting or excessively long re-pressurization time. Severe internal oil seepage in valves may lead to pressure loss failure. If hydraulic oil enters the nitrogen side of the accumulator cylinder, it can cause abnormal pressure rise, which affects the safe operation of SF6 circuit breakers.Apart from failures caused by damaged or abnormal pressure detection devices and pressure component

This article categorizes faults into two main types: SF₆ gas circuit faults and circuit breaker failure-to-operate faults. Each is described below:1.SF₆ Gas Circuit Faults1.1 Fault Type: Low gas pressure, but density relay does not trigger alarm or lockout signalCause: Faulty density gauge (i.e., contact not closing)Inspection & Handling: Calibrate actual pressure using a standard gauge. If confirmed, replace the density gauge.1.2 Density Relay Triggers Alarm or Lockout Signal (but pressure

The performance of circuit breaker operating mechanisms is decisive for reliable and safe power supply. While various mechanisms each have their advantages, the emergence of a new type does not completely replace traditional ones. For example, despite the rise of eco-friendly gas insulation, solid insulation ring main units still hold about 8% of the market, showing new technologies rarely fully displace existing solutions.The permanent magnet actuator (PMA) consists of permanent magnets, a clos

High-Voltage Circuit Breakers: Classification and Fault DiagnosisHigh-voltage circuit breakers are critical protective devices in power systems. They rapidly interrupt current when a fault occurs, preventing damage to equipment from overloads or short circuits. However, due to long-term operation and other factors, circuit breakers may develop faults that require timely diagnosis and troubleshooting.I. Classification of High-Voltage Circuit Breakers1. By Installation Location: Indoor-type: Insta

I. Inspection of Vacuum Circuit Breakers During Normal Operation1. Inspection in Closed (ON) Position The operating mechanism should be in the closed position; The main shaft roller should be disengaged from the oil damper; The opening spring should be in a charged (stretched) energy-stored state; The length of the moving contact rod of the vacuum interrupter protruding below the guide plate should be approximately 4–5 mm; The bellows inside the vacuum interrupter should be visible (this does no

The inability to manually operate the local mechanical trip of a 10kV vacuum circuit breaker is a relatively common fault type in power system maintenance work. Based on years of field experience, such issues typically stem from five core areas, each requiring troubleshooting based on specific symptoms.Operating mechanism jamming is the most common cause. The tripping process of a circuit breaker relies on mechanical energy released from spring energy storage; if rust, deformation, or foreign ob

01 PrefaceIn medium-voltage systems, circuit breakers are indispensable primary components. Vacuum circuit breakers dominate the domestic market. Therefore, correct electrical design is inseparable from the proper selection of vacuum circuit breakers. In this section, we will discuss how to correctly select vacuum circuit breakers and common misconceptions in their selection.02 Interrupting Capacity for Short-Circuit Current Need Not Be Excessively HighThe short-circuit interrupting capacity of

Low-Voltage Air Circuit Breakers vs. Vacuum Circuit Breakers: Structure, Performance and ApplicationLow-voltage air circuit breakers, also known as universal or molded frame circuit breakers (MCCBs), are designed for AC voltages of 380/690V and DC voltages up to 1500V, with rated currents ranging from 400A to 6300A or even 7500A. These breakers use air as the arc-quenching medium. The arc is extinguished through arc elongation, splitting, and cooling by an arc chute (arc runner). Such breakers c

Reactive Power Compensation and Capacitor Switching in Power SystemsReactive power compensation is an effective means to increase system operating voltage, reduce network losses, and improve system stability.Conventional Loads in Power Systems (Impedance Types): Resistance Inductive reactance Capacitive reactanceInrush Current During Capacitor EnergizationIn power system operation, capacitors are switched in to improve power factor. At the moment of closing, a large inrush current is generated.

Insulation Withstand Voltage Test Standards for Vacuum Circuit BreakersThe main purpose of the insulation withstand voltage test for vacuum circuit breakers is to verify whether the insulation performance of the equipment under high voltage is qualified, and to prevent breakdown or flashover accidents during operation. The test process must be strictly carried out in accordance with power industry standards to ensure equipment safety and power supply reliability.Test ObjectsThe test objects incl