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

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

According to statistics, the vast majority of faults on overhead power lines are transient, with permanent faults accounting for less than 10%. Currently, medium-voltage (MV) distribution networks commonly employ 15 kV outdoor vacuum automatic circuit reclosers in coordination with sectionalizers. This setup enables rapid restoration of power supply after transient faults and isolates faulty line segments in the event of permanent faults. Therefore, it is essential to monitor the operational sta

1 Current Grid StatusWith the continuous deepening of rural power grid transformation, the health level of rural grid equipment is constantly improving, and power supply reliability basically meets user needs. However, regarding the current grid status, due to funding constraints, ring networks have not been implemented, dual power supplies are unavailable, and lines adopt a single radial tree-like power supply method. This resembles a tree trunk with many branches—meaning the lines have numerou

Many people have asked me: “What’s the difference between a recloser and a pole-mounted circuit breaker?” It’s hard to explain in one sentence, so I’ve written this article to clarify. In fact, reclosers and pole-mounted circuit breakers serve very similar purposes—they are both used for control, protection, and monitoring on outdoor overhead distribution lines. However, there are significant differences in the details. Let’s examine them one by one.1.Different MarketsThis may be the biggest dis

1. What is a Recloser?A recloser is an automated high-voltage electrical switch. Similar to a circuit breaker in household electrical systems, it interrupts power when a fault—such as a short circuit—occurs. However, unlike a household circuit breaker that requires manual reset, a recloser automatically monitors the line and determines whether the fault has cleared. If the fault is temporary, the recloser will automatically reclose and restore power.Reclosers are widely used throughout distribut

Causes of Dielectric Withstand Failure in Vacuum Circuit Breakers: Surface contamination: The product must be thoroughly cleaned before dielectric withstand testing to remove any dirt or contaminants.Dielectric withstand tests for circuit breakers include both power-frequency withstand voltage and lightning impulse withstand voltage. These tests must be performed separately for phase-to-phase and pole-to-pole (across the vacuum interrupter) configurations.Circuit breakers are recommended to be t

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