Introduction to the safety characteristics and protective measures of vacuum circuit breakers

Introduction to the safety characteristics and protective measures of vacuum circuit breakers

Vacuum circuit breakers occupy a place in the power system due to their unique arc extinguishing method and superior breaking performance. The following will provide a detailed introduction to the safety characteristics and corresponding protective measures of vacuum circuit breakers.

1、 Safety characteristics of vacuum circuit breakers

1. Compact size and lightweight: Vacuum circuit breakers use vacuum as the arc extinguishing medium, making them relatively compact in size, lightweight, and easy to install and maintain.

2. Frequent and worry free operation: Due to its good mechanical durability and electrical life, vacuum circuit breakers are suitable for frequent operation.

3. Maintenance free arc extinguishing: The arc extinguishing chamber of the vacuum circuit breaker adopts a vacuum sealed design, which does not require regular maintenance and reduces maintenance costs.

4. Small contact opening distance and short arc time: The contact opening distance of vacuum circuit breakers is small, the operating power of the operating mechanism is small, the mechanical part stroke is small, and its mechanical life is long. Meanwhile, the arc ignition time is short and independent of the switch current, usually only half a cycle.

5. After extinguishing the arc, the recovery speed of the contact gap medium is fast: it has good performance in breaking near area faults, and the electrical life of the contact is long.

2、 Protective measures for vacuum circuit breakers

To ensure the safe operation of vacuum circuit breakers, the following protective measures need to be taken:

1. Regular inspection: Although vacuum circuit breakers have maintenance free characteristics, regular inspections are still necessary. The main inspection is to check whether the appearance, operating mechanism, vacuum arc extinguishing chamber and other components of the circuit breaker are intact and undamaged.

2. Use circuit breakers with lower cutoff values: Choose vacuum circuit breakers with lower cutoff values because the cutoff overvoltage is related to the cutoff value of the circuit breaker. The smaller the cutoff value, the smaller the amplitude of the overvoltage generated.

3. Capacitor protection: Connecting capacitors in parallel at the inductive load end can effectively reduce the load impedance, thereby reducing the amplitude of the cut-off overvoltage and slowing down the steepness of the overvoltage front.

4. Resistance capacitance protection: Connect resistor R and capacitor C in series as protective elements in parallel at the load input terminal to form an RC overvoltage suppressor, in order to reduce the generation of overvoltage and lower the value of overvoltage.

5. Nonlinear resistor protection: Using nonlinear resistors (such as metal oxide varistors) as protective components, when overvoltage occurs, the nonlinear resistor can quickly respond and limit the amplitude of the overvoltage.

6. Cable connection: Cable connection is used between vacuum circuit breakers and transformers or motors. Due to the large distributed capacitance of cables, their function is equivalent to parallel capacitance, which has a good effect on reducing overvoltage.

In summary, vacuum circuit breakers have many safety features, but corresponding protective measures still need to be taken in practical applications to ensure their safe operation. By conducting regular inspections, selecting appropriate types of circuit breakers, and implementing electrical protection measures, the safety and reliability of vacuum circuit breakers can be effectively improved.